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This study investigated the effects of clogging in Pervious Concrete (PC) from January 2015 to December 2022. Three different PC mixtures were used, which included coarse aggregate (4.75-9.5 mm), fine aggregate (0-20% weight of coarse aggregate), cement (340 kg/m3), and w/c ratio of 0.35. The samples were tested for compressive strength, permeability, and porosity. The best PC mixture containing 10% fine aggregate was selected for monitoring clogging over time. This mixture had a compressive strength of 24.7 MPa, permeability of 1.19 mm/s, and void content of 13.96%. A large-scale prototype of PC10 (10% of fine aggregate) measuring 3.5 m in length, 1.7 m in width, and 0.20 m in depth was constructed in Mashhad City, Iran. The in-place infiltration rate was measured on a monthly basis as the PC experienced different rainfall levels. The results showed that due to clogging, the infiltration rate was reduced by an average of 10% for the first four years of the experiments. This was followed by a substantial reduction of 20% in 2019 and 16.75% in 2020. Due to a high level of clogging, the infiltration rate was reduced by 5.02% and 2.23% in 2021 and 2022, respectively. However, the system still has the capacity to infiltrate at 1.14 mm/s. Although no maintenance was performed on the PC system, its efficiency and lifespan were substantially reduced. Nonetheless, the system can still be considered as an effective solution for stormwater management.

In the present study, the mechanical characteristics and environmental aspects of lignite pervious concrete (LPC) in reducing stormwater pollution were investigated. Therefore, fine-grained lignite (0.6–1.2 mm) in various portions (up to 15% w/w of coarse aggregate) was added to the PC mixture. The workability, strength, cementitious paste thickness, and physical properties of LPC were examined for further application in urban areas with a focus on stormwater treatment. The statistical analysis of the results of ANOVA and visualization of the microstructure of LPC by means of scanning electron microscopy and energy-dispersive X-ray spectroscopy were also presented. The results showed that LPC is a sticky paste with no slump (0). Adding lignite also slightly reduced the compressive strength of LPC up to 23% lower than the control sample (13.8 MPa). In addition, the presence of lignite led to a considerable reduction in permeability (40%) and porosity (51%) compared to the control sample. It was also found that the increase in cementitious paste thickness resulted in an increase of the compressive strength, which was mainly concentrated between 0.3 and 1.8 mm. However, the performance of LPC in reducing stormwater contamination was promising. Sample L15, with the highest removal efficiency, reduced the chemical oxygen demand, total suspended solids, and turbidity up to 42.14%, 63.38%, and 67.24%, respectively, while no significant changes were observed in pH, total dissolved solids, and nitrate (NO3). In short, although adding lignite to PC caused a reduction in the strength and physical properties of LPC, its efficiency in reducing stormwater pollution is quite promising, and it is recommended for use in green spaces of urban areas. Graphical Abstract

The Architecture, Engineering and Construction (AEC) industry is known to be slow in technology adoption. Higher education is an industry that well-placed to assist the AEC industry to move towards...

Peat is known as problematic ground with low bearing capacity and extensively high compressibility. Bio-cementation or commonly known as microbial-induced calcite precipitation (MICP) has been recently introduced as a ground improvement alternative for peat under waterlogged condition. Using isolated bacteria strains P19 and P21 from tropical peat, it is found that unconfined compression strength (UCS) increases with bacteria concentration at a reducing rate. A maximum unconfined compressive strength of 82.05 kPa was measured with bacteria strain P21 at 108 CFU/mL. For the range of cementation reagent varying from 0.1 to 4.0 mol/kg, the largest strength improvement occurred at 1 mol/kg and 2 mol/kg using indigenous bacteria and bacteria strain P21, respectively, for peat with sand content of 25%. At 4.0 mol/kg, the cementation reagent has detrimental effect to MICP resulting in significant reduction in strength. Due to MICP, the UCS of peat increases with sand content. Calcium carbonate precipitation results in a reduction of permeability and an increment of strength of peat–sand mixture under a submerged condition up to 28 days.

