Use of MgO expansion agent to compensate concrete shrinkage in jointed reinforced concrete pavement under high-altitude environmental conditions

To mitigate concrete pavement cracking at high-altitude locations, jointed reinforced slabs made with concrete containing MgO expansion agent (MEA) were investigated in this study. Firstly, concrete mixtures with varying MEA contents were tested in the lab to evaluate the effect of MEA on concrete's mechanical properties (compressive strength and flexural strength), volume change, and presence of microcracking. Field data including the strain of the concrete slab and the stress of the steel reinforcement in the concrete pavements with and without MEA were collected subsequently at the Shigatse Aiport in Tibet, China. The lab results indicate that the addition of MEA decreases concrete's compressive strength (up to 27%), but a slight improvement (up to 12%) in flexural strength is achieved when the MEA content is limited to 8%. The field study shows that the volume expansion caused by MEA hydration can effectively compensate concrete shrinkage. The concrete expansion could reduce the width of the transverse crack and make concrete slab act like a prestressed member, which could lead to better pavement performance.