A comparative study on the performance of limestone-blended cement mortars exposed to cold curing conditions

In recent years concrete producers have increasingly preferred limestone-blended cements as they offer some technical and economical advantages as well as environmental benefits. The long-term performance of these cement types in extreme conditions such as acidic or basic environments in cold regions may, however, be problematic if the blend includes a large amount of limestone powder. In the present study, the effects of different pH environments on the mechanical performance of limestone-blended cement mortars at normal (20°C) and low (5°C) temperatures were investigated. For this purpose, prismatic mortar samples (40 mm × 40 mm × 160 mm) were prepared with limestone-blended cements (0, 10, 20, 30, 40 and 50% limestone powder was replaced by cement) and cured under different solutions (acidic, neutral and basic) at 5°C. In addition, standard curing at 20°C was also performed. Compressive and flexural strength developments of mortars were monitored at different ages and microstructure studies using scanning electron microscopy–energy dispersive spectroscopy and X-ray diffraction were performed on selected samples. It was concluded that the addition of limestone decreased both the strength and rate of strength development of the mortars at standard conditions. For cold and acidic solutions, the compressive strength loss was more significant than flexural strength loss as the amount of limestone replacement increased. The possible causes of strength loss were investigated using microstructure analysis.