Abstract
The development of cemented paste backfilling (CPB) technology has made an important contribution to the mining economy. As a kind of porous material, the pore structure characteristic of cemented paste backfill (CPB) is strongly correlated to its mechanical properties. In this study, CPB specimens were prepared with tailings/cement ratios (T/C ratio) of 4, 6, 10 and curing durations of 3, 7, 14, and 28 days, respectively. Pore structures characteristics of CPB specimens were investigated using nuclear magnetic resonance (NMR) and scanning electronic microscopy (SEM). The uniaxial compressive strength (UCS) was adopted to illustrate the mechanical property of CPB specimens. The coupling effects of T/C ratio and curing time on the pore characteristics of CPB as well as the effect of pore size on the UCS were analyzed. The results indicated that: 1) the microstructural integrity of CPB was highly related to the development status of the pore structure, which can be represented by micro-parameters like porosity, average pore area, etc. 2) a similar normal distribution curve was observed from the four kinds of pore structure in CPB. As the curing time increased, the peak of the pore size curve shifted left, and the peak value decreased, which means that the pore size in CPB decreased and became much concentrated; 3) the extension of the most probable pore size led to the cross-connection of pores and resulted in the fracture of CPB, which was shown as a crack on the main section.
Highlights
The cemented paste backfill (CPB) technology has been widely used in recent years due to technical, economical, and environmental benefits (Yilmaz et al, 2011a; Lu et al, 2018; Qi et al, 2018a; Liu et al, 2020)
The objective of this paper was to assess the coupling effect of tailings cement ratio and curing time on microstructural parameters and UCS of CPB specimens, which were prepared with different tailings cement ratios
It is a twodimensional parameter, which could indirectly indicate the pore variation trend in CPB (Koohestani and Belem, 2017). It is a parameter which depends on the average pore length and average pore width. It could indicate the average size of pores and reflect the pore size variation in CPB specimens (Koohestani and Belem, 2017)
Summary
The cemented paste backfill (CPB) technology has been widely used in recent years due to technical, economical, and environmental benefits (Yilmaz et al, 2011a; Lu et al, 2018; Qi et al, 2018a; Liu et al, 2020). The objective of this paper was to assess the coupling effect of tailings cement ratio and curing time on microstructural parameters (such as average pore area, T2 spectrum area etc.) and UCS of CPB specimens, which were prepared with different tailings cement ratios. The SEM images were quantitatively analyzed using the software of Particles (Pores) and Cracks Analysis System (PCAS) to evaluate the micro-parameters such as apparent porosity ratio, average pore area etc For the former, it is a ratio of the pore area to the total specimen area in SEM test. It is a twodimensional parameter, which could indirectly indicate the pore variation trend in CPB (Koohestani and Belem, 2017). It could indicate the average size of pores and reflect the pore size variation in CPB specimens (Koohestani and Belem, 2017)
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