Mohammed Binhussain

Mechanical and microstructural evaluations of lightweight aggregate geopolymer concrete before and after exposed to elevated temperatures

This paper presents the mechanical and microstructural characteristics of a lightweight aggregate geopolymer concrete (LWAGC) synthesized by the alkali-activation of a fly ash source (FA) before and after being exposed to elevated temperatures, ranging from 100 to 800 °C. The results show that the LWAGC unexposed to the elevated temperatures possesses a good strength-to-weight ratio compared with other LWAGCs available in the published literature. The unexposed LWAGC also shows an excellent strength development versus aging times, up to 365 days. For the exposed LWAGC to the elevated temperatures of 100 to 800 °C, the results illustrate that the concretes gain compressive strength after being exposed to elevated temperatures of 100, 200 and 300 °C. Afterward, the strength of the LWAGC started to deteriorate and decrease after being exposed to elevated temperatures of 400 °C, and up to 800 °C. Based on the mechanical strength results of the exposed LWAGCs to elevated temperatures of 100 °C to 800 °C, the relationship between the exposure temperature and the obtained residual compressive strength is statistically analyzed and achieved. In addition, the microstructure investigation of the unexposed LWAGC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ). However, this bonding is subjected to deterioration as the LWAGC is exposed to elevated temperatures of 400, 600 and 800 °C by increasing the microcrack content and swelling of the unreacted silicates.

Study on Fly Ash Based Geopolymer for Coating Applications

Geopolymer is cementitious binders that do not require the presence of ordinary Portland cement (OPC). Fly ash with geopolymer formulations prepared with mixing alumino-silicate with the alkaline activator solution has been applied as protective coating material that suitable for high temperature applications such as fire resistant panel. Geopolymer coating samples were cured at 70 °C for 24 hours before sintered using temperatures range from 600 °C to 1500 °C in order to increase strength and improve thermal properties. Curing conditions also have a significant effect on the development of mechanical strength in most cementitious systems. The chemical compositions, microstructure and FTIR were studied. Geopolymer coating samples cures to a glassy texture and effectively used to create a resistant surface. Fly ash geopolymer coating was improved the compressive strength of the coatings materials as high as 40 MPa. This technology develop a geopolymeric mix design that superior use as cementitious coatings with high thermal application.

Preparation and characterization of PMMA/stone waste nanocomposites for marmoreal artificial stone industry

The current study concerns the preparation and characterization of marmoreal solid surface materials based on polymethylmethacrylate (PMMA) nanocomposites filled with waste stones of marble, granite and basalt. Hydrophilic nanosilica and clay Halloysite nanotubules (HNTs) were the two types of nanofillers used to prepare PMMA/stone waste nanocomposites. The effect of nanofiller type and stone nature was investigated by Rockwell hardness, flexural strength, impact toughness, abrasion loss, water absorption and luminous transmittance measurements. The prepared artificial stone samples have an eye-catching decorative effect of alabaster when lighted from rear using a low energy light source.

Application of clay - based geopolymer in brick production: A review

This paper reviews and summarizes the current knowledge and application of clay as a geopolymer material in production of geopolymer brick. As we understand, the nature of source materials give a significant impact to the strength of geopolymer. For example, geopolymer made from calcined source material such as calcined kaolin, fly ash, ground granulated blastfurnace slag (GGBS) and others produce a higher compressive strength compared to geopolymer made from non-calcined source material such as kaolin. This paper is reviewing on the suitability of clay application as a geopolymer material in geopolymer brick production. The chemical composition of clay-based material show high content of SiO2 and Al2O3 compound which is similar to the fly ash. Clay-based Geopolymer showed a good potential in a brick production.

