The concern about coconut shell disposal and natural fine aggregate depletion has prompted researchers to utilize coconut shell as aggregate in recent years. However, the majority of the present literature has focused on utilizing coconut shell as a coarse aggregate replacement in concrete via the traditional method. In this study, concrete incorporating coconut shell as a fine aggregate replacement (10–100%) was evaluated using permeability and water absorption tests in a systematic way. The response surface methodology (RSM) was first used to design the experimental works. In addition, an artificial neural network (ANN) and genetic expression programming (GEP) were also taken into account to mathematically predict the permeability and water absorption. Based on both experimental and theoretical modeling, three scenarios were observed. In the first scenario, high quality concrete was achieved when the replacement percentage of sand by coconut shell ranged from 0% to 10%. This is because both the permeability and water absorption were less than 1.5 × 10⁻¹¹ m and 5%, respectively. In the second scenario, an acceptable and reasonable low permeability (less than 2.7 × 10⁻¹¹ m/s) and water absorption (less than 6.7%) were also obtained when the replacement percentage increased up to 60%. In contrast, the high content coconut shell, such as 90% and 100%, developed concrete with a high permeability and water absorption and was defined in the third scenario. It was also inferred that both the experimental and mathematical models (ANN, GEP, and RSM) have consistent and accurate results. The correlation statistics indicators (R²) were greater than 0.94 and the error was less than 0.3, indicating a strong correlation and minimum error. In conclusion, coconut shell could act as a good alternative material to produce cleaner concrete with an optimum value of 50% as a fine aggregate replacement.

Given that rubber tires are almost immune to biological degradation, this vast amount of solid waste is a major environmental concern worldwide. Reuse of these waste tires in the construction industry is one of the strategies to minimize their environmental pollution and landfill problems, while contributing to more economical building design. Thus, we assessed the improved traits of rubberized concrete made by combining palm oil fuel ash (POFA) with tire rubber aggregates (TRAs). Studies on the effects of POFA inclusion on the durability properties of rubberized concrete with TRAs as the replacement agent for fine or coarse aggregates remain deficient. Herein, the rubberized concrete contained 20% POFA as ordinary Portland cement (OPC) substitute, and various amounts of TRAs (5, 10, 20 and 30%). The proposed mixes enclosing three types of TRAs (fiber, fine and coarse aggregates) were characterized to determine their durability and acoustic performance. The water absorption, fire endurance performance, chloride penetration, and acoustic properties of the proposed concrete were evaluated. The designed concrete showed a systematic increase in water absorption and chloride penetration with the increase in rubber amount and particle size. These POFA-modified rubberized concretes displayed a satisfactory performance up to 500 °C, and superior acoustic properties in terms of sound absorption. The presence of TRA as 30% coarse aggregate replacement was found to improve the sound absorption properties by as much as 42%.

The effect of soil shear strength at the shoreline area is the focus of this study. Pantai Punggur, Batu Pahat, Johor, has been chosen as the subject location for the soil shear strength investigation. It is located on the west coast of Johor, with latitudes ranging from 1.62° to 1.87° N and longitudes ranging from 102.78° to 103.19° E. The purpose of this study is to use a field vane shear test (VST) to determine the undrained shear strength of shoreline areas. Soil samples were collected at specific locations known as Zones A, B, C, D, and E, and data for sediment shear strength was obtained from field vane shear test (VST) methods. From the undrained shear strength test at 0.5 m depth at high tide (HT) and medium tide (MT) data for December 2021, Zone A had a Cu reading of more than 4.5 kPa, followed by Zones B, C, and D, and lowest at Zone E. Next, in the December 2021 data at the HT level, Zone A has a Cu reading greater than 4.5 kPa at 0.5 m and 1.0 m, while other Zones have readings less than 3.0 kPa. It can be concluded that the depth of a part also influences the data in this study. When the depth increases, the shear strength of the data also increases. This study will serve as a benchmark for future conservation efforts. Based on the findings, more effective control measures for preserving and conserving coastal areas may be developed.

Cement mortar offers an excellent replacement for materials such as fine aggregate with tire rubber waste in the form of crumbs. It provides excellent environmental and technical benefits to concrete production using recycled materials. As such, it contributes to the sustainable development of the construction industry. This paper mainly emphasizes the strength of untreated and treated crumb rubber from waste tires in cement mortar. Crumb rubber that has been pre-treated with Silica fume (SF) and sodium hydroxide (NaOH) to improve the strength of the mortar mix. This research used a cement-aggregate mix ratio of 1:4 and a water-cement ratio of 1:2. Five different percentages of fine aggregate replacement (0, 3, 6, 9, and 12%) was selected. The compressive strength, density, and water absorption of the mortar were measured at 28 days to find optimum strength. The compressive strength of the cement mortar mixed with treated crumb rubber showed significantly higher values, with an increase of 92% for 12% treated crumb rubber by sodium hydroxide (TN12) compared to untreated crumb rubber. The density value of the mortar cube mixed with treated crumb rubber decreased when the percentage of replacement for treated crumb rubber increased. In the application of roof tiles, lower density values provide an advantage for workability during installation. For water absorption, the treated crumb rubber contributes to a lower percentage of water absorption (acceptable until 6% for SF and 9% for NaOH) compared to the control sample as untreated crumb rubber. Therefore, a mixture of mortar with treated crumb rubber, especially NaOH solution, is better than the untreated crumb rubber specimen.

This study was conducted at Pantai Perpat, Batu Pahat, Johor, to investigate the correlation between suspended sediment concentration and particle size distribution. The objectives included identifying water quality parameters, assessing suspended sediment levels, and studying correlations across coastal zones. Water and sediment samples were collected from twelve stations using the grab sampler method, with parameters such as pH, temperature, total suspended solids (TSS), turbidity, sediment size, and moisture content analyzed in designated laboratories. Variability in coastal water quality was observed, with pH values ranging from 7.40 to 7.77 and temperatures from 24.97°C to 26.33°C, indicating acceptable levels. Zone 1 exhibited high turbidity (699 NTU) and TSS concentration (12,393.33 mg/L), suggesting potential issues. Sediment size distribution varied among coastal zones: Zone 1 had a mix of various sediment sizes, primarily silty clay, while Zones 2, 3, and 4 consisted mainly of sandy sediments. Correlations between turbidity and median grain size (D50) varied across the zones, with strong correlations in Zone Middle Tide (MT) (R² = 0.7836) and Zone High Tide (HT) (R² = 0.5846), and a weak correlation in Zone Low Tide (LT) (R² = 0.0124). Strong correlations were also found between TSS and D50 in Zone MT (R² = 0.9924), with moderate and weak correlations in Zones HT (R² = 0.3384) and LT (R² = 0.146), respectively. Understanding water quality and sediment characteristics is crucial for effective environmental management and coastal planning. These findings provide valuable insights for decision-makers involved in coastal development projects. Further research should focus on long-term monitoring and sediment transport dynamics to support sustainable coastal management.