Factors of FGD-gypsum Replacement and Alkaline Solution Ratio on Compressive Strength and Microstructure of Fly Ash Geopolymer

The production of ordinary Portland cement (OPC) consumes considerable amount of natural resources, energy and at the same time contribute in high emission of CO2 to the atmosphere. A new material replacing cement as binder called geopolymer is alkali-activated concrete which are made from fly ash, sodium silicate and sodium hydroxide (NaOH). The alkaline solution mixed with fly ash producing alternative binder to OPC binder in concrete named geopolymer paste. In the process, NaOH was fully dissolved in water and cooled to room temperature. This study aims to eliminate this process by using NaOH in solid form together with fly ash before sodium silicate liquid and water poured into the mixture. The amount of NaOH solids were based on 10M concentration. The workability test is in accordance to ASTM C230. Fifty cubic mm of the geopolymer paste were prepared which consists of fly ash to alkaline solution ratio of 1: 0.5 and the curing regime of 80℃ for 24 hours with 100% humidity were implemented. From laboratory test, the workability of dry method geopolymer paste were decreased. The compressive strength of the dry mix of NaOH showed 55% and the workability has dropped to 58.4%, it showed strength reduction compared to the wet mix method.

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Experimental study of effect additional water on high performance geopolymer concrete

MATEC Web of Conferences ◽

10.1051/matecconf/201927001004 ◽

2019 ◽

Vol 270 ◽

pp. 01004

Author(s):

Rachmansyah ◽

Harianto Hardjasaputra ◽

Meilanie Cornelia

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Alkaline Solution ◽

Greenhouse Effect ◽

Environmental Conservation ◽

Cement Industry ◽

Geopolymer Concrete ◽

Green Concrete ◽

The World ◽

Additional Water

The Earth Summit 1997 in Kyoto (Japan), industrialized countries agreed to reduce gas emissions by 21% to avoid global warming due to greenhouse effect with the release of CO2 into the air. From the research result, cement industry sector all over the world contributes about 8 - 10% of total CO2 emission. This number is quite high and if there is not a special action to reduce, CO2 emissions will continue to increase along with the rapid development of infrastructure in various parts of the world including in Indonesia. To support greenhouse effect reduction efforts due to CO2 emissions and environmental conservation, civil engineers in the world are taking steps to achieve Sustainable Concrete Technology, in order to create “Green Concrete”. For that reason in the direction of “Green Concrete”, innovation is needed to reduce or replace cement in the concrete mixing. The ash waste electrical power generating plants of fly ash is a material containing many SiO2 and Al2O3 which can be used to replace the overall of cement in concrete. Geopolymer concrete is a fly ash-based concrete that replaces the entire cement in its manufacture. Workability in mixing geopolymer concrete is very low, due to the rapid reaction of the alkaline solution when it reacts with fly ash. To improve the workability can be added water at the time of mixing. The fly ash used in the mixing from the Paiton power plant in East Java with grain size 12.06 μm with round granules and chemical composition of fly ash containing SiO2, Al2O3 and Fe2O3 with a total of 75.151%. The planned compressive strength of the concrete is 45 MPa, with a variation of 8M, 12M and 16M NaOH molarity and the ratio of NaOH and Na2SiO3 is 1. Addition of water in concrete mixing with variations of 15, 17.5, 20, 22.5 and 25 liters / m3. The results of this study indicate that the more addition of water in the manufacture of geopolymer concrete can also increase the value of slump, but the excessive addition of water will result in a decrease in the compressive strength of the concrete caused by a decrease in the concentration of the alkaline solution. High molarity values will require additional water to reach the same slump value compared to lower NaOH molarity. With the same mix design, the optimal compressive strength at 8M NaOH was 48.18 MPa with 17.5 liters/m3 of water added with a slump of 12 cm, for 12M NaOH the optimal compressive strength was 51.65 MPa with the addition of 20 liter/m3 with 10 cm slump, while for 16M NaOH the optimum compressive strength is 59.70 MPa with 22.5 liters/m3 of water added with a 5 cm slump. The higher the NaOH molarity will result in a higher compressive strength value and geopolymer concrete compressive strength at early age is higher than conventional concrete.

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The Effect of Variation of Molarity of Alkali Activator and Fine Aggregate Content on the Compressive Strength of the Fly Ash: Palm Oil Fuel Ash Based Geopolymer Mortar

Advances in Materials Science and Engineering ◽

10.1155/2014/245473 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 17

Author(s):

