15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad Module 3: Concrete The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged 1 15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad • Fresh state – shows behavior similar to that of a fluid, can be pumped, acquires the shape of the mold in which it is poured and little resistance to deformation. • Hardened state – solid material with substantial compressive strength and durability characeristics The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged 2 15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad Properties that we look for Fresh Properties • Workability • Air content • Segregation • Setting time • Bleeding • Temperature The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged Hardened Properties • Compressive strength • Tensile strength • Flexural strength • Shrinkage and creep • Durability • Permeability 3 15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad Workability • Workability of Concrete is a broad and subjective term describing how easily freshly mixed concrete can be mixed, placed, consolidated, and finished with minimal loss of homogeneity. • As per ASTM C 125, Workability is the property determining the effort required to manipulate a freshly mixed quantity of concrete with minimum loss of homogeneity • ACI defines workability as property of freshly mixed concrete or mortar which determines the ease and homogeneity with which it can be mixed, placed, consolidated and finished The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged 4 15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad • Workability is a property that directly impacts strength, quality, appearance, and even the cost of labor for placement and finishing operations. • The desired workability is not same for all types of concrete. More workability is required for a thin inaccessible section or heavily reinforced section rather than a mass concrete body The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged 5 15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad Desirable Workability for Construction • Section size, amount and spacing of reinforcement: When a section is narrow, complicated, several narrow corners, inaccessible parts; a highly workable concrete is desirable to obtain full compaction through a reasonable amount of effort. • When the section is crowded with steel reinforcement and spacing of bars is relatively small, compaction can be difficult and hence highly workable concrete is recommended in such cases. • If there are no limitations of the critical section or heavy reinforcement, we can get a wide range of workability for concrete casting. • Method of compaction: If concrete is compacted manually, more workability is recommended because hand compaction is not very much uniform and effective. • If there is a scope of the vibrator or machine compaction, we can choose workability from a wide range. The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged 6 15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged 7 15-09-2021 CEC203: Building Material, Construction and Management Department of Civil Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad Factors Affecting Workability • • • • • • Cement type and quantity Water content Aggregate shape and surface texture Aggregate gradation Admixtures Ambient Temperature The content should be used only for educational purpose because it contains various copyright content. In the development of the course material published content of several authors have been used and their contribution is gratefully acknowledged 8
