Kim Wonchang, Choi Hyeonggil, Lee Taegyu
Department of Fire and Disaster Prevention, Semyung University, Choongbuk 27136, Republic of Korea.
School of Architecture and Civil Engineering, Kyungpook National University, Daegu 41566, Republic of Korea.
Materials (Basel). 2023 Jan 27;16(3):1099. doi: 10.3390/ma16031099.
Research on alternative cement materials is active worldwide, and in terms of fire safety, research on the evaluation of high-temperature properties of alternative materials is very important. Studies on concrete mixed with hwangto have been conducted by several researchers, but studies on high-temperature properties are lacking. Therefore, in this study, we evaluated the mechanical properties of concrete by partially replacing cement with non-sintered hwangto (NSH) at high temperatures. Normal concrete without NSH mixing and non-sintered hwangto concrete (NSHC) with HNT replacement were prepared as the specimens. The W/B of the concrete was set to 41 and 33, whereas the NSH replacement ratio was 15 and 30% of the cement. The target heating temperatures were set to 20, 100, 200, 300, 500, and 700 °C, and the heating rate was maintained at 1 °C/min. The following were calculated to evaluate the mechanical properties of the specimens: mass loss, compressive strength, ultrasonic pulse velocity (UPV), and modulus of elasticity. After analyzing the correlation between residual compressive strength and UPV, we proposed a compressive strength prediction model using different values of W/B for NSHC. Experimental results suggest that mass loss (%) shows a decreasing trend as NSH increases. In terms of residual compressive strength, residual compressive strength at W/B 41 increased with NSH replacement, whereas residual compressive strength values for W/B 33 were observed regardless of NSH replacement. Residual UPV showed a similar trend, regardless of the NSH replacement ratio, and residual modulus of elasticity was low at all W/B ratios as NSH replacement increased. A linear equation with a high correlation coefficient (R) was proposed to predict compressive strength, and the linear value of W/B 41 was slightly higher than that of W/B 33.
全球范围内对替代水泥材料的研究十分活跃，就消防安全而言，对替代材料高温性能评估的研究非常重要。已有多位研究人员对掺有黄土的混凝土进行了研究，但缺乏对其高温性能的研究。因此，在本研究中，我们通过在高温下用非烧结黄土（NSH）部分替代水泥来评估混凝土的力学性能。制备了未掺NSH的普通混凝土和用HNT替代的非烧结黄土混凝土（NSHC）作为试件。混凝土的水胶比设定为41和33，而NSH替代率为水泥的15%和30%。目标加热温度设定为20、100、200、300、500和700℃，加热速率保持在1℃/分钟。计算以下指标以评估试件的力学性能：质量损失、抗压强度、超声波脉冲速度（UPV）和弹性模量。在分析残余抗压强度与UPV之间的相关性后，我们针对NSHC提出了使用不同水胶比的抗压强度预测模型。实验结果表明，随着NSH含量的增加，质量损失（%）呈下降趋势。就残余抗压强度而言，水胶比为41时，残余抗压强度随NSH替代量的增加而提高，而水胶比为33时，无论NSH替代量如何，残余抗压强度值基本不变。无论NSH替代率如何，残余UPV都呈现类似趋势，并且随着NSH替代量的增加，所有水胶比下的残余弹性模量都较低。提出了一个相关系数（R）较高的线性方程来预测抗压强度，水胶比为41时的线性值略高于水胶比为33时的线性值。
