Effect of chemical admixtures on loaded reinforced concrete columns in fire

This investigation reports on a comparative study of the residual capacity at elevated temperature of loaded reinforced concrete column specimens containing different types of chemical admixtures and coarse aggregate. Three types of aggregate were employed named gravel, dolomite and basalt as well as three types of admixtures named superplasticizer, setting retarder and setting accelerator. 12 concrete mixes were prepared. Each mix contained two column specimens. One of them was tested at ambient temperature to determine its load capacity and the second was loaded with working load and exposed to 650°C for 30 minutes. During heating, the temperature at different locations on the mid height section of the specimen were recorded every 5 minutes. The results showed better performance of basalt and dolomite concretes without admixtures, after firing. Adversely, when admixtures are included, gravel concrete performs better than basalt and dolomite concretes, after firing.