Mechanical and microstructural properties of metakaolin-based geopolymer cements from sodium waterglass and phosphoric acid solution as hardeners: A comparative study

Tchakouté, Hervé K.; Rüscher, Claus H.

doi:10.1016/j.clay.2017.02.002

Cited by 150 publications

(56 citation statements)

References 17 publications

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“…The diffraction line centered at 21.90°, thereafter called S, can be assigned to an amorphous silica network [41] or to an aluminophosphate network [27]. The peak at 26.49°, thereafter called G, which position is quite constant during geopolymerization, is in agreement with a previous study [6].…”

Section: B) Xrd Datasupporting

confidence: 90%

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Acid-based geopolymers: Understanding of the structural evolutions during consolidation and after thermal treatments

Mathivet

Jouin

Gharzouni

et al. 2019

Journal of Non-Crystalline Solids

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Materials such as ceramic matrix composites are developed for mechanical applications at high temperature, but their cost remains a limitation. Consequently, the use of acid-based geopolymer matrices may be an alternative to reduce costs. In this study, the sample was prepared from metakaolin and phosphoric acid. FTIR and NMR spectroscopies, XRD and thermal measurements were used to understand the structural evolution of acid-based geopolymers (binders) during consolidation and after thermal treatments. According to the results, the consolidation of the binder has been divided into four steps: the dissolution of the metakaolin, the polycondensation reactions forming AlPO 4 entities and hydrated phases, the breakdown of Si-O-Al bonds with formation of various hydrated silica *Manuscript Click here to download Manuscript: manuscript.docx Click here to view linked References

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Section: B) Xrd Datasupporting

confidence: 90%

“…Several studies were carried out on acid-based geopolymers with various aluminosilicate sources, different Si/Al ratios and various Al/P ratios [6,7,8 ]. Optimal mechanical properties were obtained for an Al/P ratio close to 1 [9] and a H 3 PO 4 concentration of 10 mol.L -1 [10].…”

Section: Introductionmentioning

confidence: 99%

Acid-based geopolymers: Understanding of the structural evolutions during consolidation and after thermal treatments

Mathivet

Jouin

Gharzouni

et al. 2019

Journal of Non-Crystalline Solids

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“…Tchakouté et al also conducted comparative studies between water glass activated and phosphoric acid activated metakaolin based geopolymers. It was shown that both geopolymer binders had a homogeneous microstructure and the phosphoric acid activated binder formed crystalline berlinite, which served as a matrix filler [ 9 ]. Douiri et al investigated the thermal and dielectric properties of phosphoric acid based geopolymers in dependence on the SiO 2 /H 3 PO 4 ratio.…”

Section: Introductionmentioning

confidence: 99%

Formation of Geopolymers Using Sodium Silicate Solution and Aluminum Orthophosphate

et al. 2020

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This paper reports the formation and structure of fast setting geopolymers activated by using three sodium silicate solutions with different modules (1.6, 2.0 and 2.4) and a berlinite-type aluminum orthophosphate. By varying the concentration of the aluminum orthophosphate, different Si/Al-ratios were established (6, 3 and 2). Reaction kinetics of binders were determined by isothermal calorimetric measurements at 20 °C. X-ray diffraction analysis as well as nuclear magnetic resonance (NMR) measurements were performed on binders to determine differences in structure by varying the alkalinity of the sodium silicate solutions and the Si/Al-ratio. The calorimetric results indicated that the higher the alkalinity of the sodium silicate solution, the higher the solubility and degree of conversion of the aluminum orthophosphate. The results of X-ray diffraction and Rietveldt analysis, as well as the NMR measurements, confirmed the assumption of the calorimetric experiments that first the aluminum orthophosphate was dissolved and then a polycondensation to an amorphous aluminosilicate network occurred. The different amounts of amorphous phases formed as a function of the alkalinity of the sodium silicate solution, indicate that tetrahydroxoaluminate species were formed during the dissolution of the aluminum orthophosphate, which reduce the pH value. This led to no further dissolution of the aluminum orthophosphate, which remained unreacted.

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“…Recent work carried out by H. Tchakoute et al was also focused [24] on comparing the acidic activated system to the alkali one, demonstrating once more the superiority of the CBPCs in terms of strength. They studied the mechanical and microstructural properties of both systems and addressed the effect of the formation of berlinite (AlPO 4 ) in the acidic activated ones.…”

Section: Introductionmentioning

confidence: 99%

Metakaolinite Phosphate Cementitious Matrix: Inorganic Polymer Obtained by Acidic Activation

et al. 2019

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This work aims to study an aluminosilicate phosphate cementitious matrix. The cementitious matrix was studied on paste samples. The synthesis of metakaolinite phosphate cement (MKPC) was investigated using calorimetric techniques. A systematic study was performed by emphasizing a broad range of Al/P molar ratios, covering the different behavior of the material to the extremes, as well as the optimum composition. X-ray diffraction and scanning electron microscopy revealed that the final structure was mainly an amorphous network, albeit with some non-reacted phases. The compressive strength was studied on mortars using a cement/sand ratio of 1:3. MKPC specimens with Al/P ratios close to 1/1 showed optimal behavior. MKPCs with Al/P ratios above 1/1 were characterized by high porosity and low strength, whereas MKPCs with Al/P < 1 contained an excess of phosphates. The influence of the Al/P molar ratio on compressive strength was also studied, reaching a maximum of 68 MPa for the optimum composition. Based on the results, MKPC may be a promising candidate for construction purposes.

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Mechanical and microstructural properties of metakaolin-based geopolymer cements from sodium waterglass and phosphoric acid solution as hardeners: A comparative study

Cited by 150 publications

References 17 publications

Acid-based geopolymers: Understanding of the structural evolutions during consolidation and after thermal treatments

Acid-based geopolymers: Understanding of the structural evolutions during consolidation and after thermal treatments

Formation of Geopolymers Using Sodium Silicate Solution and Aluminum Orthophosphate

Metakaolinite Phosphate Cementitious Matrix: Inorganic Polymer Obtained by Acidic Activation

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