Siti Jahara Matlan

Natural fibers such as coconut and oil palm offer sustainable reinforcement for cement composites, but their variability in properties and compatibility with cement matrices present challenges. Both fibers exhibit variations and inconsistent characteristics, necessitating tailored mixing protocols to ensure consistent fiber dispersion in cement mixtures. The mixing method largely governs the dispersion of fibers within a matrix, which influences both the fresh and hardened properties of fiber-reinforced materials. Hence, this study attempts to evaluate the impact of five different mixing methods on cement composites reinforced with coconut and oil palm fibers, formulating 15 mix designs and characterizing the fibers for replication accuracy. The effects of mixing methods on water absorption, flowability, setting time, compressive, and flexural strength were assessed, along with fiber–matrix interactions in hardened samples. It was observed that the premix II produced the best flowability, improving it by approximately 3.7% for coconut and 3.0% for oil palm composites, while also reducing water absorption by 87% and 85%, respectively, without affecting setting time. For mechanical performance, coconut composites achieved the highest compressive (37.1%) and flexural (19.3%) strengths with the postmix method. In contrast, oil palm composites reached the highest compressive strength (19.2%) with comixing, and the highest flexural strength (9.1%) with premix III methods. However, some mixing methods produced more consistent performance while not achieving the highest mechanical or fresh properties because the fiber dispersion in the mix was more uniform. In conclusion, coconut and oil palm fibers are abundant, underutilized tropical agricultural wastes with demonstrated mechanical potential. They are cost-effective, sustainable, and applicable in non-load-bearing construction materials; hence, this study investigates appropriate mixing methods to optimize both fresh and hardened properties for broader construction applications.

Fiber-reinforced cementitious composites (FRCC) are innovative materials that address the limitations of traditional cementitious composites, such as low tensile strength and brittleness. This review investigates the effects of fiber content, mixing sequence, and mixing time on the engineering properties of FRCC. The findings reveal that fiber content significantly impacts tensile and compressive strength, but excessive amounts can reduce workability and compromise mechanical performance due to poor dispersion. Optimising the mixing sequence enhances fiber distribution, improving homogeneity and engineering properties. Furthermore, mixing time influences fiber dispersion and interfacial bonding, with prolonged mixing improving matrix uniformity but risking fiber damage. Future research is also highlighted to enhance understanding of the relationship between fiber content, mixing sequence, and mixing time article of fiber-reinforced cementitious composites.

The unsaturated behaviour of residual soil in Malaysia has been studied, yet the impact of particle size distribution (PSD) on soil-water characteristics still needs to be more adequately explored. Previous research highlights the significance of fine particles in controlling geotechnical properties. This study investigates how the PSD of five soil samples influences the Soil-Water Characteristic Curve (SWCC) parameters, water retention, storage properties and permeability. The study involved five samples, four samples from Ibrahim et al., [1] research, such as reserved forest, gravelly sand, silty sand, kaolin and silty clay soil from the Garinono Formation soil. A pressure plate extractor determined the samples' Soil-Water Characteristic Curve (SWCC) and bulk density. The van Genutchen (1980) model fitted experimental data and the hydraulic response was studied on the five soil samples. The results show that Kaolin and silty clay have higher volumetric water content than gravelly and silty sand due to a higher percentage of silty and clay particles. However, the reserve forest sample has volumetric water content like kaolin and silty clay due to its natural location. Reserved forest, kaolin and silty clay samples have higher water storage, i.e., effective soil porosity (ESP) values than gravelly sand due to higher clay and silty contents. Silty sand, reserve forest and gravelly sand have higher shape parameter (n) values due to their higher sand and gravel content. Clay-rich samples had smaller (n) values, indicating a more uniform distribution. Hydraulic conductivity function (K(θ)) is influenced by scale parameter (α), Air-Entry Value (AEV) and Saturated Hydraulic Conductivity K_s. Kaolin and silty clay samples exhibit lower α values, resulting in higher suction at AEV than other soils as they contain high silty and clay contents. Saturated conductivity values directly affect hydraulic conductivity function, while AEV inversely affects the unsaturated flow. Understanding unsaturated hydraulic responses and SWCC characteristics could assist in anticipating slope instability and ground stabilisation in residual soil and soil behaviour during and after rainfall.

