土木工程概论(英文版)Chapter-2-Materials-for-Civil-Engineering课件

土木工程概论（英文版）Chapter 2 Materials for Civil Engineering,土木工程概论（英文版）Chapter 2 Materials,Materials for Civil Engineering,What is Materials of Civil Engineering?,It covers the development,processing,evaluation,applications,and performance of construction materials in civil engineering.,Wide varieties of materials are used for making engineering structures and buildings.It is necessary for an engineer to have a basic knowledge of these materials which are available either from natural resource or manufactured.,Materials for Civil Engineerin,Stones:,Stones are used in Civil Engineering constructions in different forms.,Stone blocks irregular in size called rubbles are used for building walls.,Smaller irregular stones are used for constructing the base of floors and roads.,Stones broken into smaller pieces are called aggregates.,Stones required in these ways are obtained from rocks.,Materials for Civil Engineering,Stones:Materials for Civil Eng,Bricks:,Common building bricks are rectangular solids,made of burnt clay.,The earth used for the manufacture of bricks should contain 2030%of clay,2540%of sand and 2535%of silt.,The manufacture of bricks involves the following four operations:,Preparation of clay,Moulding,Dry,Burning,Materials for Civil Engineering,Bricks:Materials for Civil Eng,Uses of bricks:,The construction of walls to carry the loads from roofs to the foundation,To construct walls for partitioning a room or enclosing an area,The construction of gutters,drains and arches,Hollow bricks are used for sound and heat insulation purposes,Fire bricks are used for insulating chimneys and ovens,Facing bricks are used for ornamental purposes,Sometimes,bricks are used for paving of footpaths or industrial floors,Materials for Civil Engineering,Uses of bricks:Materials for C,Cements:,Even in 100 BC,Roman builders used a special volcanic ash for cementing stones.,When this ash was mixed with limestone,burnt and combined with water,it became a very strong cement.,The builders found this cement would harden with water.,Hence,it was called Hydraulic cement.,Materials for Civil Engineering,Cements:Materials for Civil E,Uses of cements:,To make cement mortar and cement concrete,Wide varieties of purposes staring from ordinary foundation to roofs of multistory skyscrapers,Sulphate resisiting cement is used to protect the foundations and other components in contact with the earth against the chemical action of sulphate in the soil,Rapid hardening cement and early strength cement have been used in works which need early strength gain like chimneys and underwater concreting,White and colored cements are used for making ornamental plastering and floor finish,Materials for Civil Engineering,Uses of cements:Materials for,Concrete:,When stone or gravel,sand,cement and water are mixed together,they form an easily workable plastic mixture which can be moulded and cast into desired shapes or structures.,This cement and water in the plastic mixture undergo a chemical combination in a few hours after the mixing results in a solidification and gradual hardening.,This mixture is called concrete.,Materials for Civil Engineering,Concrete:Materials for Civil,Concrete:,Concrete is a structural material which consists of Portland cement,aggregate(sand and rock),and water(to make the chemical reaction called hydration occur).,Concrete can sometimes contain other substances,such as fly ash from industrial smoke stacks,which can change its properties.,Materials for Civil Engineering,Concrete:Materials for Civil,Concrete:,Concrete is a very strong material when it is placed in compression.It is,however,extremely weak in tension.It is for this reason that we use reinforcement in concrete structures.The reinforcement,which is usually steel,takes up the slack for the weakness of the concrete in tension.,Materials for Civil Engineering,Concrete:Materials for Civil,Concrete:,There are many ways to test the strength of a batch of concrete.The tests used can be categorized as destructive and nondestructive tests.We will perform both types of tests in this class.,Materials for Civil Engineering,Concrete:Materials for Civil,Concrete:,Usually when a batch of concrete is ordered on a job site it is specified to be of a specific compressive strength-4000 psi,for instance.When the concrete comes to the job site in a ready-mix truck,the contractor places some of the batch in cylinders which are 6 inches in diameter and 12 inches in height.,Materials for Civil Engineering,Concrete:Materials for Civil,Concrete:,These cylinders are cured for 28 days and tested by compression until they are crushed.This will give the contractor or the engineer the compressive strength for that batch of concrete.He or she can then compare that value to the design value used to make sure that the structure was constructed properly.,Materials for Civil Engineering,Concrete:Materials for Civil,Concrete:,Once the concrete has been placed for a particular structure,there is a nondestruc