Phosphate-based geopolymer: Formation mechanism and thermal stability

Wang, Yanshuai; Dai, Jian‐Guo; Zhu, Ding; Wang, Xu

doi:10.1016/j.matlet.2017.01.022

Cited by 106 publications

(34 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In this case, maintaining the reactive medium at 60 °C is generally helpful to get reliable cements [25-27, 29, 32-36]. The hardening of phosphate based geopolymers results in the formation of -Si-O-P-O, Si-O and -Al-O-P-O bonds by partial replacement of SiO 4 tetrahedra by PO 4 [33,37]. This partial replacement have been observed firstly by Louati et al [29,34,35] from FTIR in amorphous phase cement during the phosphoric acid activation of calcined clay.…”

Section: Introductionmentioning

confidence: 99%

Amorphous phase of volcanic ash and microstructure of cement product obtained from phosphoric acid activation

et al. 2020

View full text Add to dashboard Cite

Alkaline activation of volcanic ash using Na 2 SiO 3 as activator showed its limits because of their low reactivity, nevertheless, phosphoric acid activation using H 3 PO 4 as activator can offer a great possibility of utilization of the latter aluminosilicate. The present study aims to determine the chemical composition of amorphous phase of volcanic ash and examine through the microstructure of the obtained cement-based phosphoric acid activation the relation between silicon and phosphorus atoms. Chemical composition of amorphous phase was determined by dissolution with NaOH and HCl. Cement fresh paste was subjected to isothermal calorimetry and temperature variation. Meanwhile, the hardened paste was characterized by X-ray diffraction, thermogravimetry analysis, scanning electron microscopy, energy dispersive spectrometry and Fourier transform infrared spectroscopy in order to study the microstructure. Also, the cement product was submitted to compressive strength test. The results obtained showed that, the amorphous phase of volcanic ash contain SiO 2 , Al 2 O 3 , Fe 2 O 3 , MgO and CaO oxides. This study allowed to understand the fact that phosphoric acid activation of volcanic ash at ambient temperature is an exothermic reaction and its described as a dissolution/precipitation process. Also, the obtained product was hydrated. Compressive strength of the cement product aged 1 and 28 days was respectively 20.6 and 30.5 MPa. Based on SEM/EDS analysis, silicon are partially replaced by phosphorus atoms and the product is made of-Si-O-Al-O-P-O-phospho-sialate network. Phosphoric acid activation is a promising route of valorisation of volcanic ash.

show abstract

Section: Introductionmentioning

confidence: 99%

Amorphous phase of volcanic ash and microstructure of cement product obtained from phosphoric acid activation

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The strong monolithic product of the phosphate activation of an aluminosilicate source, such as metakaolin, is sometimes termed a phosphate-based geopolymer [10,13]. This reaction occurs in an acidic or low-alkaline medium environment in which a phosphate or phosphoric acid solution, rather than the alkali-silicate used in conventional geopolymers, chemically activates the aluminosilicate precursors to yield a compact geopolymer matrix with a condensed structure of silico-alumino-phosphate linkages [14,15].…”

Section: Introductionmentioning

confidence: 99%

Role of soluble aluminum species in the activating solution for synthesis of silico-aluminophosphate geopolymers

Wang

Provis

Dai

2018

Cement and Concrete Composites

Self Cite

View full text Add to dashboard Cite

An aluminosilicate precursor, such as metakaolin, can be transformed into a cement-like geopolymer binder via a phosphate activation approach. This paper identifies the effect of the addition of aluminum species into the phosphate activating solution on the formation of such geopolymers, from the fresh to the hardened state. Activating solutions with Al/P molar ratios of 0, 0.1, and 0.3 were prepared by blending monoaluminum phosphate (MAP) and orthophosphoric acid (OPA). The rheological properties, fluidity, and setting times of the fresh geopolymer pastes and the compressive strength of the hardened geopolymer matrices were studied. Liquid-state 27 Al and 31 P nuclear magnetic resonance (NMR) measurements for the chemical environments of Al and P, and spectroscopic, thermal, and microscopic analyses revealed that the soluble aluminum in the phosphate activating solution played an important role during the geopolymerization process. Seeding of aluminum species through inclusion in the activating solution allowed a rapid sol/gel transition that improved the rheological properties and setting time of the fresh geopolymer pastes at ambient temperature. However, although the increased concentration of aluminum phosphate oligomers promoted by the soluble aluminum addition contributed to the formation of a compact matrix with high early strength, it hinders the ongoing reaction of metakaolin in the later period, which has a detrimental influence on ongoing strength development beyond 7 days of curing.

show abstract

“…They also showed good mechanical behavior at high temperatures (1 000 • C) (Y.S. Wang et al, 2017). This geopolymer can be described as an aluminum phosphate cement.…”

Section: Phosphate Geopolymersmentioning

confidence: 90%

“…These materials have a tetrahedral molecular structure of PO4 5− , together with AlO4 3− and SiO4 4− as their basic components (Y.S. Wang et al, 2017).…”

Section: Phosphate Geopolymersmentioning

confidence: 99%

See 1 more Smart Citation

Engineering applications of chemically-bonded phosphate ceramics

Balaguera

Botero

2019

Ing. Inv.

View full text Add to dashboard Cite

Phosphate cements originated more than a century ago for specific applications to the field of dentistry. These cements have other applications including: biomaterials with bone applications, stabilization of hazardous waste, and structural cements. However, the applications in civil infrastructure are recent and not widely known. Therefore, this review discusses and analyzes phosphate cements, presenting the most significant findings of the research to address their mechanical behavior of these cements. It also describes the impact and application of phosphate cements as a structural product (pastes, mortars and concretes), in addition to typical values of mechanical strength, workability, commercial applications, etc. As a result, the review allows to elucidate advantages and disadvantages in comparison with existing technologies and the mechanical possibilities of these cements as biomaterials and for the immobilization of radioactive waste.

show abstract

Phosphate-based geopolymer: Formation mechanism and thermal stability

Cited by 106 publications

References 11 publications

Amorphous phase of volcanic ash and microstructure of cement product obtained from phosphoric acid activation

Amorphous phase of volcanic ash and microstructure of cement product obtained from phosphoric acid activation

Role of soluble aluminum species in the activating solution for synthesis of silico-aluminophosphate geopolymers

Engineering applications of chemically-bonded phosphate ceramics

Contact Info

Product

Resources

About