Conflict of InterestsThe authors declare that there is no conflict of interests regarding the publication of this paper.AcknowledgmentThis study was supported by a Grant of the Traditional Korean Medicine R&D Project, Ministry of Health & Welfare, Republic of Korea (HI12C1886 (B120008)).
The geopolymers are interesting Axitinib in the fields of materials science and materials engineering. The geopolymer process is a chemical reaction between aluminosilicate materials and alkaline solutions under high curing temperature conditions. Generally, raw materials are prepared with a geopolymer binder consisting of fly ash and metakaolin (MK) containing SiO2 and Al2O3 which are the main chemical constituents. Geopolymers are binders that exhibit good physical and chemical properties and a wide range of potential applications [1].
However, several previous researches reported some of the limitations of geopolymer properties. Metakaolin based geopolymers show a relevant strength loss that makes them unsuitable for construction purposes [2]. There are efflorescence [3, 4] related problems with this materials, and recently, Turner and Collins [5] showed that sodium silicate ��geopolymers�� have almost the same carbon footprint as Portland cement.Previous studies [6�C8] have reported that different ratios of SiO2/Al2O3 influence the properties of the geopolymer binders. Generally, the geopolymer binder has been prepared using fly ash and metakaolin, in which the ratio of SiO2/Al2O3 varied within a range of 2:1 and 4:1. The effect of high calcium fly ash contents between 2.79:1 and 4.
79:1 (SiO2/Al2O3) on the setting time and compressive strength of geopolymers was investigated in Chindaprasirt et al. [8]. The result showed that a higher compressive strength was achieved within a range of SiO2/Al2O3 ratios of 2.57:1 and 4.24:1. However, the current study focuses on SiO2/Al2O3 and CaO/SiO2 ratios.van Jaarsveld et al. [9] used XRD and FT-IR techniques to characterize the fly ash obtained from different sources in order to gain a greater understanding of the effect of phase composition on the dissolution behavior, reactivity, and final physical and mechanical properties of fly ash-based geopolymers. The polymerization mechanism and the structure of the products were also investigated by Barbosa et al. [10] using XRD and FT-IR spectroscopy. A number of investigators [11, 12] have also studied the microstructure of geopolymers using SEM.Oil palm ash (OPA) is Brefeldin_A a by-product of the use of palm kernels, palm fibers, and palm shells as biomass fuel in place of petroleum in electricity generation. Currently, OPA is disposed of in landfills, which has the potential to cause environmental problems for the industry and health risks for the public.
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