Influence of temperature and wind on moisture transport in cementitious materials

Abstract

Moisture diffusivity is a key physical parameter linked to the early deterioration of concrete structures, requiring repairs. The effect of hot arid climate of Saudi Arabia, characterized by high ambient temperature (T) and high wind speed (ω), is investigated on the coefficient of moisture diffusivity (D) and convective surface transfer coefficient (h(f)) respectively, for ordinary concrete with varying water-cement ratio and selected repair materials. A combined experimental-numerical approach is adopted involving experimental investigation of moisture loss evolution under controlled exposure conditions in conjunction with an existing finite element based model DIANA-2D to calibrate values of D & h(f). In addition, shrinkage strains were also recorded on specimens under similar environmental regimes. It is found that moisture diffusivity increases significantly with the increase in ambient temperature and water-cement ratio of concrete.

The salient feature of the work is a proposed model for mix design of a crack free concrete subject to environmental conditions defined by temperature (T), wind speed (ω) and R.H. of 40%. This model has been postulated in terms of three invariant surfaces relating the primary variables. Also included are directions for further research to generalize the model for non-standard and new generation concretes.