Effect of phosphate addition on room-temperature-cured fly ash-metakaolin blend geopolymers

Zulkifly, Khairunnisa; Cheng-Yong, Heah; Yun-Ming, Liew; Abdullah, Mohd Mustafa Al Bakri; Shee-Ween, Ong; Khalid, Mohd Suhaimi

doi:10.1016/j.conbuildmat.2020.121486

Cited by 24 publications

(9 citation statements)

References 73 publications

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“…Metakaolin is produced under these temperatures, when kaolin-clay rich in kaolinite undergoes thermal activation and by dehydroxylation, which leads to breaking down or partial breakdown of the structure resulting in a transition phase with high reactivity [ 82 ]. The morphologies of fly ash and metakaolin particles are observed by SEM analysis and illustrated in Figure 9 [ 83 ]. It is observed that fly ash particles are quasi-spherical and smooth with a variation in sizes.…”

Section: Geopolymersmentioning

confidence: 99%

“…Therefore, careful investigation of metakaolin-based concretes should be carried out for elements that are prone to high temperatures. Figure 10 shows the metakaolin and fly ash blended geopolymer composites with different formulations of monoaluminium phosphate and aluminum dihydrogen triphosphate that provided excellent mechanical and physical properties after a 28-day curing process [ 83 ]. It is observed that both fly ash and metakaolin particles provide more compact and homogenous microstructure of the composite that leads to higher compressive strength.…”

Section: Geopolymersmentioning

confidence: 99%

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Geopolymers and Fiber-Reinforced Concrete Composites in Civil Engineering

et al. 2021

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This paper discusses the influence of fiber reinforcement on the properties of geopolymer concrete composites, based on fly ash, ground granulated blast furnace slag and metakaolin. Traditional concrete composites are brittle in nature due to low tensile strength. The inclusion of fibrous material alters brittle behavior of concrete along with a significant improvement in mechanical properties i.e., toughness, strain and flexural strength. Ordinary Portland cement (OPC) is mainly used as a binding agent in concrete composites. However, current environmental awareness promotes the use of alternative binders i.e., geopolymers, to replace OPC because in OPC production, significant quantity of CO2 is released that creates environmental pollution. Geopolymer concrete composites have been characterized using a wide range of analytical tools including scanning electron microscopy (SEM) and elemental detection X-ray spectroscopy (EDX). Insight into the physicochemical behavior of geopolymers, their constituents and reinforcement with natural polymeric fibers for the making of concrete composites has been gained. Focus has been given to the use of sisal, jute, basalt and glass fibers.

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Section: Geopolymersmentioning

confidence: 99%

Section: Geopolymersmentioning

confidence: 99%

Geopolymers and Fiber-Reinforced Concrete Composites in Civil Engineering

et al. 2021

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“…This indicated a positive effect after the addition of ATP and MAP in the blended geopolymers whereby the fire propagation index reduced. As previously discussed in previously published work [ 27 ], the inclusion of ATP and MAP formed a matrix with higher cross-linking geopolymer frameworks that reduced the fire propagation index [ 55 ].…”

Section: Resultsmentioning

confidence: 99%

“…Further increasing dosage of ATP and MAP degraded the compressive strength to 37.8 MPa (G-ATP3) and 38.7 MPa (G-MAP3). Excess free ions will inhibit the dissolution of aluminosilicate and hinder complete geopolymerisation reaction, which has been discussed in the previous paper published [ 27 ]. The slightly acidic aluminum phosphate will also partially neutralize the alkalinity of the geopolymer system [ 28 , 29 ].…”

Section: Resultsmentioning

confidence: 99%

Elevated-Temperature Performance, Combustibility and Fire Propagation Index of Fly Ash-Metakaolin Blend Geopolymers with Addition of Monoaluminium Phosphate (MAP) and Aluminum Dihydrogen Triphosphate (ATP)

et al. 2021

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Thermal performance, combustibility, and fire propagation of fly ash-metakaolin (FA-MK) blended geopolymer with the addition of aluminum triphosphate, ATP (Al(H2PO4)3), and monoaluminium phosphate, MAP (AlPO4) were evaluated in this paper. To prepare the geopolymer mix, fly ash and metakaolin with a ratio of 1:1 were added with ATP and MAP in a range of 0–3% by weight. The fire/heat resistance was evaluated by comparing the residual compressive strengths after the elevated temperature exposure. Besides, combustibility and fire propagation tests were conducted to examine the thermal performance and the applicability of the geopolymers as passive fire protection. Experimental results revealed that the blended geopolymers with 1 wt.% of ATP and MAP exhibited higher compressive strength and denser geopolymer matrix than control geopolymers. The effect of ATP and MAP addition was more obvious in unheated geopolymer and little improvement was observed for geopolymer subjected to elevated temperature. ATP and MAP at 3 wt.% did not help in enhancing the elevated-temperature performance of blended geopolymers. Even so, all blended geopolymers, regardless of the addition of ATP and MAP, were regarded as the noncombustible materials with negligible (0–0.1) fire propagation index.

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“…Coal gangue is the largest solid waste discharged in China. Most coal gangue contains clay minerals, with similar chemical composition to clay, which can be used as raw materials for preparation of geopolymer and geopolymer concrete [3,4]. e authors have used coal gangue as the main raw material to prepare coal ganguebased geopolymer concrete, and its basic mechanical properties were studied [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Study on High‐Temperature Behavior of Coal Gangue‐Based Geopolymer Concrete Beams

Sun

2022

Advances in Civil Engineering

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A newly coal gangue-based geopolymer concrete made from alkaline dry powder activator, coal gangue, and fly ash has been proposed by the authors. High-temperature behavior of the proposed geopolymer concrete beams with different cross sections reinforced with steel bars is investigated in the work here. High-temperature behavior by numerical simulation is validated by the existing experiment. High-temperature behavior is investigated by analysing the geopolymer concrete beams with different cross section dimensions. Temperature distribution and deformation of the beams from room temperature to fairly high temperature are studied. The isotherm contours of beams at different temperatures and the thermal stress contours of the beam at different time steps are obtained and analyzed. First, cracking load and ultimate load of the geopolymer beams with different concrete cover thicknesses are analyzed under different high temperature conditions. It is found that the temperature at the cross section centerline of coal gangue-based geopolymer concrete beam gradually decreases along the vertical direction. The cracking load and ultimate load of the geopolymer concrete beams at high temperature are affected by the thickness of concrete cover. With the increase of temperature, the mid-span deflection of the beam increases gradually. High temperature is a key factor for analysing the behaviors of coal gangue-based geopolymer concrete beams.

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Effect of phosphate addition on room-temperature-cured fly ash-metakaolin blend geopolymers

Cited by 24 publications

References 73 publications

Geopolymers and Fiber-Reinforced Concrete Composites in Civil Engineering

Geopolymers and Fiber-Reinforced Concrete Composites in Civil Engineering

Elevated-Temperature Performance, Combustibility and Fire Propagation Index of Fly Ash-Metakaolin Blend Geopolymers with Addition of Monoaluminium Phosphate (MAP) and Aluminum Dihydrogen Triphosphate (ATP)

Study on High‐Temperature Behavior of Coal Gangue‐Based Geopolymer Concrete Beams

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