REQUIREMENTS OF FORMWORK – QUALITY, SAFETY & ECONOMY In the selection of materials for formwork, the three general principles of quality, safety and economy must be paramount. Material quality can ensure safety, and significantly contributes to the achievement of economy. Formwork failure can result in loss of life and always causes catastrophic financial loss. Some … Read more
Types of Chemical Admixtures for Concrete Unlike mineral admixtures, which may be introduced as blended cements, chemical admixtures are typically added during the mixing process of concrete production. Depending upon the requirement, different types of chemical admixtures are manufactured such as air-entraining admixtures, accelerating admixture, water reducing admixture etc. To a civil engineer, description of … Read more
Tremie Concreting – On Site Precautions During tremie concreting the following precautions are to be taken while doing the work: The concrete should be coherent, rich in cement (not less than 370 kg/m3) and of slump between 150 and 180 mm. When concreting is carried out under water, a temporary casing should be installed to … Read more
Quality Requirements of Pumped Concrete Pumped concrete can be used for most structural concrete construction but is most useful where space for construction equipment is limited or access is difficult. Concrete pumps can be either truck- or trailer mounted and range from small units, exerting pressures from 250 to 300 psi and outputs of 15 … Read more
Concrete Placing As with the handling of concrete, certain fundamental considerations govern placing techniques. First and perhaps foremost is the need to avoid segregation of the concrete caused by improper techniques. Second is the need to ensure thorough compaction of the concrete. The manner in which concrete is placed can have a significant influence on … Read more
What is Compaction of Concrete? Compaction of concrete is one of the important site operations that together enable the fresh concrete to reach its potential design strength, density and low permeability. Properly carried out it ensures that concrete fully surrounds and protects the reinforcement, tendons and cast-in inserts. It also has a direct impact on … Read more
Placing of Concrete in Hot Weather For normal concreting operations the temperature of concrete should vary between 150C to 250C to enable it to attain its full ultimate strength within 28 days. In case concreting is carried out in extreme hot weather conditions, the rate of hydration of cement gets accelerated and the water in … Read more
Concrete Placing Precautions The concrete, as it comes out of the mixer or as it is ready for use on the platform, is to be transported and placed on the formwork. Following precautions should be taken during placing of concrete. The formwork or the surface which is to receive the fresh concrete should be properly … Read more