Lime and/or Ordinary Portland cement (OPC) are the traditional binders used in soft soil 17 stabilisation. However, their manufacture has a negative impact on the environment. This 18 paper reports the results of experimental work for the optimisation of a binary blended 19 cementitious binder (BBCB) using two types of fly ash as an alternative for use in soft soil 20 stabilisation. The optimum content of the high calcium fly ash (HCFA) was initially 21 determined along with the effect of grinding activation on the performance of HCFA. 22 Subsequently, the effect of palm oil fuel ash (POFA) pozzolanic reactivity on the engineering 23 properties of soft soil, stabilised with HCFA, was investigated by producing different binary 24 mixtures of HCFA and POFA. Based on the Atterberg limits and unconfined compressive 25 strength (UCS) tests, the combination of POFA with HCFA results in a considerably lower 26 plasticity index (PI) and higher compressive strength than those obtained from the soil treated 27 with HCFA alone. Substantial changes in the microstructure and binders of the stabilised soil 28 over curing time were evidenced by SEM imaging and XRD analysis. A solid and coherent 29 *Revised manuscript with no changes marked Click here to view linked References structure was achieved after treatment with BBCB as evidenced by the formation of C-S-H, 30 portlandite and ettringite as well as secondary calcite.

Soil stabilisation using traditional binders such as Ordinary Portland Cement (OPC), has a serious negative environmental impact, specifically carbon dioxide (CO 2) emissions as a result of the manufacture of OPC. Because of this, the use of sustainable binders has become a critical issue to help reduce cement production through the use of by-product materials. This research seeks to develop a new ternary blended cementitious binder (TBCB) to replace cement for soft soil stabilisation. Different ternary mixtures containing wastes i.e., high calcium fly ash (HCFA), palm oil fuel ash (POFA) and rice husk ash (RHA) along with flue gas desulphurisation (FGD) gypsum used as a sulphate activator and grinding agent, were examined. The results illustrate that ternary mixtures improved the engineering and mechanical properties of stabilised soil. The results indicated that the plasticity index (PI) was reduced ACCEPTED MANUSCRIPT from 20.2 to 13.0 and the unconfined compressive strength (UCS) increased after 28 days of curing from 202kPa to 944kPa using the optimum non-FGD activated mixture. FGD contributed significantly by increasing the UCS to 1464kPa at 180 days of curing, which surpassed that for the reference cement (1450kPa), and by improving the soil consistency limits; where the PI decreased to 11.7 using TBCB compared with 14.5 for the soil treated with the reference cement. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed substantial changes in the diffraction patterns and microstructure components of the TBCB paste over the curing period, confirming the formation of cementitious products. A solid, coherent and compacted structure was achieved after treatment with TBCB as evidenced by the formation of C-S-H, CH and ettringite.

The provision of safe water for people is a human right; historically, a major number of people depend on groundwater as a source of water for their needs, such as agricultural, industrial or human activities. Water resources have recently been affected by organic and/or inorganic contaminants as a result of population growth and increased anthropogenic activity, soil leaching and pollution. Water resource remediation has become a serious environmental concern, since it has a direct impact on many aspects of people’s lives. For decades, the pump-and-treat method has been considered the predominant treatment process for the remediation of contaminated groundwater with organic and inorganic contaminants. On the other side, this technique missed sustainability and the new concept of using renewable energy. Permeable reactive barriers (PRBs) have been implemented as an alternative to conventional pump-and-treat systems for remediating polluted groundwater because of their effectiveness and ease of implementation. In this paper, a review of the importance of groundwater, contamination and biological, physical as well as chemical remediation techniques have been discussed. In this review, the principles of the permeable reactive barrier’s use as a remediation technique have been introduced along with commonly used reactive materials and the recent applications of the permeable reactive barrier in the remediation of different contaminants, such as heavy metals, chlorinated solvents and pesticides. This paper also discusses the characteristics of reactive media and contaminants’ uptake mechanisms. Finally, remediation isotherms, the breakthrough curves and kinetic sorption models are also being presented. It has been found that groundwater could be contaminated by different pollutants and must be remediated to fit human, agricultural and industrial needs. The PRB technique is an efficient treatment process that is an inexpensive alternative for the pump-and-treat procedure and represents a promising technique to treat groundwater pollution.

This investigation aimed to examine the load carrying capacity of model piles embedded in sand soil and to develop a predictive model to simulate pile settlement using a new artificial neural network (ANN) approach. A series of experimental pile load tests were carried out on model concrete piles, comprised of three piles with slenderness ratios of 12, 17 and 25. This was to provide an initial dataset to establish the ANN model, in attempt at making current, in situ pile-load test methods unnecessary. Evolutionary Levenberg-Marquardt (LM) MATLAB algorithms, enhanced by T-tests and F-tests, were developed and applied in this process. The model piles were embedded in a calibration chamber in three densities of sand; loose, medium and dense. According to the statistical analysis and the relative importance study, pile lengths, applied load, pile flexural rigidity, pile aspects ratio, and sand-pile friction angle were found to play a key role in pile settlement at different contribution levels, following the order: P > δ > lc/d > lc > EA. The results revealed that the optimum model of the LM training algorithm can be used to characterize pile settlement with good degree of accuracy. There was also close agreement between the experimental and predicted data with a root mean square error, (RMSE) and correlation coefficient (R) of 0.0025192 and 0.988, respectively.

Artificial neural network (ANN) approach for modelling of pile settlement of open-ended steel piles subjected to compression load

The novel aspect of this research is the fabrication, characterisation, and application of an engineered adsorbent made from quartz sand coated with calcium ferric oxides (QS/CFO) derived from the wastepaper sludge ash (WPSA) for the removal of tetracycline (TC) from synthetic water. Initially, the new adsorbent was fabricated using a Ca/Fe molar ratio, sand/FeCl3 ratio, pH (of synthesising environment), ethylene glycol dose, and temperature of 1:0.75, 1:1, 12, 6 mL/100 mL, and 95℃, respectively. Then, the new adsorbent was applied to treat water having 50 mg/L of TC in batch experiments, taking into account the effects of the contact time (0–180 min), pH of water (2–12), the dose of adsorbent (0.05–0.5 g), and agitation speed (0–250 rpm). The results obtained proved the engineered adsorbent can remove as much as 90% of the TC (adsorption capacity of 21.96 mg/g) within 180 min at an initial pH, adsorbent dosage, and agitation speed of 7, 0.3g per 50 mL, and 200 rpm, respectively. It was also found that the pseudo-second-order model describes the kinetic measurements better than the pseudo-first-order model, which indicates that the TC molecules have been bonded with the prepared sorbent through chemical forces. Furthermore, the intra-particle diffusion model results demonstrated that the diffusion mechanism plays a significant role in TC adsorption; however, it was not the predominant one. Finally, the outcomes of the characterisation analysis proved that the newly formed layer on the quartz sand substantially contributed to the removal of the TC from the contaminated water.

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