A theory for drying creep of concrete

A theory for drying creep is proposed based on the stress concentrations ar ising from the presence of a rigid inclusion and a hole in a surrounding me dium subjected to an external stress. The analogy is made with cement paste where there are some pores filled with water and other pores empty. When f ull, the average stress acting on the solid gel is less than the nominal ex ternal stress but, when empty, the corresponding stress is greater than the external stress so that there is a stress enlargement as the pores empty o f water. By implication, there is an increase in creep of the solid gel as drying or water movement occurs. In contrast to most existing theories, the new theory does not require an interaction with drying shrinkage to accoun t for additional creep. The theory is first developed to account for the wa ter-cement ratio influence on basic creep and then the stress enlargement f actor for various pore water contents is calculated to simulate different d rying conditions. As well as drying creep, the theory explains the addition al creep in tension tinder drying conditions, transitional thermal creep an d transient thermal strain.