Investigation Of The Effects Of High-Water Temperature On Concrete Properties.

Abstract

Concrete is an extensively used construction material in the world due to its versatility and ready availability. Many structures have concrete as their principal structural material and all concrete structures are exposed to the environment. The environments within which concrete is also used vary widely (cold to warm, dry to wet, repeated temperature and humidity changes, etc.), it is a mistake to assume that any concrete are stable under all conditions. This basic concept is often neglected, thus resulting in premature deterioration of structural concrete components and products. This study was aimed to investigate the effects of high-water temperatures on concrete properties. In order to achieve the objective, an experimental study was carried out on fresh and hardened concrete properties at mixing and curing water temperatures of 22 ℃ (control), 30 ℃, 38 ℃ and 46 ℃. 25 MPa concrete grade with a mix ratio of approximately 1:2.2:2.9 having w/c of 0.56 was produced. Eighteen cubic specimens for each mixing and curing water temperature using two cement types were cast and tested for compressive strength after curing ages of 1, 3, 7, 28, 56 and 90 days; and each 3 cylindrical specimens were prepared and tested for split tensile strength after curing age of only 28 days. Based on experimental results, the specimens produced with lower mixing water temperature (at 22℃) were better in their fresh properties than specimens with higher mixing water temperatures (30℃, 38℃ and 46℃). Compressive strength test results showed 25% and 23% reduction after 90 days for OPC and PPC mixes at mixing and curing water temperature of 46 ℃ respectively. During early ages, the highest percentage increase in compressive strength was +17.18% after 1 day for OPC and +17.29% after 3 days for PPC mixes at 46 ℃. Generally, the specimens mixed and cured with higher water temperature showed better compressive strength results during their early ages (1, 3 and 7 days) than the specimens mixed and cured with lower water temperature. However, the specimens mixed and cured with lower water temperature showed better compressive strength results at their later ages (28, 56 and 90 days) than the specimens with higher water temperatures. The enhanced workability and maximum long-term compressive strength were obtained at mixing and curing water temperature of 22 ℃. Finally, it was recommended that concrete producers especially in hot or arid environmental areas should give a special attention to such parameters; hence a small parameter like water temperature could have impact on performance of concrete.