In view of economic growth, infrastructure projects are gradually increasing in terms of quantity, size and complexities. As such, construction of infrastructure projects on soft soils is unavoidab...

Urease were known to catalyze the conversion of urea to ammonia and carbon dioxide. Microbial urease has demonstrated its benefits in wide biotechnological, agricultural, medicinal and engineering application. There are number of diverse microbial species contribute to urease activity in different natural habitats like soil, ocean and in various geological formation. For this study, urease bacteria were screened and isolate from acidic peat in Sarawak, Malaysia. Five distinct and diverse bacterial strains that were able to produce urease constitutively were selected to be characterized with respect to morphology, biochemical test, growth conditions and urease activity. The selected strain showed their capability to precipitate calcium carbonate (CaCO3). Hence, the isolates could be potential source of acid ureases that can be use in various industrial utilizations. 16S rRNA sequencing and phylogenetic analysis found that the selected isolates belong to the genus of Bacillus.

Concrete in maritime structure is vulnerable to deterioration owing to external sulphate attack , which can be exacerbated by wetting-drying action (WDA), jeopardizing its resistance to cyclic loads such as wind, wave and earthquake actions. This study aims to investigate the compressive fatigue behavior of concrete exposed to sulphate attack and WDA in marine environment. Cyclic compressive loading test was conducted on concrete after 150 days of deterioration. The effects of sulphate attack and WDA, upper stress loading level and loading frequency on fatigue life, residual strain , variation of elastic modulus and post-cyclic compressive strength were investigated. The sulphate penetration profiles , volume change and mass change of concrete during the exposure time were also measured. In addition, the performance of limestone concrete and silicomanganese (SiMn) slag concrete was compared in the study. The sulphate ion was found to penetrate concrete up to a depth of 20 mm, with a maximum content of 1.72%–2.58% near the surface. The cyclic loading test showed that degraded concrete had 38.2% higher residual displacement and 1.4% lower modulus of elasticity than normal concrete. The sulphate attack and WDA weakened the concrete, reducing its fatigue resistance. SiMn slag concrete had a lower fatigue life, larger residual displacement and greater stiffness degradation than limestone concrete.

Growing concrete consumption has gradually depleted conventional resources. This research incorporates silicomanganese (SiMn) slag, marine sand and seawater as alternative concreting materials. The use of SiMn slag to replace limestone as coarse aggregate enhances sustainability, though reducing strength and durability of concrete. This research aims to enhance the SiMn slag concrete by incorporating silica fume (SF) and fly ash (FA). The interaction of SF and FA on strength, durability and workability of concrete is investigated by statistically evaluating the experimental result. In this regard, the polynomial function prediction model is developed using the Response Surface Method (RSM) for the optimization of SF and FA contents. Analysis of variance (ANOVA) using p-value at significance level of 0.05 showed that the models were statistically significant and had marginal residual errors. All models had high fitness with R 2 value ranging from 0.853 to 0.999. Adequate precision of models was above 4, indicating that the models had a low prediction error and were fit for optimization. Optimization indicated that a combination of 11.5% SF and 16.3% FA produced concrete that met the optimization criteria. Experimental validation showed that the highest prediction error was 3.4% for compressive strength , 3.2% for tensile strength , 4.9% for sorptivity and 18% for chloride permeability. The optimized concrete exhibited compact microstructure with good bonding between aggregate and cement paste . By using the established linear equation with SiMn slag concrete, the models also predicted the compressive strength of limestone concrete containing SF and FA with an error of between 0.9% and 5.4%.

