Concrete is a composite material made of aggregates, sand, cement, and water. It has high compressive strength but low tensile strength. Proper mixing and compaction are required to produce durable concrete. Mixing involves blending the ingredients into a uniform mass and coating aggregates with cement paste. Compaction removes air pockets and achieves maximum density. It is done through tamping, rodding, or vibrating the fresh concrete. Vibration uses internal or external vibrators to penetrate and settle the concrete mixture.
This document discusses the key materials used in concrete - cement, water, aggregates, and admixtures. It describes what concrete is, its types and uses. The main ingredients are described in detail, including their properties and how they affect the strength and performance of concrete. Aggregates make up the largest portion by volume and come in various sizes and grades. Proper mix design and material selection are important to produce durable concrete.
The document summarizes the key properties and classifications of aggregates used to make concrete. It discusses that aggregates provide bulk and strength to concrete. It classifies aggregates based on their geological origin, size, shape, grading, and unit weight. The summary properties of fine and coarse aggregates are also provided, including requirements for good aggregates.
Aggregates are granular materials like sand, gravel, or crushed stone used with water and cement to make concrete. They come in two sizes: fine aggregates smaller than 5 mm and coarse aggregates larger than 5 mm. Aggregates provide strength, reduce cracking, and lower the cost of concrete. They are selected based on being hard, durable, and free of organic materials or other substances that could weaken the concrete. Aggregates are classified by size, manufacturing method, and density. Physical tests are conducted to determine properties like strength, hardness, porosity, and grading.
This document discusses the properties and classification of aggregates used in concrete. It describes how aggregates can be classified based on size, weight, and composition. The key properties discussed include shape, texture, strength, density, moisture content, cleanliness, soundness, and thermal properties. Testing methods are provided for sieve analysis, grading, crushing strength, abrasion resistance, impact value, and soundness. The document also covers the workability of concrete and factors that influence it such as water-cement ratio, aggregate type and amount, cement type and amount, and use of admixtures.
B-Tech Construction Material Presentaion.pptmosesnhidza
This document provides an overview of concrete, including its definition, properties, composition, testing, and uses. Some key points:
- Concrete is a mixture of cement, aggregates (sand and gravel), and water that can be used for load-bearing construction.
- Its properties depend on the mix proportions, water-cement ratio, and type of aggregates used. Good compaction and curing are important for strength.
- Concrete has high compressive strength but low tensile strength, so it is often reinforced with steel bars or prestressed using steel tendons.
- Aggregates make up the majority of a concrete mix by weight and influence properties like strength and durability. Proper testing of aggregates is
ASSESSMENT OF SELF COMPACTING CONCRETE IMMERSED IN ACIDIC SOLUTIONS WITH PART...Ijripublishers Ijri
The present investigations are proposed to study the acid resistance behavior of M40 grade SCC with partial replacement
of cement with mineral admixture Fly Ash at 10, 20, and 30%. Rational method of mix design was adopted for mix
design of M40 grade SCC for the trial mixes in the absence of BIS code for SCC mix design. Experimental investigations
were carried out to study the acid resistance of SCC from hydrochloric acid (HCl) and sulphuric acid (H2So4) which are
effective acids expected to cause damage for strength and durability of structures, by observing the effect for 14, 28 and
60days strengths and performance at different percentages of mix with flyash. Based on these studies, inference was
drawn for durability of structures exposed to such aggressive environment.
This document summarizes the classification and properties of aggregates used in construction. It defines aggregates as inert materials mixed with cement or lime for mortar or concrete. Aggregates are classified as fine or coarse based on particle size. Common fine aggregates include sand from various sources, while coarse aggregates include crushed stone and gravel. Key properties discussed include size, shape, composition and performance in tests such as crushing value, impact value and abrasion value. Sieve analysis is also described to determine particle size distribution. An ideal aggregate is characterized as hard, strong, dense and free of impurities to provide durable concrete.
Aggregates are granular materials such as sand, gravel, crushed stone and recycled concrete used with cementing materials like cement or asphalt to produce concrete or asphalt. They make up 75% of concrete and over 90% of asphalt. Aggregates must be strong, durable and meet certain shape and size requirements. Common tests evaluate properties like strength, hardness, absorption and abrasion resistance. Sources of aggregates in Pakistan include limestone from Margalla Hills and Salt Range as well as dolomite deposits in Hazara and Kashmir regions.
This document discusses the key materials used in concrete - cement, water, aggregates, and admixtures. It describes what concrete is, its types and uses. The main ingredients are described in detail, including their properties and how they affect the strength and performance of concrete. Aggregates make up the largest portion by volume and come in various sizes and grades. Proper mix design and material selection are important to produce durable concrete.
The document summarizes the key properties and classifications of aggregates used to make concrete. It discusses that aggregates provide bulk and strength to concrete. It classifies aggregates based on their geological origin, size, shape, grading, and unit weight. The summary properties of fine and coarse aggregates are also provided, including requirements for good aggregates.
Aggregates are granular materials like sand, gravel, or crushed stone used with water and cement to make concrete. They come in two sizes: fine aggregates smaller than 5 mm and coarse aggregates larger than 5 mm. Aggregates provide strength, reduce cracking, and lower the cost of concrete. They are selected based on being hard, durable, and free of organic materials or other substances that could weaken the concrete. Aggregates are classified by size, manufacturing method, and density. Physical tests are conducted to determine properties like strength, hardness, porosity, and grading.
This document discusses the properties and classification of aggregates used in concrete. It describes how aggregates can be classified based on size, weight, and composition. The key properties discussed include shape, texture, strength, density, moisture content, cleanliness, soundness, and thermal properties. Testing methods are provided for sieve analysis, grading, crushing strength, abrasion resistance, impact value, and soundness. The document also covers the workability of concrete and factors that influence it such as water-cement ratio, aggregate type and amount, cement type and amount, and use of admixtures.
B-Tech Construction Material Presentaion.pptmosesnhidza
This document provides an overview of concrete, including its definition, properties, composition, testing, and uses. Some key points:
- Concrete is a mixture of cement, aggregates (sand and gravel), and water that can be used for load-bearing construction.
- Its properties depend on the mix proportions, water-cement ratio, and type of aggregates used. Good compaction and curing are important for strength.
- Concrete has high compressive strength but low tensile strength, so it is often reinforced with steel bars or prestressed using steel tendons.
- Aggregates make up the majority of a concrete mix by weight and influence properties like strength and durability. Proper testing of aggregates is
ASSESSMENT OF SELF COMPACTING CONCRETE IMMERSED IN ACIDIC SOLUTIONS WITH PART...Ijripublishers Ijri
The present investigations are proposed to study the acid resistance behavior of M40 grade SCC with partial replacement
of cement with mineral admixture Fly Ash at 10, 20, and 30%. Rational method of mix design was adopted for mix
design of M40 grade SCC for the trial mixes in the absence of BIS code for SCC mix design. Experimental investigations
were carried out to study the acid resistance of SCC from hydrochloric acid (HCl) and sulphuric acid (H2So4) which are
effective acids expected to cause damage for strength and durability of structures, by observing the effect for 14, 28 and
60days strengths and performance at different percentages of mix with flyash. Based on these studies, inference was
drawn for durability of structures exposed to such aggressive environment.
