AN INVESTIGATION INTO THE FEASIBILITY OF FORMULATING SELF-CURE CONCRETE

To achieve good cure, excessive evaporation of water from a freshly ca st concrete surface should be prevented. Failure to do this will lead to the degree of cement hydration being lowered and the concrete devel oping unsatisfactory properties. Curing can be performed in a number o f ways to ensure that an adequate amount of water is available for cem ent hydration to occur. However, it is not always possible to cure con crete satisfactorily. This paper is concerned with achieving optimum c ure of concrete without the need for applying external curing methods. The feasibility of curing concrete by adding water-soluble chemicals during mixing that reduce water evaporation in the set concrete, makin g it 'self-curing' is discussed. The chemicals' abilities to reduce ev aporation from solution and to improve water retention in ordinary Por tland cement was monitor ed by measuring weight-loss. x-Ray powder dif fraction and thermogravimetry measurements were made to assess whether any improvement in water retention was matched by an increase in degr ee of cement hydration. Initial surface absorption tests and compressi ve strength measurements were made to determine surface permeability a nd strength development, respectively. The scanning electron microscop e was used to determine the influence of the admixtures on cement past e microstructure. It was found that two of the chemicals studied had a significant 'self-curing' effect. One of these chemicals enhanced hyd ration further than simply by means of water retention. A possible exp lanation of this behaviour is given.