Influence of Cement on the Durability of Concrete Pavements

Cement for concrete pavements has to meet special requirements. Besides cement properties which influence the fresh concrete, the cement is of great importance for the durability of concrete pavements. If the joints in the young concrete are not sawn early after paving, cracks can form in the pavement. With cracking-frame tests it is possible to choose a cement which yields a young concrete with a low cracking sensitivity. Cements with a high early strength should only be used during the cold season or for fast-track concrete paving. To enable sufficient resistance to frost and de-icing salt. blast-furnace slag cements with a high content of slag should not be used. In some older concrete pavements surface cracks were observed. Investigations of coiiuiele pavements and of laboratory specimens showed that intrinsic stmsses due to non-linear moisture gradients over the slab thickness were the reason for the surface cracks. The investigations showed also that to avoid those surface cracks cements with a sodium equivalent above 1.0 wt.-% should not be used