Department of Civil Engineering, University of Engineering and Technology (UET), Taxila, 47080, Pakistan.
National Institute of Transportation (NIT), National University of Sciences and Technology (NUST), Risalpur, 23200, Pakistan.
Environ Sci Pollut Res Int. 2022 Mar;29(12):17001-17016. doi: 10.1007/s11356-021-16912-w. Epub 2021 Oct 16.
The balanced amelioration of mechanical characteristics of fat clay with an additive refers to the attainment of high strength without compromising ductility, which is unattainable by solitary usage of a cementing additive. For this purpose, an amalgamated binary admixture (ABA) is proposed by assimilating shredded face mask (FM) waste, which is posing serious environmental concerns these days, with a cementitious waste material, i.e., silica fume (SF). However, for such ABA, the optimization of mix design is desirable because an excessive amount of one component could disturb the required balance. To address this issue, response surface methodology (RSM) is used in the current study, which is a strong technique used during the process of production to develop, improve, and optimize product inputs. Several experiments are designed and conducted to evaluate mechanical responses, i.e., unconfined compressive strength (q), brittleness index (I), deformability index (I), and California bearing ratio (CBR) value, of treated fat clay by varying mix designs of ABA. Based on the test results, mathematical models are developed which are found to be statistically valid to predict the subjected responses using SF and FM as inputs. Afterward, an optimized mix design is determined by integrating developed models with a desirability function model and setting maximization of strength and ductility as the optimization goals. An ABA having 7.9% SF and 1.2% FM is observed to provide the highest strength and ductility for multiple applications, i.e., road and buildings, with desirability factor close to unity; responses of which are also validated by performing tests. Furthermore, analysis of cleaning aspect shows that the use of optimized ABA in place of cement for subgrade improvement of 1 km two-lane road could avoid CO emission of around 79,032 kg of C, save 42,720 kWh and 1174.8 GJ of electrical and thermal energy, respectively, and clean 43 Mg of FM waste; however, astute protocols of COVID-19 FM waste handling and disinfection are needed to be established and followed.
添加物对脂肪土力学特性的均衡改良是指在不牺牲延性的情况下获得高强度，而这是单独使用胶凝添加剂所无法实现的。为此，本研究提出了一种混合二元外加剂（ABA），即将目前严重影响环境的废弃口罩（FM）与硅灰（SF）等胶凝废料结合起来。然而，对于这种 ABA，需要优化配合比设计，因为一种成分过多可能会破坏所需的平衡。为了解决这个问题，本研究采用响应面法（RSM），这是一种在生产过程中用于开发、改进和优化产品投入的强大技术。通过设计和进行多项实验，评估了处理后的脂肪土的机械响应，即无侧限抗压强度（q）、脆性指数（I）、变形指数（I）和加州承载比（CBR）值，这些响应通过改变 ABA 的混合设计来改变。基于测试结果，建立了数学模型，发现这些模型使用 SF 和 FM 作为输入来预测所受响应具有统计学上的有效性。之后，通过将开发的模型与适宜性函数模型集成，并将强度和延性的最大化设定为优化目标，确定了优化的混合设计。结果表明，ABA 中 SF 含量为 7.9%，FM 含量为 1.2%，可同时提高强度和延性，适用于道路和建筑等多种应用，适宜性系数接近 1；通过实验验证了模型的有效性。此外，清洁分析表明，在 1 公里双车道道路的路基改良中，用优化后的 ABA 替代水泥可以避免约 79032 千克 C 的 CO 排放，分别节省 42720 千瓦时和 1174.8 吉焦耳的电能和热能，并清洁 43 吨 FM 废物；然而，需要建立和遵循 COVID-19 FM 废物处理和消毒的敏锐协议。