This document summarizes the classification and properties of aggregates used in construction. It defines aggregates as inert materials mixed with cement or lime for mortar or concrete. Aggregates are classified as fine or coarse based on particle size. Common fine aggregates include sand from various sources, while coarse aggregates include crushed stone and gravel. Key properties discussed include size, shape, composition and performance in tests such as crushing value, impact value and abrasion value. Sieve analysis is also described to determine particle size distribution. An ideal aggregate is characterized as hard, strong, dense and free of impurities to provide durable concrete.
Aggregates are granular materials such as sand, gravel, crushed stone and recycled concrete used with cementing materials like cement or asphalt to produce concrete or asphalt. They make up 75% of concrete and over 90% of asphalt. Aggregates must be strong, durable and meet certain shape and size requirements. Common tests evaluate properties like strength, hardness, absorption and abrasion resistance. Sources of aggregates in Pakistan include limestone from Margalla Hills and Salt Range as well as dolomite deposits in Hazara and Kashmir regions.
Aggregates make up 70-80% of concrete and influence its properties. Coarse aggregates are retained on a 4.75mm sieve while fine aggregates pass through. Concrete is made through batching, mixing, transporting, placing, compacting, and curing its ingredients which include cement, water, sand, gravel, and sometimes admixtures. Proper testing ensures aggregates meet requirements for properties like strength, durability, and grading. Recycled aggregates can also be used from construction debris.
This document discusses aggregates and mortar. It defines aggregates as granular materials used in concrete, which occupy 70-80% of concrete volume. Aggregates are classified based on size, source, unit weight, and shape. Tests conducted on aggregates include particle size, impact value, crushing value, and abrasion value. Mortar is made by mixing a binding material, fine aggregate, and water. The types of mortar discussed are cement mortar, lime mortar, mud mortar, lightweight mortar, and fire resistant mortar. Mortar properties like workability, water retention, stiffening, and strength are also covered.
Concrete has several benefits including low cost, strength in compression, and ease of shaping when wet. However, it also has limitations such as low tensile strength and ductility. Concrete strength is determined by its compressive crushing strength and is affected by the materials and techniques used. It is strong in compression but weak in tension, so reinforcing with steel is common. Modern concrete contains aggregates, cement paste, water, and sometimes admixtures. Proper aggregate properties greatly influence the performance of concrete.
Aggregates are materials such as sand, gravel, crushed stone and recycled concrete that are mixed with cement and water to form concrete. There are various types of aggregates classified based on grain size, density, geographical origin and shape. Fine aggregates are smaller than 4.75mm while coarse aggregates are larger. Aggregates provide properties like volume, stability and resistance to wear or erosion in concrete. Admixtures are added to concrete to improve properties during casting, setting or service and include chemicals to improve workability or minerals to reduce water requirements.
Aggregates make up 70-80% of concrete by volume and can be classified by source, size, shape, and other properties. Their properties affect the workability, strength, and economics of concrete. Igneous, sedimentary, and metamorphic rocks are common sources. Aggregate size, shape, texture, strength, and durability all impact the performance of concrete. Tests are used to evaluate aggregate crushing strength, impact resistance, and abrasion characteristics important for different concreting applications. Proper aggregate selection and testing are essential for producing high quality concrete.
This document provides information on self-compacting concrete (SCC) and light-weight concrete. It defines SCC as concrete that can flow and fill formwork without vibration due to its high fluidity. Benefits of SCC include faster construction, improved quality, and a safer work environment. Light-weight concrete is defined as having a density of less than 2200kg/m3, containing porous aggregates, and including an expanding agent. Examples of structures built with SCC include Burj Dubai and an airport control tower in Stockholm. Requirements for producing SCC and light-weight concrete are also outlined.
In its simplest form, concrete is a mixture of paste and aggregates, or rocks. The paste, composed of portland cement and water, coats the surface of the fine (small) and coarse (larger) aggregates
Aggregates are a combination of different sized stones used in construction. They are classified based on size, source, and density. Common types include natural and crushed coarse and fine aggregates. Aggregates must be hard, durable, and free of organic matter or other impurities. Tests are conducted to determine properties like strength, hardness, porosity, and water absorption. Sieve analysis tests the particle size distribution and grading of aggregates.
Cement mortar is a mixture used for masonry construction, such as between bricks. It binds the materials together and provides strength, stability, and durability to building structures. There are different types of mortars including lime, cement, surkhi, and mud mortars. Mortar hardens when it sets, forming an aggregate structure. Concrete is similar but contains coarse aggregates like gravel or stone, in addition to the binding materials, sand, and water. The document discusses the ingredients, mixing, curing, and testing of concrete, including its compressive strength and workability. Aggregates make up the bulk of a concrete mixture and affect its properties.
Concrete is made up of ingredients like Cement, Fine Aggregate (Sand), Coarse Aggregate, Water and admixtures. Concrete mix design is done to Optimize the requirements of Cement, Sand, Aggregate and Water in order to ensure that concrete parameters in both Plastic Stage (like workability) and in Hardened Stage (like Compressive Strength and durability) are achieved. The Concrete mix design is as per Indian Standards (IS 10262) and might vary from country to country. The nominal mix design ratios available for concrete less than M30 in strength are only thumb rules and are generally over designed. As the actual site conditions vary and the mix design should be adjusted as per the location and other factors.
Concrete is the most common building material used in construction. It is made by mixing cement, aggregate such as sand or gravel, and water. Concrete can be molded into any shape needed and hardens over time. It provides strength and durability as a building material. Concrete properties depend on its composition, with cement binding the aggregates and filling spaces between them. Proper mixing, placing, and curing of concrete results in a strong, long-lasting building material. Common concrete elements in construction include foundations, slabs, columns, beams, bridges, and highways.
Understanding of concrete 28.june-08 (2) - copyARIVU SUDAR
The document discusses various cement replacement materials like fly ash, ground granulated blast furnace slag (GGBS), and silica fume. Fly ash is a byproduct of coal combustion that can replace up to 30% of cement. GGBS is a byproduct of steel production that can replace up to 70% of cement. Silica fume improves strength but requires higher replacement levels. These materials provide benefits like reduced water demand, permeability, heat of hydration, and increased strength. The document also discusses admixtures that can improve workability, setting time, and other concrete properties.
