Freezing–thawing durability and its improvement of high strength shrinkage compensation concrete with high volume mineral admixtures

Abstract

Freeze–thaw durability of high volume mineral admixture shrinkage compensation concrete was studied by using accelerated freeze–thaw procedure in this paper. Three types of concrete were investigated, namely High Strength Concrete (HSC), High Strength Shrinkage Compensation Concrete (HSSCC) and Steel Fiber Reinforced High Strength Shrinkage Compensation Concrete (SFRHSSCC). The hydration products and microstructure were investigated by using X-ray diffractometer (XRD) and Scanning electron microscopy (SEM). Results show that freeze–thaw durability of HSSCC is 34.2% shorter than that of HSC, and the deterioration is characterized by the surface cracks induced by the dilation due to the transformation of AFm–AFt. Steel fiber can restrain the damage caused by mineral admixtures, and the freeze–thaw life of SFRHSSCC is prolonged by 33.5% when compared with HSSCC. SEM images of SFRHSSCC show that its microstructure is mainly composed of close-grained CSH gel plank, among which AFt and AFm crystals are wrapped. Deterioration is characterized by surface scaling, which is caused by the combined effect of hydraulic pressure, infiltration pressure and dilation pressure, among which the dilation pressure of AFt makes important contribution.