J.L. MIRANDA DIAS LNEC (National Civil Engineering Laboratory – Portugal)
Movement in masonry walls of buildings is frequently associated with changes in temperature and moisture in the constituent materials and in the surrounding elements such as reinforced concrete beams, slabs and roofs. These changes also induce stresses in the walls that may lead to considerable damage in them and consequently affect the performance and durability of the building. The purpose of this paper is to discuss the factors that influence temperature and moisture movements in walls. It is well known that masonry units (concrete units and clay bricks) usually expand when wet and shrink when dry. So, experimental tests were developed to assess the dimensional and weight variations of masonry unit specimens (with or without a mortar joint) subjected to moisture and temperature changes and to evaluate the behaviour of masonry walls when exposed to weathering which results in cyclic moisture content and dimensional changes to the wall. The results of these tests reveal the significant contribution of the dimensional variation of masonry constituent materials to the overall movement of the wall.