Abstract:
Pouring concrete in hot weather has a significant impact on the concrete pouring process, due to the ability of the high temperature to evaporate the water present in the concrete mixture, whose main task is to complete the hydration process of the cement.
In Khartoum city – Sudan, the air temperature is very high during the summer and there is fluctuation in temperature throughout the year, and in hot weather it is difficult to carry out concrete work. The main problem in hot weather is the increased demand for water due to the high temperature , the most important of which is reducing the compressive Strength of concrete.
In this study a questionnaire was made and distributed to engineers , tests were conducted on four concrete mixes designed according to the British code (BS) to know the effect of high temperature of the mix on the compressive strength . In the first mixture coarse aggregate was heated to temperature of ( 50cº ) to simulate the natural conditions in the site , the second mixture sprayed aggregate with water for cooling, the third mixture used cold water for mixing , the fourth mixture aggregate was sprayed with normal water 24cº for cooling and cold water 12.3cº was used for mixing.
The first mixture is considered a standard mixture and the rest of the mixtures are attempts to reduce the temperature of the concrete mix and the compressive strength was measured during (7&28) days.
It was found that use of cold water in concrete mixing leads to a decrease in the temperature of the fresh concrete during mixing and pouring, as in the third and fourth mixture the temperature decreased to 32.9 cº and 27.2 cº compared to the first (standard) mix of 38.5 cº.
The results show that the lowest temperature of mixture 27.2 cº ,was in fourth mixture, has the highest compressive strength at 28 days of 39.99 N/mm².
The results of the questionnaire that were distributed to the engineers at the construction site showed that 56.76% of the engineers did not care about the weather conditions during the mixing and pouring concrete and 56.76% did not care about the temperature measurement degree of the concrete mix.
