The document discusses different types of pavements and pavement materials. It describes flexible pavements which distribute wheel loads through layers and rigid pavements which use concrete slabs. The typical layers of a flexible pavement are described including the surface course, binder course, base course, and subgrade. Common pavement materials like soils, aggregates, and concrete are also outlined. Key tests for evaluating soils used in pavements are shear tests, bearing tests, and penetration tests such as the California Bearing Ratio test.
This document discusses different types of soil admixtures used for ground improvement, including inert and chemical admixtures. It focuses on lime treatment of soils, describing how lime modifies soil properties through cation exchange, flocculation, and pozzolanic reactions. These reactions can increase shear strength, reduce permeability and swelling, and change plasticity. The document discusses factors in choosing lime modification or stabilization, describes lime treatment processes, and compares advantages and disadvantages of different lime application methods.
Piles are deep foundations used to transfer structural loads through weak or wet soils to stronger soils below. Piles can be classified based on function (end bearing, friction, tension), material (concrete, timber, steel), or installation method (driven, cast-in-place). Key factors in pile design include soil properties, load types, and groundwater conditions. The ultimate load capacity of a pile considers end bearing and side friction, while the allowable load uses a factor of safety. Dynamic testing and soil parameters can be used to estimate pile capacities.
Bulk sand increases in volume due to moisture content forming water films around sand particles. Maximum bulking occurs at 6-10% moisture content, with finer sands bulking more. Beyond 20% moisture content, the volume equals dry sand as water films break. An experiment showed 25% bulking when wet sand was added to a container, compared to dry sand.
Soil stabilization with cement, bitumen, lime, chemical stabilization,geotextile, grouting etc. are discussed. It is a method of improving soil properties by blending and mixing other materials.
The presentation discussed various methods of dewatering on construction sites, including sump pumping, wellpoint systems, ejector wells, ground freezing, and deep wells. It described the purpose of dewatering, factors that influence selection of methods, and advantages and limitations of each approach. The methods vary in their suitability based on soil type, required depth of drawdown, and other site-specific factors. Proper dewatering is important for construction efficiency and stability.
In this presentation, following topics are covered:
1- Introduction to soil liquifaction.
2- Causes and effects of soil liquifaction
3- Methods to remove soil liquifaction.
4- Mechanism of soil liquifaction.
5- Conclusion.
The document describes different types of shallow foundations, including spread footings, combined footings, and raft/mat foundations. Spread footings include wall footings, reinforced concrete footings, inverted arch footings, and column footings. Combined footings are used when columns are close together or near a property line. Raft foundations consist of a thick concrete slab covering the entire structure area and are used when soil capacity is low or loads are large. The document also discusses advantages, limitations, and construction procedures of shallow foundations.
The document discusses different types of foundations for structures, including shallow and deep foundations. It describes spread footings, mat/raft foundations, piles, piers, and caissons. Spread footings are the most common shallow foundation and involve concrete slabs under columns and load-bearing walls. Mat/raft foundations use a continuous slab to spread loads over a large area, especially for high loads or poor soil. Deep foundations like piles, piers, and caissons extend deeper into the ground to bear loads in stronger soil layers. Piles transfer loads through end bearing or friction, while piers and caissons are constructed by excavating holes and filling with concrete.
This document discusses different types of soil admixtures used for ground improvement, including inert and chemical admixtures. It focuses on lime treatment of soils, describing how lime modifies soil properties through cation exchange, flocculation, and pozzolanic reactions. These reactions can increase shear strength, reduce permeability and swelling, and change plasticity. The document discusses factors in choosing lime modification or stabilization, describes lime treatment processes, and compares advantages and disadvantages of different lime application methods.
Piles are deep foundations used to transfer structural loads through weak or wet soils to stronger soils below. Piles can be classified based on function (end bearing, friction, tension), material (concrete, timber, steel), or installation method (driven, cast-in-place). Key factors in pile design include soil properties, load types, and groundwater conditions. The ultimate load capacity of a pile considers end bearing and side friction, while the allowable load uses a factor of safety. Dynamic testing and soil parameters can be used to estimate pile capacities.
Bulk sand increases in volume due to moisture content forming water films around sand particles. Maximum bulking occurs at 6-10% moisture content, with finer sands bulking more. Beyond 20% moisture content, the volume equals dry sand as water films break. An experiment showed 25% bulking when wet sand was added to a container, compared to dry sand.
Soil stabilization with cement, bitumen, lime, chemical stabilization,geotextile, grouting etc. are discussed. It is a method of improving soil properties by blending and mixing other materials.
The presentation discussed various methods of dewatering on construction sites, including sump pumping, wellpoint systems, ejector wells, ground freezing, and deep wells. It described the purpose of dewatering, factors that influence selection of methods, and advantages and limitations of each approach. The methods vary in their suitability based on soil type, required depth of drawdown, and other site-specific factors. Proper dewatering is important for construction efficiency and stability.
In this presentation, following topics are covered:
1- Introduction to soil liquifaction.
2- Causes and effects of soil liquifaction
3- Methods to remove soil liquifaction.
4- Mechanism of soil liquifaction.
5- Conclusion.
The document describes different types of shallow foundations, including spread footings, combined footings, and raft/mat foundations. Spread footings include wall footings, reinforced concrete footings, inverted arch footings, and column footings. Combined footings are used when columns are close together or near a property line. Raft foundations consist of a thick concrete slab covering the entire structure area and are used when soil capacity is low or loads are large. The document also discusses advantages, limitations, and construction procedures of shallow foundations.
The document discusses different types of foundations for structures, including shallow and deep foundations. It describes spread footings, mat/raft foundations, piles, piers, and caissons. Spread footings are the most common shallow foundation and involve concrete slabs under columns and load-bearing walls. Mat/raft foundations use a continuous slab to spread loads over a large area, especially for high loads or poor soil. Deep foundations like piles, piers, and caissons extend deeper into the ground to bear loads in stronger soil layers. Piles transfer loads through end bearing or friction, while piers and caissons are constructed by excavating holes and filling with concrete.
This document discusses liquefaction of soil. It begins by defining liquefaction as the loss of strength in saturated, cohesionless soils due to increased pore water pressure during dynamic loading. This causes the soil particles to lose contact with one another and behave like a liquid. The document then discusses two types of liquefaction - flow liquefaction, which occurs when static shear stresses exceed residual strength, and cyclic mobility, which occurs due to lower static stresses and develops incrementally. Several effects of liquefaction are also described, such as loss of bearing strength, lateral spreading, sand boils, flow failures, and ground oscillations. Finally, methods to reduce liquefaction risk are presented, including avoiding susceptible soils, using deep foundations, soil improvement techniques
SOIL COMPACTION AND ITS EFFECT ON PROPERTIESGeorgeThampy
soil compaction occurs when soil particles are pressed together so that reduction in pore space between them.soil compaction increases the shear strength of the soil.And soil compaction is much effective in earth dams.
The document discusses various ground improvement techniques including dry soil mixing, dynamic compaction, injection systems, rapid impact compaction, rigid inclusions, vibro compaction, vibro concrete columns, vibro piers, and wet soil mixing. It provides details on each technique such as how it is performed, the types of soils it can be used to treat, and examples of how it has been used to improve soil properties like bearing capacity, settlement, and liquefaction potential.
Certain Soils don’t permit the construction of specific structures on it. The alternative is to improve the strength of the soil by various methods like:
Mechanical modification
Chemical Modification
Lime stabilization
Geo textile etc.,
The document discusses various ground improvement techniques used to modify the engineering properties of soils, including densification, consolidation, reinforcement, and chemical treatment. It provides details on specific techniques like vibroflotation, ground freezing, and soil nailing. Geosynthetics are also introduced as natural or artificial products used in geotechnical constructions to improve properties of soils.
