It is advisable to use clean water fit for drinking purposes for making cement concrete. However, at places where sea water is available in abundance and potable water is costly, the sea water can be used for making cement concrete. The problem of using sea water for making cement concrete has to be studied from … Read more
Advantages of Slump Test It grants the facility to easily detect the difference in water content of successive batches of concrete of the same identical mix. The apparatus is cheap, portable and convenient to be used at site. Limitation of Slump Test As such, there is no direct relationship between the workability and the value … Read more
The grading of coarse aggregate may be varied through wider limits than that of fine aggregates, since it does not affect the workability, uniformity and finishing qualities of concrete mix. As per IS-383 the grading limit of coarse aggregate, both for single size as well as graded should be as per the table given below. … Read more
Aggregate Classification [Based on Shape] According to shape the aggregate is classified as Rounded aggregate Irregular or partly rounded aggregate Angular aggregate Flaky aggregate Elongated aggregate Flaky and elongated aggregate 1. Rounded Aggregate The aggregate with rounded shape has the minimum percentage of voids ranging from 32 to 33%. It gives minimum ratio of surface … Read more
Concrete is prepared by mixing aggregate, cement and water in such a proportion that it becomes workable in its plastic state and durable in its hardened state. Our aim is to satisfy both of these requirements i.e. workability and durability. Importance in terms of Workability A workable concrete can be achieved by adding more water, … Read more
Aggregate should have the following qualities Quality Requirements of Aggregate Aggregates should be strong, hard, dense, durable, clear and free from veins and adherent coating. Aggregates should be free from injurious amounts of disintegrated pieces, alkalis, vegetable matter and other deleterious substances. Flaky and Elongated pieces should not be present in aggregate mass. Aggregate crushing … Read more
Determination of setting time of concrete helps a site engineer in guiding the following areas. Importance of Setting Time of Concrete Whether or not to use any plasticizer To find out effectiveness of set controlling admixture Regulating maximum time of mixing transit, placing and compacting Whether or not to provide protection against adverse weather condition … Read more
The setting time of concrete depends upon following factors, such as Water-cement ratio Temperature condition Type of cement used Use of mineral admixture Use of chemical admixture (such as plasticizer) Other factors which may affect the setting time of concrete includes Absorption of mixing water by aggregates Grinding of aggregates in the mixer Of all … Read more
The various process involved in any concreting operation involves the following stages. Mixing Transporting Placing Consolidating As concrete passes from one stage to another, it starts to lose its plasticity characteristics. If after placing it is not disturbed for a longer time period, then it starts to become stiffening. As a result concrete changes its … Read more
California Bearing Ratio or CBR test is the ratio of the force per unit area required to penetrate a soil mass with a standard circular piston of 50 mm dia, at the rate of 1.25 mm/min to that of force required to penetrate sample of compacted stone having CBR of 100%. The standard load corresponding … Read more