The influence of stray current flow on the level of maturity of cement-based materials

Abstract

“Maturity” method is commonly used to predict concrete strength development based on the temperature history of concrete. Basically, concrete strength development is estimated using the relationship between maturity index and strength e.g. ASTM C 1074 elaborates the procedure of this standard practice, where the, maturity index can be expressed either as temperature-time factor using the Nurse-Saul equation or as the equivalent age at a specific temperature using the Arrhenius equation. According to Saul, concretes of the same mix at the same maturity have approximately the same strength whatever combination of temperature and time are relevant in order to make up that maturity. In cement-based materials, strength increases with the progress of cement hydration. The amount of hydrated cement depends on how long the concrete has been cured and at what temperature levels. When electrical current flows through the cement-based material, the temperature development will be increased compared to control conditions, initially leading to accelerated cement hydration and increased strength. Various experiments on electrical curing and maturity method of cement-based materials have been performed and reported. However, the effect of electrical current flow on the maturity of cement-based materials is still not well understood.This paper deals with the influence of stray current on the maturity levels of cement-based materials. Varying levels of electrical current density were applied to mortar specimens. The maturity levels were determined based on the relationship of electrical properties (i.e. electrical resistance), thermal properties (i.e. temperature development) and mechanical properties (i.e. strength) of cement-based materials.