The document provides information on aggregates used in concrete, including their definition, classification, properties, grading, and tests. It defines aggregates as materials such as sand and gravel used to make concrete and mortar. Aggregates are classified by their geological origin, size, and shape. Their properties including strength, absorption, and density are described. The importance of proper grading of aggregates for density and strength of concrete is discussed. Common tests on aggregates like crushing value, impact value, and abrasion value are outlined.
This document discusses aggregates which are inert materials mixed with cement to produce concrete. It defines aggregates and describes their properties and types. Aggregates can be classified based on grain size, origin, density or shape. The main types are fine aggregates like sand, and coarse aggregates like gravel. Fine aggregates pass through a 4.75mm sieve while coarse aggregates are retained. Properties of aggregates that affect concrete like composition, size and texture are also covered. The goal is to educate civil engineers on aggregates used in construction.
Highway Materials: Desirable Properties, Testing Procedures, Standards, and standard values relating to Soil, Stone Aggregates, Bitumen and Tar, fly- ash/pond-ash. Role of filler in Bituminous mix, materials of filler.
Specifications of DLC and PQC for rigid pavement
This document discusses aggregates and bituminous materials used in construction. It describes various types of aggregates including sand, gravel, crushed stone, and recycled concrete that are used as a base material or to extend asphalt and concrete. It outlines important properties of aggregates like density, absorption and shape. It also discusses uses of aggregates in bases, asphalt, and Portland cement. Further, it describes types and testing of bituminous materials like penetration graded bitumen, viscosity graded bitumen and modified bitumens used in construction.
This document provides information about different types of cement and concrete. It discusses the key constituents of concrete including cement, sand, gravel and water. It describes different types of cement such as Portland cement and their uses. The document also covers topics like mix design, properties and testing of concrete, and properties and testing of aggregates used in concrete.
Aggregates such as sand and gravel are mixed with cement and water to form concrete. There are several key properties of aggregates including being clean, hard, durable, and having a shape that provides good workability and strength. The most common aggregate sources are river stones or crushed rock. Proper grading of aggregate sizes is important to prevent voids when mixed. Concrete is formed by mixing aggregates, cement, and water. The exact proportions and mixing process affect the workability and strength properties of the resulting concrete. Curing the concrete is also important for the hardening and strength development process.
The document discusses several areas in Dire Dawa that could be improved or developed, including:
1. The Juma Mosque which is an important historic and religious site that serves the local Muslim community.
2. The Konele Konele and Chat Tera areas which are busy markets and transportation hubs but also have issues with drugs, poor sanitation, and deterioration.
3. Indigenous housing, the Addis Ababa Hotel, and the Kefira market which were once prominent landmarks but have lost their glory and deteriorated over time. Upgrades and developments are proposed for these areas.
4. The Dechatu area which currently has many bars and residences mixed together.
The document provides background information on a client named Linda, a 32-year old recently divorced woman who is seeking counseling for relationship problems. It details her family history, educational and employment backgrounds, hobbies and social factors. Linda reveals feelings of aimlessness, anxiety and depression since her divorce and has contemplated ending her life, though doubts she would act on it.
Aggregates make up 70-80% of concrete and influence its properties. Coarse aggregates are retained on a 4.75mm sieve while fine aggregates pass through. Concrete is made through batching, mixing, transporting, placing, compacting, and curing its ingredients which include cement, water, sand, gravel, and sometimes admixtures. Proper testing ensures aggregates meet requirements for properties like strength, durability, and grading. Recycled aggregates can also be used from construction debris.
This document discusses aggregates and mortar. It defines aggregates as granular materials used in concrete, which occupy 70-80% of concrete volume. Aggregates are classified based on size, source, unit weight, and shape. Tests conducted on aggregates include particle size, impact value, crushing value, and abrasion value. Mortar is made by mixing a binding material, fine aggregate, and water. The types of mortar discussed are cement mortar, lime mortar, mud mortar, lightweight mortar, and fire resistant mortar. Mortar properties like workability, water retention, stiffening, and strength are also covered.
Concrete has several benefits including low cost, strength in compression, and ease of shaping when wet. However, it also has limitations such as low tensile strength and ductility. Concrete strength is determined by its compressive crushing strength and is affected by the materials and techniques used. It is strong in compression but weak in tension, so reinforcing with steel is common. Modern concrete contains aggregates, cement paste, water, and sometimes admixtures. Proper aggregate properties greatly influence the performance of concrete.
Aggregates are materials such as sand, gravel, crushed stone and recycled concrete that are mixed with cement and water to form concrete. There are various types of aggregates classified based on grain size, density, geographical origin and shape. Fine aggregates are smaller than 4.75mm while coarse aggregates are larger. Aggregates provide properties like volume, stability and resistance to wear or erosion in concrete. Admixtures are added to concrete to improve properties during casting, setting or service and include chemicals to improve workability or minerals to reduce water requirements.
Aggregates make up 70-80% of concrete by volume and can be classified by source, size, shape, and other properties. Their properties affect the workability, strength, and economics of concrete. Igneous, sedimentary, and metamorphic rocks are common sources. Aggregate size, shape, texture, strength, and durability all impact the performance of concrete. Tests are used to evaluate aggregate crushing strength, impact resistance, and abrasion characteristics important for different concreting applications. Proper aggregate selection and testing are essential for producing high quality concrete.
This document provides information on self-compacting concrete (SCC) and light-weight concrete. It defines SCC as concrete that can flow and fill formwork without vibration due to its high fluidity. Benefits of SCC include faster construction, improved quality, and a safer work environment. Light-weight concrete is defined as having a density of less than 2200kg/m3, containing porous aggregates, and including an expanding agent. Examples of structures built with SCC include Burj Dubai and an airport control tower in Stockholm. Requirements for producing SCC and light-weight concrete are also outlined.
In its simplest form, concrete is a mixture of paste and aggregates, or rocks. The paste, composed of portland cement and water, coats the surface of the fine (small) and coarse (larger) aggregates
Aggregates are a combination of different sized stones used in construction. They are classified based on size, source, and density. Common types include natural and crushed coarse and fine aggregates. Aggregates must be hard, durable, and free of organic matter or other impurities. Tests are conducted to determine properties like strength, hardness, porosity, and water absorption. Sieve analysis tests the particle size distribution and grading of aggregates.
Cement mortar is a mixture used for masonry construction, such as between bricks. It binds the materials together and provides strength, stability, and durability to building structures. There are different types of mortars including lime, cement, surkhi, and mud mortars. Mortar hardens when it sets, forming an aggregate structure. Concrete is similar but contains coarse aggregates like gravel or stone, in addition to the binding materials, sand, and water. The document discusses the ingredients, mixing, curing, and testing of concrete, including its compressive strength and workability. Aggregates make up the bulk of a concrete mixture and affect its properties.
