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Characterisation at the bonding zone between fly ash based Geopolymer Repair Materials (GRM) and Ordinary Portland Cement Concrete (OPCC)

2020 , Warid Wazien Ahmad Zailani , Mohd. Mustafa Al Bakri Abdullah , Mohd Fadzil Arshad , Rafiza Abd Razak , Muhammad Faheem Mohd. Tahir , Remy Rozainy Mohd Arif Zainol , Marcin Nabialek , Andrei Victor Sandu , Jerzy J. Wysłocki , Katarzyna Błoch

In recent years, research and development of geopolymers has gained significant interest in the fields of repairs and restoration. This paper investigates the application of a geopolymer as a repair material by implementation of high-calcium fly ash (FA) as a main precursor, activated by a sodium hydroxide and sodium silicate solution. Three methods of concrete substrate surface preparation were cast and patched: as-cast against ordinary Portland cement concrete (OPCC), with drilled holes, wire-brushed, and left as-cast against the OPCC grade 30. This study indicated that FA-based geopolymer repair materials (GRMs) possessed very high bonding strength at early stages and that the behavior was not affected significantly by high surface treatment roughness. In addition, the investigations using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy have revealed that the geopolymer repair material became chemically bonded to the OPC concrete substrate, due to the formation of a C–A–S–H gel. Fundamentally, the geopolymer network is composed of tetrahedral anions (SiO4)4− and (AlO4)5− sharing the oxygen, which requires positive ions such as Na+, K+, Li+, Ca2+, Na+, Ba2+, NH4+, and H3O+. The availability of calcium hydroxide (Ca(OH)2) at the surface of the OPCC substrate, which was rich in calcium ions (Ca2+), reacted with the geopolymer; this compensated the electron vacancies of the framework cavities at the bonding zone between the GRM and the OPCC substrate.

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Evaluation on the mechanical properties of Ground Granulated Blast Slag (GGBS) and fly ash stabilized soil via geopolymer process

2021 , Syafiadi Rizki Abdila , Mohd. Mustafa Al Bakri Abdullah , Romisuhani Ahmad , Shayfull Zamree Abd. Rahim , Małgorzata Rychta , Izabela Wnuk , Marcin Nabiałek , Krzysztof Muskalski , Muhammad Faheem Mohd. Tahir , Muhammad Syafwandi , Marek Isradi

This study intended to address the problem of damaged (collapsed, cracked and decreased soil strength) road pavement structure built on clay soil due to clay soil properties such as low shear strength, high soil compressibility, low soil permeability, low soil strength, and high soil plasticity. Previous research reported that ground granulated blast slag (GGBS) and fly ash can be used for clay soil stabilizations, but the results of past research indicate that the road pavement construction standards remained unfulfilled, especially in terms of clay’s subgrade soil. Due to this reason, this study is carried out to further investigate soil stabilization using GGBS and fly ash-based geopolymer processes. This study investigates the effects of GGBS and ratios of fly ash (solid) to alkaline activator (liquid) of 1:1, 1.5:1, 2:1, 2.5:1, and 3:1, cured for 1 and 7 days. The molarity of sodium hydroxide (NaOH) and the ratio of sodium silicate (Na2SiO3) to sodium hydroxide (NaOH) was fixed at 10 molar and 2.0 weight ratio. The mechanical properties of the soil stabilization based geopolymer process were tested using an unconfined compression test, while the characterization of soil stabilization was investigated using the plastic limit test, liquid limit test, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results showed that the highest strength obtained was 3.15 MPA with a GGBS to alkaline activator ratio of 1.5 and Na2SiO3 to NaOH ratio of 2.0 at 7 days curing time. These findings are useful in enhancing knowledge in the field of soil stabilization-based geopolymer, especially for applications in pavement construction. In addition, it can be used as a reference for academicians, civil engineers, and geotechnical engineers.

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Physical and mechanical studies of kaolin-based geopolymer masonry brick

2015 , Muhammad Faheem Mohd. Tahir

A brick is mainly applied as a building material in construction of walls. Conventional construction bricks are usually made from Portland cement, clay and sand, which are mixed and molded in various method and need to be dried and burned with the temperature range between 900 to 1200 degree centigrade. The drying and firing process takes 2 to 4 days to be done. Other than that, the production of Portland cement consume high energy and can emit 1 to 1.2 ton of carbon dioxide (CO2) for every 1 ton of Portland cement product. Nowadays, a novel family of building materials which is geopolymer cement has seen a great development around the world. It is caused by the environmental issues that pressured the industries to manufacture a products and materials that are more environmental friendly. The aim of this research was to produce a product that would provide an alternative to the conventional bricks with a good properties by utilizing a geopolymer material which is kaolin, reduce the pollution of environment by replacing the usage of Portland cement in brick making industry, and produce effectively usable product by enhance the properties of ordinary product. This study has been conducted to produce kaolin-based geopolymer bricks by means of pressure forming without firing procedure and low energy consumptions.