The document discusses the basics of foundation design. It defines a foundation as the part of a structure that interfaces with the soil or rock below to transfer loads without overstressing the subsurface materials. Foundations must be properly located, stable, and prevent excessive settlement. Shallow foundations like pad, strip, and raft foundations transmit loads to adjacent soil, while deep foundations like piles, piers, and caissons transfer loads to deeper soil layers or rock. The document also provides details on pad footing design.
Vibration method for ground improvement techniqueABHISHEK THAKKAE
This document discusses various ground improvement techniques, including vertical drains, soil nailing, stone columns, vibro compaction, and dynamic compaction. Vertical drains accelerate consolidation by facilitating drainage of pore water through columns of pervious material placed in soil. Soil nailing uses steel tendons drilled and grouted into soil to create a reinforced composite mass. Stone columns form vertical columns of compacted aggregate through problem soils to increase strength and reduce compressibility. Vibro compaction densifies loose sands using vibratory probes to achieve a denser soil structure. Dynamic compaction improves soil by repeatedly dropping heavy weights onto the ground from heights of 40 to 80 feet.
This document discusses lateral earth pressures, including the calculation of at-rest (Ko), active (Ka), and passive (Kp) pressure coefficients. It provides equations to calculate these coefficients based on soil properties like internal friction angle (φ). Graphs show the stress distributions for different cases, such as with and without cohesion (c) and the influence of a water table. Practice problems are recommended from Chapter 12 involving calculating active and passive pressures using the provided equations.
soil liquefaction and quicksand conditionazlan ahmad
Soil liquefaction occurs when water-saturated soils lose strength during earthquakes or other vibrations, causing the soil particles to separate and behave like a liquid. This happens because earthquake shaking increases water pressure between soil particles. Buildings and structures can sink or collapse into liquefied soils. Techniques to prevent liquefaction include compacting soils or setting deep foundations below unstable layers. Quick sand conditions occur when upward seepage flow reduces effective stress in loose soils like sand, causing a floating effect with little weight-bearing capacity.
The document summarizes key aspects of prefabricated vertical drains (PVDs) used for soil improvement. It discusses how PVDs work by shortening drainage paths in clay soils to accelerate consolidation from preloading. The document covers PVD installation methods, factors affecting their performance over time, advantages over sand drains, and applications such as embankment stabilization. It also reviews several studies on PVD performance in soft soil improvement projects.
This document discusses foundation settlements and provides methods for estimating different types of settlements. It discusses:
- Immediate/elastic settlement which occurs during or right after construction and can be estimated using elastic theory equations.
- Consolidation settlement, which is time-dependent and occurs over months to years as water is squeezed out of clay soils. It includes primary consolidation from excess pore pressure dissipation and secondary compression from soil reorientation.
- Methods for estimating settlement in sandy soils using a strain influence factor approach.
- Equations for calculating primary and secondary consolidation settlement based on soil properties and changes in effective stress over time.
- Relationships between time factor, degree of consolidation, and rate of consolidation
Loose granular sand deposits formed during the land reclamation process are vulnerable to
liquefaction upon imparting seismic forces. These loose granular sand fills could encounter
bearing failures or compress beyond tolerable limits under static and dynamic loads
The document discusses various ground improvement techniques including removal and replacement, in-situ densification methods like dynamic compaction, preloading, use of vertical drains and stone columns. It provides details on specific in-situ densification methods like vibro-float compaction using a vibrating probe, dynamic compaction using heavy weights, and explosive compaction using detonated charges. The document also summarizes advantages and limitations of preloading using surcharge fills and uses of vertical drains and geosynthetics to accelerate consolidation.
Geotechnical Engineering-II [Lec #7: Soil Stresses due to External Load]Muhammad Irfan
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
This document discusses the scope of soil engineering and its applications in various civil engineering works. It lists six key applications: 1) foundation design for buildings and structures, 2) retaining structures to retain soil at different levels, 3) analyzing slope stability for natural and man-made slopes, 4) designing underground structures like tunnels, 5) pavement design which involves layers of soil, base and surfacing, and 6) earthen dam design for water reservoirs. The document provides brief descriptions of foundation design, retaining structures, slope stability analysis, and underground structures as important applications of soil engineering.
Soil stabilization techniques fall into two categories: mechanical and chemical. Mechanical stabilization alters the physical properties of soil particles through vibration or compaction. Chemical stabilization relies on chemical reactions between stabilizing materials like cement and minerals in the soil. Most stabilization is needed for soft soils in order to achieve good engineering properties, as clay soils respond well due to their large surface area while silty soils are sensitive to moisture changes.
Effect of expansive soils on buildings and its preventionSailish Cephas
This document discusses expansive soils and their effects on building structures. It defines expansive soils as soils that swell when water is added and shrink when drying out, due to minerals like montmorillonite that absorb water. Common expansive soils in India include black cotton soils. When the moisture content of expansive soils changes, it can cause problems like cracking in buildings due to uneven swelling or shrinkage. Solutions discussed include replacing expansive soil, compacting or chemically stabilizing soil to reduce swelling, and using moisture barriers to control moisture variation.
This document discusses different types of pavements and their components. It describes that a highway pavement consists of superimposed layers that distribute vehicle loads to the subgrade. The two main types are flexible and rigid pavements. Flexible pavements transmit loads through grain-to-grain contact in granular layers, while rigid pavements have enough strength to transmit loads over a wider area. It also details the typical layers in a flexible pavement and provides requirements and examples of tests used to evaluate pavement materials like soils, aggregates.
The document discusses different types of pavements used for highways. It describes flexible pavements which transmit wheel loads through grain-to-grain contact and consist of multiple layers including the surface course, binder course, base course, and sub-base course. Rigid pavements have sufficient strength to distribute loads over a wider area and typically consist of concrete over a single granular or stabilized layer. The document also covers pavement materials like soils, aggregates, and asphalt concrete and tests used to evaluate soil strength properties important for pavement design like the California Bearing Ratio test.
This document discusses liquefaction of soil. It begins by defining liquefaction as the loss of strength in saturated, cohesionless soils due to increased pore water pressure during dynamic loading. This causes the soil particles to lose contact with one another and behave like a liquid. The document then discusses two types of liquefaction - flow liquefaction, which occurs when static shear stresses exceed residual strength, and cyclic mobility, which occurs due to lower static stresses and develops incrementally. Several effects of liquefaction are also described, such as loss of bearing strength, lateral spreading, sand boils, flow failures, and ground oscillations. Finally, methods to reduce liquefaction risk are presented, including avoiding susceptible soils, using deep foundations, soil improvement techniques
SOIL COMPACTION AND ITS EFFECT ON PROPERTIESGeorgeThampy
soil compaction occurs when soil particles are pressed together so that reduction in pore space between them.soil compaction increases the shear strength of the soil.And soil compaction is much effective in earth dams.
The document discusses various ground improvement techniques including dry soil mixing, dynamic compaction, injection systems, rapid impact compaction, rigid inclusions, vibro compaction, vibro concrete columns, vibro piers, and wet soil mixing. It provides details on each technique such as how it is performed, the types of soils it can be used to treat, and examples of how it has been used to improve soil properties like bearing capacity, settlement, and liquefaction potential.
