Effect of Activating Solution Modulus on the Synthesis of Sustainable Geopolymer Binders Using Spent Oil Bleaching Earths as Precursor

The valorization of spent oil bleaching earths (SOBE) is crucial for the protection of the environment and the reuse of resources. In this research, alkali-activated binders were manufactured at room temperature using SOBE as a precursor by varying the mass ratio between the activating solutions of sodium silicate (Na2SiO3) and 6 M sodium hydroxide (NaOH) (activating solution modulus) (Na2SiO3/NaOH ratio = 1/1; 1/2; 1/3; 1/4) to investigate the influence on the technological properties of the materials. This process intends to evaluate the potential of SOBE, heat-treated at 550 °C (1 h), as a precursor of the reaction (source of aluminosilicates). Samples produced with higher amounts of sodium silicate developed a denser structure, with lower porosity and a higher amount of geopolymer gel. Maximum flexural (8.35 MPa) and compressive (28.4 MPa) strengths of samples cured at room temperature for 28 days were obtained with a Na2SiO3/NaOH mass ratio of 1/1. The study demonstrates that SOBE waste can be used as a precursor in the manufacture of geopolymer binders that show a good compromise between physical, mechanical and thermally insulating characteristics.

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Thermal Resistance of Fly Ash Geopolymers with Alumina as Additive

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.281.182 ◽

2018 ◽

Vol 281 ◽

pp. 182-188

Author(s):

Yong Sing Ng ◽

Yun Ming Liew ◽

Cheng Yong Heah ◽

Mohd Mustafa Al Bakri Abdullah ◽

Kamarudin Hussin

Keyword(s):

Elevated Temperature ◽

Fly Ash ◽

Thermal Resistance ◽

Sodium Hydroxide ◽

Sodium Silicate ◽

Room Temperature ◽

Strength Degradation ◽

Alumina Addition ◽

Higher Temperature ◽

Temperature Exposure

The present work investigates the effect of alumina addition on the thermal resistance of fly ash geopolymers. Fly ash geopolymers were synthesised by mixing fly ash with activator solution (A mixture of 12M sodium hydroxide and sodium silicate) at fly ash/activator ratio of 2.5 and sodium silicate/sodium hydroxide ratio of 2.5. The alumina (0, 2 and 4 wt %) was added as an additive. The geopolymers were cured at room temperature for 24 hours and 60°C for another 24 hours. After 28 days, the geopolymers was heated to elevated temperature (200 - 1000°C). For unexposed geopolymers, the addition of 2 wt % of alumina increased the compressive strength of fly ash geopolymers while the strength decreased when the content increased to 4 wt.%. The temperature-exposed geopolymers showed enhancement of strength at 200°C regardless of the alumina content. The strength reduced at higher temperature exposure (> 200°C). Despite the strength degradation at elevated temperature, the strength attained was relatively high in the range of 13 - 45 MPa up to 1000°C which adequately for application as structural materials.

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Microstructure Features of Ternary Alkali-activated Binder Based on Tungsten Mining Waste, Slag and Metakaolin

KnE Engineering ◽

10.18502/keg.v5i4.6810 ◽

2020 ◽

Author(s):

Naim Sedira ◽

João Castro-Gomes

Keyword(s):

Sodium Silicate ◽

Room Temperature ◽

Mining Waste ◽

Dense Matrix ◽

Microstructural Properties ◽

Reaction Products ◽

Granulated Blast Furnace Slag ◽

Alkaline Activator ◽

Furnace Slag ◽

Alkali Activated

This study determines the effect of ground granulated blast furnace slag (GGBFS) and metakaolin (MK) on the microstructural properties of the tungsten mining waste-based alkali-activated binder (TMWM). During this investigation, TMWM was partially replaced with 10 wt.% GGBFS and 10 wt.% MK to improve the microstructure of the binder. In order to understand the effect of the substitutions on the microstructure, two pastes were produced to make a comparative study between the sample contain 100% TMWM and the ternary precursors. Both precursors were activated using a combination of alkaline activator solutions (sodium silicate and sodium hydroxide) with the ratio of 1:3 (66.6 wt.% sodium silicate combined with 33.33 wt.% of NaOH 8M). The alkali-activated mixes were cured in oven at temperature of 60 °C in the first day and at room temperature for the next 27 days. The reaction products N-A-S-H gel and (N,M)-A-S-H gel resulted from the alkaline activation reaction process. In addition, a formation of natrite (Na2CO3) with needles shape occurred as a reaction product of the fluorescence phenomena. However, a dense matrix resulted from the alkline activation of the ternary precursors containg different gels such as N-A-S-H, C-A-S-H and (N,M)-C-A-S-H gel, these results were obtained through SEM-EDS analyses, as well FTIR tests. Keywords: Mining Waste, Alkali-activated, Microstructure, Slag, Metakaolin

