Overview on Study on Properties of Concrete Canvas

Since there is expeditious increase in the materials extensively used in construction, there is a great demand for construction materials in the current generation to follow different conventional methods. There is no provision for very quick and workable concrete installation procedures in the event of an emergency. Concrete as a construction material is well-known around the world, but the hunt to improve its flexibility has always piqued researchers' interest. Although concrete has many advantages, one disadvantage is that it is not flexible when hardened. The rising cost of repair work as a result of weathering, ground surface damage, and seepage in water canals has always been a source of concern. Concrete cloth, a new technology that removes faults from concrete and is flexible and simple to apply, has been invented. Concrete Canvas has a ceramic property which is semi rigid that makes it fire resistant and water proof.

Mechanical Properties of Concrete Modified with Silica Fume and Integral Waterproof and Comparison with Waste Glass Aggregate Concrete

This study includes the effect of using different dosages of integral waterproof Admixture and silica fume on some mechanical properties of concrete. Concrete improved by using different ratios of integral water proof admixture(IWP admixture) to increase strength and durability, this admixture used as percentages from cement weight in each mix ranged from 0.0% to 2% ( 0.0, 1.0%, 1.2%,1.4%,1.6%,1.8%, and 2%), compressive strength test done for cubes with (10*10*10) cm for each mix. The flexural strength test was done by (10*10*40) cm beams and tested after 28 days of curing. comparison study was made between silica fume mixes properties and mixes without silica fume. Adding IWP admixture leads to increase mechanical properties of ordinary concrete, the reference mix shows compressive strength equal to 26.38 MPa, while mixes with 2% IWP gives 38.8 MPa in this study. The study also includes the effect of using 2 main dosages of silica fume to the mixes that contain IWP, the new concrete with two admixtures show better values of compressive, tensile and flexural strength comparing with mixes with only IWP, the compressive strength increased from 38.8 MPa for ordinary IWP mixes to 52.3 MPa for 10% silica fume concrete mixes, and also the flexural strength increased from 4.8 MPa for mixes with only IWP to 7.3 MPa for mixes modified with 10 % silica fume. Study include also using waste glass as fine aggregate in mixes contain IWP and 10% silica fume and that show more increment in mechanical properties also.

Control of the Internal and External Staggered Distance of Coal Mining Face to the Water-Conducting Fissures in the Overlying Strata of the Near Coal

In Northwest China, rainfall is low, water resources are scarce, and the ecological environment is fragile. For shallow-buried and close-spaced coal seams with a thickness of upper coal bed >60∼70 m, the water-conducting fissures of the overlying rock will not penetrate the water-isolating layer after the upper coal seam is mined; the internal and external gap angles of the water-conducting fissures are not generated from the water-isolating layer. We set out to explore the critical internal and external dislocations for the second significant development of water-conducting fissures in the overlying rock after coal mining under control. A calculation model for the critical internal and external staggered distances of coal mining face in shallow-buried and close-spaced coal seams is established, the calculation formula is given, and the calculation formula for the critical seam mining ratio under the condition of internal staggered mining mode is given. Numerical simulation performed by UDEC methods: taking the overburden strata in the shallow-buried and close-spaced coal seam mining area of Shigetai Coal Mine as a prototype, it was verified that the critical internal and external offsets of the coal mining face in shallow-buried and close-spaced coal seams have a significant effect on the overlying water flow cracks in the mining of the lower coal seam. For the feasibility of developmental control, according to the engineering geological conditions of Shigetai, through the calculation method of external staggered distance, it is concluded that the distance of the open cut of the lower coal face and the upper coal face is only 21∼27 m, which is much smaller than the water barrier. It does not produce the critical distance of the water-conducting cracks. Therefore, in the process of mining the lower coal seam, the water-proof layer will produce water-conducting cracks, lose its water-proof performance, and cause water loss. This is also the cause of the water inrush accident in Shigetai Coal Mine.

Justification of engineering safety criteria for undermining of water-proof layer in the Upper Kama Salt Deposit

Safety of a water-proof pillar between the stoping void and the aquifers defines the key feature of water-soluble mineral mining. In this regard, the most important element of geomechanical supervision of mining operations, especially, at the mine project stage, is the engineering safety criteria aimed at the adequate valuation of safe undermining of water-proof strata (WPS). The WPS safety procedures now in force calculate only maximal sagging of undermined beds and disregard deformation in the edge area of WPS. In the meanwhile, the edges of WPS are the areas of localization of maximal horizontal strains, and the hazard of vertical jointing is the highest in these areas. In this connection, in the capacity of the index of the manmade load on WPS, it is proposed to use the maximal slope of the edge area of the subsidence trough. The evaluations were carried out in 6 Uralkali’s mine sites selected from the mathematical modeling and geophysical survey data which exhibited considerable damage of WPS. Based on the implemented research and justifications, it is recommended to use the generalized safety criterion for undermining of WPS as a maximal subsidence/mining depth ratio which is directly proportional to the ground slope. This engineering procedure describes more adequately the fracture mechanism in WPS rocks, in particular, damage localization in edge areas of the subsidence trough, or influence of mining depth on WPS stability and, which is main thing, is based on the criteria derived from the long-term observations and measurements performed in the Upper Kama deposit. The study was supported by the Russian Science Foundation, Grant No. 19-77-30008.

The Use of Overburden Clay in Ceramic Production

How the degree of grinding of clays with carbonate inclusions in the form of dolomite affects the quality of ceramic products, is examined. It is shown that unusable clay with large dolomite inclusions can be used in ceramic production after grinding particles to a size of less than 0.5 mm. It has been established that fine grinding of clay can eliminate the formation of “blowing” defect, while the frost resistance of ceramics increases. Clay unsuitable in the ceramic production can be used after fine processing to produce facing building bricks with a compressive strength above 15 MPa and frost resistance of more than 50 cycles, ceramic roof tiles with frost resistance of more than 100 cycles, majolica and water-proof pottery products.

Determination of Water-Proof Coal (Rock) Pillar Height in Mining Coal Seam Group under Water-Bearing Rock Stratum

In order to determine the reasonable height of water-proof coal (rock) pillar when mining multiple coal seams under aquifer, this paper analyzes the expansion height of water-conducting fracture zone when coal seams mining. Considering the expansion law of water-conducting fracture zone in coal seams mining, two schemes of coal seams mining in upper and lower groups and one-time mining of all coal seams are designed for comparative analysis, and the height of water-proof coal (rock) pillar is determined based on the expansion height of water-conducting fracture zone. The results show that the height of water-proof coal (rock) pillar is calculated as 91.08 m when mining upper and lower groups and 105.46 m when mining all coal seams at the same time. According to UDEC numerical simulation results, the height of water-proof coal (rock) pillar is 56.08 m when mining upper and lower groups and 86.36 m when mining all coal seams at the same time. Comparing the results of theoretical calculation and numerical analysis, the maximum value is selected as the final result, and the reasonable water-proof coal (rock) pillar height is determined to be 105.46 m.