Certain Soils don’t permit the construction of specific structures on it. The alternative is to improve the strength of the soil by various methods like:
Mechanical modification
Chemical Modification
Lime stabilization
Geo textile etc.,
The document discusses various ground improvement techniques used to modify the engineering properties of soils, including densification, consolidation, reinforcement, and chemical treatment. It provides details on specific techniques like vibroflotation, ground freezing, and soil nailing. Geosynthetics are also introduced as natural or artificial products used in geotechnical constructions to improve properties of soils.
The document discusses the basics of foundation design. It defines a foundation as the part of a structure that interfaces with the soil or rock below to transfer loads without overstressing the subsurface materials. Foundations must be properly located, stable, and prevent excessive settlement. Shallow foundations like pad, strip, and raft foundations transmit loads to adjacent soil, while deep foundations like piles, piers, and caissons transfer loads to deeper soil layers or rock. The document also provides details on pad footing design.
Vibration method for ground improvement techniqueABHISHEK THAKKAE
This document discusses various ground improvement techniques, including vertical drains, soil nailing, stone columns, vibro compaction, and dynamic compaction. Vertical drains accelerate consolidation by facilitating drainage of pore water through columns of pervious material placed in soil. Soil nailing uses steel tendons drilled and grouted into soil to create a reinforced composite mass. Stone columns form vertical columns of compacted aggregate through problem soils to increase strength and reduce compressibility. Vibro compaction densifies loose sands using vibratory probes to achieve a denser soil structure. Dynamic compaction improves soil by repeatedly dropping heavy weights onto the ground from heights of 40 to 80 feet.
This document discusses lateral earth pressures, including the calculation of at-rest (Ko), active (Ka), and passive (Kp) pressure coefficients. It provides equations to calculate these coefficients based on soil properties like internal friction angle (φ). Graphs show the stress distributions for different cases, such as with and without cohesion (c) and the influence of a water table. Practice problems are recommended from Chapter 12 involving calculating active and passive pressures using the provided equations.
soil liquefaction and quicksand conditionazlan ahmad
Soil liquefaction occurs when water-saturated soils lose strength during earthquakes or other vibrations, causing the soil particles to separate and behave like a liquid. This happens because earthquake shaking increases water pressure between soil particles. Buildings and structures can sink or collapse into liquefied soils. Techniques to prevent liquefaction include compacting soils or setting deep foundations below unstable layers. Quick sand conditions occur when upward seepage flow reduces effective stress in loose soils like sand, causing a floating effect with little weight-bearing capacity.
The document summarizes key aspects of prefabricated vertical drains (PVDs) used for soil improvement. It discusses how PVDs work by shortening drainage paths in clay soils to accelerate consolidation from preloading. The document covers PVD installation methods, factors affecting their performance over time, advantages over sand drains, and applications such as embankment stabilization. It also reviews several studies on PVD performance in soft soil improvement projects.
This document discusses foundation settlements and provides methods for estimating different types of settlements. It discusses:
- Immediate/elastic settlement which occurs during or right after construction and can be estimated using elastic theory equations.
- Consolidation settlement, which is time-dependent and occurs over months to years as water is squeezed out of clay soils. It includes primary consolidation from excess pore pressure dissipation and secondary compression from soil reorientation.
- Methods for estimating settlement in sandy soils using a strain influence factor approach.
- Equations for calculating primary and secondary consolidation settlement based on soil properties and changes in effective stress over time.
- Relationships between time factor, degree of consolidation, and rate of consolidation
Loose granular sand deposits formed during the land reclamation process are vulnerable to
liquefaction upon imparting seismic forces. These loose granular sand fills could encounter
bearing failures or compress beyond tolerable limits under static and dynamic loads
The document discusses various ground improvement techniques including removal and replacement, in-situ densification methods like dynamic compaction, preloading, use of vertical drains and stone columns. It provides details on specific in-situ densification methods like vibro-float compaction using a vibrating probe, dynamic compaction using heavy weights, and explosive compaction using detonated charges. The document also summarizes advantages and limitations of preloading using surcharge fills and uses of vertical drains and geosynthetics to accelerate consolidation.
Geotechnical Engineering-II [Lec #7: Soil Stresses due to External Load]Muhammad Irfan
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
This document discusses the scope of soil engineering and its applications in various civil engineering works. It lists six key applications: 1) foundation design for buildings and structures, 2) retaining structures to retain soil at different levels, 3) analyzing slope stability for natural and man-made slopes, 4) designing underground structures like tunnels, 5) pavement design which involves layers of soil, base and surfacing, and 6) earthen dam design for water reservoirs. The document provides brief descriptions of foundation design, retaining structures, slope stability analysis, and underground structures as important applications of soil engineering.
Soil stabilization techniques fall into two categories: mechanical and chemical. Mechanical stabilization alters the physical properties of soil particles through vibration or compaction. Chemical stabilization relies on chemical reactions between stabilizing materials like cement and minerals in the soil. Most stabilization is needed for soft soils in order to achieve good engineering properties, as clay soils respond well due to their large surface area while silty soils are sensitive to moisture changes.
Effect of expansive soils on buildings and its preventionSailish Cephas
This document discusses expansive soils and their effects on building structures. It defines expansive soils as soils that swell when water is added and shrink when drying out, due to minerals like montmorillonite that absorb water. Common expansive soils in India include black cotton soils. When the moisture content of expansive soils changes, it can cause problems like cracking in buildings due to uneven swelling or shrinkage. Solutions discussed include replacing expansive soil, compacting or chemically stabilizing soil to reduce swelling, and using moisture barriers to control moisture variation.
This document discusses different types of pavements and their components. It describes that a highway pavement consists of superimposed layers that distribute vehicle loads to the subgrade. The two main types are flexible and rigid pavements. Flexible pavements transmit loads through grain-to-grain contact in granular layers, while rigid pavements have enough strength to transmit loads over a wider area. It also details the typical layers in a flexible pavement and provides requirements and examples of tests used to evaluate pavement materials like soils, aggregates.
The document discusses different types of pavements used for highways. It describes flexible pavements which transmit wheel loads through grain-to-grain contact and consist of multiple layers including the surface course, binder course, base course, and sub-base course. Rigid pavements have sufficient strength to distribute loads over a wider area and typically consist of concrete over a single granular or stabilized layer. The document also covers pavement materials like soils, aggregates, and asphalt concrete and tests used to evaluate soil strength properties important for pavement design like the California Bearing Ratio test.
Types of pavement- Transportation Engg. IGauri kadam
This document discusses different types of pavements, including flexible, rigid, semi-rigid, composite, and interlocking concrete block pavements. It provides details on the layers and materials used in flexible pavements, including surface, binder, base, and sub-base courses. Requirements for a good pavement and comparisons between flexible and rigid pavements are also presented. Design factors for pavements include wheel load, subgrade soil properties, climatic conditions, materials used, traffic characteristics, and cross-sectional elements.
This document provides information on different types of pavements, including flexible and rigid pavements. It describes the key components and layers of a flexible pavement, such as the surface course, binder course, base course, and subgrade. Rigid pavements are made of concrete slabs and can be jointed plain, jointed reinforced, continuous reinforced, or prestressed concrete. Composite pavements combine aspects of flexible and rigid pavements for benefits such as a strong concrete base with a smooth asphalt surface.
The document discusses different types of flexible pavements, including conventional layered flexible pavement, full-depth asphalt pavement, and contained rock asphalt mat. It describes the typical layers of a flexible pavement and their purposes. The major types of flexible pavement failures are identified as fatigue cracking, rutting, and thermal cracking. Specific causes and characteristics of different failure types like alligator cracking, rutting, shear failure cracking, and longitudinal cracking are explained.