Concrete is made up of ingredients like Cement, Fine Aggregate (Sand), Coarse Aggregate, Water and admixtures. Concrete mix design is done to Optimize the requirements of Cement, Sand, Aggregate and Water in order to ensure that concrete parameters in both Plastic Stage (like workability) and in Hardened Stage (like Compressive Strength and durability) are achieved. The Concrete mix design is as per Indian Standards (IS 10262) and might vary from country to country. The nominal mix design ratios available for concrete less than M30 in strength are only thumb rules and are generally over designed. As the actual site conditions vary and the mix design should be adjusted as per the location and other factors.
Concrete is the most common building material used in construction. It is made by mixing cement, aggregate such as sand or gravel, and water. Concrete can be molded into any shape needed and hardens over time. It provides strength and durability as a building material. Concrete properties depend on its composition, with cement binding the aggregates and filling spaces between them. Proper mixing, placing, and curing of concrete results in a strong, long-lasting building material. Common concrete elements in construction include foundations, slabs, columns, beams, bridges, and highways.
Understanding of concrete 28.june-08 (2) - copyARIVU SUDAR
The document discusses various cement replacement materials like fly ash, ground granulated blast furnace slag (GGBS), and silica fume. Fly ash is a byproduct of coal combustion that can replace up to 30% of cement. GGBS is a byproduct of steel production that can replace up to 70% of cement. Silica fume improves strength but requires higher replacement levels. These materials provide benefits like reduced water demand, permeability, heat of hydration, and increased strength. The document also discusses admixtures that can improve workability, setting time, and other concrete properties.
The document provides information on aggregates used in concrete, including their definition, classification, properties, grading, and tests. It defines aggregates as materials such as sand and gravel used to make concrete and mortar. Aggregates are classified by their geological origin, size, and shape. Their properties including strength, absorption, and density are described. The importance of proper grading of aggregates for density and strength of concrete is discussed. Common tests on aggregates like crushing value, impact value, and abrasion value are outlined.
This document discusses aggregates which are inert materials mixed with cement to produce concrete. It defines aggregates and describes their properties and types. Aggregates can be classified based on grain size, origin, density or shape. The main types are fine aggregates like sand, and coarse aggregates like gravel. Fine aggregates pass through a 4.75mm sieve while coarse aggregates are retained. Properties of aggregates that affect concrete like composition, size and texture are also covered. The goal is to educate civil engineers on aggregates used in construction.
Highway Materials: Desirable Properties, Testing Procedures, Standards, and standard values relating to Soil, Stone Aggregates, Bitumen and Tar, fly- ash/pond-ash. Role of filler in Bituminous mix, materials of filler.
Specifications of DLC and PQC for rigid pavement
This document discusses aggregates and bituminous materials used in construction. It describes various types of aggregates including sand, gravel, crushed stone, and recycled concrete that are used as a base material or to extend asphalt and concrete. It outlines important properties of aggregates like density, absorption and shape. It also discusses uses of aggregates in bases, asphalt, and Portland cement. Further, it describes types and testing of bituminous materials like penetration graded bitumen, viscosity graded bitumen and modified bitumens used in construction.
This document provides information about different types of cement and concrete. It discusses the key constituents of concrete including cement, sand, gravel and water. It describes different types of cement such as Portland cement and their uses. The document also covers topics like mix design, properties and testing of concrete, and properties and testing of aggregates used in concrete.
Aggregates such as sand and gravel are mixed with cement and water to form concrete. There are several key properties of aggregates including being clean, hard, durable, and having a shape that provides good workability and strength. The most common aggregate sources are river stones or crushed rock. Proper grading of aggregate sizes is important to prevent voids when mixed. Concrete is formed by mixing aggregates, cement, and water. The exact proportions and mixing process affect the workability and strength properties of the resulting concrete. Curing the concrete is also important for the hardening and strength development process.
The document discusses several areas in Dire Dawa that could be improved or developed, including:
1. The Juma Mosque which is an important historic and religious site that serves the local Muslim community.
2. The Konele Konele and Chat Tera areas which are busy markets and transportation hubs but also have issues with drugs, poor sanitation, and deterioration.
3. Indigenous housing, the Addis Ababa Hotel, and the Kefira market which were once prominent landmarks but have lost their glory and deteriorated over time. Upgrades and developments are proposed for these areas.
4. The Dechatu area which currently has many bars and residences mixed together.
The document provides background information on a client named Linda, a 32-year old recently divorced woman who is seeking counseling for relationship problems. It details her family history, educational and employment backgrounds, hobbies and social factors. Linda reveals feelings of aimlessness, anxiety and depression since her divorce and has contemplated ending her life, though doubts she would act on it.
This document provides an introduction to the concept of shaping sustainable built environments through site planning and design. It discusses how human populations have historically modified landscapes but are now exceeding the earth's capacity to mitigate environmental impacts. The functions of nature that are essential to human welfare are organized into four categories: production, regulation, carrier, and information. However, human activities are degrading these functions and negatively impacting air and water quality. Sustainable design aims to balance human needs with environmental carrying capacity by minimizing impacts, resource use, and waste generation.
1. Metals are classified as ferrous, containing iron as the main constituent like steel and cast iron, or non-ferrous without iron.
2. Iron ore, limestone, and coke are used to produce pig iron in a blast furnace. Pig iron is then processed to produce wrought iron or steel.
3. Steel has a variety of uses in construction and manufacturing due to its high strength, ductility, and ability to be cast and formed into different shapes. Its properties can be altered through adjusting carbon content, adding alloys, and heat treatment.
1. Wood can be classified as softwood or hardwood. Softwoods are lighter, weaker woods from coniferous trees while hardwoods are heavier, stronger woods from deciduous trees.
2. Many factors affect the properties and uses of wood, including moisture content, grain direction, density, and defects from growth or processing. Proper drying and treatment can improve wood's strength, durability, and resistance to decay or fire.
3. Wood products are produced through several steps including logging, sawing, drying, grading, and optional treatment or surfacing. New engineered wood products like plywood, LVL, and OSB combine wood elements for consistent structural properties.
Portland cement is one of the most widely used construction materials and is made through a series of steps. It is produced using a wet or dry process. The wet process involves mixing raw materials like limestone, clay, and iron ore with water to form a slurry before burning in a kiln. The dry process uses dried raw materials that are ground and heated without water. The manufactured clinker is then ground with gypsum and packaged for use. Portland cement has various properties that depend on its chemical composition and production methods.
This document discusses the requirements and types of stone used for building materials. It outlines that stone must be hard, workable, durable, aesthetically pleasing, and able to be quarried and transported easily. It then describes the common processes for quarrying dimension stone, quarry stone, and crushed stone production. Finally, it lists the most common types of stone used in Ethiopia - basalt, trachyte, granite, limestone, marble, sandstone, ignimbrite, pumice, and scoria - and their typical uses in construction.
