Imposed Deformation Reduction in Semimassive Walls of RC Tanks by Internal Cooling

Early-age cracks in the RC walls of the tanks very often cause leaks. In turn, limiting the value of imposed strains reduces the risk of cracking or the width of cracks if cracking is not to be excluded in general. In the paper the analysis of the impact of a cooling pipe system (CPS) on the changes of temperature and strains in a RC semimassive wall was presented. In the numerical calculations a model covering non-linear and non-stationary temperature field variations resulting from cement hydration, internal cooling and heat exchange with the surroundings was used. It was demonstrated that during concrete maturing CPS contributes not only to mean temperature changes reduction but also to the reduction of temperature gradients, which helps effectively limit or eliminate concrete cracking. The analysis of the so-called “self-equilibrated stress” inducing temperature indicated that the application of CPS contributes to the reduction to zero the positive temperature difference in the immediate surroundings of the cooling pipes and to the reduction of temperature extreme changes, i.e. positive changes in the wall interior and negative ones in its corners. As a result, the restrained part of the imposed strains, to a greater extent, may remain below the tensile strain capacity of concrete. This solution can protect the tank wall from cracking or significantly reduce it.