Geopolymers are novel binding materials produced by the alkaline activation of rich aluminosilicate materials. Geopolymer binders are considered as green building materials that have increasing potential to replace the ordinary Portland cement in the concrete industry. This study investigated the alkali solution effects on the physical and mechanical properties of the high calcium fly ash based geopolymers. The parameters involved in this study were the NaOH solution molarity and the Na2SiO3/NaOH ratio. Three NaOH concentrations (8, 10, and 12 molars) were investigated. The Na2SiO3/NaOH ratio was varied between 1 and 2.5. The results showed that the studied parameters significantly affected the properties of the produced geopolymer mortars. The workability and setting time were found to decrease by increasing the NaOH concentration or by increasing the Na2SiO3/NaOH ratio. The influence of the NaOH concentration was higher on the workability and setting time while the Na2SiO3/NaOH ratio highly affected the compressive strength. The initial setting time was in the range of 45-105minutes while the final setting occurred quickly after that within 70-115minutes. Oven curing method resulted in high strength at early ages where all of the mixes were able to achieve more than 75% of the 28 days strength within the first 3 days. The 28-days compressive strength ranged between 60-85MPa, which promotes the use of the high calcium fly ash for the production of early high strength geopolymer concrete

To improve water quality, total daily loads must be established, and this requires determining the quality of the water in rivers, storage tanks, ponds, and coastal areas. Current methods to evaluate water quality involve the collection of water samples for subsequent laboratory analysis. Although these technologies offer precise measurements for a specific location and time, they are expensive, time-consuming, and do not provide the continuous, temporal, or spatial conditions of water quality that are required for managing, assessing, and monitoring water quality. In order to calculate the water quality, the water quality index is modeled using artificial neural network models that incorporate feedforward neural network backpropagation neural networks and radial neural networks. The water quality index of Malaysia’s Klang River was determined by training the artificial network using six major sub-quality parameters. Compared to the current method, the artificial neural network simplifies and expedites the computation of the water quality index. The artificial neural network method could provide a significant saving in terms of money and time while offering a robust assessment of water quality. The proposed method could also be used as an early warning system for pollution of water bodies. The best artificial neural network was the feedforward neural network with one hidden layer containing 5 neurons. Furthermore, conventional approaches for calculating the water quality index rely on empirical equations, often introducing a high degree of approximation and uncertainty into the results. Moreover, these equations cannot be applied when some parameters are not measured. In contrast, the artificial neural network methods and technique offer an efficient and straightforward process for estimating and creating prediction models for water quality index. Doi: 10.28991/CEJ-2024-010-07-012 Full Text: PDF

This paper presents a detailed investigation of the effects of refined sugarcane bagasse ash (SCBA) as partial replacement for cement on the properties of fresh and hardened concrete. The study verified that SCBA shows promising results of its use as a cement replacement material (CRM). The potential of SCBA as a CRM was found because of its chemical composition, fineness and well-controlled incineration process. The availability of bagasse is also a positive indicator for the sustainable supply of SCBA as CRM. In the world, approximately 1500 Mt of sugarcane is annually produced, which yields approximately 40–45% bagasse after juice extraction in sugar mills. In this study, SCBA content was varied from 5 to 50% as partial replacement of cement. The effects of SCBA on the workability, compressive strength, splitting tensile strength and bond strength of concrete were investigated. The results showed that the addition of SCBA (5–50% content) increased the slump value of fresh concrete. The mechanical properties (compressive strength, splitting tensile strength and bond strength) of concrete made of 5–30% SCBA showed a reasonable enhancement in the results in comparison with the 100% cement concrete.