Physical-mechanical properties of mine production wastes for road construction

Abstract

Experimentally proved the possibility of using mining waste for road construction. The proposed compositions mixtures for the construction of pavement layers. A prospective and economically viable way is to use waste from mine production. Old and completely burnt mine waste heaps often contain high quality burned rocks. To assess the physico-mechanical characteristics of burnt rocks with cement addition, samples were prepared for each test mixture for testing compressive strength at a standard age (3 samples per point for each type of test). Preparation mixtures of waste coal industry fortified with cement was performed in a laboratory mixer.  When preparing mixtures in burned rocks, a mineral binder was added, and then the required amount of water was injected. The manufacture of cylindrical specimens with diameters and heights of 50 and 70 mm was performed under laboratory conditions at a temperature of 20°C. Samples were formed by compacting the mixture with a hydraulic press under a load of              150 kgf/cm² for 3 minutes, after which they were placed in a hydraulic bath and solidified under normal conditions, tested after the calculated period. The studied waste from the mine production Novovolinsky coal-mining region is characterized by the following indicators of physical and mechanical properties: the content of powdered-clay particles - 2.1%; crushability - 26.9%; bulk density - 1330 kg/m³. At the same time, with the addition of 5% cement, the strength of the samples was                    7.3 MPa, and with the addition of 20% cement, the strength of the products increased 2-fold - 15.1 MPa on the 28th day of hardening. Increasing the strength of the samples when adding cement increases due to the hydration cement minerals, which are evenly distributed throughout the volume of the material. Moreover, the more additives, the higher the density and strength of the samples.