This document discusses four common soil-based building materials: rammed earth, adobe bricks, cob, and stabilized cement bricks (hydraform). Rammed earth is a mixture of soil, sand, cement and additives that is compacted into walls. Adobe bricks use clay, sand, straw and water molded into bricks and dried in the sun. Cob uses a wet mixture of soil, sand, straw and water applied by hand to form thick walls. Hydraform blocks are made by compressing a mixture of soil/fly ash and cement into blocks with interlocking grooves. The materials and basic construction techniques of each are described.
This document outlines the syllabus for a construction management course. It provides the instructor's contact information, course details including objectives, topics, assignments, exams and policies. The course will cover construction industry overview, the architect's role, project lifecycles, emerging technologies and more. Students will complete individual assignments, a group project, quizzes, a midterm and final exam throughout the semester.
A high-Speed Communication System is based on the Design of a Bi-NoC Router, ...DharmaBanothu
The Network on Chip (NoC) has emerged as an effective
solution for intercommunication infrastructure within System on
Chip (SoC) designs, overcoming the limitations of traditional
methods that face significant bottlenecks. However, the complexity
of NoC design presents numerous challenges related to
performance metrics such as scalability, latency, power
consumption, and signal integrity. This project addresses the
issues within the router's memory unit and proposes an enhanced
memory structure. To achieve efficient data transfer, FIFO buffers
are implemented in distributed RAM and virtual channels for
FPGA-based NoC. The project introduces advanced FIFO-based
memory units within the NoC router, assessing their performance
in a Bi-directional NoC (Bi-NoC) configuration. The primary
objective is to reduce the router's workload while enhancing the
FIFO internal structure. To further improve data transfer speed,
a Bi-NoC with a self-configurable intercommunication channel is
suggested. Simulation and synthesis results demonstrate
guaranteed throughput, predictable latency, and equitable
network access, showing significant improvement over previous
designs
Better Builder Magazine brings together premium product manufactures and leading builders to create better differentiated homes and buildings that use less energy, save water and reduce our impact on the environment. The magazine is published four times a year.
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
travelling which makes the life of the people easier. When compared to other
means of transport, a railway is the cheapest means of transport. The maintenance
of the railway database also plays a major role in the smooth running of this
system. The Online Train Ticket Management System will help in reserving the
tickets of the railways to travel from a particular source to the destination.
Sri Guru Hargobind Ji - Bandi Chor Guru.pdfBalvir Singh
Sri Guru Hargobind Ji (19 June 1595 - 3 March 1644) is revered as the Sixth Nanak.
• On 25 May 1606 Guru Arjan nominated his son Sri Hargobind Ji as his successor. Shortly
afterwards, Guru Arjan was arrested, tortured and killed by order of the Mogul Emperor
Jahangir.
• Guru Hargobind's succession ceremony took place on 24 June 1606. He was barely
eleven years old when he became 6th Guru.
• As ordered by Guru Arjan Dev Ji, he put on two swords, one indicated his spiritual
authority (PIRI) and the other, his temporal authority (MIRI). He thus for the first time
initiated military tradition in the Sikh faith to resist religious persecution, protect
people’s freedom and independence to practice religion by choice. He transformed
Sikhs to be Saints and Soldier.
• He had a long tenure as Guru, lasting 37 years, 9 months and 3 days
Sachpazis_Consolidation Settlement Calculation Program-The Python Code and th...Dr.Costas Sachpazis
Consolidation Settlement Calculation Program-The Python Code
By Professor Dr. Costas Sachpazis, Civil Engineer & Geologist
This program calculates the consolidation settlement for a foundation based on soil layer properties and foundation data. It allows users to input multiple soil layers and foundation characteristics to determine the total settlement.
This study Examines the Effectiveness of Talent Procurement through the Imple...DharmaBanothu
In the world with high technology and fast
forward mindset recruiters are walking/showing interest
towards E-Recruitment. Present most of the HRs of
many companies are choosing E-Recruitment as the best
choice for recruitment. E-Recruitment is being done
through many online platforms like Linkedin, Naukri,
Instagram , Facebook etc. Now with high technology E-
Recruitment has gone through next level by using
Artificial Intelligence too.
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Effectiveness of Talent Acquisition through E-
Recruitment in this topic we will discuss about 4important
and interlinked topics which are
2. 1.4.1 GENERAL
What is Concrete?
Concrete is one of the most commonly
used building materials.
Concrete is a composite material made
from several readily available constituents
(aggregates, sand, cement, water).
Concrete is a versatile material that can
easily be mixed to meet a variety of
special needs and formed to virtually any
shape.
3. Advantages
Ability to be cast- ability to be molded or cast into almost any desired
shape.
Economical- when ingredients are readily available.
Durable- relatively low maintenance requirements
Fire resistant
Energy efficient
On-site fabrication
It is not as likely to rot, corrode, or decay as other building materials.
It is a non-combustible material which makes it fire-safe and able
withstand high temperatures.
It is resistant to wind, water, rodents, and insects. Hence, concrete is
often used for storm shelters.
It has high compressive strength, resistance to weathering, impact and
abrasion
Building of the molds and casting can occur on the work-site which
reduces costs.
4. Disadvantages
Low tensile strength
Low ductility
Volume instability
Low strength to weight ratio
High cost of cement, steel and formwork ( in developing countries).
Difficult quality control on building sites, with the risk of cracking and
gradual deterioration, if wrongly mixed, placed and insufficiently cured
with water.
6. Aggregates
Aggregates generally occupy 65-
80% of the volume of concrete.
Hence due consideration should be
given in their selection and
proportioning.
Earlier, aggregates were considered
as chemically inert materials but now
it has been recognised that their
physical, thermal and at times
chemical properties influence those
of the concrete.
7. Basically aggregate serves
the following purposes:
Form the inert mineral filler material which the cement
paste binds together.
Reduce the volume changes resulting from the setting
and hardening process and from moisture changes in the
paste.
Provides better durability than hydrated cement paste
alone.
Economical advantages.
10. In choosing aggregate for use in
particular concrete attention should be
given to three important requirements:
Workability when fresh for which the size and
gradation of the aggregate should be such that
undue labour in mixing and placing will not be
required.
Strength and durability when hardened for which
the aggregate should:
be stronger than the required concrete strength
contain no impurities which adversely affect strength
and durability
not go into undesirable reaction with the cement
be resistant to weathering action
11. Economy of the mixture: the aggregate should be
available from local and easily accessible
deposit or quarry
well graded in order to minimize paste, hence
cement requirement.
13. Aggregates
Based on source
Natural
Artificial
Recycled
Based on mode of
formation
Igneous
Sedimentary
Metamorphic
Based on
weight
Light
weight
Normal weight
Heavy
weight
Based on
size
Fine
Coarse
Based on chemical
composition
Argillaceous
Calcareous
Siliceous
13
14. Classification of aggregates
based on source
Natural aggregates are taken from natural
deposits without change in their nature during
production, with the exception of crushing, sizing,
grading, or during production. In this group
crushed stone, gravel, and sand are the most
common.
