Summer season is all over us. The temperatures are soaring high all across India, marking the arrival of the summer season in full force. The temperature has crossed 40°C in many areas. Also similar to the rising temperature, another thing that is also rising is the construction of buildings. As we know excessive heat is not good for the people involved in the construction, well it is the same case for the buildings. More specifically, the setting of concrete.
What is Hot weather concreting?
Hot weather is defined as a condition in which the temperatures are significantly high such that it is quite difficult for us to endure. In the case of concrete hot weather has the tendency to compromise the quality of freshly prepared or hardened concrete by accelerating the rate of moisture loss and rate of cement hydration. Hot weather is more common during the summer season and it usually arises due to any one of the following causes
Hot weather must be taken into consideration when planning building construction. Also, the preparation and curing of concrete must be taken great care in hot weather. During the hot weather, certain problems can be encountered in the preparation, placement and curing of concrete. The high temperatures result in rapid hydration of cement, increased evaporation of mixing water which in turn require more water demand for mixing and large volume changes, resulting in cracks etc.
The presence of high temperatures resulting from hot weather is not good for the concrete. This, in turn, can cause the following effects which are as follows:
Reduction in strength: High-temperature results in faster hydration of water in the concrete mix which in turn requires more water for concrete mixing. This eventually reduces the strength of the concrete which in turn reduces the strength of the constricting structure.
Forming cracks: Due to the rapid evaporation of water in the concrete either before or after hardening, the formation of cracks results in the hardened concrete. Cracks may also develop from the cooling of concrete from its elevated initial temperature.
Rapid Evaporation: As mentioned earlier, hot weather rapidly evaporates the concrete mix which makes it difficult to retain moisture and maintain reasonably uniform temperature conditions during the curing period.
In order to minimise the above-mentioned problems, it is recommended to take the following precautions. During hot temperatures avoid concreting, especially during the time period 11 am to 4 pm. Handling and storing the materials such as cement, sand, stone aggregates and water in a place where hot temperatures do not directly affect like a shed. The most important attention should be to protect all the surfaces from rapid drying. When the mixing of concrete is completed, it must be protected from the evaporation of moisture by placing wet gunny bags, hessian cloth etc. The bags must not be dripping.
Construction is an ongoing and necessary process that cannot be personalised, and so steps to overcome the difficulties presented by the climatic and seasonal changes should be adopted. The heatwave is just one such difficulty experienced in construction phase which can be overcome with proper precaution and necessary steps. But a major factor to note is to ensure the safety of labourers especially during times of heatwaves and to plan and implement steps to reduce the chances of workers in peril due to heatwaves.