Effect of Entrained Air Voids on Salt Scaling Resistance of Concretes Containing Composite Cements

Concrete pavements are subjected to light and heavy traffic loads and different climatic conditions. Salt scaling is a major durability issue for concrete and concrete pavements, so the phenomenon has been the subject of extensive research efforts in the world. Salt scaling is defined as superficial damage caused by freezing a saline solution on the surface of a concrete body. The damage is progressive and consists of the removal of small chips or flakes of material. This study examines the performance of concrete made of modified Portland (type II) and composite cements, with and without entrained air bubbles subjected to the salt scaling and proposed mechanisms, are discussed. Visual inspection results and rate of mass loss due to salt scaling for every five cycles of freezing - thawing are presented. This study shows that surface strength of concrete plays an important role on salt scaling resistance. Entrained air bubbles in concrete reduce bleeding and will result in increased surface resistance. Therefore, entrained air bubbles improve concrete salt scaling resistance. Results show that performance of type II Portland cement was more appropriate than the composite cement for mixture without air bubble in salt scaling test. The mixture containing composite cement with entrained air bubbles shows the best performance in salt scaling test.