Experimental Study and Application of Inorganic Solidified Foam Filling Material for Coal Mines

Abstract

Spontaneous combustion of residual coal in a gob due to air leakage poses a major risk to mining safety. Building an airtight wall is an effective measure for controlling air leakage. A new type of inorganic solidified foam-filled material was developed and its physical and chemical properties were analyzed experimentally. The compressive strength of this material increased with the amount of sulphoaluminate cement. With an increasing water-cement ratio, the initial setting time was gradually extended while the final setting time firstly shortened and then extended. The change in compressive strength had the opposite tendency. Additionally, as the foam expansion ratio increased, the solidification time tended to decrease but the compressive strength remained approximately constant. With an increase in foam production, the solidification time increased and the compressive strength decreased exponentially. The results can be used to determine the optimal material ratios of inorganic solidified foamfilled material for coal mines, and filling technology for an airtight wall was designed. A field application of the new material demonstrated that it seals crossheadings tightly, leaves no fissures, suppresses air leakage to the gob, and narrows the width of the spontaneous combustion and heat accumulation zone.

Fly Ash Particle Size Effect on Pore Structure and Strength of Fly Ash Foamed Geopolymer

“…Apart from being used in the traditional building elds, FLA has been applied in di erent areas as a good raw material for the preparation of geopolymer [8][9][10][11][12]. For example, to prove the possibility of in-situ resource utilization of FLA, there are a good many scholars having done plenty of basic studies on this aspect [13][14][15], among which there is one proposing that y ash foamed geopolymer (FAFG) as back lling material can be an excellent combination of y ash consumption and coal mine re prevention [16,17]. e complex underground environment demands highly for some speci c properties of FAFG, mainly focusing on its pore structure and strength.…”

Experimental Study and Application of LASC Foamed Concrete to Create Airtight Walls in Coal Mines

“…As can be seen, under the same conditions, the longer the curing time, the greater the compressive strength owing to the more stable crystal structure of the hydration product [30]. is was because the higher the foam dosage, the higher the bubble rate of the solidified foam cement, the better the compressibility, and the greater the yield strength [39].…”

“…Finally, the foam slurry was poured into the mold to prepare the foamed cement module (100 × 100 × 100 mm). Studies have shown that the strength of the cured foam cement is higher when the water-cement mass ratio is approximately 0.5 [30]. erefore, the water-cement ratio used in this study was 0.5. e foam and gel slurry were mixed in a volume ratio.…”

“…Lim et al [28] investigated the effects of waste ceramic powder on both the mechanical and microstructural properties of mortar. Böke et al [29] and Wen et al [30,31] studied the method of preparing solidified foam filling materials using fly ash, and they analyzed the influence of factors such as the watercement ratio and foaming multiple on the foam. e use of fly ash foam cement in plugging air leakages has greatly reduced coal dust pollution on the ground.…”

Experimental Study and Application of a Novel Foamed Concrete to Yield Airtight Walls in Coal Mines

“…Because of their long solidification times, low foam expansion rates, and poor resistance to dynamic pressure, these materials cannot be used extensively in deep coal mines. To overcome these shortcomings, Wen et al [20] and Tan et al [21] developed a type of inorganic solidified foamfilling material and analyzed the effects of constituent materials on its basic physical and chemical properties in various experiments. Jambor [22] and Tang [23] probed the effects of pore structure on the FC strength.…”