Whenever concrete is to be placed under extreme weather conditions or under water its performance is affected to a great extent if appropriate measures are not taken to control these conditions. Extreme weather conditions include situations where environmental temperature during the production, and placing of concrete and subsequent curing period are markedly different from those of normal conditions i.e., either [...]
In this article we will discuss about the placement of large concrete masses. When large volumes of plain (un-reinforced) concrete are placed in position such as in gravity dams or spillways, the concrete is known as mass concrete. In mass concrete there is always a danger of thermal cracking due to restraint to contraction of concrete on cooling from a [...]
The following measures suggested by IS 7861-Part-II 1981 should be adopted to avoid freezing of concrete: 1. Preservation and Utilization of Heat of Hydration 2. Selection of Suitable Type of Cement 3. Pre-Heating of Concrete Ingredients (Materials) 4. Aggregate Heating 5. Cement Heating 6. Use of Accelerating Admixtures 6. Use of Accelerating Admixtures 7. Use of Air Entrainment and a [...]
In this article we will discuss about the precautions to be taken in hot weather and cold weather concreting. Precautions of Concreting in Hot Weather: To improve the quality of concrete, it is necessary that the temperature of the freshly mixed concrete should be as low as possible. It can be obtained by keeping the temperature of its ingredients as [...]
Following methods can be adopted for placing concrete under water. The methods are: 1. Placing of Concrete in Dewatered Caissons or Coffer Dams 2. Tremie Method 3. Bucket Placing Method 4. Concrete Filling in Bags 5. Pre-Packed Concrete or Grouting Method. Method # 1. Placing of Concrete in Dewatered Caissons or Coffer Dams: In this method same procedure is used [...]