ABSTRACT
One of the major difficulties with concrete as a construction material is the volume instability as a function of time. The hydration products have a smaller volume than the reacting products, which is called chemical shrinkage. Furthermore, the consumption of water leads to some internal drying, especially in the case of binders with a low water/cement ratio. Consequently, a volume reduction is noticed, called autogenous shrinkage. In addition to drying shrinkage, concrete also shows carbonation shrinkage. Carbonation shrinkage can lead to damage in autoclaved aerated concrete. Due to the chemical shrinkage, the pore volume inside the hardening cement paste will increase with increasing degree of hydration. Autogenous shrinkage strains of concrete can widely range from about 50 mm/m to about 500 mm/m or even larger. The main influencing factor seems to be the water/cement ratio of the concrete, although other influencing factors can be mentioned.
