This research aims to study the effect of the dosage of anhydrous sodium metasilicate activator on the long-term properties of fly ash-based one-part alkali-activated binders (OPAAB) cured at ambient conditions. Powdered sodium metasilicate activator was utilized in the range of 8–16% by weight of the fly ash in producing the OPAAB. The properties examined are hardened density, compressive strength, flexural strength, water absorption, efflorescence formation, and microstructural analysis. The experimental result revealed that the binders exhibited excellent long-term strength properties. The compressive strength of the OPAAP is well correlated with its hardened density. The pastes were found to exhibit good soundness characteristics over the long-term. The absorption of water decreases with an increase in the activator dosage from 8–12%, and beyond that, the water absorption relatively remains the same. Field emission scanning electron microscope (FESEM) micrograph revealed uniformly formed solid matrices with the micro-crack present were observed in the samples. The larger pore size promotes the crystallization of the resulting hydrate substances (N, C)-A-S-H gel. The initial dissolution of the OPAAP occurred within the first 30 min. At longer age of curing, mixtures with a higher dosage of powdered activator tend to absorb less water. Strength properties beyond 28 days are considered as the long-term strength.

In the industries of petroleum extraction, a large volume of oily sludge is being generated. This waste is usually considered difficult to dispose of, causing environmental and economic issues. This study presented the novel experimental method of manufacturing mortar used in civil construction by cement and oily sludge ash (OSA). The defined method was described with a logical experimental study conducted to examine a feasible manufacturing method for casting cement-based mortars by partially replacing cement with OSA. Replacement concentrations for OSA ranged from 0 to 20 percent by cement weight, while the water-to-cement (w/c) ratio was varied from 0.4 to 0.8, and the amount of sand was kept constant. The strengths and absorption rate of the mortar were monitored for 28 days. The OSA contains a crystalline structure with packs of angular grains. Because of OSA in the cement-based mortar mixtures and water-to-cement ratios, the mechanical strength was improved significantly. However, the water absorption trend increased linearly. Using variance analysis, the influence of OSA and w/c ratio on the behavior of mortar was acquired. The developed models were significant for all p-value reactions of <5%. Numerical optimization results showed that the best mixture can be obtained by replacing 8.19 percent cement with OSA and 0.52 as a ratio of w/c.

Petroleum sludge is a waste product resulting from petroleum industries and it is a major source of environmental pollution. Therefore, developing strategies aimed at reducing its environmental impact and enhance cleaner production are crucial for environmental mortar. Response surface methodology (RSM) was used in designing the experimental work. The variables considered were the amount of petroleum sludge ash (PSA) in weight percent and the ratio of sodium silicate to sodium hydroxide, while the concentration of sodium hydroxide was kept constant in the production of geopolymer mortar cured at a temperature of 60 °C for 20 h. The effects of PSA on density, compressive strength, flexural strength, water absorption, drying shrinkage, morphology, and pore size distribution were investigated. The addition of PSA in the mortar enhanced the mechanical properties significantly at an early age and 28 days of curing. Thus, PSA could be used as a precursor material in the production of geopolymer mortar for green construction sustainability. This study aimed to investigate the influence of PSA in geopolymer mortar.

The development of sustainable building materials and construction to decrease environmental pollution in both production and operational stages of the materials’ life cycle is appealing to great interest in the construction industries worldwide. This study evaluated the negative effect of temperature up to 1000 °C on the compressive strength and microstructure of fly ash and petroleum sludge ash (PSA) geopolymer mortar. A sodium silicate and sodium hydroxide mixture is used as an activator. The synthesized mortar was investigated using X-ray Diffraction (XRD), Fourier Transformation Infrared Spectroscopy (FTIR), Mercury Intrusion Porosimetry (MIP), and Field Emission Scanning Electron Microscopy (FESEM). As the temperature increased, the compressive strength of the geopolymer mortar decreased. The strength degradation is due to the damage to microstructure because of the temperature-induced dehydroxylation, dehydration thermal incompatibility between geopolymer aggregate and paste of geopolymer mortar at high temperatures. With an increase in temperature, the cumulative pore volume increased. The FESEM image showed the decomposition of the geopolymer matrix started at a temperature of 600 °C. Incorporating PSA in geopolymer mortar could result in an eco-friendly and sustainable environment that may reduce the problems associated with sludge disposal.