An investigation into the feasibility of formulating 'self-cure' concrete

To achieve good cure, excessive evaporation of water from a freshly cast concrete surface should be prevented. Failure to do this will lead to the degree of cement hydration being lowered and the concrete developing unsatisfactory properties. Curing can be performed in a number of ways to ensure that an adequate amount of water is available for cement hydration to occur. However, it is not alway possible to cure concrete satisfactorily. This paper is concerned with achieving optimum cure 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, making it 'self-curing' is discussed. The chemicals' abilities to reduce evaporation from solution and to improve water retention in ordinary Portand cement was monitored by measuring weight-loss. x-Ray powder diffraction and thermogravimetry measurements were made to assess whether any improvement in water retention was matched by an increase in degree of cement hydration. Initial surface absorption tests and compressive strength measurements were made to determine surface permeability and strength development, respectively. The scanning electron microscope was used to determine the influence of the admixtures on cement paste microstructure. It was found that two of the chemicals studied had a significant 'self-curing' effect. One of these chemicals enhanced hydration further than simply by means of water retention. A possible explanation of this behaviour is given.