This document discusses highway pavement materials and design. It covers types of pavements like flexible, rigid, and composite pavements. It describes the ideal requirements for road pavements and compares the characteristics of flexible and rigid pavements. The document outlines the typical layers of a flexible pavement and factors that affect pavement design like wheel load, climate, materials used, and subgrade quality. It also discusses road aggregates, their desirable properties, and testing methods.
The document discusses flexible and rigid pavements. Flexible pavements are composed of layers with bituminous material and aggregates that transmit wheel loads through grain-to-grain contact. Rigid pavements have sufficient strength to distribute loads over a wide area through their rigidity. Key types of each include jointed plain concrete pavement for rigid and conventional layered flexible pavement for flexible. Both pavement types can fail through cracking and rutting due to traffic and environmental loads.
This document provides an overview of pavement design. It discusses the different types of pavements including flexible, rigid, and composite pavements. For flexible pavements, it describes the layers of base course, sub-base course, and subgrade. It also discusses requirements for an ideal pavement and considerations for pavement design such as material characteristics and traffic volume.
This document is a seminar report on advanced pavement design submitted to the Head of the Civil Engineering Department at World College of Technology & Management. It provides an introduction to pavement design, describing the requirements and types of pavements including flexible, rigid, and composite pavements. It also outlines the functions of individual pavement layers such as the surface course, binder course, base course, sub-base course, and sub-grade. The report concludes by stating that a pavement design report presents all analyses, data, policies and considerations used to structurally design a pavement.
The document provides information on various materials used in highway construction. It discusses the types and functions of pavement, including flexible and rigid pavements. It describes the requirements of ideal pavements. It also discusses various pavement materials like soil, aggregates, bitumen and their properties. It outlines various tests conducted on these materials like penetration test, abrasion test, crushing test, to evaluate their suitability for pavement construction.
Pavement is a layered structure constructed over soil to support vehicle loads. It has multiple layers - subgrade, sub-base, base, and surface course. Pavements are classified as flexible, rigid, or composite based on material properties. Flexible pavements are made of asphalt and deform under loads, while rigid pavements are made of concrete and resist deformation. Pavement design considers factors like traffic loads, material properties, environment, and failure criteria to determine layer thickness to support loads over the design life.
A highway pavement is a structure consisting of superimposed layers of processed materials above the natural soil sub-grade, whose primary function is to distribute the applied vehicle loads to the sub-grade. The pavement structure should be able to provide a surface of acceptable riding quality, adequate skid resistance, favorable light reflecting characteristics, and low noise pollution. The ultimate aim is to ensure that the transmitted stresses due to wheel load are sufficiently reduced, so that they will not exceed bearing capacity of the sub-grade. Two types of pavements are generally recognized as serving this purpose, namely flexible pavements and rigid pavements.
Get an overview of pavement types, layers, and their functions, and pavement failures as Improper design of pavements leads to early failure of pavements affecting the riding quality.
Pavements form the basic supporting structure in highway transportation. Each layer of pavement has a multitude of functions to perform which has to be duly considered during the design process. Different types of pavements can be adopted depending upon the traffic requirements.
The document provides an overview of highway engineering and flexible pavements. It defines a highway pavement as a structure consisting of superimposed layers that distribute vehicle loads to the subgrade. There are two main types of pavements - rigid (concrete) and flexible. Flexible pavements are layered structures that rely on aggregate interlock and friction to distribute loads through the base and subbase layers to the subgrade. The layers of a flexible pavement include the surface course, base course, and subbase course, with each layer serving structural and drainage functions to support traffic loads.
The document discusses different types of pavements. It describes flexible pavements as having multiple layers that distribute loads through aggregate interlock. Rigid pavements distribute loads through the beam strength of concrete slabs. Flexible pavements are composed of surface, base, and sub-base layers over a subgrade, while rigid pavements typically only require a concrete surface layer. Both pavement types are designed to reduce loads from vehicles to prevent damage to the subgrade. The document compares advantages and disadvantages of flexible and rigid pavements.
The document discusses the construction of subbase for highway flexible pavements. It begins by explaining that flexible pavements are composed of layers that distribute loads, with the subbase layer located between the base course and subgrade. The subbase functions to structurally support loads, prevent intrusion of fines, improve drainage, minimize frost damage, and provide a work platform. It then describes the materials and testing requirements for subbase construction, as well as the steps for spreading, compacting, and testing the subbase to ensure it meets density specifications before additional layers are placed.
A highway pavement is a structure consisting of superimposed layers of processed materials above the natural soil sub-grade, whose primary function is to distribute the applied vehicle loads to the sub-grade. The pavement structure should be able to provide a surface of acceptable riding quality, adequate skid resistance, favorable light reflecting characteristics, and low noise pollution.
The document discusses various types of soils used in subgrade for road construction. It describes desirable properties of subgrade soil including stability, drainage, and ease of compaction. It also discusses different soil types commonly used in India and their classification. Various laboratory tests conducted on soil include shear tests, bearing tests, penetration tests, and California Bearing Ratio tests. The document also covers soil compaction and evaluation of soil strength.
The document discusses various types of soils used in subgrade for road construction. It describes desirable properties of subgrade soil including stability, drainage, and ease of compaction. It also discusses different soil types commonly used in India and their classification. Various laboratory tests conducted on soil are outlined including shear tests, bearing tests, and penetration tests like the California Bearing Ratio test. The test procedures for CBR and plate bearing tests are summarized.
Similar to He unit iii 3d0f5751f8e65e10a1c08bba8255d4bc (20)
Design of-steel-structures bhavakkati- by easy engineering.netsaibabu48
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The document outlines the key terms of a lease agreement between John Doe as the landlord and Jane Smith as the tenant. It specifies the monthly rent amount and due date, the security deposit required, allows for pets but prohibits smoking, and describes the process for repairs, entry by the landlord, and early termination of the lease. The landlord and tenant must both sign the agreement prior to the tenant moving into the rental property.
This document provides information about structural steel materials and specifications used in steel structures. It discusses different grades of structural steel like IS 226, IS 2062, and IS 961. It also describes common rolled steel sections like I-sections, channel sections, angle sections, and their designations. Key concepts covered are materials properties, stress-strain curves, working stress method, limit state design method, analysis and design of steel structures. The document is intended as a reference for the design of steel structures course.
This document discusses tension members in structural engineering. It defines tension members as linear members that experience axial forces that elongate or stretch the member. Examples given include ropes, ties in trusses, suspenders in bridges. The document discusses the types of cross-sections used for tension members like angles, channels, rods. It also discusses the calculation of net effective sectional area and provides examples. Other topics covered include types of failures in tension members, design strength calculations, limiting slenderness ratios, tension splices, and lug angles.
This document contains a question bank for the subject of Design of Steel Structures. It includes multiple choice and numerical questions covering various topics in steel design such as bolted and welded connections, tension members, riveted joints, and limit state design approach. Some sample 16-mark design questions are provided related to designing tension members using angles, plates, and bolted/riveted connections to gusset plates to transmit axial forces. The document is intended as a study guide for students in the third year of a Civil Engineering program.
This document contains a question bank for a steel structures design course. It includes 20 questions in Part A testing basic knowledge of steel structures terminology and concepts. Part B contains 14 design problems testing application and evaluation skills. Topics covered include riveted and bolted connections, tension members, compression members, beams, plate girders, roof trusses, and crane girders. Students are asked to calculate strengths, suitable dimensions, and designs meeting loading criteria. Design factors like load magnitudes, member lengths, connection materials, and support conditions are provided.