Manufactured aggregates include blast furnace
slag and lightweight aggregates.
Recycled Aggregate – e.g. crushed concrete,
clay bricks
15. Classification of aggregates
based on size
• Fine aggregate: < 4.75 (No.4 sieve)
• Coarse aggregate: predominantly retained
on the No.4 (4.75mm) sieve.
Coarse aggregate > 5 mm (10 mm, 20 mm,
40mm)
16. Classification based on
Condition
• Crushed
From quarry - sharp, angular
particles, rough surface, good
bond strength, low workability
• uncrushed
From river - round shapes,
smooth surface, low bonding
properties, high workability
17. Aggregate Terms and
Types
The terms used to describe aggregates are many
and varied. These descriptive terms are based on
source, size, shape, type, use and other properties.
Some typical terms used in describing
aggregates are:
1. Fine aggregate- aggregate particles passing the
No. 4 (4.75mm) sieve and retained on the No. 200
(75µm) sieve.
18. 2. Coarse aggregate- aggregate predominantly
retained on the No.4 (4.75mm) sieve.
3. Crushed gravel (gravel and sand)- that has
been put through a crusher either to break many of
the rounded gravel particles to a smaller size or to
produce rough surfaces.
19. 4. Crushed rock- aggregate from the crushing of
rock. All particles are angular, not rounded as in
gravel.
5. Screenings- the chips and dust or powder that are
produced in the crushing of rock for aggregates.
6. All-in-aggregate- aggregate composed of both
fine and coarse aggregate.
7. Concrete sand- sand that has been washed
(usually) to remove dust & fines.
8. Fines- silty-clay or dust particles smaller than 75
micro m (No.200 sieve) usually undesirable
impurities in aggregates.
20. Properties of Aggregates
Important properties of aggregates include:
Gradation (grain size distribution)
Shape and surface texture
Specific gravity (relative density)
Absorption
Hardness (resistance to abrasion or wear)
Durability (resistance to weathering)
Crushing strength
Cleanliness (deleterious substances)
Chemical stability
22. Grading: is the distribution of
particles of angular materials
among various sizes
23. The gradation of
aggregates influences:
the amount of paste required
the workability of the concrete
the strength and
water tightness of the finished product
In general, it is desirable that the size
increase uniformly from fine sand to the
maximum allowed for a given job.
Most specifications for concrete require a
grain size distribution that will provide a
dense and strong mixture.
24. Types of gradation
Aggregates may be:
Dense
Well graded
Gap-graded
Uniform
Open-graded
24
Well-graded
Poorly graded
25. 25
Grading of aggregates
The range of sizes
is approximately in
equal amounts
Well graded Uniform graded Gap graded
Most particles
are of large or
small size
Most particles
are of the
same size
26. Well graded aggregates:
Improve workability of the concrete and
economy of the cement.
Such aggregate has a decreased amount
of voids between the particles and
consequently requires less cement paste.
Produces a stronger concrete than a poorly
graded one (less water is required to give
suitable workability).
27. SIEVE ANALYSIS
The grading or particle size
distribution of aggregate is determined
by sieve analysis.
29. Special Use Gap-Graded
aggregates
When certain particle sizes are intentionally
omitted. Ex., for an aggregate of 19 mm maximum
size, the 4.75 mm to 9.5 mm particles can be
omitted without making the concrete harsh subject
to segregation.
Gap-graded mixes are used in architectural
concrete to obtain uniform textures in exposed –
aggregate finishes.
35. Rough-textured, angular, and
elongated particles require more
water to produce workable concrete
than smooth, rounded compact
aggregate. Consequently, the cement
content must also be increased to
maintain the water-cement ratio.
Flat, slivery pieces make concrete
more difficult to finish
36. Aggregate should be free of flat or
elongated particles. Because they
require an increase in mixing water
and thus may affect the strength of
concrete particularly in flexure.
Generally, flat and elongated particles
are avoided or are limited to about 15
percent by weight of the total
aggregate.
37. Chemical Stability
Aggregates need to be chemically
stable so that they will neither react
chemically with cement nor be
affected chemically by outside
influences.
In some cases aggregates with certain
chemical constituents react with alkalis
in cement. This reaction may cause
abnormal expansion and resultant
cracking of concrete.
39. Handling and Stockpiling of Aggregates
The purpose of appropriate handling and stock piling of
aggregates is to avoid breakage, segregation,
contamination, and degradation.
Precautions:
Storing on hard and dry ground or on platforms of
planks, sheets, lean concrete
Storing separately each aggregate size in compartments
Avoiding segregation of aggregates resulting from free
fall
Damping consignments at different places.
Proper collection and mixing of test batches is important
to ensure that test samples accurately represent the
aggregate in the entire stockpile.
44. The aim of mixing is to blend all of
the ingredients of the concrete to
form a uniform mass and to coat the
surface of aggregates with cement
paste.
45. Ready-Mix concrete: In this type
ingredients are introduced into a
mixer truck and mixed during
transportation to the site.
• Wet – Water added before
transportation
• Dry – Water added at site
Mixing at the site
• Hand mixed
47. Mixing time should be sufficient to
produce a uniform concrete. The
time of mixing depends on the
type of mixer and also to some
properties of fresh concrete.
Undermixing → non-homogeneity
Overmixing → danger of water loss,
breakage of aggregate particles
48. Hand Mixing
Adopted for small works and quantity of
concrete used is small
Procedure:
a. Sand + cement dry mix
b. Spread the sand -cement mix on a flat
platform
c. Spread the measured quantity of
coarse aggregate on the cement-sand
mix
49. d. Mix the cement + sand + c.agg. At least three times by
shoveling from center to the side and then back to the
center and again to the side
e. Make a hallow in the middle of the mixed pile and pour
slowly into it half to three-quarter of the total quantity of
water required
f. Add the remainder of the water slowly, turning the
mixture over and again until the color and consistency are
uniform throughout the pile
Note: 1. Time of mixing should not exceed 3 minutes
2. Mixing platform is cleaned at the end of the days
work, so that it is ready for use the next day
50. Machine mixing
Used in case of a
large quantity of
concrete is to be
produced
Concrete can be
produced at a faster
rate at a lesser cost
and of better quality
51. Transporting Concrete
1. Pans
- When quantity is small
- When access to work is restricted
- Method is tedious, slow and
costly
53. Transporting Concrete
3. Truck mixer
- When place of
deposit of concrete is at a
very long distance from the
mixer such that the
concrete cannot be
transported and placed
in the forms within 30
minutes
- Happens in case of
ready-mixed concrete
- Drum containing the
concrete rotates
continuously to prevent the
concrete from being stiff
and to prevent
segregation
54. 4. Belt conveyors
- When the concrete is to be transported continuously and to a
higher level
- Installed in an inclined position
- Concrete should be stiff consistency having a slump not more than
50 mm
5. Chutes
- When concrete is to be placed below ground level, the mixer may be
placed on an upper level and concrete discharged to the lower level
through a chute of corrugated iron or timber
55. 7. Pumps
- When large quantity of
concrete is to be
transported
continuously to
congested sites where
mixing plant can not be
installed
- To a maximum of 300
m horizontally and 40m
vertically
56. Placing of concrete
- Concrete should be placed and
compacted before setting commences
- Method of placing should be in such a
way as to prevent segregation ( should
not be dropped from a height more than
about 1m)
57. An elevation
column of
h=3.71m is being
casted with out a
window at
h=1.50m (one of
the reasons for
segregation).