This study investigates the hydraulic response and stability of silty clays from the Garinono Formation during the rainy season, utilizing peak monthly rainfall data recorded over a decade by the Department of Irrigation and Drainage, Sabah. The research focuses on the impact of rainfall infiltration on slope stability under extreme hydrological conditions, modelled using a 31-day antecedent rainfall event from January 2011. The study incorporates both field and laboratory data, assessing the Soil-Water Characteristic Curve (SWCC) and bulk density for three distinct soil samples: (i) MI (Intermediate Plasticity Silt), (ii) ML (Low Plasticity Silt), and (iii) CI (Intermediate Plasticity Clay). The SWCC and hydraulic properties were characterized using the Fredlund, & Xing (1994) model, with subsequent numerical simulations conducted using GEO-SLOPE International. Results indicated that sample (ii) ML exhibited increased cumulative water volume with rising rainfall intensity, influenced by its saturated and unsaturated hydraulic conductivity, as well as the FX model's fitting parameter . The study revealed that high ratios in samples (i) MI and (iii) CI led to greater runoff and reduced infiltration, characterized by lower water storage and higher discharge rates. Conversely, lower ratios in sample (ii) ML facilitated infiltration, increasing water storage and reducing discharge rates. A notable decrease in matric suction was observed during rainfall, with sample (ii) ML showing the most significant reductions, leading to early and substantial decreases in the Factor of Safety (FS), indicating potential instability. In contrast, samples (i) MI and (iii) CI maintained higher stability due to negative Pore-Water Pressure (PWP) and minimal suction reductions. These findings underscore the critical influence of soil permeability on slope hydrological response and stability during intense rainfall events. This study contributes to the understanding of the hydro-mechanical behaviour of the Garinono Formation, with implications for geotechnical design and slope stability analysis in tropical regions.

The Garinono Formation in the Sandakan area is prone to geomorphological hazards such as landslides and slope instability due to its complex geological composition. Despite their importance for understanding the region's soil behaviour, the unsaturated hydraulic properties of the Garinono Formation remain largely unstudied. This research addresses this gap by investigating these properties, which are crucial for regulating water flow, nutrient transport and ensuring geotechnical stability. Ten silt-clay samples were analysed for bulk density and Soil-Water Characteristic Curves (SWCC) using a pressure plate extractor. The Fredlund and Xing (FX) model (1994) was applied to fit the SWCC data and assess the influence of model parameters on unsaturated soil behaviour. The results showed that Garinono Formation soils have a unimodal distribution and are highly sensitive to water. Samples with higher silt and clay concentrations exhibited increased volumetric water content, including both saturated 〖(θ〗_s) and residual (θ_r ) The samples also demonstrated elevated Effective Soil Porosity (ESP), indicating a greater capacity for water retention, infiltration and pore water pressure development. Slow water extraction and desaturation were observed, attributed to low FX fitting parameter n values, while significant saturation differences at higher suction were reflected by variations in parameter m. Additionally, the soils demonstrated low unsaturated hydraulic conductivity (K(θ)), which can be attributed to their high plasticity, low saturated conductivity (K_s), wide range parameter a, high air entry value (AEV) and residual suctions (ψ_r). These findings provide new insights into the unsaturated hydraulic behaviour of Garinono Formation soils and offer essential data for future engineering applications. This research establishes a foundation for improving predictive models and enhancing infrastructure resilience in geomorphologically sensitive areas like Garinono.

This study aims to use attapulgite (ATT) and cement to modify loess as the lining material of landfills in loess areas and to exert the adsorption property of modified loess to ensure seepage prevention. It provides a safe, efficient, low-cost anti-seepage material for constructing a landfill in a loess area. For ATT-modified loess, when the content of ATT is less than 10%, the decrease rate of permeability coefficient is obvious, and when the content is more than 10%, the decrease rate becomes slow. After adding 5% cement on this basis, the permeability coefficient of ATT cement-modified loess is 8 × 10⁻⁸ cm/s, which meets the standard requirements (≤10⁻⁷ cm/s). The results show that the adsorption of Cu and Pb ions on ATT cement-modified loess is higher than that on pure loess. Cu and Pb ions’ adsorption rates are 99.2 and 98.5% in a single solution. In the mixed solution, the adsorption rates of copper and lead ions were 97.5 and 98.2%, respectively. Therefore, the study obtained the ratio of modified loess (85% loess + 10% ATT + 5% cement) that can not only meet the seepage prevention requirements of the landfill but also can adsorb heavy metal ions in the leachate, providing security for the landfill.

