Ibraheem Muhammad, Butt Faheem, Waqas Rana Muhammad, Hussain Khadim, Tufail Rana Faisal, Ahmad Naveed, Usanova Ksenia, Musarat Muhammad Ali
Department of Civil Engineering, University of Engineering and Technology, Taxila 47050, Pakistan.
Department of Civil Engineering, Wah Campus, COMSATS University Islamabad, Wah Cantt 47040, Pakistan.
Materials (Basel). 2021 Nov 15;14(22):6890. doi: 10.3390/ma14226890.
The purpose of this research is to study the effects of quarry rock dust (QRD) and steel fibers (SF) inclusion on the fresh, mechanical, and microstructural properties of fly ash (FA) and ground granulated blast furnace slag (SG)-based geopolymer concrete (GPC) exposed to elevated temperatures. Such types of ternary mixes were prepared by blending waste materials from different industries, including QRD, SG, and FA, with alkaline activator solutions. The multiphysical models show that the inclusion of steel fibers and binders can enhance the mechanical properties of GPC. In this study, a total of 18 different mix proportions were designed with different proportions of QRD (0%, 5%, 10%, 15%, and 20%) and steel fibers (0.75% and 1.5%). The slag was replaced by different proportions of QRD in fly ash, and SG-based GPC mixes to study the effect of QRD incorporation. The mechanical properties of specimens, i.e., compressive strength, splitting tensile strength, and flexural strength, were determined by testing cubes, cylinders, and prisms, respectively, at different ages (7, 28, and 56 days). The specimens were also heated up to 800 °C to evaluate the resistance of specimens to elevated temperature in terms of residual compressive strength and weight loss. The test results showed that the mechanical strength of GPC mixes (without steel fibers) increased by 6-11%, with an increase in QRD content up to 15% at the age of 28 days. In contrast, more than 15% of QRD contents resulted in decreasing the mechanical strength properties. Incorporating steel fibers in a fraction of 0.75% by volume increased the compressive, tensile, and flexural strength of GPC mixes by 15%, 23%, and 34%, respectively. However, further addition of steel fibers at 1.5% by volume lowered the mechanical strength properties. The optimal mixture of QRD incorporated FA-SG-based GPC (QFS-GPC) was observed with 15% QRD and 0.75% steel fibers contents considering the performance in workability and mechanical properties. The results also showed that under elevated temperatures up to 800 °C, the weight loss of QFS-GPC specimens persistently increased with a consistent decrease in the residual compressive strength for increasing QRD content and temperature. Furthermore, the microstructure characterization of QRD blended GPC mixes were also carried out by performing scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS).
本研究的目的是研究掺入采石场岩粉（QRD）和钢纤维（SF）对暴露于高温下的以粉煤灰（FA）和磨细粒化高炉矿渣（SG）为基础的地质聚合物混凝土（GPC）的新拌性能、力学性能和微观结构性能的影响。通过将来自不同行业的废料（包括QRD、SG和FA）与碱性活化剂溶液混合来制备此类三元混合料。多物理模型表明，掺入钢纤维和粘结剂可以提高GPC的力学性能。在本研究中，总共设计了18种不同的配合比，其中QRD的比例不同（0%、5%、10%、15%和20%），钢纤维的比例也不同（0.75%和1.5%）。在粉煤灰和基于SG的GPC混合料中，用不同比例的QRD替代矿渣，以研究掺入QRD的效果。分别通过对立方体、圆柱体和棱柱体在不同龄期（7天、28天和56天）进行测试，来测定试件的力学性能，即抗压强度、劈裂抗拉强度和抗折强度。还将试件加热到800℃，以根据残余抗压强度和重量损失来评估试件对高温的抵抗能力。试验结果表明，在28天龄期时，随着QRD含量增加至15%，GPC混合料（无钢纤维）的力学强度提高了6% - 11%。相比之下，QRD含量超过15%会导致力学强度性能下降。掺入体积分数为0.75%的钢纤维，使GPC混合料的抗压强度、抗拉强度和抗折强度分别提高了15%、23%和34%。然而，进一步添加体积分数为1.5%的钢纤维会降低力学强度性能。考虑到工作性和力学性能，观察到掺入QRD的基于FA - SG的GPC（QFS - GPC）的最佳混合料为QRD含量15%和钢纤维含量0.75%。结果还表明，在高达800℃的高温下，随着QRD含量和温度的增加，QFS - GPC试件的重量损失持续增加，残余抗压强度持续降低。此外，还通过扫描电子显微镜（SEM）、X射线衍射（XRD）和能谱分析（EDS）对掺入QRD的GPC混合料进行了微观结构表征。