58. Good construction methodology, in
casting columns from convenient
height by providing a window.
59. Formwork
Material
i. Timber Most commonly
used
ii. Plywood Bounded with
water proof synthetic resin
adhesives
iii. Hard board Manufactured
from wood fibers, usually
impregnated with drying oils
and factory applied plastic
coatings
iv. Metal forms very common
nowadays
63. Compaction of Concrete
When first placed in the form, normal
concrete excluding those with very low or
very high slumps will contain between 5%
and 20% by volume of entrapped air.
Compaction is the process which expels
entrapped air from freshly placed concrete
and packs the aggregate particles together
so as to increase the density of concrete.
64. Proper compaction
Increase significantly the ultimate strength of concrete
and Enhances the bond with reinforcement.
Increases the abrasion resistance and general durability
of the concrete,
Decreases the permeability and helps to minimize its
shrinkage-and-creep characteristics.
Also ensures that the formwork is completely filled – i.e.
there are no pockets of honeycombed material – and
that the required finish is obtained on vertical surfaces.
65. Stages of Compaction
Compaction of concrete is a two-
stage process.
First the aggregate particles are
set in motion and slump to fill
the form giving a level top
surface.
In the second stage, entrapped
air is expelled.
67. VIBRATION OF CONCRETE
The process of compacting concrete
consists essentially of the elimination of
entrapped air. This can be achieved by:
– Tamping or rodding the concrete
– Use of vibrators
68. VIBRATORS
Internal vibrator: The poker is immersed
into concrete to compact it. The poker is
easily removed from point to point.
External vibrators: External vibrators
clamp direct to the formwork requiring
strong, rigid forms.
70. Internal Vibrators
Diameter
of head,
(mm)
Recommended
frequency,
(vib./min.)
Approximate
radius of
action, (mm)
Rate of
placement,
(m3/h)
Application
20-40 9000-15,000 80-150 0.8-4
Plastic and flowing
concrete in thin
members. Also used for
lab test specimens.
30-60 8500-12,500 130-250 2.3-8
Plastic concrete in
thin walls, columns,
beams, precast piles,
thin slabs, and along
construction joints.
50-90 8000-12,000 180-360 4.6-15
Stiff plastic concrete
(less than 80-mm
slump) in general
construction .
Adapted from ACI 309
71. Systematic Vibration
CORRECT
Vertical penetration a few inches
into previous lift (which should not
yet be rigid) of systematic
regular intervals will give
adequate consolidation
INCORRECT
Haphazard random penetration
of the vibrator at all angles and
spacings without sufficient
depth will not assure intimate
combination of the two layers
72. To aid in the removal of trapped air the
vibrator head should be rapidly plunged into
the mix and slowly moved up and down.
Internal Vibrators
The actual completion
of vibration is judged
by the appearance of
the concrete surface
which must be neither
rough nor contain
excess cement paste.
73. External Vibrators
Form vibrators
Vibrating tables (Lab)
Surface vibrators
– Vibratory screeds
– Plate vibrators
– Vibratory roller
screeds
– Vibratory hand floats
or trowels
74. External vibrators are rigidly clamped to the
formwork so that both the form & concrete are
subjected to vibration.
A considerable amount of work is needed to
vibrate forms.
Forms must be strong and tied enough to
prevent distortion and leakage of the grout.
External Vibrators
75. Vibrating Table:
used for small
amounts of
concrete
(laboratory and
some precast
elements)
External Vibrators
76. Finishing concrete
Concrete that will be
visible, such as slabs like
driveways, highways, or
patios, often needs
finishing. Concrete slabs
can be finished in many
ways, depending on the
intended service use.
77. Options include various colors and textures, such as
exposed aggregate or a patterned-stamped surface.
Some surfaces may require only strike off and screeding
to proper contour and elevation, while for other surfaces
a broomed, floated, or troweled finish may be specified.
In slab construction, screeding or strike off is the process
of cutting off excess concrete to bring the top surface of
the slab to proper grade. A straight edge is moved across
the concrete with a sawing motion and advanced forward
a short distance with each movement.
78. Curing Concrete
Curing is the process which controls the loss of
moisture from concrete either after it has been
placed in position (or during the manufacture of
concrete products), thereby providing time for the
hydration of the cement to occur.
Since the hydration of cement does take time –
days, and even weeks rather than hours – curing
must be undertaken for a reasonable period of
time if the concrete is to achieve its potential
strength and durability.
79. CURING OF CONCRETE
Properties of concrete can improve with age as
long as conditions are favorable for the
continued hydration of cement. These
improvements are rapid at early ages and
continues slowly for an indefinite period of
time.
Curing is the procedures used for promoting
the hydration of cement and consists of a
control of temperature and the moisture
movement from and into the concrete.
80. Curing Methods
1. Methods which supply additional water to the surface
of concrete during early hardening stages.
– Using wet covers
– Sprinkling
– Ponding
81. Curing Methods
2. Methods that prevent loss of moisture
from concrete by sealing the surface.
– Water proof plastics
– Use liquid membrane-forming compounds
– Forms left in place
82. 3. Methods that accelerate strength gain by supplying
heat & moisture to the concrete.
– By using live steam (steam curing)
– Heating coils.
Curing Methods
83. PROPERTIES OF FRESH
CONCRETE
Workability
Consistency
Segregation
Bleeding
Setting Time
Unit Weight
Uniformity
84. WORKABILITY
It is desirable that freshly mixed concrete
be relatively easy to transport, place,
compact and finish without harmful
segregation.
A concrete mix satisfying these
conditions is said to be workable.
85. Factors Affecting Workability
Method and duration of transportation
Quantity and characteristics of cementing
materials
Aggregate grading, shape and surface texture
Quantity and characteristics of chemical
admixtures
Amount of water
Amount of entrained air
Concrete & ambient air temperature
86. WORKABILITY
Workability is the most
important property of
freshly mixed concrete.
