Investigation of drying shrinkage of concrete in local conditions

Abstract

Drying shrinkage of concrete is a commonly occurring phenomenon after the concrete hydration process that affects the stability and long-term performance of the concrete. This occurs due to the volume reduction of the concrete in the drying process. This leads to various problems with construction causing shrinkage induced cracking. These problems affect the performance of various elements such as slabs, floors, walls, pavements and beams leading to cracks and strength reduction. While numerous studies have been conducted in temperate regions, limited research exists on drying shrinkage behaviour under tropical climatic conditions, such as those found in Sri Lanka. This study investigates the drying shrinkage characteristics of concrete exposed to local conditions. In this study, the effect of the water cement ratio, grade of concrete and type of concrete were compared. Concrete specimens were prepared using three mix designs to evaluate the effect of the change of the grade (C30/37, C25/30, C20/25) of concrete to the drying shrinkage. The effect of change from the w/c ratio (0.48, 0.52, 0.55) was evaluated from the same mix design samples. Also to compare the effect of cement materials to the drying shrinkage of concrete both Portland Composite Cement and Ordinary Portland Cement were used. Sample preparation and test were carried out following the BS ISO 1920-8. This paper investigates the drying shrinkage behaviour of concrete with Portland Composite Cement (PCC) and Ordinary Portland Cement (OPC) for the concrete grade of C30/37, C25/30, 20/25 considering local environmental conditions and construction practices. An attempt has been made to propose suitable modifications to the Eurocode 2 recommendations, if necessary, to enhance the accuracy of predicting drying shrinkage under local conditions.