Research On Activated Coal Gangue And Impact On The Performance Of Fiber Brucite Reinforced Cement Mortar

With the fast development of modern industry, the fact that the coal dominates the main energy structure will not change for a long time. While the output of coal gangue has accounted for 15%-20% in that of coal. Therefore, coal gangue has been one of the greatest contributions to industrially discharged solid waste in our country currently. These coal gangue have caused many disadvantageous influences:not only occupies large amount of farmland, destroys environmental conditions, affects natural condition, but also causes the atmosphere, soil, water pollution even geological disasters. Our country has been paying attention to the comprehensive utilization of coal gangue. However, the overall level is not pleased so far. The comprehensive utilization ratio is less than 20%. As a consequence, there is so much room for the activity and comprehensive utilization of coal gangue.In this article, the coal gangue in Tongchuan stimulated by thermal, mechanical and chemical activation has been used as supplementary gelatinize material in cement. The main researching factors includes calcining temperature, holding time, kinds of alkali-activator, adding method, mixing amount and scale. The optimal activation ways and technological parameter have been selected by the test of strength, fluidity, water requirement for normal consistency of cement paste, and stability. Also XRD and SEM are used to discuss the change of microstructure which has taken place in activated coal gangue preliminarily. Furthermore, fiber brucite has been added into the experiment to enhance the strength of coal gangue cement motar, and improve the contractibility, so that to expand sphere of application. The fiber brucite is advantaged mineral resources in our country, which has been widely used because of its excellent mechanical property, alkali resistance, consistency with cement and safety.The main research conclusion are as follows:1. The activation of coal gangue could be effectively promoted by many stimulating methods combining together. The crystal structure of coal gangue could be destoried by stimulation, which results in growing amorphousbody and generating activity.2. Taking water glass as alkali-activator, adding water glass before thermal activation is better than after that. Because it is beneficial to the whole mixing process, and also reduce the heating temperature, which brings more economic benefits. The optimized parameters are as follows:the modulus of water glass is 0.9, the dosage of water glass is 2%, calcining temperature is 625℃, and water glass should be added before thermal activation.3. Taking lime as alkali-activator, the adding method should be conducted after thermal activation.Because this adding method plays a better role in the mixing process of coal gangue and lime, makes weighing more accurately which contributes to the raising of strength and decreasing experimental residual. The optimized parameters are as follows:the volume dose of coal gangue and lime is 40% of cement, the lime accounts for 40% proportions of coal gangue, and lime should be added after thermal activation.4. The pressive strength and tensile strength of cement mortar in 28 days which employs the optimal stimulation of coal gangue shows 3.8% and 1.1% higher than pure cement motar. The setting time of activated coal gangue cement motar is a bit longer than pure cement motar. Water requirement for normal consistency increases. And the stability is within the range of qualified standard.