The document contains 43 pages of lecture notes from Srividya College of Engineering and Technology on the design of steel structures. The notes cover various topics related to the design of tension members, compression members, and beams under the bending, shear, and axial forces. Design examples are included for the analysis and design of different steel structural elements.
1. The document discusses best practices for analyzing risks related to dam and levee spillway gates.
2. It describes different types of spillway gates and their vulnerabilities, including issues that led to the 1995 failure of Gate 3 at Folsom Dam in California due to trunnion pin friction.
3. Key factors that influence spillway gate risk are discussed, such as reservoir water level, seismic hazard, gate size, maintenance practices, and the potential for multiple gate failures. Event tree and fragility curve methods are presented for evaluating failure probabilities under different loading conditions.
This document discusses the analysis of safety and stability for concrete gravity dams. It begins with an outline of the topics to be covered in Lecture 5, including a summary of loading cases, design of concrete gravity dams, safety analysis, and stability analysis. The document then provides detailed descriptions and diagrams for each of the 8 loading cases to be considered in the safety and stability analysis. It discusses the design of gravity dams and the procedures for analysis. Key aspects of the safety and stability analysis are described, including checking for overturning, sliding, shear stresses, and overstressing of the concrete. Diagrams are provided to illustrate the concepts of checking for overturning, sliding, and factors of safety.
Spillways are designed to safely pass excess water from a reservoir to prevent overtopping of a dam. They come in many forms depending on site conditions but commonly include an overflow structure like an ogee crest to control reservoir levels. Proper spillway capacity is essential for dam safety as inadequate capacity contributes to 40% of dam failures. Spillway design considers hydrologic factors, hydraulic performance including discharge coefficients, and structural aspects like cost-effectiveness. Gates may be added to overflows to allow flexible reservoir operation while preventing overtopping during floods.
The document provides information on diversion headworks for water resources engineering projects. It discusses the different types of diversion headworks including storage and temporary diversion structures. Key components of diversion headworks are described such as weirs, barrages, divide walls, fish ladders, and canal head regulators. Factors for selecting sites for diversion structures are outlined. Causes of failures for weirs built on permeable foundations and remedies are summarized.
1) Canals are artificial channels constructed to carry water from a source like a river or reservoir to agricultural fields.
2) Canals are classified based on their water source (permanent or inundation), function (irrigation, navigation, power), alignment (watershed, contour, side slope), discharge (main, branch, distributary), and whether they have lining.
3) The cross-section of a canal includes components like side slopes, berms, freeboard, banks, and may involve partial cutting and filling to achieve a balancing depth.
Canal lining involves adding an impermeable layer to canal beds and banks to reduce water seepage losses. Common lining materials include compacted earth, concrete, and plastic membranes. Lining can conserve up to 50% of irrigation water by preventing seepage and allowing canals to maintain higher water velocities using smaller cross-sections. It also stabilizes canal banks, prevents erosion, and increases the command area by allowing flatter canal slopes. Hard linings include cast concrete while earth linings use compacted soil or soil-bentonite mixes. Buried plastic membranes are another option but are susceptible to damage.
Spillways are structures constructed near dams to safely discharge surplus water from reservoirs. There are several types of spillways classified by their utility and prominent features. Main spillways are designed to pass the entire design flood volume, while auxiliary spillways supplement the main spillway. Emergency spillways activate only during emergencies. Common spillway types include overflow, which guides water smoothly over a curved crest; side channel, which diverts flow through a parallel channel; and tunnel, which conveys flow through a closed channel around the dam. Shaft spillways similarly direct water vertically then horizontally through a tunnel.
A gravity dam resists external forces through its own weight. It is a solid, durable structure constructed of masonry or concrete. Forces acting on a gravity dam include water pressure, the weight of the dam, uplift pressure, silt pressure, wave pressure, ice pressure, and pressure from earthquake forces. Water pressure is the major external force and varies with depth, while the weight of the dam is the main resisting force.
This document discusses different types of earth and rockfill dams. It describes rolled fill dams which are constructed by compacting soil in thin layers. Homogeneous dams consist of a single material throughout while zoned dams have distinct core, shell, and filter zones. Diaphragm dams contain an impervious core like a thin wall. Key elements of earth dam design include the top width, freeboard, slopes, central core, and downstream drainage system.
This document discusses different types of subsurface irrigation methods, including natural and artificial subsurface irrigation. Natural subsurface irrigation involves using the natural water table to irrigate crops through capillary action, while artificial subsurface irrigation uses buried perforated pipes to maintain the water table below the soil surface. The document also discusses sprinkler irrigation systems, how they work, their advantages of uniform water distribution and adaptability, and disadvantages like high costs and interference from wind. Finally, it defines and discusses drip irrigation, how it efficiently applies water directly to plant roots, and its advantages like water and fertilizer efficiency as well as disadvantages like sensitivity to clogging.
The document discusses different types of spillways used in dam construction including:
- Main and emergency spillways which provide controlled water release from dams.
- Straight (free overfall) spillways where water freely drops over the crest edge.
- Ogee spillways with an S-shaped crest profile that are commonly used in rigid dams.
- Side channel spillways which divert water away from the main dam through an adjacent channel.
- Chute spillways which lower water levels through steeply inclined channels.
- Tunnel spillways which pass water through underground tunnels.
- Siphon spillways which use siphonic action through enclosed conduits to discharge water downstream.
Spillways are structures used to release water from reservoirs to prevent overflow of dams. There are two main types of spillways: controlled and uncontrolled. Controlled spillways have gates to regulate water flow, while uncontrolled spillways release water once the reservoir level rises above the spillway crest. Spillways can also be classified based on their shape, such as ogee, side channel, labyrinth, chute, conduit, and baffled chute spillways. Each type has distinct hydraulic characteristics that make it suitable for different dam designs and site conditions.
This presentation discusses different types of spillways used in dam structures. Spillways are needed to safely discharge water from the reservoir during floods to prevent overtopping of the dam. The main types discussed are chute, shaft, saddle, and side channel spillways. Chute spillways convey water down an excavated open channel with a steep slope. Shaft spillways allow water to pass through a vertical shaft and horizontal conduit below the dam. Saddle spillways use natural depressions as spillway routes. Side channel spillways route flood water parallel to the dam.
Online train ticket booking system project.pdfKamal Acharya
Rail transport is one of the important modes of transport in India. Now a days we
see that there are railways that are present for the long as well as short distance
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This is an overview of my career in Aircraft Design and Structures, which I am still trying to post on LinkedIn. Includes my BAE Systems Structural Test roles/ my BAE Systems key design roles and my current work on academic projects.
Covid Management System Project Report.pdfKamal Acharya
CoVID-19 sprang up in Wuhan China in November 2019 and was declared a pandemic by the in January 2020 World Health Organization (WHO). Like the Spanish flu of 1918 that claimed millions of lives, the COVID-19 has caused the demise of thousands with China, Italy, Spain, USA and India having the highest statistics on infection and mortality rates. Regardless of existing sophisticated technologies and medical science, the spread has continued to surge high. With this COVID-19 Management System, organizations can respond virtually to the COVID-19 pandemic and protect, educate and care for citizens in the community in a quick and effective manner. This comprehensive solution not only helps in containing the virus but also proactively empowers both citizens and care providers to minimize the spread of the virus through targeted strategies and education.
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Networking is a telecommunications network that allows computers to exchange data. In
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An In-Depth Exploration of Natural Language Processing: Evolution, Applicatio...DharmaBanothu
Natural language processing (NLP) has
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2. Pavements
• highway pavement is a structure consisting of superimposed
layers of processed materials above the natural soil sub-grade,
whose primary function is to distribute the applied vehicle
loads to the sub-grade. The pavement structure should be able
to provide a surface of acceptable riding quality, adequate
skid resistance, favourable light reflecting characteristics, and
low noise pollution. The ultimate aim is to ensure that the
transmitted
• stresses due to wheel load are sufficiently reduced, so that
they will not exceed bearing capacity of the subgrade.
