The effect of titanium nitride (TiN) thickness as the support layer for carbon nanotubes (CNTs) growth was investigated by depositing three different thicknesses: 20 nm, 50 nm and 100 nm. This TiN support layer was deposited on SiO2 pads before depositing nickel (Ni) as the catalyst material. The Ni distribution on different TiN thicknesses was studied under hydrogen environment at 600°C. Then, the samples were further annealed at 600°C in acetylene and hydrogen environment for CNTs growth. The results show that, the optimum TiN thickness was obtained for 50 nm attributed by the lowest D to G ratio (0.8).

Currently, one of the main challenges of civil engineering and science materials engineers is to develop a sustainable substitute for Ordinary Portland Cement. While the most promising solution is provided by the geopolymerisation technology, most of the studied geopolymers are based on natural raw materials (kaolin). The metakaolin is mainly preferred because of its rapid rate of dissolution in the activator solution, easy control of the Si/Al ratio, and white color. However, its high cost prevents it from being widely used in geopolymer composites or other materials that can become an industrial alternative for Ordinary Portland Cement. Several studies have shown that geopolymers with good performance can also be obtained from secondary raw materials (industrial wastes such as coal ash or slag). This explains why countries with rapidly developing economies are so interested in this technology. These countries have significant amounts of industrial waste and lack a well-developed recycling infrastructure. Therefore, the use of these by-products for geopolymers manufacturing could solve a waste problem while simultaneously lowering virgin raw material consumption. This study evaluates the effect of replacing different amounts of coal ash with sand on the microstructure of sintered geopolymers. Accordingly, scanning electron microscopy and energy dispersive X-ray analysis were involved to highlight the morphological particularities of room-cured and sintered geopolymers.

The effects of supplementary cementitious materials (SCM) on the characteristics and internal structure of synthetic aggregate made from ground granulated blast furnace slag are investigated in this study (GGBS). Due to its high pozzolanic activity, GGBS was shown to be superior to other SCM materials, enhancing both the strength and durability of synthetic aggregate. Because sintering uses a lot of energy and generates a lot of pollutants, using a cold-bonded approach to make low density lightweight aggregates is particularly significant from an economic and environmental standpoint. Thus, the utilisation of ground granulated blast furnace slag (GGBS) as a substitute material in the production of green artificial lightweight aggregate (GLA) using the cold bonding method was discussed in this work. Admixtures of ADVA Cast 203 and Hydrogen Peroxide were utilised to improve the quality of GLA at various molar ratios. The freshly extracted GLA was then evaluated for specific gravity, water absorption, aggregate impact, and aggregate crushing in order to determine the optimal proportion blend. As a result, the overall findings offer great application potential in the development of concrete (GCLA). It has been determined that aggregates with a toughness of 14.6% and a hardness of 15.9% are robust. The compressive strength test found that the GCLA has a high strength lightweight concrete of 37.19 MPa and a density of 1845.74 kg/m3. The porous features developed inside the internal structure of GLA have led to GCLA’s less weight compared to conventional concrete.

Kaolin-based geopolymers are alternatives for producing high-strength ceramics for construction materials. Creating high-performing kaolin ceramics utilizing the regular technique requires a high handling temperature (higher than 1200°C). Thus, the structure and properties such as pore size and distribution are affected at higher sintering temperatures. Along these lines, information with respect to the sintering system and related pore structure is essential for advancing the properties of the previously mentioned materials. This study investigated the microstructure and the density of a kaolin-based geopolymer at various sintering temperatures. The unsintered sample has the highest density of 1610 kg/cm3, while the samples sintered at 1100°C haves the lowest density of 1203 kg/cm3. The result also shows that increasing the sintering temperature to 1100°C resulted in increasing the water absorption of the kaolin-based geopolymer ceramic.

The increasing needs of using aluminum epoxy composite as a replacement to solid metal rapid prototyping has opened to interests in optimizing its machining processes. This paper reported on the success of optimizing the surface roughness of aluminium epoxy composite using milling process along with a new finding on the best combination parameters. Taguchi method was used as the optimization method whereas spindle speed, feed rate, and depth of cut were set as input factors using an L9 Orthogonal Array. Analysis of Variance was used to identify the significant factors influencing the surface roughness. Experiment was conducted in dry condition using a vertical milling machine and the surface roughness after the machining was evaluated. Optimum combination of cutting parameters was identified after the finest surface roughness (response) based on the signal-to-noise ratio calculated. Cutting parameters selected after preliminary testing are cutting speeds of (2000, 3000 and 4000) rpm, feed rate (300, 400 and 500) mm/min, and cutting depth (0.15, 0.20, and 0.25) mm. The result showed that cutting speed had the largest percentage contribution to surface roughness with 69% and the second highest contribution was feed rate with 22% and depth of cut at 9%. The spindle speed was found as the most significant factor influencing the quality of surface roughness. The result is significant particularly in providing important guidelines for industries in selecting the right combination of parameters as well as to be cautious with the most significant factor affecting the milling process of metal epoxy composite.

Flexible and rigid road pavement deteriorates over time and needs high-performance patching repair materials. Cold mix asphalt patching is an easy and inexpensive repair material to repair potholes and other damaged roads. However, the repaired road pavement fails because it doesn’t have adequate compressive and bonding strength to the substrate. Thus, this research uses high-performance geopolymer repair materials to patch against road pavement potholes substrate. Geopolymer repair materials could improve the bonding strength, making them suitable for road repair purposes. For making geopolymer repair materials, the main materials used were high calcium aluminosilicate source materials such as fly ash, sodium hydroxide, sodium silicate, and water. This study tested the compressive and bonding strength of geopolymer repair materials after 1, 7, 14, and 28 days. This study found that the compressive strength of 90 g of alkali activator was the highest, at 37.0 MPa. The bonding strength improved gradually from day 1 to day 14, and then considerably on day 28. The compressive strength and bonding strength both increase in direct proportion to the amount of alkali activator present. Alkali activator is optimal at 90 grams for compressive strength and bonding strength of geopolymer repair materials.