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ii. Drying Shrinkage. It refers to changes of hardened cement volume due to water loss. Dry shrinkage takes place in 3-4 days or maybe numerous months after  concreting. Before the concrete is subjected to any form of loading, drying shrinkage will increase the tensile stress and cause cracking and external deflection. Mixing of high cement and water content, insufficient curing of concrete, improper compaction of concrete, and lack of attention to control evaporation of water from the concrete surface are factors that lead to drying shrinkage.

To prevent the occurrence of drying shrinkage, mix the concrete with materials with lower water content. Next, perform good curing on slabs. This can ensure the concrete gain better tensile capacity before drying out. Providing movement joints and enough crack control reinforcement can also help to reduce the extent of shrinkage cracking.

iii. Carbonation Shrinkage. Carbonation shrinkage occurs when concrete is exposed to air containing carbon dioxide. The carbonation shrinkage process is slow and can be observed in areas with moderate humidity. The shrinkage process will decompose some cement compounds and form carbonates. Carbonates fill up the pores and water is released during the shrinkage process. The released water promotes hydration and reduces permeability. The permeability of concrete, moisture and carbon dioxide content, grade of concrete and the depth of core are the factors that influence the rate of carbonation. When the shrinkage is restrained internally or externally, the cracks are formed.

One of the prevention methods is to add adequate contraction joints and steel detailing. Suitable joints are provided for contraction and expansion movement. The combination of concrete with appropriate detailing of steel bars can help in reducing the effect of shrinkage and controlling the development of cracks. Prolonging the curing process can also help in reducing the effect of carbonation shrinkage.