• Two types of pavements are generally recognized as serving
this purpose, namely flexible pavements and rigid pavements.
4. Requirements of a pavement
• An ideal pavement should meet the following requirements:
• Sufficiently thickness to distribute the wheel load stresses to a safe
value on the sub-grade soil,
• Structurally strong to withstand all types of stresses imposed upon
it,
• Adequate coefficient of friction to prevent skidding of vehicles,
• Smooth surface to provide comfort to road users even at high
speed,
• Produce least noise from moving vehicles,
• Dust proof surface so that tract safety is not impaired by reducing
visibility,
• Impervious surface, so that sub-grade soil is well protected, and
• Long design life with low maintenance cost.
5. Types of pavements
• The pavements can be classified based on the
structural performance into two, flexible
pavements and rigid pavements. In flexible
pavements, wheel loads are transferred by
grain-to-grain contact of the aggregate
through the granular structure
8. Flexible pavements
• Flexible pavements will transmit wheel load stresses
to the lower layers by grain-to-grain transfer
through the points of contact in the granular
structure. The wheel load acting on the pavement
will be distributed to a wider area, and the stress
decreases with the depth. Taking advantage of this
stress distribution characteristic, flexible pavements
normally has many layers. Hence, the design of
flexible pavement uses the concept of layered system.
12. Typical layers of a flexible pavement
• Typical layers of a conventional flexible pavement
includes seal coat, surface course, tack coat, binder
course, prime coat, base course, sub-base course,
compacted sub-grade, and natural sub-grade Seal Coat:
Seal coat is a thin surface treatment used to water-proof
the surface and to provide skid resistance.
• Tack Coat: Tack coat is a very light application of
asphalt, usually asphalt emulsion diluted with water. It
provides proper bonding between two layer of binder
course and must be thin, uniformly cover the entire
surface, and set very fast.
13. Typical layers of a flexible pavement
• Prime Coat: Prime coat is an application of low
viscous cutback bitumen to an absorbent surface like
granular bases on which binder layer is placed. It
provides bonding between two layers. Unlike tack
coat, prime coat penetrates into the layer below,
plugs the voids, and forms a water tight surface.
• Surface course
• Surface course is the layer directly in contact with
traffic loads and generally contains superior quality
materials. They are usually constructed with dense
graded asphalt concrete(AC).
14. Typical layers of a flexible pavement
• It provides characteristics such as friction, smoothness, drainage, etc. Also
it will prevent the entrance of excessive quantities of surface water into
the underlying base, sub-base and sub-grade, It must be tough to resist
the distortion under traffic and provide a smooth and skid- resistant
riding surface, It must be water proof to protect the entire base and sub-
grade from the weakening effect of water.
• Binder course
• This layer provides the bulk of the asphalt concrete structure. It's chief
purpose is to distribute load to the base course The binder course
generally consists of aggregates having less asphalt and doesn't require
quality as high as the surface course, so replacing a part of the surface
course by the binder course results in more economical design.
15. Typical layers of a flexible pavement
• Base course
• The base course is the layer of material immediately beneath the surface of
binder course and it provides additional load distribution and contributes to
the sub-surface drainage It may be composed of crushed stone, crushed slag,
and other untreated or stabilized materials.
• Sub-Base course
• The sub-base course is the layer of material beneath the base course and the
primary functions are to provide structural support, improve drainage, and
reduce the intrusion of fines from the sub-grade in the pavement structure If
the base course is open graded, then the sub-base course with more fines can
serve as a filler between sub-grade and the base course A sub-base course is
not always needed or used. For example, a pavement constructed over a high
quality, stiff sub-grade may not need the additional features offered by a sub-
base course. In such situations, sub-base course may not be provided.
16. Typical layers of a flexible pavement
Sub-grade
• The top soil or sub-grade is a layer of natural
soil prepared to receive the stresses from the
layers above. It is essential that at no time soil
sub-grade is overstressed. It should be
compacted to the desirable density, near the
optimum moisture content.
17. Rigid pavements
• Rigid pavements have sufficient flexural strength
to transmit the wheel load stresses to a wider
area below.
• Compared to flexible pavement, rigid pavements
are placed either directly on the prepared sub-
grade or on a single layer of granular or
stabilized material. Since there is only one layer
of material between the concrete and the sub-
grade, this layer can be called as base or sub-
base course.
20. Pavement materials
• Soils
• Pavements are a conglomeration of materials.
These materials, their associated properties, and
their interactions determine the properties of the
resultant pavement. Thus, a good understanding
of these materials, how they are characterized,
and how they perform is fundamental to
understanding pavement. The materials which
are used in the construction of highway are of
intense interest to the highway engineer.
21. Sub grade soil
• Soil is an accumulation or deposit of earth material,
derived naturally from the disintegration of rocks or
decay of vegetation, that can be excavated readily
with power equipment in the field or disintegrated by
gentle mechanical means in the laboratory. The
supporting soil beneath pavement and its special
under courses is called sub grade. Undisturbed soil
beneath the pavement is called natural sub grade.
Compacted sub grade is the soil compacted by
controlled movement of heavy compactors.
23. Soil Types
• The wide range of soil types available as
highway construction materials have made it
obligatory on the part of the highway engineer
to identify and classify different soils.
• Broadly, the soil types can be categorized as
Laterite soil, Moorum / red soil, Desert sands,
Alluvial soil, Clay including Black cotton soil.
26. Soil Types
• Gravel: These are coarse materials with particle size under 2.36
mm with little or no fines contributing to cohesion of materials.
• Moorum: These are products of decomposition and weathering of
the pavement rock. Visually these are similar to gravel except
presence of higher content of fines.
• Silts: These are finer than sand, brighter in color as compared to
clay, and exhibit little cohesion. When a lump of silty soil mixed
with water, alternately squeezed and tapped a shiny surface makes
its appearance, thus dilatancy is a specific property of such soil.
• Clays: These are finer than silts. Clayey soils exhibit stickiness, high
strength when dry, and show no dilatancy. Black cotton soil and
other expansive clays exhibit swelling and shrinkage properties.
Paste of clay with water when rubbed in between fingers leaves
stain, which is not observed for silts.
27. Tests on soil
• Sub grade soil is an integral part of the road pavement structure as it
provides the support to the pavement from beneath. The sub grade soil
and its properties are important in the design of pavement structure. The
main function of the sub grade is to give adequate support to the
pavement and for this the sub grade should possess sufficient stability
under adverse climatic and loading conditions. Therefore, it is very
essential to evaluate the
• sub grade by conducting tests.
• The tests used to evaluate the strength properties of soils may be broadly
divided into three groups:
• Shear tests
• Bearing tests
• Penetration tests
28. California Bearing Ratio Test
• California Bearing Ratio (CBR) test was developed by the California Division of
Highway as a method of classifying and evaluating soil-sub grade and base course
materials for flexible pavements.
• CBR test, an empirical test, has been used to determine the material properties for
pavement design. Empirical tests measure the strength of the material and are not a
true representation of the resilient modulus. It is a penetration test wherein a
standard piston, having an area of 3 in2 (or 50 mm diameter), is used to penetrate
the soil at a standard rate of 1.25 mm/minute. The pressure up to a penetration of
12.5 mm and it's ratio to the bearing value of a standard crushed rock is termed as
the CBR. In most cases, CBR decreases as the penetration increases. The ratio at 2.5
mm penetration is used as the CBR. In some case, the ratio at 5 mm may be greater
than that at 2.5 mm. If this occurs, the ratio at 5 mm should be used.
