Explore the vast range of titles available.

As the demand for nonrenewable natural resources, such as aggregate, is increasing worldwide, new production of artificial aggregate should be developed. Artificial lightweight aggregate can bring advantages to the construction field due to its lower density, thus reducing the dead load applied to the structural elements. In addition, application of artificial lightweight aggregate in lightweight concrete will produce lower thermal conductivity. However, the production of artificial lightweight aggregate is still limited. Production of artificial lightweight aggregate incorporating waste materials or pozzolanic materials is advantageous and beneficial in terms of being environmentally friendly, as well as lowering carbon dioxide emissions. Moreover, additives, such as geopolymer, have been introduced as one of the alternative construction materials that have been proven to have excellent properties. Thus, this paper will review the production of artificial lightweight aggregate through various methods, including sintering, cold bonding, and autoclaving. The significant properties of artificial lightweight aggregate, including physical and mechanical properties, such as water absorption, crushing strength, and impact value, are reviewed. The properties of concrete, including thermal properties, that utilized artificial lightweight aggregate were also briefly reviewed to highlight the advantages of artificial lightweight aggregate.

This paper details the properties, microstructures, and morphologies of the fly ash-based alkali-activated material (AAM), also known as geopolymers, under various steam curing temperatures. The steam curing temperature result in subsequent high strengths relative to average curing temperatures. However, detailed studies involving the use of steam curing for AAM remain scarce. The AAM paste was prepared by mixing fly ash with an alkali activator consisting of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH). The sample was steam cured at 50°C, 60°C, 70°C, and 80°C, and the fresh paste was tested for its setting time. The sample also prepared for compressive strength, density, and water absorption testings. It was observed that the fastest time for the fly ash geopolymer to start hardening was at 80°C at only 10 minutes due to the elevated temperature quickening the hydration of the paste. The compressive strength of the AAM increased with increasing curing time from 3 days to 28 days. The AAM’s highest compressive strength was 61 MPa when the sample was steam cured at 50°C for 28 days. The density of AAM was determined to be ~2122 2187 kg/m3, while its water absorption was ~6.72-8.82%. The phase analyses showed the presence of quartz, srebrodolskite, fayalite, and hematite, which indirectly confirms Fe and Ca’s role in the hydration of AAM. The morphology of AAM steam-cured at 50°C showed small amounts of unreacted fly ash and a denser matrix, which resulted in high compressive strength.

Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. One of the methods involves using geopolymer technology. On this basis, this current research focuses on the inter-particle effect on the properties of fly ash geopolymer aggregates with different molarities of sodium hydroxide (NaOH). The effects of synthesis parameters (6, 8, 10, 12, and 14 M) on the mechanical and microstructural properties of the fly ash geopolymer aggregate were studied. The fly ash geopolymer aggregate was palletized manually by using a hand to form a sphere-shaped aggregate where the ratio of NaOH/Na2SiO3 used was constant at 2.5. The results indicated that the NaOH molarity has a significant effect on the impact strength of a fly ash geopolymer aggregate. The highest aggregate impact value (AIV) was obtained for samples with 6 M NaOH molarity (26.95%), indicating the lowest strength among other molarities studied and the lowest density of 2150 kg/m3. The low concentration of sodium hydroxide in the alkali activator solution resulted in the dissolution of fly ash being limited; thus, the inter-particle volume cannot be fully filled by the precipitated gels.

This paper elucidates the mechanical performance, microstructure, and porosity evolution of fly ash geopolymer after 10 years of curing age. Given their wide range of applications, understanding the microstructure of geopolymers is critical for their long-term use. The outcome of fly ash geopolymer on mechanical performance and microstructural characteristics was compared between 28 days of curing (FA28D) and after 10 years of curing age (FA10Y) at similar mixing designs. The results of this work reveal that the FA10Y has a beneficial effect on strength development and denser microstructure compared to FA28D. The total porosity of FA10Y was also lower than FA28D due to the anorthite formation resulting in the compacted matrix. After 10 years of curing age, the 3D pore distribution showed a considerable decrease in the range of 5–30 µm with the formation of isolated and intergranular holes.