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Development of alkali-activated binders from sodium silicate powder produced from industrial wastes

New Materials in Civil Engineering ◽

10.1016/b978-0-12-818961-0.00017-x ◽

2020 ◽

pp. 591-612

Author(s):

Parthiban Kathirvel

Keyword(s):

Sodium Silicate ◽

Industrial Wastes ◽

Alkali Activated Binders ◽

Alkali Activated

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Drying shrinkage of alkali activated binders cured at room temperature

Construction and Building Materials ◽

10.1016/j.conbuildmat.2018.12.223 ◽

2019 ◽

Vol 201 ◽

pp. 563-570 ◽

Cited By ~ 14

Author(s):

Faris Matalkah ◽

Talal Salem ◽

Mamoon Shaafaey ◽

Parviz Soroushian

Keyword(s):

Room Temperature ◽

Drying Shrinkage ◽

Alkali Activated Binders ◽

Alkali Activated

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Study of Manufacture Process and Properties of Tailings and Slag Based Geopolymers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.156-157.803 ◽

2010 ◽

Vol 156-157 ◽

pp. 803-807

Author(s):

Fu Sheng Niu ◽

Shan Shan Zhou ◽

Shu Xian Liu ◽

Jin Xia Zhang

Keyword(s):

Compressive Strength ◽

Sodium Hydroxide ◽

Sodium Silicate ◽

Raw Material ◽

Silicate Concentration ◽

High Compressive Strength ◽

Curing Period ◽

Manufacture Process ◽

Alkali Activated

The tailings and slag based geopolymers was prepared by sodium silicate, sodium hydroxide alkali-activated tailings and slag. The compressive strength in 7 d under different raw material proportion were tested. The result indicated that tailings and slag based geopolymers has high compressive strength . As the tailings in slag is 80%, the compressive strength in 7d can reach 45.10 MPa . As the Na2SiO3 to NaOH ratio is 0.5, the compressive strength in 7d can reach 63.79 MPa. As the NaOH and sodium silicate concentration in the solution is 35%, the compressive strength in 7d can reach 38.35 MPa respectively; As the curing period is 14 d , the compressive strength can reach 71.25 MPa. As the steel scoria in solid is 20%, the compressive strength in 7d can reach 61.86 MPa respectively.

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Pressure-Induced Geopolymerization in Alkali-Activated Fly Ash

Sustainability ◽

10.3390/su10103538 ◽

2018 ◽

Vol 10 (10) ◽

pp. 3538 ◽

Cited By ~ 4

Author(s):

Sol Park ◽

Hammad Khalid ◽

Joon Seo ◽

Hyun Yoon ◽

Hyeong Son ◽

...

Keyword(s):

Fly Ash ◽

Sodium Hydroxide ◽

Sodium Silicate ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

Elevated Pressure ◽

X Ray Diffraction ◽

27Al Mas Nmr ◽

Alkali Activated

The present study investigated geopolymerization in alkali-activated fly ash under elevated pressure conditions. The fly ash was activated using either sodium hydroxide or a combination of sodium silicate solution and sodium hydroxide, and was cured at 120 °C at a pressure of 0.22 MPa for the first 24 h. The pressure-induced evolution of the binder gel in the alkali-activated fly ash was investigated by employing synchrotron X-ray diffraction and solid-state 29Si and 27Al MAS NMR spectroscopy. The results showed that the reactivity of the raw fly ash and the growth of the zeolite crystals were significantly enhanced in the samples activated with sodium hydroxide. In contrast, the effects of the elevated pressure conditions were found to be less apparent in the samples activated with the sodium silicate solution. These results may have important implications for the binder design of geopolymers, since the crystallization of geopolymers relates highly to its long-term properties and functionality.

