Shrinkage behavior of foam concrete

In the absence of coarse aggregate, the relative influence of factors affecting the shrinkage of foam concrete are likely to be different as compared to normal concrete. This paper presents the shrinkage behavior of preformed foam concrete for the influences of basic parameters, viz, density, moisture content, composition like filler-cement ratio, levels of replacement of sand with fly ash, and foam volume. Shrinkage of foam concrete is lower than the corresponding base mix. For a foam concrete with 50% foam volume, the shrinkage was observed to be about 36% lower than that of a base mix. The shrinkage of foam concrete is a function of foam volume and thus indirectly related to the amount and properties of shrinkable paste. Shrinkage increases greatly in the range of low moisture content. Even though removal of water from comparatively bigger artificial air pores will not contribute to shrinkage, artificial air voids may have, to some extent, an effect on volume stability indirectly by allowing some shrinkage; this effect was more at a higher foam volume. © 2009 ASCE.