• The CBR is a measure of resistance of a material to penetration of standard plunger
under controlled density and moisture conditions. The test procedure should be
strictly adhered if high degree of reproducibility is desired. The CBR test may be
conducted in re-moulded or undisturbed specimen in the laboratory. The test is
simple and has been extensively investigated for field correlations of flexible
pavement thickness requirement.
30. Plate Bearing Test
• Plate bearing test is used to evaluate the support capability of sub-grades,
bases and in some cases, complete pavement. Data from the tests are
applicable for the design of both flexible and rigid pavements. In plate
bearing test, a compressive stress is applied to the soil or pavement layer
through rigid plates relatively large size and the deflections are measured
for various stress values. The deflection level is generally limited to a low
value, in the order of 1.25 to 5 mm and so the deformation caused may be
partly elastic and partly plastic due to compaction of the stressed mass
with negligible plastic deformation. The plate-bearing test has been
devised to evaluate the supporting power of sub grades or any other
pavement layer by using plates of larger diameter.
• The plate-bearing test was originally meant to find the modulus of sub
grade reaction in the Westergaard's analysis for wheel load stresses in
cement concrete pavements.
32. Pavement materials
• Aggregates
• Aggregate is a collective term for the mineral materials such as
sand, gravel, and crushed stone that are used with a binding
medium (such as water, bitumen, Portland cement, lime, etc.)
to form compound materials (such as bituminous concrete
and Portland cement concrete). By volume, aggregate
generally accounts for 92 to 96 percent of Bituminous
concrete and about 70 to 80 percent of Portland cement
concrete. Aggregate is also used for base and sub-base
courses for both flexible and rigid pavements. Aggregates can
either be natural or manufactured.
34. Desirable properties
• Strength
• The aggregates used in top layers are subjected to (i) Stress action due to traffic
wheel load, (ii) Wear and tear, (iii) crushing. For a high quality pavement, the
aggregates should posses high resistance to crushing, and to withstand the stresses
due to traffic wheel load.
• Hardness
• The aggregates used in the surface course are subjected to constant rubbing or
abrasion due to moving traffic. The aggregates should be hard enough to resist the
abrasive action caused by the movements of traffic. The abrasive action is severe
when steel tyred vehicles moves over the aggregates exposed at the top surface.
• Toughness
• Resistance of the aggregates to impact is termed as toughness. Aggregates used in
the pavement should be able to resist the effect caused by the jumping of the steel
tyred wheels from one particle to another at different levels causes severe impact
on the aggregates
35. Desirable Properties
• Shape of aggregates
• Aggregates which happen to fall in a particular size range may have rounded, cubical,
angular, flaky or elongated particles. It is evident that the flaky and elongated particles
will have less strength and durability when compared with cubical, angular or
rounded particles of the same aggregate. Hence too flaky and too much elongated
aggregates should be avoided as far as possible.
• Adhesion with bitumen
• The aggregates used in bituminous pavements should have less affinity with water
when compared with bituminous materials, otherwise the bituminous coating on the
aggregate will be stripped o in presence of water.
• Durability
• The property of aggregates to withstand adverse action of weather is called soundness.
The aggregates are subjected to the physical and chemical action of rain and bottom
water, impurities there-in and that of atmosphere, hence it is desirable that the road
aggregates used in the construction should be sound enough to withstand the
• weathering action
36. Aggregate tests
• In order to decide the suitability of the aggregate for use in
pavement construction, following tests are carried
• out:
• Crushing test
• Abrasion test
• Impact test
• Soundness test
• Shape test
• Specific gravity and water absorption test
• Bitumen adhesion test
37. Aggregate tests
Crushing test
• One of the model in which pavement material
can fail is by crushing under compressive
stress. A test is standardized by IS:2386 part-
IV and used to determine the crushing
strength of aggregates. The aggregate
crushing value provides a relative measure of
resistance to crushing under gradually
applied crushing load. The
38.
39. Abrasion test
• Abrasion test is carried out to test the hardness
property of aggregates and to decide whether they
are suitable for different pavement construction
works. Los Angeles abrasion test is a preferred one
for carrying out the hardness property and has been
standardized in India (IS:2386 part-IV). The
principle of Los Angeles abrasion test is to find the
percentage wear due to relative rubbing action
between the aggregate and steel balls used as
abrasive charge.
41. Aggregate tests
Impact test
• The aggregate impact test is carried out to
evaluate the resistance to impact of
aggregates.
• Aggregates to be used for wearing course, the
impact value shouldn't exceed 30 percent. For
bituminous macadam the maximum
permissible value is 35 percent. For Water
bound macadam base courses the maximum
permissible value defined by IRC is 40 percent
43. Aggregate tests
• Soundness test
• Soundness test is intended to study the resistance
of aggregates to weathering action, by
conducting accelerated weathering test cycles.
The Porous aggregates subjected to freezing and
thawing are likely to disintegrate prematurely.
To ascertain the durability of such aggregates,
they are subjected to an accelerated soundness
• test as specied in IS:2386 part-V.
44. Aggregate tests
• Shape tests
• The particle shape of the aggregate mass is determined
by the percentage of flaky and elongated particles in it.
• Aggregates which are flaky or elongated are detrimental
to higher workability and stability of mixes.
• The flakiness index is defined as the percentage by
weight of aggregate particles whose least dimension is
less than 0.6 times their mean size. Test procedure had
been standardized in India (IS:2386 part-I)
46. Aggregate tests
• The flakiness index is defined as the percentage
by weight of aggregate particles whose least
dimension is less than 0.6 times their mean size.
Test procedure had been standardized in India
(IS:2386 part-I) The elongation index of an
aggregate is defined as the percentage by weight
of particles whose greatest dimension (length) is
1.8 times their mean dimension. This test is
applicable to aggregates larger than 6.3 mm.
• This test is also specified in (IS:2386 Part-I).
47. Aggregate tests
Specific Gravity and water absorption
• The specific gravity and water absorption of
aggregates are important properties that are
required for the design of concrete and
bituminous mixes.
49. Pavement materials
Bitumen
• Bituminous materials or asphalts are extensively used for roadway
construction, primarily because of their excellent binding
characteristics and water proofing properties and relatively low cost.
Bituminous materials consists of bitumen which is a black or dark
coloured solid or viscous cementations substances consists chiefly
high molecular weight hydrocarbons derived from distillation of
petroleum or natural asphalt, has adhesive properties, and is
soluble in carbon disulphide. Tars are residues from the destructive
distillation of organic substances such as coal, wood, or petroleum
and are temperature sensitive than bitumen. Bitumen will be
dissolved in petroleum oils where unlike tar.
50. Pavement materials
• Production of Bitumen
• bitumen is the residue or by-product when the
crude petroleum is refined. A wide variety of
refinery processes, such as the straight distillation
process, solvent extraction process etc. may be
used to produce bitumen of different consistency
and other desirable properties. Depending on the
sources and characteristics of the crude oils and
on the properties of bitumen required, more than
one processing method may be employed.
51. Different forms of bitumen
• Cutback bitumen
• Normal practice is to heat bitumen to reduce its viscosity. In some
situations preference is given to use liquid binders such as cutback
bitumen. In cutback bitumen suitable solvent is used to lower the
viscosity of the bitumen. From the environmental point of view also
cutback bitumen is preferred. The solvent from the bituminous
material will evaporate and the bitumen will bind the aggregate.
