Cracking in Concrete Water Tank due to Restrained Shrinkage and Heat of Hydration: Field Investigations and 3D Finite Element Simulation

Abstract

Concrete water tanks have a stringent serviceability requirement in terms of limiting crack widths. Excessive cracks or cracks running across the full depth of these tanks could result in loss of serviceability from leakage and affect their integrity. This scenario is particularly true for liquid retaining structures, such as water tanks. In this paper, following a field inspection that revealed considerable cracking in the walls of a water tank constructed in the arid Arabian Gulf environment, a diagnostic investigation was carried out on the water tank, which was 30×20 m in plan and 3.6 m in height. Field inspection and assessment, laboratory investigation, and a three-dimensional (3D) finite element simulation of the water tank structure was carried out to investigate the causes of the cracking. A repair strategy was implemented, and its performance was assessed. The heat of hydration characteristics of the concrete mix used was obtained using a semi adiabatic calorimeter. The heat of hydration, free shrinkage strain, mechanical properties of the concrete, and the ambient conditions at the time of construction were used in a three-dimensional (3D) finite element simulation model. Tensile stresses resulting from restrained temperature and shrinkage strains exceeded the tensile stress capacity, resulting in cracks in the tank walls. A repair strategy was proposed and implemented to restore the functionality of the tank. Based on the diagnostic methodology proposed in this paper, guidelines have been suggested that address the mitigation of the risk of cracking attributable to thermal and shrinkage stresses in the harsh and arid environment in the Arabian Gulf.