Coal gangue is one of the largest industrial solid wastes produced and discharged in my country. Its composition and properties are similar to those of sand and gravel. Using coal gangue as raw material for machine-made sand can not only expand the source of machine-made sand and increase the output of machine-made sand, but also Effectively realize the resource utilization of coal gangue.
(1)As Lightweight And Fine Aggregate Concrete
Compared with waste rock and tailings, coal gangue has a smaller dead weight and rough surface, which makes coal gangue exhibit strong hygroscopicity, and water and sludge products are easy to enter, so it can improve the adhesion between aggregate and cement. Coal gangue can also have pozzolanic reaction with calcium hydroxide in cement, which is beneficial to improve the performance of concrete.
(2)Preparation Of New Concrete
Coal gangue sand can be used to prepare foamed concrete and other new types of concrete. This kind of concrete replaces red bricks or sintered coal gangue bricks as walls. It can not only reduce the weight of the wall, improve the seismic and safety performance, but also replace 40%-70% of the Cement, its cost is only 1/2-3/4 of ordinary cement concrete, and its economic benefits are obvious.
(3)Fill The Road Section
The study found that after the coal gangue is crushed and screened, 10% fly ash is added to the base mixture, which can significantly improve the density, durability and crush resistance of the roadbed material, and at the same time improve the unconfined compression resistance of the roadbed The strength, splitting resistance and compressive resilience modulus meet the relevant technical requirements of secondary roads.
Compared with natural aggregate, coal gangue fine aggregate mixed with fly ash can not only increase the compressive strength of the material, but also increase the splitting strength and compressive strength of the base material. The test results show that although the strength of the coal gangue aggregate base material is lower than that of the natural aggregate base material, the mixture prepared with 0-5mm coal gangue as the fine aggregate can still meet the requirements of the 7d unconfined compressive strength. Construction Technical Instructions (JTGTF20-2015) requires the strength of the secondary road base, and the incorporation of fly ash can increase its compressive strength, especially the strength of the coal gangue fine aggregate after cement stabilization has increased significantly. Very good late strength growth, the growth rate of fly ash acting on coal gangue aggregate base material is greater than that of natural aggregate base material.
Coal gangue aggregate is mixed with fly ash base material, and the alkaline hydration product Ca(OH)2 produced by cement hydration activates the pozzolanic reaction, thereby enhancing the later strength and stiffness of the material, and meeting the "Code for Design of Highway Asphalt Pavements" 》(JTG50-2006) The recommended range of compressive resilience modulus of highway cement stabilized crushed stone is 1300-1700MPa. Coal gangue machine-made sand fine aggregate is used for highway base materials, and its compressive resilience modulus meets the requirements of the specification.
(4)Used For The Repair And Construction Of Bridge Pavement
The angularity and rough surface characteristics of coal gangue machine-made sand make the cohesive force and mechanical occlusion force between particles greater than natural sand, making it stronger against disturbance and cracking, and can be used in bridge deck and road repair projects. The slump and expansion of the high-strength concrete reach 250mm and 615mm, respectively, the 28d compressive strength exceeds 70MPa, and the 180d shrinkage rate is 315×10-6, so it can be used to build high-stability bridges.