There is no single test
method that can
simultaneously measure all
the properties involved in
workability.
It is determined to a large
extent by measuring the
“consistency” of the mix.
87. Consistency is the fluidity or degree of
wetness of concrete.
It is a major factor in indicating the workability
of freshly mixed concrete.
Test methods for measuring consistency are:
Flow test → measures the amount of flow
Kelly-Ball test → measures the amount of
penetration
Slump test (Most widely used test!)
CONSISTENCY
88. Slump Test is related with the ease with
which concrete flows during placement
89. 10 cm
20 cm
30 cm
The slump cone is filled in 3 layers. Every
layer is evenly rodded 25 times.
Measure the slump by determining the vertical difference
between the top of the mold and the displaced original center
of the top surface of the specimen.
90.
91. Segregation refers to a separation of the components of
fresh concrete, resulting in a non-uniform mix
The primary causes of segregation are differences in
specific gravity and size of constituents of concrete.
Moreover, improper mixing, improper placing and
improper consolidation also lead to segregation.
SEGREGATION
92. Some of the factors affecting segregation:
– Larger maximum particle size (25mm) and
proportion of the larger particles.
– High specific gravity of coarse aggregate.
– Decrease in the amount of fine particles.
– Particle shape and texture.
– Water/cement ratio.
SEGREGATION
93. Bleeding is the tendency of water to rise to
the surface of freshly placed concrete.
BLEEDING
It is caused by the
inability of solid
constituents of the
mix to hold all of
the mixing water
as they settle
down.
A special case of
segregation.
94. Undesirable effects of bleeding are:
• With the movement of water towards the top, the top
portion becomes weak & porous (high w/c). Thus
the resistance of concrete to freezing-thawing decreases.
• Water rising to the surface carry fine particles of
cement -This portion is not resistant to abrasion.
• Water may accumulate under the coarse agg. and
reinforcement. These large voids under the particles may
lead to weak zones and reduce the bond between
paste and agg. or paste and reinforcement.
BLEEDING
95. The tendency of concrete to bleeding
depends largely on properties of cement.
It is decreased by:
Increasing the fineness of cement
Increasing the rate of hydration
Adding pozzolans
Reducing water content
BLEEDING
96. Hot Weather Concrete
Rapid hydration early setting rapid loss of
workability
Extra problems due to
– Low humidity
– Wind, excessive evaporation
– Direct sunlight
Solutions
– Windbreaks
– Cooled Concrete Ingredients
– Reflective coatings/coverings
97. Cold Weather Concrete
Keep concrete temperature above 5 °C to
minimize danger of freezing
Solutions
– Heated enclosures, insulation
– Rely on heat of hydration for larger sections
– Heated ingredients --- concrete hot when placed
– High early strength cement
98. UNIFORMITY OF CONCRETE
Concrete uniformity is
checked by conducting
tests on fresh and
hardened concretes.
Slump, unit weight, air
content tests
Strength tests
99. UNIFORMITY OF CONCRETE
Due to heteregeneous nature of concrete,
there will always be some variations. These
variations are grouped as:
– Within-Batch Variations : inadequate mixing,
non-homogeneous nature
– Batch-to-Batch Variations : type of materials
used, changes in gradation of aggregates,
changes in moisture content of aggregates
100. PROPERTIES OF
HARDENED CONCRETE
The principal properties of hardened
concrete which are of practical importance
can be listed as:
1. Strength
2. Permeability & durability
3. Shrinkage & creep deformations
4. Response to temperature variations
Of these compressive strength is the most
important property of concrete.
101. PROPERTIES OF
HARDENED CONCRETE
Of the abovementioned hardened
properties compressive strength is one
of the most important property that is
often required, simply because;
1. Concrete is used for compressive loads
2. Compressive strength is easily obtained
3. It is a good measure of all the other
properties.
105. STRENGTH OF CONCRETE
The strength of a concrete specimen
prepared, cured and tested under
specified conditions at a given age depends
on:
1. w/c ratio
2. Degree of compaction
106. COMPRESSIVE STRENGTH
Compressive Strength is determined by
loading properly prepared and cured
cubic, cylindrical or prismatic specimens
under compression.
107. COMPRESSIVE STRENGTH
Cubic: 15x15x15 cm
Cubic specimens are crushed after rotating
them 90° to decrease the amount of friction
caused by the rough finishing.
Cylinder: h/D=2 with h=15
To decrease the amount of friction,
capping of the rough casting surface is
performed.
111. Leaching & Efflorescence
When water penetrates into concrete, it
dissolves the non-hydraulic CH (and
various salts, sulfates and carbonates of
Na, K, Ca)
Remember C-S-H and CH is produced
upon hydration of C3S and C2S
These salts are taken outside of concrete
by water and leave a salt deposit.
112.
113. Sulfate Attack
Ground water in clayey soils containing alkali
sulfates may affect concrete.
These solutions attack CH to produce gypsum.
Later, gypsum and calcium alumina sulfates
together with water react to form “ettringite”.
Formation of ettringite is hardened cement
paste or concrete leads to volume expansion
thus cracking.
Moreover, Magnesium sulfate may lead to the
decomposition of the C-S-H gel.
114.
115. Seawater contains some amount of Na and Mg
Sulfates. However, these sulfates do not cause
severe deleterious expansion/cracking because
both gypsum and ettringite are soluble in
solutions containing the Cl ion. However, problem
with seawater is the frequent wetting/drying and
corrosion of reinforcing steel in concrete.
To reduce the sulfate attack
1. Use low w/c ratio→ reduced permeability & porosity
2. Use proper cement → reduced C3A and C3S
3. Use pozzolans → they use up some of the CH to
produce C-S-H
Sulfate Attack
116. Acid Attack
Concrete is pretty resistant to acids. But in
high concentrations:
Causes leaching of the CH
Causes disintegration of the C-S-H gel.
117. Carbonation
Ca(OH)2 + CO2 → CaCO3 + H2O
Accompanied by shrinkage → carbonation
shrinkage
Makes the steel vulnerable to corrosion
(due to reduced alkalinity)
118.
119. Alkali-Agg. Reactions
Alkalies of cement + Reactive Silica of Aggs
→ Alkali-Silica Gel
Expansions in volume
Slow process
Don’t use aggs with reactive silica or use
cements with less alkalies.
120.
121. Corrosion
Electrochemical reactions in the steel rebars
of a R/C structure results in corrosion
products which have larger volumes than
original steel.
Thus this volume expansion causes cracks in
R/C. In fact, steel is protected by a thin film
provided by concrete against corrosion.
However, that shield is broken by CO2 of air
or the Cl- ions.
122.
123. Freezing and Thawing
Water when freezes expands in volume.
This will cause internal hydraulic pressure
and cracks the concrete.
To prevent the
concrete from this
distress air-entraining
admixtures are used
to produce air-
entrained concrete.