Papers by Keyword: Geopolymer

Abstract: The awareness of environmental protection, with the conservation of resources and the efficient use of industrial waste, has attracted the attention in recent decades as both the overexploitation of natural resources and the disposal of industrial waste have a negative impact on the environment and sustainability [1]. Under such circumstances, replacing ordinary Portland cement (OPC) with industrial waste has been shown as a sustainable and practical way to reduce the use of natural resources, as well as landfill waste and pollution [2]. The discussion of this issue is part of a path, which sees as its starting point the design of a hydraulic pipeline prototype (Figure 1) made of geopolymer mortar instead of conventional concrete pipes. The environmental sustainability of geopolymer mortars was demonstrated through the Life Cycle Assessment (LCA) methodology. Analysis results indicate that the use of eco-friendly materials contributes to minimizing the environmental impact of new technologies for engineering sector.

Abstract: The strength of a fine-grained lateritic soil from three (3) different locations on Abuja – Lokoja road where road failure occur was treated with sodium silicate activator (SSA), cement and rice husk ash (RSA) with varying percentage scrutinized by means of Atterberg, compaction and triaxial shear tests. The result reveals that cement additive improved the lateritic soil from Liquid limit values of 41.25 at 0% to 44.36 at 8%, but reduces at 10% to 35.67, while RHA increases at increased percentages. The MDD improved with increase in the quantities of all the additive (SSA, cement and RHA) content, while OMC for both cement and RHA reduces from 18.65% at 0% to 11.71 and 18.05 respectively. It reveals cohesion of the soil at 0, 2, 4, 6, 8 and 10% to be 19, 39, 49, 55, 58 and 65 KN/m² respectively, with highest angle of 65⁰ and lowest of 37⁰. This implies that the cohesion of the improved sample was satisfied since the improved angle of internal friction is above the angle that makes soil very plastic which is 28⁰. Keywords: Geopolymer. Sodium silicate, rice hush ash, Triaxial, Abuja.

Abstract: Existing masonry buildings become more and more outdated depending on the actual state of conservation, but also in relation to the renovation of the performance requirements stated in current code and guidelines. Therefore, two fundamental aspects emerge as drawbacks: mechanical resistance and thermal conductivity. The structural retrofitting often consists of a covering by means of Composite Reinforced Mortar (CRM), which involves a pre-impregnated fiber mesh into an inorganic binder (e.g. lime-based mortar), while an additional insulation layer is designed for thermal scope. In this study a new composite, concerning a fly-ash based geopolymer and a glass fiber mesh (namely Composite Reinforced Geopolymer Mortar - CRGM), is proposed. The goal is to demonstrate its ability of improving both the shear strength and the thermal resistance of a masonry panel (simulating an existing structure). At this scope, an experimental investigation put in contrast the proposal with respect to a traditional CRM-system (i.e. lime-based matrix and the same glass fiber mesh). The results confirmed the validity of the CRGM. Moreover, a theoretical simulation evidenced the potential impact of the CRGM on the commonly used types of masonry all around Italy from the thermal point of view.

Abstract: Geopolymeric mortars derived from residues of the Peruvian formal mining industry were manufactured and mechanically evaluated under normal conditions of temperature and atmosphere. The mechanical results found in geopolymeric mortars were compared with those found in conventional Portland cement mortars (control). The values of maximum uniaxial compressive strengths for geopolymeric mortars were between 15.5 and 31.5 MPa, finding the best results when considering a ratio binder:fine sand of 1:2, hardener solution molarity of 20M and a ratio hardener solution:binder of 0.6. The microstructure found for both types of mortars studied (control and geopolymeric) consisted of an interconnected continuous phase of binder (cement or geopolymerized mining tailings) and another discontinuous one of fine sand particles, located within the binder phase.

Abstract: This paper presents the physical and chemical properties of fly ash obtained from two coal power plants; the Sultan Salahuddin Abdul Aziz Power Plant in Kapar, Selangor and Sultan Azlan Shah Power Plant in Manjung, Perak. Moisture and radionuclide contents, and chemical composition in the fly ash were characterized. It was found that moisture content for Kapar and Manjung fly ash were at 0.41% and 0.11%, respectively. XRF result showed that Kapar fly ash sample is of class C due to the total percentage of SiO2, Al2O3, and Fe2O3 being less than 70% while Manjung fly ash sample is of class F due to the total percentage of SiO2, Al2O3, and Fe2O3 of more than 70%. Gamma spectrometry analysis indicated presence of ²²⁶Ra, ²³²Th, and ⁴⁰K in the samples. These data can be used to establish a technical standpoint in supporting the development of radioactive waste immobilization technology using geopolymer material. This study is expected to benefit the nuclear fuel cycle specifically in conditioning of low-level radioactive waste produced in nuclear power plants.

