School of Building Engineering. Universidad Politécnica de Madrid

In this article the use of waste products, from various industrial sources, added as matrixes in construction materials is analyzed. Indeed, this will lead to the development of sub products to be used in construction: the results of this research define a lightened mortar using rubber granules from recycled tires. This new mortar can substitute lightened mortars with expanded clay. In addition, it has non structural applications in the construction field such as: packing material for slabs, slopes in flat roofs, etc. To achieve this, an experimental plan has been designed. Series of prismatic 40x40x160 mm specimens of cement mortar have been performed, where sand has been substituted by rubber granules or by a mixture of different percentages of clay and rubber. The specimens produced have been tested for mechanical strength (flexural strength and compressive strength, according to UNE 102-031) and Shore C hardness (UNE 102-039). At the same time, the loss of weight –from dismoulding until fracture– is also assessed. From the test results and conclusions, for mortars lightened with expanded clay, the substitution of 50% of expanded clay by rubber granulate is recommended. This rubber addition provides also an improvement in the sustainability of these mortars, as they use a great volume of waste and thus, natural materials (sand, aggregates, etc) used presently for mortar in the market can be substituted.

Key words
cement, lightened mortars, rubber, expanded clay