Yaseri Sajad, Jafarinoor Ashkan, Mahdikhani Mahdi
Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran.
Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran.
Environ Sci Pollut Res Int. 2023 Mar;30(11):31035-31059. doi: 10.1007/s11356-022-24219-7. Epub 2022 Nov 28.
Reusing industrial by-products and agricultural waste as supplementary cementitious materials for producing sustainable concrete is one of the most promising ways to reduce cement production and the detrimental effects of concrete constructions on the environment. However, when it comes to preparing self-consolidating concrete (SCC) and mortar (SCMO) containing such materials in high volume, bleeding, and segregation of their fresh mixture are the crucial factors hindering their large-scale application. In this regard, the main aim of this study is to address such issues by designing sustainable SCMO using ground granulated blast furnace slag (GGBS) in high volume and rice husk ash (RHA) with comparatively lower environmental impact and high quality. To achieve this goal, the workability of fresh mixture and all its three main characteristics, including segregation resistance, passing ability, and filling ability, were evaluated with recently developed empirical apparatuses. For this purpose, 12 mixtures with different compositions were prepared to investigate the fresh properties, compressive strength, setting time, and environmental impact index. The results indicate that there are inextricable links between mixing proportions, strength, and carbon emissions of the mixture. Sustainable SCMO with an embodied-CO index lower than 4.5 kg/MPa.m, good workability, and compressive strength of 49.7 MPa was designed by optimizing cementitious content, while the e-CO index of the control mixture was around 8 kg/MPa.m. The addition of GGBFS and RHA not only decreased the e-CO index but also increased the unit cement strength contribution index. The results also indicated that by increasing GGBFS, the fluidity and segregation of the mixture increased while adding RHA increased viscosity and modified bleeding and the segregation index. Moreover, the growth rate of the compressive strength in mixtures containing GGBFS was much higher than that of the control mix at the same age. The promising results of this experimental study indicate that utilization of GGBFS and RHA in SCMO mixture can provide a practical way to reduce the environmental effects of cement production and pave the way for friendly disposal of slag and waste products.
将工业副产品和农业废弃物作为补充胶凝材料用于生产可持续混凝土，是减少水泥生产以及混凝土建筑对环境不利影响的最具前景的方法之一。然而，在大量制备含有此类材料的自密实混凝土（SCC）和砂浆（SCMO）时，其新拌混合物的泌水和离析是阻碍它们大规模应用的关键因素。在这方面，本研究的主要目的是通过大量使用磨细粒化高炉矿渣（GGBS）和环境影响相对较小且质量较高的稻壳灰（RHA）来设计可持续的SCMO，以解决此类问题。为实现这一目标，使用最近开发的经验性仪器评估了新拌混合物的工作性及其三个主要特性，包括抗离析性、通过能力和填充能力。为此，制备了12种不同组成的混合物，以研究其新拌性能、抗压强度、凝结时间和环境影响指数。结果表明，混合比例、强度和混合物的碳排放之间存在着密不可分的联系。通过优化胶凝材料含量，设计出了 embodied-CO指数低于4.5 kg/MPa·m、工作性良好且抗压强度为49.7 MPa的可持续SCMO，而对照混合物的e-CO指数约为8 kg/MPa·m。添加GGBFS和RHA不仅降低了e-CO指数，还提高了单位水泥强度贡献指数。结果还表明，增加GGBFS会使混合物的流动性和离析性增加，而添加RHA会增加粘度并改善泌水和离析指数。此外，在相同龄期下，含GGBFS的混合物中抗压强度的增长率远高于对照混合物。本试验研究取得的良好结果表明，在SCMO混合物中使用GGBFS和RHA可为减少水泥生产的环境影响提供一种切实可行的方法，并为矿渣和废弃物的友好处置铺平道路。