Abstract: Geopolymer is an alternative cementitious material produced by rich aluminosilicate mineral materials (Si-Al) combine with an alkaline activator. The objectives of this study are to study the effect of adding hydrogen peroxide (H₂O₂) and sodium dodecyl sulphate (SDS) as foaming and stabilizing agents, respectively to the fly ash (FA)-based geopolymer mortar properties. The geopolymer mortars were synthesized with a mixture of FA, alkaline activator and SDS with different H₂O₂ content. The geopolymer mortars were analyzed using compressive strength test, porosity test and Scanning Electron Microscopy (SEM) analysis. Geopolymer mortar with 1 wt% H₂O₂ content and 0.5 wt% SDS has the lowest compressive strength (8.67 N) compare to the other geopolymer mortar composition. As H₂O₂ content increase with presence of SDS, the formation of the pores also increased hence resulting in the low compressive strength of geopolymer mortar.

Abstract: Infrastructural developments are inevitable for the developing countries and hence the production of sustainable building materials is promoted worldwide. Sustainable development in the vicinity of tiles is bewildered for more than a decade. Production of conventional tiles such as cement concrete tiles, clay tiles and ceramic tiles is energy intensive approach and levies lot of strain over the adjunct ecosystem. On the other hand there are serious problems related to the disposal of flyash, Rice Husk Ash throughout the world. An approach has been taken to synthesis tiles based on these industrial byproducts as the base materials through Geopolymer technology. In this work, Geopolymer mortar after heat curing is applied as tiles. In this work, Flyash is replaced by Rice Husk Ash in various proportions such as 20, 40, 60, 80 and 100 percent. Tests such as workability, flatness, straightness, perpendicularity, water absorption, modulus of rupture and abrasion are conducted and fair results are obtained. This research also portrays the effect of Rise Husk Ash addition over the flyash based Geopolymer binder in the utility as tiles. The findings of this research work encourages the development of energy efficient tiles using industrial wastes. Keywords: Geopolymer, Rice Husk Ash, Tiles

Abstract: The exploitation of different kind of clayey waste (halloysitic, smectitic/illitic, kaolinitic) for the production of geopolymers in the view of a circular economy of mines is the main goal of this study. In particular, the addition of low percentages of metakaolin (5-15%) was evaluated to improve the chemical-physical properties and the consolidation degree of geopolymeric formulations produced with clays classified as mine’s by-products. In fact, these secondary raw materials are often not sufficient alone to obtain chemically stable formulations with acceptable mechanical properties but require the addition of reactive fillers. All samples contained thermally treated clays (600°C-700°C) and metakaolin as aluminosilicate precursors, alkaline solution of NaOH and Na₂SiO₃, and were cured at room temperature. The influence on the final products with MK addition was monitored with the evaluation of the chemical stability in water (pH and ionic conductivity measures), the comparison of setting times (Vicat needle) and mechanical performance.

Abstract: Research of alkali-activated materials and geopolymers suggests their increased ability to transfer the electric charge thus indicating their suitability for self-sensing and other multifunctional composites. In this paper, the electrical properties of metakaolin geopolymer are enhanced by the incorporated steel microfibres that also improve the mechanical and fractural properties of the composite. Selected electrical properties of metakaolin geopolymer mortars with steel microfibres (up to 30 % of metakaolin wt.) were assessed via impedance spectroscopy analysis and followed by testing their compressive and flexural strength. Mercury intrusion porosimetry and SEM imaging enabled to characterize the binder microstructure and quality of fibre-matrix bonding.

Abstract: Climate change is recognized as a global problem and even the industrial and construction sectors are trying to reduce the green-house gas emissions, especially on CO₂ emissions. In Vietnam, the coal-fired thermal power plants are discharging millions of tons of CO₂ and coal ash annually. This coal ash is comprised of about 80% of fly ash and the rest is bottom ash. This study would like to introduce one of the potential solutions in a carbon-constrained society that would not only manage the fly ash but also utilized this as raw material for green materials through geopolymerization. The geopolymer-based material has lower energy consumption, minimal CO₂ emissions and lower production cost as it valorizes industrial waste. The fly ash containing high alumino-silicate resources from a coal-fired power plant in Vietnam was mixed with sodium silicate and sodium hydroxide solutions to obtain the geopolymeric pastes. The pastes were molded in 10x10x20cm molds and then cured at room temperature for 28 days. The 28-day geopolymer specimens were carried out to test for engineering properties such as compressive strength (MPa), volumetric weight (kg/m³), and water absorption (kg/m³). The microstructure analysis was also conducted for this eco-friendly materials using X ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Differential Thermal Analysis - Thermal Gravimetric Analysis (DTA-TGA).