Cutback bitumen is used for cold weather bituminous road
construction and maintenance. The distillates used for preparation
of cutback bitumen are naphtha, kerosene, diesel oil, and furnace
oil. There are different types of cutback bitumen like rapid curing
(RC), medium curing (MC), and slow curing (SC). RC is
recommended for surface dressing and patchwork.
53. Pavement materials
• Bitumen Emulsion
• Bitumen emulsion is a liquid product in which bitumen is
suspended in a finely divided condition in an aqueous
medium and stabilised by suitable material. Normally cationic
type emulsions are used in India. The bitumen content in the
emulsion is around 60% and the remaining is water. When
the emulsion is applied on the road it breaks down resulting
in release of water and the mix starts to set. The time of
setting depends upon the grade of bitumen. The viscosity of
bituminous emulsions can be measured as per IS: 8887-
1995. Three types of bituminous emulsions are available,
which are Rapid setting (RS), Medium setting (MS), and Slow
setting (SC).
55. Pavement materials
• Bituminous primers
• In bituminous primer the distillate is absorbed
by the road surface on which it is spread. The
absorption therefore depends on the porosity
of the surface. Bitumen primers are useful on
the stabilised surfaces and water bound
macadam base courses. Bituminous primers
are generally prepared on road sites by
mixing penetration bitumen with petroleum
distillate.
57. Pavement materials
• Modified Bitumen
• Certain additives or blend of additives called as
bitumen modifiers can improve properties of
Bitumen and bituminous mixes. Bitumen treated
with these modifiers is known as modified
bitumen. Polymer modified bitumen (PMB)/
crumb rubber modified bitumen (CRMB) should
be used only in wearing course depending upon
the requirements of extreme climatic variations.
59. Requirements of Bitumen
• The desirable properties of bitumen depend on the mix type and
construction. In general, Bitumen should posses following desirable
properties.
• The bitumen should not be highly temperature susceptible: during the
hottest weather the mix should not become too soft or unstable, and
during cold weather the mix should not become too brittle causing
cracks.
• The viscosity of the bitumen at the time of mixing and compaction
should be adequate. This can be achieved by use of cutbacks or
emulsions of suitable grades or by heating the bitumen and aggregates
prior to mixing.
• There should be adequate affinity and adhesion between the bitumen
and aggregates used in the mix.
60. Tests on bitumen
There are a number of tests to assess the properties of bituminous materials.
The following tests are usually conducted to evaluate different properties of
bituminous materials.
1. Penetration test
2. Ductility test
3. Softening point test
4. Specific gravity test
5. Viscosity test
6. Flash and Fire point test
7. Float test
8. Water content test
9. Loss on heating test
61. Penetration test
• It measures the hardness or softness of bitumen by measuring the depth in
tenths of a millimetre to which a standard loaded needle will penetrate
vertically in 5 seconds. BIS had standardised the equipment and test
procedure. The penetrometer consists of a needle assembly with a total
weight of 100g and a device for releasing and locking in any position. The
bitumen is softened to a pouring consistency, stirred thoroughly and
poured into containers at a depth at least 15 mm in excess of the expected
penetration. The test should be conducted at a specified temperature of
25o C. It may be noted that penetration value is largely influenced by any
inaccuracy with regards to pouring temperature, size of the needle,
weight placed on the needle and the test temperature.
• A grade of 40/50 bitumen means the penetration value is in the range 40
to 50 at standard test conditions.
• In hot climates, a lower penetration grade is preferred.
63. Ductility test
• Ductility is the property of bitumen that permits
it to undergo great deformation or elongation.
Ductility is defined as the distance in cm, to
which a standard sample or briquette of the
material will be elongated without breaking.
• The ductility value gets affected by factors such
as pouring temperature, test temperature, rate of
pulling etc. A minimum ductility value of 75 cm
has been specified by the BIS.
65. Softening point test
• Softening point denotes the temperature at which
the bitumen attains a particular degree of softening
under the specifications of test. The test is conducted
by using Ring and Ball apparatus. A brass ring
containing test sample of bitumen is suspended in
liquid like water or glycerine at a given temperature.
A steel ball is placed upon the bitumen sample and
the liquid medium is heated at a rate of 5o C per
minute. Temperature is noted when the softened
bitumen touches the metal plate which is at a
specified distance below
68. Specific gravity test
• In paving jobs, to classify a binder, density property is of great
use. In most cases bitumen is weighed, but
• when used with aggregates, the bitumen is converted to
volume using density values. The density of bitumen is greatly
inuenced by its chemical composition. Increase in aromatic
type mineral impurities cause an increase in specific gravity.
• The specific gravity of bitumen is defined as the ratio of mass
of given volume of bitumen of known content to the mass of
equal volume of water at 27o C. The specific gravity can be
measured using either pycnometer or preparing a cube
specimen of bitumen in semi solid or solid state. The specific
gravity of bitumen varies from 0.97 to 1.02.
69. Viscosity test
• Viscosity denotes the fluid property of bituminous material and it is a
measure of resistance to flow. At the application temperature, this
characteristic greatly influences the strength of resulting paving mixes.
Low or high viscosity during compaction or mixing has been observed to
result in lower stability values. At high viscosity, it resist the comp active
effort and thereby resulting mix is heterogeneous, hence low stability
values.
• And at low viscosity instead of providing a uniform film over aggregates,
it will lubricate the aggregate particles.
• Orifice type viscometers are used to indirectly find the viscosity of liquid
binders like cutbacks and emulsions.
• The viscosity expressed in seconds is the time taken by the 50 ml bitumen
material to pass through the orifice of a cup, under standard test
conditions and specified temperature. Viscosity of a cutback can be
measured with either 4.0 mm orifice at 25o C or 10 mm orifice at 25 or
40o C.
71. Flash and fire point test
• At high temperatures depending upon the grades of
bitumen materials leave out volatiles. And these
volatiles catches fire which is very hazardous and
therefore it is essential to qualify this temperature
for each bitumen grade. BIS defined the flash point
as the temperature at which the vapour of bitumen
momentarily catches fire. in the form of ash under
specified test conditions. The fire point is defined as
the lowest temperature under specified test
conditions at which the bituminous material gets
ignited and burns.
73. Float test
• Normally the consistency of bituminous material can be
measured either by penetration test or viscosity test.
• But for certain range of consistencies, these tests are not
applicable and Float test is used. The apparatus consists of an
aluminium float and a brass collar filled with bitumen to be
tested. The specimen in the mould is cooled to a temperature
of 5oC and screwed in to float. The total test assembly is
floated in the water bath at 50oC and the time required for
water to pass its way through the specimen plug is noted in
seconds and is expressed as the float value.
75. Water content test
• It is desirable that the bitumen contains minimum
water content to prevent foaming of the bitumen
when it is heated above the boiling point of water.
The water in a bitumen is determined by mixing
known weight of specimen in a pure petroleum
distillate free from water, heating and distilling of
the water. The weight of the water condensed and
collected is expressed as percentage by weight of the
original sample. The allowable maximum water
content should not be more than 0.2% by weight.
76. Loss on heating test
• When the bitumen is heated it loses the volatility
and gets hardened. About 50gm of the sample is
weighed and heated to a temperature of 1630C for
5hours in a specified oven designed for this test. The
sample specimen is weighed again after the heating
period and loss in weight is expressed as percentage
by weight of the original sample. Bitumen used in
pavement mixes should not indicate more than 1%
loss in weight, but for bitumen having penetration
values 150-200 up to 2% loss in weight is allowed.
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