Liew Yun Ming

Review of Geopolymer Materials for Thermal Insulating Applications

Geopolymer is an environmentally cementitious binder that does not require the existence of ordinary Portland cement (OPC). Geopolymer has many excellent advantages, including high early strength, low shrinkage, good thermal resistance and good chemical resistance. Based on previous research, geopolymer offered good resistance to corrosion, abrasion and heat. Fly ash, metakaolin, kaolin, and slag are regularly used raw materials for the preparation of geopolymer composites. Geopolymer composites also offer a potential environmental friendly product by reduce the carbon dioxide (CO2) emissions. This geopolymer material also offers an innovative and sustainable solution for maintaining infrastructure and also provides superior thermal, chemical and mechanical performance. This paper summarizes some research outcomes on alkali-activated binders along with the potential of geopolymer composites for thermal insulating applications.

Influence of Solidification Process on Calcined Kaolin Geopolymeric Powder

This paper aims at investigating the influence of solidification condition on the processing of calcined kaolin geopolymeric powder. This is a new process developed using the geopolymerization process. Geopolymer slurry was prepared from calcined kaolin and activating solution (mixture of NaOH and Na2SiO3). This slurry was allowed to solidify in oven and then crushed and grounded to fixed particle size. Compressive testing and SEM analysis were performed in this study. The results showed that the solidification condition at 80 °C for 4 hours was the best to synthesize the geopolymeric powder where this solidification condition results in geopolymeric powder which can produce higher strength resulted geopolymer paste. The microstructure showed more intervening gel phase which indicates that the geopolymerization process continued to react after the addition of water to the calcined kaolin geopolymeric powder.

A Review on Mechanical Properties of Geopolymer Composites for High Temperature Application

Geopolymer is cementitious binder that has enormous potential to become an alternative to ordinary Portland cement (OPC). Geopolymer composites have the potential to substantially curb the carbon dioxide (CO2) emissions. Kaolin, metakaolin, slag and fly ash have been used as the prime materials for forming geopolymers composites. Geopolymers have been studied for the past decade due to its unique properties such as low shrinkage, substantially chemical resistance, and higher fire resistance. The geopolymer offer an innovative for coating application at higher thermal application. Based on historical review, geopolymer materials exhibit resistance to corrosion, abrasion and heat. This paper summarizes some research finding about alkali-activated binders over the past decades along with outlines of the potential of geopolymer composites for high temperature application.

Fire Resistant Properties of Geopolymers: A Review

This paper presents fire and thermal properties on geopolymer binders, composed of metakaolin, slag and fly ash as precursor. Geopolymers are inorganic polymeric materials that are believed being capable to resist heat, high temperature and fire. Based on the previous researches, geopolymers offer a feasible alternative to fire resistance applications and with further deep studies, it has great potential to be fabricated for engineering applications.

Flood Mud as Geopolymer Precursor Materials: Effect of Curing Regime on Compressive Strength

This paper studies the effect of curing temperature and curing duration to the flood mud based geopolymer on compressive strength properties. Flood mud was used as a raw material for geopolymer and geopolymer samples were synthesized by using sodium silicate and sodium hydroxide 14M solution. These samples were cured at different temperature (100°C, 150°C, 200°C and 250°) for different curing duration (6h, 12h and 24h) respectively. Compressive strength tests were carried out at after 28 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Result showed that the maximum compressive strength was 24 MPa at temperature of 150°C for 24 hours. With increasing ageing day, densification of geopolymer gel was observed.

Correlation of the Processing Parameters in the Formation of Granulated Ground Blast Furnace Slag Geopolymer

Geopolymers are inorganic materials with huge potential applications including building material, fire resistant materials, and agricultural construction materials. Various parameters influenced the final properties of these geopolymer concretes. This study developed the effects of several factors such as solid-to-liquid ratio, NaOH concentration, and Na2SiO3/NaOH ratio on the compressive strength of granulated ground blast furnace slag (GGBFS) by statistical design of experiment (DOE) approach. Analysis of the experimental results through ANOVA exhibited that the specimen with NaOH concentration of 10M, Na2SiO3/NaOH ratio equals to 2.5, and solid-to-liquid ratio of 3.0 curing at room temperatures for 28 days was potential of highest strength (168.705 MPa) in the considered procedure. Besides, the relationship between compressive strength and influential factors could be suitably by fraction factorial design method.

Durability of metakaolin geopolymers with various sodium silicate/sodium hydroxide ratios against seawater exposure

This work presents an investigation of the performance of metakaolin geopolymers exposed to the continuous immersion of seawater. The geopolymers were prepared from metakaolin by activating with a mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions and cured at 80°C. The ratios of sodium silicate to sodium hydroxide were varied from 0.20 to 0.32. The result showed that metakaolin geopolymers reduce in strength after immersion in seawater for 28 days. The unexposed samples with highest compressive strength attained greatest strength retention. White deposits were formed on the surface of the geopolymers after the exposure to seawater which was believed due to the depolymerisation process of the geopolymer network. Even so, the metakaolin geopolymers did not substantially change in dimension and remain structurally intact.

Density and morphology studies on bottom ash and fly ash geopolymer brick

This paper studies the finding density and morphology analysis of geopolymer bricks using bottom ash and fly ash as a geopolymer raw material. The study has been conducted to produce bottom ash and fly ash geopolymer bricks by varying the ratio of fly ash/bottom ash, ratio solid/liquid and ratio sodium silicate (Na2SiO3)/ sodium hydroxide (NaOH) in the mix design. The compressive strength range between 3.8-4.5 Mpa was obtained in theprevious study [9]. The density and morphology analysis are done based on the optimum ratio selected from bottom ash/fly ash, solid/liquidand Na2SiO3/NaOH which is 1:2, 2.0 and 4.0 respectively for non-loading application brick. The morphology analysis of the bricks is closely related to the density recorded. The highest density shows the highest value of compressive strength and a denser microstructure of morphology.

Manufacturing parameters influencing fire resistance of geopolymers: A review

Geopolymers exhibit various unique properties and characteristics, including high compressive strength, high temperature stability, and low thermal conductivity. As a relatively new and perspective material, the behavior of geopolymers subjected to high temperatures is being intensively studied nowadays. This review summarizes the recent achievements in the development of geopolymer-based fire resistance materials. Technological parameters, which influence thermal behavior of geopolymer-based materials, are also discussed. Besides that, recent applications of geopolymers according to their composition are presented.

Synthesis of Alum from Discarded Aluminium Beverage Cans

This study provides a chemical process that recycles waste aluminium cans to alum crystals that has plenty applications in industry today. The study was performed with concentrated acidic and alkaline solution containing principal components K+ and SO42- ions. It involved the dissolution of aluminium can in KOH solution, neutralization by H2SO4 solution and cooling crystallization to produce alum crystals. Emphasis was placed on the percentage yield of alum and recovery of aluminium from waste aluminium can to useful product. The result obtained the highest yield of 80% when 1.5M of KOH solution and 9M of H2SO4 solution were used with 5 g of aluminium beverage cans. When the concentration of KOH and H2SO4 solution was increased, the yield of alum production was also increased. It was found that the crystallization process was effective in recovering aluminium in the form of alum from waste aluminium beverage cans.