Kinetics of dolomite-portlandite reaction - Application to Portland cementconcrete

The dedolomitization reaction kinetics are studied through several long-ter m experiments consisting of an aqueous dispersion of fine powders of dolomi te and portlandite with different alkalinity, temperature and silica conten t. The experimental results are reproduced through computer simulation, whi ch allows the estimation of the apparent dissolution constant rates for dol omite. These are discussed together with other parameters influencing the k inetics, in particular the modification of the specific surface of dolomite . The parameters obtained make it possible to predict the behavior of the s ystem beyond experimental periods. Both experimental and simulated results are discussed in connection with the expansion and cracking occurrences obs erved in portland mortars and concretes made with dolomitic limestone. (C) 2001 Elsevier Science Ltd. All rights reserved.