The impact of lime as a replacement of cement-based mortar, on the water absorption and rain penetration of masonry

Abstract

Since the 1970s, the rise of cement-based mortars has overtaken the traditional lime mortar in construction. This marks a drastic change from circular traditions of reusing ceramic facade materials to a linear economy with an increased difficulty in the reuse of bricks. Lime mortar joints make the recovery of bricks manageable, while cracks can easily occur during dismantling of cement-based masonry. This has prompted a resurgence in the use of lime mortar especially in historical restoration and renovation. It also presents lower CO2 emissions compared to cement mortar, which is a crucial aspect in an industry responsible for 37% of global CO2 emissions. Lime has the ability to capture up to 90% of its production CO2 through carbonation further emphasizes its environmental advantages. This study investigates the hygrothermal behaviour of a hybrid construction with load-bearing masonry, and an interior lime-hemp insulation. Typically, lime mortar exhibits higher moisture transport and storage characteristics, enhancing masonry waterproofing compared to cement mortar. Eighteen setups are subjected to rain-tightness tests in order to monitor potential water infiltration. During these tests, visual evaluations, weight, and moisture measurements are conducted to monitor moisture absorption and rain infiltration to assess the performance of lime mortar versus cement-mortar. This research contributes to sustainable building practices by promoting the advantages of lime mortar in enhancing material reuse, reducing CO2 emissions, and improving the hygrothermal performance.