Microstructure Study on Optimization of High Strength Fly Ash Based Geopolymer

The compressive strength and microstructural characteristics of fly ash based geopolymer with alkaline activator solution were investigated. The sodium hydroxide and sodium silicate were mixed together to form an alkaline activator. Three parameters including NaOH molarity, mix design (fly ash/alkaline activator ratio and Na2SiO3/NaOH ratio), and curing temperature were examined. The maximum strength of 71 MPa was obtained when the NaOH solution of 12M, fly ash/alkaline activator of 2.0, Na2SiO3/NaOH of 2.5 and curing temperature of 60°C were used at 7th days of testing. The results of SEM indicated that for geopolymer with highest strength, the structure was dense matrix and contains less unreacted fly ash with alkaline activator

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.

Effect of Microwave Curing to the Compressive Strength of Fly Ash Based Geopolymer Mortar

With the advancement of technology and the economic crisis in Malaysia, has been promoting the development of infrastructure in the use of new structural materials but overall is unsatisfactory in terms of cost savings. One of the alternatives that can be used is to use fly ash as a cement replacement in manufacturing mortar. Replacement of cement with geopolymerization mortar can reduce manufacturing costs and could reduce global warming arising from the production of cement for the production of Portland cement for the release of CO2 into the atmosphere, where CO2 gas gives the largest contribution to global warming . The study will be focused on the effect of microwave curing with various durations and temperature to the mechanical and physical properties of fly ash based geopolymer mortar. For the conventional heating technique, heat is distributed in the specimen from the exterior to the interior leading to the non-uniform and long heating period to attain the required temperature. Application of microwave to the fresh concrete results in removal of water, collapse of capillary pore and densification of sample. Heat curing has been applied to construction materials especially for the precast concrete to improve the strength development process. This concrete attains sufficient strength in short curing time, so the molds can be reused, and the final products can be rapidly delivered to the site. The effect of curing temperature together with their aging days of the cured product will also be investigated. Mechanical properties of the product will be tested using compressive test, and density of the samples.

Features of hyperbolic metamaterials with extremal optical characteristics

The possibility is shown and conditions are found for the realization of the type I or II epsilon-near-zero (ENZ) metamaterials based on a multilayer metal-dielectric structure. It is found that, for both propagating and evanescent extraordinary waves, diffraction-free energy transportation occurs with low losses within narrow channels inside the type I ENZ metamaterial on the basis of such a structure. The research presents the possibility of forming the type II ENZ metamaterial inside the two kinds of propagating light waves for which the amplitude decays from the boundary and the phase fronts move away from and towards the boundary of the metamaterial, respectively. The interaction between Gaussian light beams and metamaterials with extremal characteristics is theoretically investigated. The prospect of the practical application of these media is considered.

Epoxy Layered Silicates with Fly Ash-Based Geopolymer: Flexural Properties

The effect of fly ash-based geopolymer in epoxy-layered silicates nanocomposites was studied through flexural properties and morphological characterization. In this study, a series of nanocomposites with fly ash-based geopolymer containing 1-7% wt were prepared. It was found that the addition of fly ash with lower content in the beginning showed lower flexural strength than nanocomposites without fly ash. However, flexural properties suddenly increased at 3% wt of fly ash geopolymer content in comparison to origin. This indicates the blending of fly ash geopolymer in nanocomposites systems have the ability for further studied.

A Review of Fly Ash-Based Geopolymer Lightweight Bricks

This paper offers a review on production of fly ash-based geopolymer bricks.Bricks are the world’s most versatile, durable and reliable construction material.Conventional bricks are produced from clay with high temperature kiln firing or from ordinary Portland cement (OPC) concrete,and thus contain high embodied energy and have large carbon footprint. In many areas of the world,there is already a shortage of natural source material for production of the conventional bricks. For environmentalprotection and sustainable development, extensive research has been conducted on productionof bricks from waste materials.Fly ash is a waste material of coal firing thermal plants and its accumulation near power plants causes severe pollution problems. Therefore, its utilization as a raw material for brick making will be a very beneficial solution in terms of economic and environmental aspects.