The adverse effects of hostile marine environment on concrete structure have inevitably resulted in huge economic loss and may contribute to catastrophic failure. Concrete is susceptible to weathering, particularly under wetting-drying action (WDA), although its current state of the art is well established. The diverse characteristics of WDA at different site locations have compromised the reliability of laboratory works. The objective of this study is to review the impact of WDA on concrete and to provide an overview of the research trend, aiming to identify the research gap. Concrete deterioration mechanisms in marine environment in respect of WDA are identified. The influential factors of WDA are analyzed. The physical and mechanical properties and corrosion resistance of concrete exposed to WDA are discussed. WDA aggravates concrete deterioration by hastening intrusion of inimical compounds such as chloride, sulphate and carbon dioxide. Chloride convection zone can be expanded by two to three times to cause a significant concrete cover loss. Physical damage of concrete starts with efflorescence staining, followed by mortar delamination, aggregate detachment and concrete spalling, leading to loss of mechanical properties. The use of mineral admixtures such as fly ash and silica fume improves concrete resistance against corrosion, but its refining effect may lead to over-accumulation of chloride, risking the long-term durability. Limited research works are identified on synergy between physical and chemical deteriorations, validation of simulated experiment, volume expansion, mass change and tensile strength of concrete.

Microbial-induced calcite precipitation (MICP) has been used for geotechnical engineering purpose of improving soil properties. This method utilizes the metabolic pathways of non-pathogenic urealytic bacteria to produce calcite (CaCO3) as a binder to bridge soil particles together which lead to increased soil strength and stiffness. Most studies of MICP involving strength improvement were practice with inorganic soil covering sand and fined grain soil. Current study intends to investigate the MICP on the improvement of strength of tropical organic soil. MICP treatment was performed using pre-mixing method instead injection and surface percolation method. Sand as a filler was added to observe its effect on MICP. For this laboratory scale study, the shear response of the treated and untreated samples was evaluated through unconfined compressive strength (UCS) and it was observed that more than 300% increase in strength was achieved.Microbial-induced calcite precipitation (MICP) has been used for geotechnical engineering purpose of improving soil properties. This method utilizes the metabolic pathways of non-pathogenic urealytic bacteria to produce calcite (CaCO3) as a binder to bridge soil particles together which lead to increased soil strength and stiffness. Most studies of MICP involving strength improvement were practice with inorganic soil covering sand and fined grain soil. Current study intends to investigate the MICP on the improvement of strength of tropical organic soil. MICP treatment was performed using pre-mixing method instead injection and surface percolation method. Sand as a filler was added to observe its effect on MICP. For this laboratory scale study, the shear response of the treated and untreated samples was evaluated through unconfined compressive strength (UCS) and it was observed that more than 300% increase in strength was achieved.

In the paper, we present newly developed hydro-mechanical hypoplastic model for partially saturated soils predicting small strain stiffness. Hysteretic void ratio dependent water retention model has been incorporated into the existing hypoplastic model. This required thorough revision of the model structure to allow for the hydro-mechanical coupling dependencies. The model is formulated in terms of degree of saturation, rather than of suction. Subsequently, the small strain stiffness effects were incorporated using the intergranular strain concept modified for unsaturated conditions. New features included degree of saturation-dependent size of the elastic range and an updated evolution equation for the intergranular strain. The model has been evaluated using two comprehensive data sets on completely decomposed tuff from Hong-Kong and Zenos Kaolin from Iran. It has been shown that the modified intergranular strain formulation coupled with the hysteretic water retention model correctly reproduces the effects of both the stress and suction histories on small strain stiffness evolution. The model can correctly predict also different other aspects of partially saturated soil behaviour, starting from the very small strain range up to the asymptotic large-strain response.