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Rheology of Alkali-Activated Blended Binder Mixtures

Materials ◽

10.3390/ma14185405 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5405

Author(s):

Biruk Hailu Tekle ◽

Ludwig Hertwig ◽

Klaus Holschemacher

Keyword(s):

Sodium Hydroxide ◽

Rheological Properties ◽

Yield Stress ◽

Sodium Silicate ◽

Total Solid ◽

Environmental Benefits ◽

Total Water ◽

The Past ◽

Binder Ratio ◽

Alkali Activated

Alkali-activated cement (AAC) is an alternative cement that has been increasingly studied over the past decades mainly because of its environmental benefits. However, most studies are on heat-cured AACs and are focused on mechanical properties. There is a lack of research on the fresh properties of ambient-cured AAC systems. This study investigates the rheological properties of ambient-temperature-cured alkali-activated blended binder mixtures activated with sodium silicate and sodium hydroxide solutions. The influence of binder amount, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water content to total solid (from the binding materials) ratio (TW/TS) on the rheological properties are investigated. The effect of borax as an admixture and silica fume as a replacement for fly ash is also investigated. The results showed that both the yield stress and plastic viscosity are mainly affected by the binder content and TW/TS ratio decreasing with the increase of each parameter. The yield stress increased with the increase of the SS/SH ratio. Borax significantly reduced the yield stress, while silica fume’s effect was dependent on its dosage.

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Interaction of Magnesia with Limestone-Metakaolin-Calcium Hydroxide Ternary Alkali-Activated Systems

Advances in Materials Science and Engineering ◽

10.1155/2018/1249615 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

A. Cwirzen ◽

L. Metsäpelto ◽

K. Habermehl-Cwirzen

Keyword(s):

Sodium Hydroxide ◽

Calcium Hydroxide ◽

Sodium Silicate ◽

Ternary Systems ◽

Sodium Sulphate ◽

Crystalline Phases ◽

Amorphous Phases ◽

Porous Microstructure ◽

Alkali Activated

The effect of magnesia on ternary systems composed of limestone, metakaolin and calcium hydroxide, alkali activated with sodium silicate, sodium hydroxide, and sodium sulphate was studied by determination of the compressive strength, X-ray powder diffraction (XRD), thermogravimetry (TG), and scanning electron microscope (SEM). Pastes activated with sodium silicate and sodium sulphate showed strength regression caused by a formation of an unstable prone to cracking geopolymer gel. The presence of magnesia in sodium hydroxide-activated system hindered this trend by promoting a formation of more stable crystalline phases intermixed with brucide. In general, magnesia densified the binder matrix by promoting a formation of amorphous phases while sodium hydroxide produced the most porous microstructure containing high amount of crystalline phases.

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Durability of Alkali-Activated Fly Ash/Slag Concrete

Materials Science Forum ◽

10.4028/www.scientific.net/msf.904.157 ◽

2017 ◽

Vol 904 ◽

pp. 157-161 ◽

Cited By ~ 3

Author(s):

Mao Chieh Chi ◽

Hsian Chen ◽

Tsai Lung Weng ◽

Ran Huang ◽

Yih Chang Wang

Keyword(s):

Fly Ash ◽

Total Charge ◽

Test Results ◽

Mass Ratio ◽

Modulus Ratio ◽

Granulated Blast Furnace Slag ◽

Alkali Activated Binders ◽

Furnace Slag ◽

Alkali Activated ◽

Better Than

This study investigated the durability of alkali-activated binders based on blends of fly ash (FA) and ground granulated blast furnace slag (GGBFS). Five fly ash-to-slag ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 by mass were selected to produce alkali-activated fly ash/slag (AAFS) concrete. Sodium oxide (Na2O) concentrations of 6% and 8% of binder weight and activator modulus ratios (mass ratio of SiO2 to Na2O) of 0.8, 1.0, and 1.23 were used as alkaline activators. Test results show that the total charge passed of AAFS concrete is between 2500 and 4000 coulombs, higher than the comparable OPC concrete. However, AAFS concrete exposed to sulfate attack performed better than OPC concrete. Based on the results, 100% slag-based AAFS concrete with Na2O concentration of 8% and activator modulus ratio of 1.23 has the superior performances.

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