Why cement mortar need to be consumed within 30 min just after it is mixed? Cement mortar is a mixture of cement, sand, and water used for various construction purposes such as plastering, masonry, and laying bricks. The reason why cement mortar needs to be consumed within 30 minutes after its preparation is due to … Read more
Types of Concrete additives Concrete additives are usually liquid and are only added in very small amounts whilst mixing the concrete. They have a physico-chemical action and are classified into so-called efficiency groups depending on their effect in freshly mixed or hardened concrete. 1. Concrete deflocculants These concrete additives depressurise the water, improving workability while … Read more
Distinctions are drawn between different types of concrete based on the composition, additives, surfaces, production process, or the nature of the reinforcement.
The packing density of aggregate gives an indication of how efficiently aggregate fill a certain volume and for that reason is such an important concept in concrete technology.
From High Strength to High Performance Concrete Durability of concrete is now becoming the major concern for engineers as concrete may deteriorate with time in several ways. The most common durability failures in an outdoor climate are due to reinforcement corrosion or frost attack. In special environments concrete may suffer from chemical attack by various … Read more
Essential requirements of formwork are it should be strong enough to take the dead loads, live loads, incidental loads and other loads expected during construction before attaining the strength by the concrete.
The process of selecting concrete mixture proportions is a process of optimization of several desirable characteristics based on the project requirements. The characteristics to be optimized are economy, strength, durability, and placeability. 1. Economy. The primary reason for systematically determining mixture proportions is economy. The maximum economy can be achieved by minimizing the amount of … Read more
Rebound Hammer Test The Schmidt rebound hammer is principally a surface hardness tester with little apparent theoretical relationship between the strength of concrete and the rebound number of the hammer. However, within limits, empirical correlations have been established between strength properties and the rebound number. Further, scientist has attempted to establish a correlation between the … Read more
Properties of Hardened Concrete 1. Strength: Concrete is strong in compression but relatively weak in tension and bending. It takes a great deal of force to crush concrete, but very little force to pull it apart or cause bending cracks. Compressive strength is determined primarily by the amount of cement used, but is also … Read more
INFLUENCE OF AGGREGATE PROPERTIES ON CONCRETE Aggregates influence the properties of concrete/mortar such as water requirement, cohesiveness and workability of the concrete in plastic stage, while they influence strength, density, durability, permeability, surface finish and colour in hardened stage. Aggregates are generally classified into two categories viz. natural and manufactured/processed. Geologically aggregates may be obtained … Read more