Peat is known as problematic ground with low bearing capacity and extensively high compressibility. Ordinary Portland cement (OPC) and lime were usually used to tackle unfavourable characteristics of peat by improving it with its cementation effect. However, little was known of the effect of bio-cementation towards peat improvement. Bio-cementation or commonly known as Microbial-induced calcite precipitation (MICP) has been recently introduced as a ground improvement alternative for geotechnical engineering application. MICP performed by utilising metabolic pathways of non-pathogenic urealytic bacteria that precipitates calcium carbonate (CaCO3) crystal as cementation binder that seal soil particles together increasing soil strength. MICP of inorganic soil was extensively explored, and only limited was done for organic soil. This study explores on the effect of different surcharge preloading of 18kPa, 36kPa and 48kPa towards Microbial-Induced Calcite Precipitation (MICP) treatment of tropical peat. Fibrous peat studied were obtained from Miri, Sarawak and cured under a submerged condition with different vertical preload for seven days. Laboratory study including unconfined compression test, quantification of carbonates precipitated, and moisture content of stabilised specimens was observed to evaluate the performance of stabilisation effort. Unconfined compressive strength (UCS) of treated specimens was observed to be higher than untreated specimens with the highest increase of UCS up to 469%. However, CaCO3 precipitation amount for this study was observed to decrease with increasing surcharge preload.

Sludge treatment in vertical flow constructed wetlands (VFCWs) is a promising alternative to conventional treatment, which provides adequate treatment at low-cost, while being energy efficient. They may dewater and mineralize various kinds of sludge, including surplus sludge from activated sludge systems, agricultural slurries, and septage and faecal sludge effectively. This paper presents a review of the state-of-the-art of VFCWs treating sludge. The effects of varying design and operational parameters, as well as environmental factors on treatment performance are discussed. The paper also summarizes the performance of various pilot- and full-scale systems in terms of final dry matter content and degree of mineralization. In order to understand the governing processes and predict its performance, modelling of VFCWs in sludge treatment is suggested.

Tunnelling is one of the major construction methods to sustain the increasing demand on development in cities. Although many studies have been carried out to investigate the active failure mechanism of tunnel face in sand, the study of passive failure of tunnel face is relatively rare and most of studies are analytical solutions based on the upper bound theorem. In this paper, centrifuge model tests and three-dimensional finite element analyses have been conducted to study the passive failure mechanisms of tunnel face in sand for tunnels located at cover over diameter (C/D) ratios equal to 2.2 and 4.3. Passive failure pressures of tunnel face as well as ground surface displacements were investigated in centrifuge tests. From both centrifuge and numerical investigations, it is found that for a tunnel located at C/D ratio equals to 2.2, the soil in front of the tunnel face is displaced by the advancing tunnel face while the soil further away from the tunnel face is forced upwards to the ground surface. A funnel-type failure mechanism is observed and the extent of the failure mechanism is narrower than a five-block failure mechanism commonly assumed in an existing upper bound solution. However, the calculated passive failure pressure by the upper bound solution is fairly consistent with the measured face pressure. It is observed that the funnel-type failure mechanism induces surface heaves. Both observed longitudinal and transverse heaves are well described by Gaussian distributions. For a tunnel located at C/D ratio equals to 4.3, the displacements of soil are confined around the vicinity of an advancing tunnel face and a localised failure mechanism associated with ground settlement is observed and computed. There is a large discrepancy between the localised failure mechanism and the five-block failure mechanism. The calculated failure face pressure is higher than the corresponding measured value by 50%. However, reasonable consistency can be found between measured and computed passive face pressures.

With the growth of economy and population, there is an increase in infrastructure construction projects. As such, it is unavoidable to have construction projects on soft soil. Without proper risk management plan, construction projects are vulnerable to different types of risks which will have negative impact on project's time, cost and quality. Literature review showed that little or none of the research is focused on the risk assessment on the infrastructure project in soft soil. Hence, the aim of this research is to propose a risk assessment framework in infrastructure projects in soft soil during the construction stage. This research was focused on the impact of risks on project time and internal risk factors. The research method was Analytical Hierarchy Process and the sample population was experienced industry experts who have experience in infrastructure projects. Analysis was completed and result showed that for internal factors, the five most significant risks on time element are lack of special equipment, potential contractual disputes and claims, shortage of skilled workers, delay/lack of materials supply, and insolvency of contractor/sub-contractor. Results indicated that resources risk factor play a critical role on project time frame in infrastructure projects in soft soil during the construction stage.