Use of basaltic quarry waste in renders, examples from Hungary

A particular use of quarry waste is presented in this study. The aggregate quarries produce high amounts of quarry waste, especially dust, that has been considered for many years as ’no need materials. One possible use of this dust is as aggregate in renders. Four Hungarian basaltic quarries provides a high amount of dust: Uzsa, Recsk, Egerbakta and Vidornyaszőlős. 15% of the mass waste of dust from these quarries were added to the renders. Both standard size (quarry fresh) and nano-grinded dust were tested. Test specimens were made from the dust added render, and physical properties were tested 28 days after casting. Bending strength tests, uniaxial compressive strength tests were made to assess the mechanical properties of the renders. Carbonate formation, porosity and pore-size distribution were also analyzed to obtain valuable information on the binding and textural characteristics. Reference samples without basalt dust were also cast, and the test results were compared in order to assess the performance of basalt dust containing renders. The basalt dust and nano dust containing samples have lower bending strength than the reference ones, while the uniaxial compéressivbe strength increased when basalt dust was added. Nano dust containing samples show an increased porosity but a decrease in mean pore diameters. Our results show that adding basalt dust to renders could be a useful solution in the reduction of quarry waste and the obtained render has fairly good mechanical properties.