The effects of SiO2/Na2O molar ratio on the characteristics of alkali-activated waste catalyst–metakaolin based geopolymers

Cheng, Hui; Lin, Kae‐Long; Cui, Rong; Hwang, Chao‐Lung; Chang, Yu‐Min; Cheng, Ta‐Wui

doi:10.1016/j.conbuildmat.2015.07.028

Cited by 53 publications

(26 citation statements)

References 49 publications

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“…The alkaline activator was used to dissolve the r-MK [22][23][24]. At the same time, alkali cations Na + balanced the negative charge of Al 3+ in IV-fold coordination and existed in the cavities of the geopolymer network with 2 mole of IV-fold coordinated Al 3+ requiring 1 mole of Na 2 O for electrical neutrality theoretically [42].…”

Section: Influences Of Constituents For Preparation Of Geopolymersmentioning

confidence: 99%

“…From the previous reports, it was stated that the mechanical properties, such as flexural strength and compressive strength, of the MK based geopolymers could be improved by adjusting the synthesis parameters such as pH value, curing time, temperature, and the concentration and type of alkali activators [22]. Typically, the compressive strength of a MK based geopolymer can attain above 70 MPa, which is comparable to the normal concrete [23][24][25][26]. In order to extend the applications of geopolymers, such as ultrahigh-performance-concrete (over 120 MPa) [27] and human bone replacement (over 160 MPa) [28], the compressive strength of geopolymers and their composites are required to be further improved.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and compressive properties of silicon carbide reinforced geopolymer

Xie

Zhang

et al. 2016

Composites Part B: Engineering

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Geopolymers (GPs) have emerged as a promising alternative to ordinary cement due to its attractive physical and thermal properties. The typical compressive strength of geopolymers and their composites is usually limited to around 80 MPa, therefore they should be further strengthened for wider applications, such as ultrahigh strength concrete, and bone replacement. This paper presents a facile method of enhancing the compressive strength by incorporating silicon carbide particles (SiC p) and silicon carbide whiskers (SiC w) into the geopolymer matrix via the geopolymerization of metakaolin (MK). The effects of the reinforcement of SiC p and SiC w on the microstructure, thermal properties and compressive properties of the composites were investigated. The SEM images showed that both SiC p and SiC w were well dispersed in the geopolymer matrix. Due to the bridging effect among the SiC w particles, SiC w /GP composites possessed higher porosity and lower density, and thus lower thermal stability and thermal conductivity as compared with SiC p /GP. The mechanical tests showed that the compressive strength of SiC p /GP composites increased with the increase of SiC p concentration. With an optimum concentration of 10 wt. % of SiC p , the compressive strength of the composite was enhanced to 155 MPa, corresponding to a 100% increase as compared with the unfilled geopolymer.

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Section: Influences Of Constituents For Preparation Of Geopolymersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructure and compressive properties of silicon carbide reinforced geopolymer

Xie

Zhang

et al. 2016

Composites Part B: Engineering

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“…The authors attributed the poorer performance of some mortars to a reduced alkalinity in the activating solution, which decreased the dissolution of the precursor and, consequently, the binder formation. Cheng et al [30,31], who investigated the influence of FCC additions in alkali-activated metakaolin, established 10% as the optimum percentage of substitution. These authors also concluded that the SiO 2 /Na 2 O and solid/liquid ratios strongly determined the properties of the blended system.…”

Section: Introductionmentioning

confidence: 99%

Influence of Addition of Fluid Catalytic Cracking Residue (FCC) and the SiO2 Concentration in Alkali-Activated Ceramic Sanitary-Ware (CSW) Binders

et al. 2018

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Production of Portland cement requires a large volume of natural raw materials and releases huge amounts of CO 2 to the atmosphere. Lower environmental impact alternatives focus on alkali-activated cements. In this paper, fluid catalytic cracking residue (FCC) was used to partially replace (0 wt %-50 wt %) ceramic sanitaryware (CSW) in alkali-activated systems. Samples were activated with NaOH and sodium silicate solutions and were cured at 65 • C for 7 days and at 20 • C for 28 and 90 days. In order to increase CSW/FCC binders' sustainability, the influence of reducing the silica concentration (from 7.28 mol•kg −1 up to 2.91 mol•kg −1) was analyzed. The microstructure of the developed binders was investigated in pastes by X-ray diffraction, thermo tests and field emission scanning electron microscopy analyses. Compressive strength evolution was assessed in mortars. The results showed a synergetic effect of the CSW/FCC combinations so that, under the studied conditions, mechanical properties significantly improved when combining both waste materials (up to 70 MPa were achieved in the mortars containing 50 wt % FCC cured at room temperature for 90 days). Addition of FCC allowed CSW to be activated at room temperature, which significantly broadens the field of applications of alkali-activated CSW binders.

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“…The second phase in the geopolymer formation consisted of preparing the alkaline solution. This solution was prepared with a specific SiO 2 /Na 2 O ratio = 1.5 1 day ahead of the production of geopolymers since it was considered as an exothermic reaction . The following products were used for the activator solutions, laboratory grade pellets of NaOH (97%, Merck, Germany), and some ultrapure sodium silicate solution (≥10% NaOH, ≥27% SiO 2 , Sigma Aldrich, Germany).…”

Section: Materials and Experimental Resultsmentioning

confidence: 99%

Assessment of aluminosilicate raw material used in L ebanon: Effect of curing

Saba

Georges

Absi

2019

Mat Design Process Comm

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This research assesses the effect of curing and porosity on the microstructure and mechanical properties of aluminosilicate‐based material. Within the first 24 hours of production, all samples endured the same influence of curing temperature that was set to 60°C. Throughout the aging process, all samples were kept at ambient temperature. Simultaneously, the impacts on the microstructure and mechanical properties were studied. The results indicated that while aging and with the same physical conditions, the dissolution, polymerization, and precipitation processes of the geopolymerization reaction were quite different. This variation was mainly affected by the porous and nonporous characteristics of the aluminosilicate material produced. From a mechanical point of view, the optimum samples obtained were the ones having low porosity, where the mechanical properties such as load at failure reached 59 MPa after being cured for 28 days.

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The effects of SiO2/Na2O molar ratio on the characteristics of alkali-activated waste catalyst–metakaolin based geopolymers

Cited by 53 publications

References 49 publications

Microstructure and compressive properties of silicon carbide reinforced geopolymer

Microstructure and compressive properties of silicon carbide reinforced geopolymer

Influence of Addition of Fluid Catalytic Cracking Residue (FCC) and the SiO2 Concentration in Alkali-Activated Ceramic Sanitary-Ware (CSW) Binders

Assessment of aluminosilicate raw material used in L ebanon: Effect of curing

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