Yee Hooi Min

Modern civilisation is increasingly prioritising sustainability to address environmental challenges like resource depletion and waste accumulation. Repurposing discarded materials such as vehicle tires and seashells into sustainable materials is vital for mitigating these issues. However, the mechanical properties of concrete may be weakened by including scraps of rubber. Similar problems related to the disposal of seashell waste include soil solidification and illegal dumping. This study looks at the possibility of using rubber powder (1%, 5%, 10%, and 15%) and clamshell powder (5%), respectively, as partial substitutes for sand and cement. Objectives include evaluating the physical and mechanical properties of mortar and determining the optimal percentage of rubber powder when combined with clamshell powder. After creating the mortar mixes, tests were conducted to determine flexural strength, density, and compression after 7, 14, and 28 days of curing. According to the results, compression strength decreases with increasing rubber powder percentages. 15% showed the lowest compression strength (20.163 MPa) and 1% the greatest (28.197 MPa). Furthermore, flexural testing showed that a 1% rubber powder combined with clamshell powder was best. By recycling waste materials, using 1% rubber powder and 5% clamshell powder in mortar can help solve environment challenges. However, it’s crucial to properly balance these amounts to ensure the strength of the mortar. Although this strategy contributes significantly to sustainability, it is not a comprehensive solution to the larger environmental problems; it is only one aspect of the picture. It can be concluded that the optimum percentage of rubber that can be used with 5% clam shell powder is 1%.

Malaysia's industrial sector generates a lot of non-biodegradable solid waste. By products of industrialisation including plastic bags, PET bottles, and pulverised waste LDPE, coir must be disposed of. Reusing waste helps reduce pollution, and conserve non-renewable resources. However, the use of LDPE in mortar mixes as a partial replacement for sand adversely affects the compressive strength. In order to mitigate this issue, steel fibre was included as an addition. This study examined the use of LDPE recyclable plastic bags in cement mortar to determine the best proportion of LDPE to steel fibre. The study replaced 0% to 15% of fine aggregates in mortar mixes with LDPE, increasing by 5%. The mortar's density, compressive, and flexural strengths were measured at 7, 14, and 28 days. The experiment indicated that adding 15% of LDPE to cement mortar decreased density (1736 kg/m3), compressive strength (21.61 MPa), and flexural strength (3.562 MPa). From this, it can be concluding that 5% LDPE and 2% steel fiber are the optimum percentage that can be use in the future study.

Modern society's growing concern for sustainability is evident in efforts to combat environmental issues like waste accumulation and resource depletion. Recycling waste materials, such as tires and seashells, into sustainable concrete aggregates is crucial for addressing these challenges. However, integrating rubber scraps into concrete can weaken its mechanical properties, with the thickness of the interface between rubbers and cement matrix increasing with higher rubber content. Researchers are exploring ways to mitigate this strength loss by incorporating additional components into rubberized cementitious materials. Similarly, seashell waste presents challenges like soil solidification and illegal dumping, further highlighting the need for innovative solutions in waste management and construction practices. This study investigates the viability of using rubber powder (at 1%, 5%, 10%, and 15%) and clamshell powder (at 5%) as partial substitutes for sand and cement in concrete. Objectives include evaluating concrete’s mechanical properties and determining the optimal rubber powder percentage in combination with clamshell powder. Concrete proportions are meticulously calculated according to mixed design, and materials are mixed in a laboratory concrete mixer. Concrete’s fresh density was determined before pouring into cube moulds with size 100mm x 100mm x 100 mm and prism moulds with size 100mm x 100mm x 500 mm for curing. Samples are cured for 7, 14, and 28 days in water, and then subjected to compression and flexural tests. Results indicate a decrease in compression strength with higher rubber powder percentages, with 15% exhibiting the lowest compression strength (25.06 MPa) and 1% the highest (39.02 MPa). Flexural testing revealed that a combination of 1% rubber powder with clamshell powder yielded optimal results (4.97MPa). In conclusion, the study suggests that the ideal proportion of rubber with 5% clamshell powder is 1%, offering insights into sustainable construction practices.

One of the significant by products of Malaysia's industrial sector is the generation of solid waste that does not biodegrade. Coir, along with other by products of industrialisation such as plastic bags, PET bottles, and pulverised waste LDPE, must be disposed of in an appropriate manner. Utilising discarded items contributes to pollution prevention and resource conservation. A few researchers have investigated the possibility of recycling waste materials to lessen pollution and preserve important resources. An experiment revealed that replacing fine particles (sand) with low-density polyethylene (LDPE) negatively affects the compressive strength of concrete cement. To solve this issue, steel fibre was included as an additional component after it was applied. This study investigated a variety of ratios of LDPE substitution for fine aggregates. These ratios ranged from 0% to 15%, with increments of 5%. Following 7, 14, and 28 days, the density, compressive strength, and flexural strength of the concrete were measured and analysed. The findings showed that adding 15% LDPE to concrete cement made it less dense (1840 kg/m3) and weaker in its compressive strength (32.87 MPa) and flexural strength (4.627 MPa) at 28 days. Based on this, it has been determined that a combination consisting of a 5% substitution of LDPE and an additional 2% of steel fibre is the most effective combination for further research endeavours.

In this paper, a Stieltjes integral approximation method for uncertain variational inequality problem (UVIP) is studied. Firstly, uncertain variables are introduced on the basis of variational inequality. Since the uncertain variables are based on nonadditive measures, there is usually no density function. Secondly, the expected value model of UVIP is established after the expected value is discretized by the Stieltjes integral. Furthermore, a gap function is constructed to transform UVIP into an uncertain constraint optimization problem, and the optimal value of the constraint problem is proved to be the solution of UVIP. Finally, the convergence of solutions of the Stieltjes integral discretization approximation problem is proved.

Hydrophobic coating generally been classified as the ability to protect the surface against the penetration of substances such as water into the capillary pores of a surface which later resulting the depletion of strength and durability of the material. Tremendous efforts have been made for the hydrophobic coating using silane and siloxane as functionalizing agent, but it was claimed to be expansive and hazardous. In this present work, a non-toxic hydrophobic formulation using Rice Husk Ash (RHA) as the silica source and fatty acid (oil) as surface functionalizing agent were investigated for the water repellent material. Two (2) different types of fatty acid which were olive oil (OL) and waste cooking oil (WCO) were compared. It was found that the hydrophobicity was developed for both type of functionalizing agent with the WCA of greater than 104⁰. Highest value of WCA was developed when coating on the glass substrate with the ratio of OL: RHA (1:3). The water absorption test was carried out to further examined the effect of coating onto the concrete surface. The findings showed that for both type of fatty acids, the water absorption was reduced but not fully prevented.