To alleviate the environmental problems caused by scrap tire and tailings disposal, the performance of recycled tire polymer fiber (RTPF)-reinforced cemented paste backfill (CPB) was investigated. Ordinary CPB, commercial poly-propylene fiber (CPPF) and reinforced CPB were also investigated for comparison. Slump tests, unconfined compression tests and a cost–benefit analysis were conducted. The results indicate that the flowability of the RTPF-reinforced CPB decreased with the increasing fiber content. The failure strain, unconfined compressive strength, and toughness values were generally higher than that of ordinary CPB (i.e., CPB without any fiber reinforcement). However, the mechanical properties would not be improved continuously with increasing RTPF content. It was found that the inclusion of RTPFs achieved the best improvement effect with the best mechanical properties of CPB at the fiber content of 0.6%. The failure mode of the RTPF-reinforced CPB was safer than that of the ordinary CPB. Microscopic observations indicated that the bond between RTPFs and the CPB matrix could affect the mechanical properties of the RTPF-reinforced CPB. From the cost–benefit analysis, the inclusion of RTPFs to reinforce CPB could gain relatively high mechanical properties with a low material cost.

The ductility of cemented paste backfill at different moisture content were researched in this paper. The cemented paste backfill specimens at three different moisture content were prepared and the uniaxial compressive tests were conducted. The results show that the compressive strength of specimen decreases with the increase of moisture content. However, the ductility of specimen increases with the increase of moisture content. The elastic modulus and the rate of post peak stress reduction decreases with the increase of moisture content. The obtained results are helpful to better understand the behavior of the cemented paste backfill under different moisture condition, which could provide guidance for safe mining.

In order to study the influence of uniaxial compression test conditions on the strength and deformation characteristics of single-fractured similar rock with different penetration degrees, the author conducted the uniaxial compression test on prefabricated single-fractured similar rock using TAW-200 electronic multifunctional material mechanics testing machine. And quantitatively analysed the relationship between strength, elastic modulus and stress-strain of single fracture similar rock under uniaxial compression. The results show that the influence of uniaxial compression test on the peak strength is related to the penetration degree. The peak strength of specimens is the largest when there is no damage and the smallest when there is complete penetration (100%), but the peak strength of specimens not only decreases with the increase of penetration degree, but also relates to the crack dip angle. When the crack dip angle is different, the variation law of peak strength with penetration degree is also inconsistent; The influence of uniaxial compression test on elastic modulus is also related to penetration degree and crack dip angle, but the influence degree is different.

Increasing amounts of tailings and waste rubber tires have caused threats to the environment. In order to reuse these solid wastes, this study proposed a cemented tailings material containing crumb rubber recovered from waste tires. Unconfined compression tests and thermal conductivity measurements were conducted to evaluate the feasibility and performance of the proposed cemented tailings. Results revealed that the stress-strain behavior of the cemented tailings changed by the inclusion of crumb rubber. The unconfined compressive strength of cemented tailings decreased with increasing crumb rubber content. The inclusion of crumb rubber increased the failure strain and nonlinearity index of the cemented tailings. It was found that the addition of 4% crumb rubber provided the greatest improvement in ductility. The increase of the rubber content further increased the thermal insulation capacity of the cemented tailings. The low stiffness and the dimpled surface of the crumb rubber were responsible for the reduced compressive strength and thermal conductivity of the cemented tailings. In conclusion, the crumb rubber had both positive and negative effects on the cemented tailings. In practical application, the rubber admixture amount should be flexibly adjusted for different use case to make the cemented tailings material show the most suitable performance characteristic.

Backfilling mining method is a green mining method which is being used widely, nevertheless, the uniaxial compressive strength (UCS) of the cement backfill paste (CPB) on site is difficult to measure, and it is impossible to know the internal cementation, for this reason, the rebound method is improved and introduced in this paper. Standard specimens of CPB were made and cured for different curing age under standard curing conditions. The hardness test of each part of the CPB is completed, the unconfined compression test is carried out, and the functional model of the hardness of each part of the CPB is established, which was a function of radius and age. Based on the nonuniformity of the filling material, the failure mode of CPB is analyzed and verified in the test. The results show that the exponential function model is more suitable for the relationship between the external hardness and the overall strength, and this conclusion is of great significance in construction site. In addition, the corresponding relationship between hardness and local strength was calculated and verified, the results show that the simple model can predict the variation of local strength with hardness better, and the quadratic function model is the best choice.