Month: January 2023

Compaction of concrete has to be done as early as possible after placing the concrete in place. The purpose of compaction is to expel air and bring the particles closer so as to reduce the void and make the concrete denser. This increased density will give higher strength and make the concrete impermeable. Over-compaction leads… Continue reading Compaction of Concrete

The mixed concrete should be conveyed to the concreting yard as early as possible but within the initial setting time of the cement. The choice of conveyance depends on several factors, viz., nature of work, distance from the mixing place to the construction site, height to be lifted, type of cement, etc. During the transit… Continue reading Conveyance of Concrete

Mixing of concrete may be done by hand or by a machine. Mixing should be done thoroughly so that the ingredients are uniformly distributed, and this can be judged by uniform colour and the consistency of concrete. On a clean, hard and water-tight platform cement and sand are mixed dry using shovels until the mixture… Continue reading Mixing of Concrete

In this batching method, two units of measurements are employed: liquids are measured in litres and solids in cubic metres. That is all ingredients, viz., water, cement, sand and coarse aggregates are measured in litres, while the end-product concrete is measured in cubic metres. In volume batching, other quantities are measured keeping cement as the… Continue reading Volume Batching

After fixing, the desired proportion of quantity of required ingredients, viz., cement, coarse-aggregate, fine-aggregate, cement and sand, has to be measured out in batches for mixing. This process of measuring out ingredients is called batching. Batching may be done by weight or by volume. Volume batching is inferior to weight batching as using the former… Continue reading Batching of Materials

After fixing, the desired proportion of quantity of required ingredients, viz., cement, coarse-aggregate, fine-aggregate, cement and sand, has to be measured out in batches for mixing. This process of measuring out ingredients is called batching. Batching may be done by weight or by volume. Volume batching is inferior to weight batching as using the former… Continue reading Batching of Materials

Selection of the proper quantity of cement, coarse aggregate, sand and water to obtain the desired quality is known as proportioning of concrete. Concrete is formed by successive filling of voids in aggregate by sand, the voids in sand by cement and voids in cement by water and undergoing a chemical reaction. The concrete formed… Continue reading Proportioning of Concrete

While manufacturing concrete, it should be ensured that every batch of concrete has the same proportions. This is a mandatory requirement so as to satisfy two aspects, viz., same workability and uniform strength. In the manufacturing of concrete the following steps are followed:

Bureau of Indian Standards (BIS) has recommended a Mix Design Concept mainly based on the research works performed in national laboratories. This method can be applied for both medium-strength and high-strength concretes. The step-by-step approach of the BIS mix design is given below. Table 8.10 Adjustment of value in water content and sand percentage for other… Continue reading Bureau of Indian Standards (BIS) Method of Mix Design

This method has been used since 1944 and has undergone several revisions continuously. It has developed an identical procedure for angular or rounded aggregates, regular or light-weight aggregates and air-entrained or non-air-entrained concretes. The ACI mix design is based on certain factors which are established by field experience on large works. The factors are as… Continue reading American Concrete Institute (ACI) Method of Mix Design