Utilization of rice straw as an inhibitor of strength deterioration of sulfide-rich cemented paste backfill

Cemented paste backfill (CPB) has been a practical approach for mining waste manage-ment, underground goaf treatment, and green mining. Strength deterioration because of high sulfide content (SC) is a severe challenge for sulfide-rich CPB. To investigate the in-fluence of rice straw (RS) on the strength of sulfide-rich CPB, RS was utilized as an inhibitor of strength deterioration. RS dosage (RSD), RS length (RSL), and sulfide content (SC) were chosen as the factors, and two stages of the experiment were carried out. It was found that high SC produced pores, cracks, and loose microstructure of CPB, resulting in the strength deterioration of sulfide-rich CPB. The 90-day uniaxial compressive strength (90 d-UCS) was the maximum of the UCS of sulfide-rich CPB. The hydration products and microstructural characteristics observed by XRD and scanning electron microscopy (SEM) illustrated that RS has the effect of bridging and water retention. Accordingly, adding RS improved the long-term strength of sulfide-rich CPB. The optimal RSD, RSL, and SC for 90 d-UCS of sulfide-rich CPB were obtained through the response surface methodology approach. The optimal conditions within the experimental range of this study for maximum 90 d-UCS of CPB with high SC (17 wt%) were RSD of 0.032 wt% and RSL of 0.28 cm, producing a 90 d-UCS of 5.14 MPa.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Rice straw was used as an inhibitor to improve the strength deterioration of sulfide-rich CPB. The optimal dosage and length of rice straw, as well as sulfide content, were determined through experiments, leading to an enhancement of the long-term strength of sulfide-rich CPB.