This study investigated attapulgite-modified loess as an efficient and cost-effective method for creating an impermeable liner for landfills in regions with scarce clay resources. Laboratory permeability tests were conducted using a flexible wall permeameter to determine the permeability of compacted loess and attapulgite mixtures under varying osmotic conditions. The relationship between the permeability coefficient, attapulgite dosage, radial pressure, and osmotic pressure was analyzed. Nuclear magnetic resonance and scanning electron microscopy were also used to observe the microstructure of the modified loess. The results showed that attapulgite dosage significantly reduced the permeability coefficient, but the effect became limited when the content surpassed 10%. The decrease of the permeability coefficient of the modified loess is mainly due to the filling of pores between the loess by attapulgite, which makes the pore size and throat size of the modified loess smaller. The modified loess displayed a sheet structure that contributed to an increased permeability coefficient due to increased radial pressure. This study provides valuable insights into using attapulgite-modified loess as a material for landfill lining in regions with scarce clay resources.

This study investigated attapulgite-modified loess as an efficient and cost-effective method for creating an impermeable liner for landfills in regions with scarce clay resources. Laboratory permeability tests were conducted using a flexible wall permeameter to determine the permeability of compacted loess and attapulgite mixtures under varying osmotic conditions. The relationship between the permeability coefficient, attapulgite dosage, radial pressure, and osmotic pressure was analyzed. Nuclear magnetic resonance and scanning electron microscopy were also used to observe the microstructure of the modified loess. The results showed that attapulgite dosage significantly reduced the permeability coefficient, but the effect became limited when the content surpassed 10%. The decrease of the permeability coefficient of the modified loess is mainly due to the filling of pores between the loess by attapulgite, which makes the pore size and throat size of the modified loess smaller. The modified loess displayed a sheet structure that contributed to an increased permeability coefficient due to increased radial pressure. This study provides valuable insights into using attapulgite-modified loess as a material for landfill lining in regions with scarce clay resources.

In this study, fluorographene nanosheets (FG nanosheets) were prepared via the solvent-ultrasonic exfoliation method. The fluorographene sheets were observed using field-emission scanning electron microscopy (FE-SEM). The microstructure of the as-prepared FG nanosheets was characterized by X-ray diffraction (XRD) and a thermal analyzer (TG). The tribological properties of FG nanosheets as an additive in ionic liquids in high vacuum were compared to that of ionic liquid (IL) with graphene (IL-G). The wear surfaces and transfer films were analyzed via an optical microscope, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results show that FG nanosheets can be obtained from the simple solvent-ultrasonic exfoliation method. The prepared G nanosheets are a sheet, and the longer the ultrasonic time is, the thinner the sheet is. Ionic liquids with FG nanosheets had low friction and a low wear rate under high vacuum conditions. The improved frictional properties were attributed to the transfer film of FG nanosheets and more formation film of Fe-F.

This paper studied the anti-seepage ability of the modified loess by using attapulgite, which is abundant in local areas. The possibility of using the modified loess as the sustainable compacted soil liner material in a solid waste landfill was also considered in this research. The materials were then evaluated using Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and an Impermeability Mechanism (IM). The experimental results showed that the permeability coefficient of the attapulgite-modified loess decreases significantly with increasing attapulgite content. However, it becomes less significant when the attapulgite level approaches 10%. Both cases can meet the landfill impermeability requirements, based on the attapulgite content remaining at 10%, adding 15% lime or 5% cement, respectively. The triaxial consolidation and drainage experiment was carried out to investigate the shear strength of the materials under three different working circumstances. The stress–strain curves of each specimen were produced, as were the cohesion and internal friction angle values. This research lays the groundwork for using attapulgite-modified loess as a landfill lining material. It establishes a solid platform for future studies on attapulgite adsorption and purifying performance in landfills.