تخصيص مونة اسمنتية مستدامة لوحدات البنى التحتية

Characterizing Sustainable Grout for Infrastructure Units

Abstract

Cement grout is widely used for the structural rehabilitation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry buildings, and geological stabilizations. Cement production and materials usage continue to rise annually, resulting in more CO2 emissions and higher energy costs. On the other hand, drinking water production increases in the water treatment plant due to the increasing population, causing, in turn, the production of waste materials, mainly managed to landfill. Consequently, efforts to utilize supplementary cementitious materials to enhance cement compounds’ mechanical, economic, and environmental characteristics continue. This study is a unique example of partially replacing cement by calcined drinking water treatment sludge (CDWTS) in the grout production.
The calcination temperature and the fineness were optimised, and the optimum values of 700°c and (25 µm) were ultimately chosen. The chemical and physical properties (Strength activity index (SAI), X-Ray Florence (XRF), specific gravity, and particle size) of the calcined DWTS ash were characterized. CDWTS ash was substituted for 0%, 5%, 10%, and 15% of the cement’s weight. Besides, to determine the effect of CDWTS individually on the characteristics of the grout, the amount of water and superplasticizer were kept constant. The experimental work was done in the laboratory to estimate the fresh properties, including (setting time, flow-time, and mini-slump), and hardened properties, including (compressive strength, flexural strength, ultrasonic pulse velocity, and dry density supported with Scanning Electron Microscopy – Energy descriptive X-ray (SEM -EDAX) of the cement grout was produced to investigate its characteristics.
The result showed that the cement grouts with 5% DWTS substituted for cement could be found to have the best overall behaviour and were considered the most promising. Furthermore, it was shown that hardened properties decrease with increasing percentages of replacement (10% and 15%) but stay greater than a reference. According to the fresh state analysis, the workability of cement grout decreased dramatically as the proportion of DWTS increased. This shows that the DWTS can be considered a viable replacement for Portland cement in the grout. The mechanical performance was consistent and supported by the SEM-EDX analysis.
The statistical analysis was also performed utilizing the SPSS program version 26 to predict the hardened properties (compressive strength, flexural strength, and UPV) utilizing Multiple Linear Regression (MLR). For MLR modelling, the mixture proportion and the curing age were input parameters by the standard entry approach. The models’ performance was assessed using measures such as the correlation coefficient (R) and coefficient of determination (R2). The modelling results pointed out that the models used in this study effectively predicted flexural strength and ultrasonic pulse velocity with reasonable accuracy, where the compressive strength has a lower estimation. Based on the outcome of thesis-work, the CDWTS could be considered a viable replacement to cement in grout production, with up to 15% replacement.