Superplasticizers shrinkage

Most of the studies in this area have indicated that superplasticized concrete has shrinkage and creep characteristics similar to plain concrete. Figure 2.21 illustrates the shrinkage results of plain and superplasticized concrete [66], while Table 2.6 shows similar results for creep [67]. 

Such work as has been published indicates that superplasticizers do not adversely affect either creep or drying shrinkage with the possible exception that with flowing concrete early age shrinkage cracking may be increased under drying conditions, unless adequate curing precautions are taken. 

N.S. Berke, M.P. Dallaire, M.C. Hicks, and A. Kerkar New developments in Shrinkage-Reducing Admixtures. In CANMET/ACI Fifth International Conference on Superplasticizers and Other Chemical Admixtures in Concrete, Rome, Italy, (1997), p. 971-978. 

A.B. Ribeiro, A. Carrajola, and A. Gonsalves Behavior of mortars with different dosages of shrinkage reducing admixtures. In V.M. Malhotra (ed.), CANMET/ACI Eight International Conference on Superplasticizers and Other Chemical Admixtures in Concrete, Sorrento, ITALY, October (2006), ACI SP-239, p 77-92. 

The main advantages of using foam concrete is that the density of the material can be varied between 300 and 1600 kg/m, and the foam provides good insulation properties and it is easy to handle by pumping. However, several properties still need to be modified in order to make foam concrete an even more competitive material. There is a need to decrease the shrinkage and the water uptake, and to increase the strength and the insulation ability. At present, the foam structures can be enhanced by the use of various additives, such as microsilica or superplasticizers which reduce the cement/water ratio and improve the stability. Polyester fibre additives enhance the hardening and also improve the tensile properties. 

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