Lack of awareness and understanding of youth development law amongst youth and policy makers is quite significant. Among the reasons that have been identified to be the root cause of this weakness is due to the failure or less priority given by the youth societies and related organization which are responsible in providing quality programmes for youth. In light of the above gap, the paper examines youth awareness on youth development law from the perspective of policy makers and youth themselves. This is a social-legal study, which involves two types of data collection; first, interviews with 53 policy makers/management from ministries, youth departments, youth agencies and societies; and result from a survey amongst Malaysian youth amounting to 4703. This study found that a majority of the respondents (the policy makers from ministries, state youth departments, youth societies and agencies) agreed that youth in Malaysia have a very low awareness or knowledge of the law relating to the youth. The lack of awareness also may be subjected from the absence of the legal awareness programme conducted by the related governmental agencies and organizations. However, the result of youth view is in contrast where the level of awareness of youth concerning policies of youth in law is quite high at the average of 77.8%. Nevertheless, the result shows more than 20% of youth in Malaysia do not aware about the existence of youth policy in law.

This paper investigates the potential and suitability of flood mud to be used in geopolymer technique as construction materials. Flood mud was collected from Kelantan, Malaysia and crushed and sieved into powder form. Then, it was mixed with alkaline activator solution (mixture of NaOH and Na2SiO3 solutions) followed by curing process to produce flood mud geopolymers. In addition, the effect of varying solids/liquid (S/L) and Na2SiO3/NaOH ratios on the compressive strength of flood mud geopolymers were also investigated. The result showed that flood mud can be potentially used as precursor materials for geopolymer formation with favorable strength. Optimum compressive strength (24.6 MPa) of geopolymers based on flood mud was obtained at S/L = 1.25 and Na2SiO3/NaOH = 1.0.

This study was conducted to compare the mechanical properties of fly ash artificial geopolymer aggregates with natural aggregate (rock) in term of its impact strength, specific gravity and water absorption.The raw materials used were fly ash, sodium hydroxide, sodium silicate and natural aggregate. After the artificial geopolymer aggregate has been produced, its water absorption, specific gravity and aggregate impact test has been done. All results obtained were compared to natural aggregate. The result shows that the fly ash geopolymer aggregate are lighter than natural aggregate in term of its specific gravity. The impact value for fly ash artificial geopolymer aggregate slightly high compared to natural aggregate while it has high water absorption value compared to natural aggregate. As conclusion, the fly ash artificial geopolymer aggregate can be used as one of the construction materials in concrete as an alternative for coarse aggregate besides natural aggregate with more lightweight properties.

Properties of oil palm trunk fiber reinforced cement composite were investigated in this study. Oil palm trunk fiber was used to improve the properties of cement composite. It was found that increasing in oil palm trunk fiber content up to certain percentage increase the compressive strength and decrease the density of cement composite. Besides, the study also found that additional of excessive of oil palm trunk fiber in cement composite decrease the compressive strength and continues to increase the water absorption and moisture content hence decrease the density. From this study, it was found that 2 wt. % of fiber content was the optimum fiber content to give the highest compressive strength of 38.61 MPa.

Coconut fibre is the most interesting fibre as it has the lowest thermal conductivity and bulk density. Some researchers have reported that the addition of coconut fibre reduced the thermal conductivity of the composite samples [2,6,7]. Asasutjarit and co-workers [2] studied the effect of chemical composition modification and surface modification of coconut fibres as reinforcement to the mechanical properties of cement composites. They observed that the mechanical properties of composites: modulus of rupture and internal bond, increased as a result of chemical composition and surface modification. Asasutjarit and co-workers [6] also investigated the effect of fibre length, fibre pretreatment and mixture ratio that affect the physical, mechanical and thermal properties of cement composites after 28 days of hydration. Their results indicated that the boiled and washed fibre improved mechanical properties. In addition, the optimum fibre length was 1 to 6cm fraction and the optimum (cement:fibre:water) mixture ratio by weight was 2:1:2. Thermal property of composites revealed that coconut fibre-based lightweight cement board has lower thermal conductivity. A study from Khedari and co-workers [7] reported on the development of a new type of soil-cement block using coconut fibre. Various mixture ratios were considered. They concluded that the use of coconut fibre as an admixture can reduce the block thermal conductivity and weight. The optimum volume ratio of soil:cement:sand to produce good properties is 5.75:1.25:2. The ratio of coconut fibre is 20% of cement corresponding to 0.8 kg/block. The compressive strength and thermal conductivity decreased when the quantity of fibre increased. It can be seen that, from the previous investigation, major works have been focused on the effect of fibre to the mechanical properties of cement composites. However, this paper presents the development of coconut fibre based-green composites by conventional method of mixing and curing process. In this work, coconut fibre is added to substitute the portion of sand in the ratio of cement to sand. This proposed design mixture was aimed to reduce the use of sand in cement composite. The effect of weight % of coconut fibre to the modulus of rupture and compressive strength was investigated and correlation between modulus of rupture and fracture behaviour is also presented.