Preparation And Properties Of Low-clinker Composite Cement With Spontaneous Combustion Coal Gangue

Spontaneous combustion coal gangue hill is one of the main sources of pollution in coal mining region and its comprehensive management has been a difficulty for the land reclamation and ecological restoration. Coal gangue was usually used to backfill mined-out area, pave road, improve soil, make construction materials and generate electricity etc. The utilization method was low technique, low-added value, inconspicuously economy and even some serious secondary pollution. High value-added resource utilization of spontaneous combustion gangue's “turning waste into treasure” will be a major resource and environmental problem which must be resolved in the process of sustainable development.The spontaneous combustion coal gangue's cementitious activity excitation was studied in this paper. Low clinker cement was prepared with spontaneous combustion coal gangue and its application in concrete was also studied. The results show that: when the mass fraction of Na2SO4, NaOH, C6H15NO3 and Na2CO3 in the binder content is respectively 1.0%, 2.0%, 0.04% and 1.5%, the sample of orthogonal horizontal combination has the highest increase in several age compressive strength, and 3d/7d/28 d specific strength of the sample is 1.95/1.76/1.23. When mixture ratio of the cement clinker, gypsum, spontaneous combustion coal gangue, slag, fly ash, additives Q and S is 35:6:44:2.5:7.5:4:1, mixmilling in the same time, P?C32.5 low clinker composite cement is prepared, the 3d/28 d compressive strength is 16.7MPa/34.1MPa; while mixture ratio of the above mixture is 55:6:27.7:1.6:4.7:4:1, P?C42.5 low clinker composite cement will be prepared, and its 3d/28 d compressive strength is 24.4MPa/42.8MPa. The amount of spontaneous combustion coal gangue and other industrial solid waste substituted the cement clinker can be up to 60.7%. And the overall performance of the mix-milled low-clinker composite cement can reach that of the commercial cement of the same intensity level considerably. Therefore, when grinding the raw materials by the above mentioned mixture ratio, the low-cost, and high-performance low clinker composite cement will be prepared. This not only achieves the goal of the spontaneous combustion coal gangue resource recycling utilization, but also has a potential market.