Effect of metakaolin-based geopolymer concrete on the length of rigid pavement slabs

Rigid pavement is one of the pavement methods used specially in high traffic zones. Up till now, Portland cement concrete (PCC) is the most commonly used material for rigid pavement. One of the problems that faces PCC is the allowable spacing for transverse joints in rigid pavements' plain concrete slabs. As recommended by different standards and design manuals, the recommended length of slabs is about 4.5-5 m (In PCA, Thickness Design for Concrete Highway and Street Pavements. Engineering Bulletin EB109P. Skokie, IL, (1984); In ECP, Egyptian code of practice for urban and rural roads part 4: road material and its tests. Housing and Building National Research Center, Egypt, (2018); In FDOT, Rigid Pavement Design Manual. Pavement Management Office, Document No. 625-010-006-e, Tallahassee, Florida, (2009)), this is referred to the thermal volumetric changes in PCC. The low allowable transverse joints spacing in rigid pavement reduces the implementation rates and increases the cost. Geopolymer concrete (GPC) is one of the innovative types of concrete that is eco-friendly than gain early strength in ambient temperature and can gain higher strength by heating. In this research, GPC was investigated to determine its drying shrinkage and thermal expansion behavior and therefore affect the length of concrete slabs in rigid pavement. This different type of concrete showed an acceptable performance against drying shrinkage and thermal expansion more than PCC.