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

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
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.

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

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.

scholarly journals Pressure-Induced Geopolymerization in Alkali-Activated Fly Ash

2018 ◽  
Vol 10 (10) ◽  
pp. 3538 ◽  
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.

scholarly journals Rheology of Alkali-Activated Blended Binder Mixtures

Materials ◽  
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.

Effect of sodium hydroxide and sodium silicate solutions on strengths of alkali activated high calcium fly ash containing Portland cement

2016 ◽  
Vol 21 (6) ◽  
pp. 2202-2210 ◽  
Author(s):  
Tanakorn Phoo-ngernkham ◽  
Sakonwan Hanjitsuwan ◽  
Nattapong Damrongwiriyanupap ◽  
Prinya Chindaprasirt
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Alkali Activated

Optimum Mixture Design of Bottom Ash Based Alkali-Activated Mortar Using Artificial Neural Networks

2010 ◽  
Vol 452-453 ◽  
pp. 733-736
Author(s):  
Su Tae Kang ◽  
Hyun Jin Kang ◽  
Gum Sung Ryu ◽  
Gyung Taek Koh ◽  
Jang Hwa Lee
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Experimental Studies ◽  
Bottom Ash ◽  
Mixture Design ◽  
Curing Temperature ◽  
Artificial Neural ◽  
Alkali Activated

Bottom ash based alkali-activated mortar is prepared by incorporating sodium hydroxide and sodium silicate with some additional water if needed, and is activated with temperature curing. This research was conducted to derive an optimum mixture design of the bottom ash based alkali-activated mortar. The experimental studies were first performed to estimate the effect of the added water content, alkali activator to bottom ash ratio, sodium silicate to sodium hydroxide ratio as well as curing temperature on workability and strength. In order to optimize the mix proportion, based on the experimental results, artificial neural networks were introduced.

Study of Manufacture Process and Properties of Tailings and Slag Based Mine Filling Cementitious Materials

2013 ◽  
Vol 734-737 ◽  
pp. 1077-1081 ◽  
Author(s):  
Jin Xia Zhang ◽  
Shu Xian Liu ◽  
Jun Xie
Keyword(s):  
Compressive Strength ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Raw Materials ◽  
Cementitious Materials ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Manufacture Process ◽  
Alkali Activated

The tailings and slag based mine filling cementitious materials was prepared by sodium silicate and sodium hydroxide alkali-activated tailings and slag. Through the test that the cementing materials in the best ratio of raw materials: when slag and tailings admixture is 1.25, the content of NaOH was 50%, the amount of sodium hydroxide for 50%, water cement ratio of 0.22, under the condition of normal temperature curing 7 days, eventually making a compressive strength of 52.3MPa cementing materials.

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

2021 ◽  
Vol 13 (13) ◽  
pp. 7501
Author(s):  
P. Delgado-Plana ◽  
A. Rodríguez-Expósito ◽  
S. Bueno-Rodríguez ◽  
L. Pérez-Villarejo ◽  
D. M. Tobaldi ◽  
...  
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Room Temperature ◽  
Technological Properties ◽  
Mass Ratio ◽  
Heat Treated ◽  
Lower Porosity ◽  
Alkali Activated Binders ◽  
Alkali Activated ◽  
Activating Solution

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.

scholarly journals Stabilization of Crude Oil Contaminated Soils with Alkali-Activated Slag

2019 ◽  
Vol 8 (3) ◽  
pp. 117-125
Author(s):  
Hossein Sadighi ◽  
Mohammad Ali Rowshanzamir
Keyword(s):  
Crude Oil ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
New Technologies ◽  
Soil Stabilization ◽  
Steel Production ◽  
High Exposure ◽  
Alkali Activated

The high exposure of areas in the vicinity of oil plants and refineries to crude oil and oil product contaminations and the problems they cause for the physical expansion of these facilities underscore the importance of stabilization of oil-contaminated soils. Soil stabilization with cost-effective stabilizing agents is widely regarded as a simple and fast way of limiting the impacts of such contaminations. For decades, cement and lime have been the standard binders for soil remediation and stabilization applications, but with the increasing awareness about their environmental impact and the notion of sustainable development in general, there is now a growing interest in the use of cleaner alternatives based on new technologies for this purpose. In recent years, alkali-activated binders have been the subject of much interest because of their high strength and durability and limited environmental impacts. The soil treatment solution investigated in this study is the use of slag, which is a steel production byproduct mostly consisting of calcium and magnesium alumina silicates, in combination with two activators, namely sodium hydroxide and sodium silicate. Direct shear tests were performed on the crude oil contaminated soil specimens in order to determine the best alkali-activated designs and the effect of exposure time, slag content, and treatment time on the outcomes. The test results showed that adding 10% slag, 1.15% sodium silicate, and 1.61% sodium hydroxide (all by dry weight of soil) to the crude oil contaminated soil improved its cohesion and friction angle by 70% and 50% respectively.

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