ABSTRACT

This study was conducted on the impact of carbonization reaction on the performance of gangue–cemented paste backfill(GCPB). Tests were conducted using a carbonization box with CO₂ concentrations of 0%,5%,and 10%. Each test was conducted for 3,7, and 28 days. We then conducted uniaxial compressive strength(UCS)testing, as well as X-ray diffraction(XRD)and scanning electron microscopy(SEM)analyses to explore the effects of the carbonization reaction on the mechanical properties of the GCPBs under the varying carbonization concentrations. The test results showed that before 28 days, the UCS of the GCPB increased with time. The higher the CO₂ concentration, the larger the contact area with the gel material;and the longer time, the slower the growth. Hydration products, such as needle-shaped ettringite(AFt)and white fibrous calcium-silicate-hydrate(C–S–H)gel, carbonize with CO₂ in the air, mainly generating CaCO₃,and combine with incompletely carbonized hydration products to act on the GCPB, increasing the UCS in its growth state. Moreover,we established a CO₂ diffusion and mass transfer equation, indicating a negative correlation between the UCS of the GCPB and the CO₂ concentration,which verified the macroscopic test results. Controlling the CO₂ concentration provides the theoretical and experimental basis for the impact of the carbonization reaction on the performance of GCPBs.

摘要

这项研究是针对碳化反应对煤on石水泥浆回填材料（GCPB）性能的影响而进行的。使用具有₂％的CO ₂浓度的碳化箱进行测试。每个测试进行了3.7天和28天。然后，我们进行了单轴抗压强度（UCS）测试，以及X射线衍射（XRD）和扫描电子显微镜（SEM）分析，以探讨碳化反应在不同碳化浓度下对GCPB力学性能的影响。测试结果表明，在28天之前，GCPB的UCS随时间增加。CO ₂越高浓度越大，与凝胶材料的接触面积越大；时间越长，生长越慢。针状钙矾石（AFt）和白色纤维状硅酸钙水合物（C–S–H）凝胶等水合产物在空气中与CO ₂发生碳化，主要生成CaCO ₃，并与不完全碳化的水合产物结合形成对GCPB采取行动，使UCS处于增长状态。此外，我们建立了一个CO ₂扩散和传质方程，表明GCPB的UCS与CO ₂浓度呈负相关，证明了宏观测试结果。控制CO ₂ 浓度为碳化反应对GCPBs性能的影响提供了理论和实验依据。