Lognormal simulation of pore evolution during cement and mortar hardening

Cementitious materials are being used in the immobilization of radioactive waste. Conventional concrete structures are being used as engineered barriers. Low level liquid wastes are being immobilized in cement-based grouts. While these applications differ from those involving normal concrete structures, the porosities of cementitious materials are important in determining the ability of a structure to meet its functional requirements, virtually regardless of the specific applications. It is the distribution of porosity throughout cement matrix and at cement-aggregate interfacial zones that, in concert with environmental variables, determines the macroscopic rate of transport of species. A model to describe the pore sizes in cement paste and mortar, as determined by high pressure mercury intrusion porosimetry, has been developed. The model describes porosity using a compound lognormal distribution. For given material under a given set of curing conditions, the weighing factors and shape parameters of two sub-distributions in the lognormal model may be considered as constants, while the location parameters may be related to curing time and the relationship can be quantified. Therefore, it is possible to predict both the pore size distribution in cement and mortar at any age as well as the evolution in pore size during curing