Iftekhair Ibnul Bashar ◽

U. Johnson Alengaram ◽

Mohd Zamin Jumaat ◽

Azizul Islam

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Palm Oil ◽

Alkaline Solution ◽

Strength Development ◽

Fine Aggregate ◽

Palm Oil Fuel Ash ◽

Alkali Activator ◽

Fuel Ash ◽

Oil Fuel

The effect of molarity of alkali activator, manufactured sand (M-sand), and quarry dust (QD) on the compressive strength of palm oil fuel ash (POFA) and fly ash (FA) based geopolymer mortar was investigated and reported. The variable investigated includes the quantities of replacement levels of M-sand, QD, and conventional mining sand (N-sand) in two concentrated alkaline solutions; the contents of alkaline solution, water, POFA/FA ratio, and curing condition remained constant. The results show that an average of 76% of the 28-day compressive strength was found at the age of 3 days. The rate of strength development from 3 to 7 days was found between 12 and 16% and it was found much less beyond this period. The addition of 100% M-sand and QD shows insignificant strength reduction compared to mixtures with 100% N-sand. The particle angularity and texture of fine aggregates played a significant role in the strength development due to the filling and packing ability. The rough texture and surface of QD enables stronger bond between the paste and the fine aggregate. The concentration of alkaline solution increased the reaction rate and thus enhanced the development of early age strength. The use of M-sand and QD in the development of geopolymer concrete is recommended as the strength variation between these waste materials and conventional sand is not high.

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Effect of Alkaline Solution to Fly Ash Ratio on Geopolymer Mortar Properties

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.733.85 ◽

2017 ◽

Vol 733 ◽

pp. 85-88 ◽

Cited By ~ 3

Author(s):

Amir Fauzi ◽

Mohd Fadhil Nuruddin ◽

Ahmad B. Malkawi ◽

Mohd Mustafa Al Bakri Abdullah ◽

Bashar S. Mohammed

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Portland Cement ◽

Alkaline Solution ◽

Similar Pattern ◽

Ordinary Portland Cement ◽

Setting Time ◽

Pozzolanic Reaction

Geopolymer system is new binding materials in concrete industry that is produced by the alkaline solution and materials rich in aluminosilicate such as fly ash. The effect of the alkaline solution to fly ash ratios of 0.3, 0.4 and 0.5 on mortar geopolymer properties was an issue in this study. The results showed that the higher alkaline solution to fly ash ratio improves the workability and brings a longer setting time, whereas the lower alkaline solution to fly ash ratio gains the significant compressive strength. It was a similar pattern with conventional mortar used ordinary Portland cement, which the compressive strength at 7 days was 85%-90% for 28 days compressive strength, whereas conventional mortar is only 65%-75%. This was due to the higher reactivity in geopolymer system that was faster than the pozzolanic reaction.

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CRYSTALLINE PHASE REACTIVITY IN THE SYNTHESIS OF FLY ASH-BASED GEOPOLYMER

Indonesian Journal of Chemistry ◽

10.22146/ijc.21426 ◽

2011 ◽

Vol 11 (1) ◽

pp. 90-95 ◽

Cited By ~ 6

Author(s):

Lukman Atmaja ◽

Hamzah Fansuri ◽

Anggaria Maharani

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Power Plant ◽

Ambient Temperature ◽

Alkaline Solution ◽

Crystalline Phase ◽

Rietveld Method ◽

Initial Reaction ◽

Crystalline Phases ◽

Significant Change

Aluminosilicate, alkaline solution and fly ash from a power plant have been used to synthesize geopolymer at ambient temperature. SiO2/Al2O3 mole ratio of the starting materials was varied by the addition of pure, insoluble corundum and quartz. The geopolymer exhibited some differences in the ratio of initial reaction mixtures and that of final products. The corundum gave no influence to the compressive strength while the quartz at SiO2/Al2O3=4.0-6.0 produced significant change in the strength. The highest compressive strength achieved was 65 MPa. XRD using analysis Rietveld method proved that quartz has been found both in starting materials as well as in the geopolymer indicating the involvement of crystalline phases, to some extent, in geopolymerization process.

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THE INFLUENCE OF INITIAL MATERIALS ON THE COMPRESSIVE STRENGTH OF GEOPOLYMER SOILS

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2014.30 ◽

2014 ◽

Vol 1 (1) ◽

Author(s):

Hong Chan Nguyen ◽

Anh Tuan Nguyen ◽

Namshik Ahn

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Sodium Silicate ◽

Alkaline Solution ◽

Building Materials ◽

Clay Content ◽

Carbon Dioxide Production ◽

Environmental Benefits ◽

Curing Temperature ◽

Low Carbon

In recent years, geopolymers have received significant attention because they show environmental benefits, such as a reduction in the consumption of natural resources and a decrease in the net production of CO2. In addition, as green material, soil has low carbon dioxide production emissions compared to other building materials. In this research, soil was combined with activator alkaline to produce hardening materials as geopolymer soils. An alkaline solution with sodium hydroxide, sodium silicate and fly ash was used. The influence of clay content on the geopolymer soils’ compressive strength was investigated. The best strengths were obtained from 5% to 12% clay content. SEM photos were also taken from specimens to investigate the structure of geopolymer soils. When combined with soil and fly ash in geopolymerization, fly ash reacted to the alkali solution quickly. The relationships between many variables such as clay content, fly ash, alkaline solution, curing time, and curing temperature were investigated by using a statistical analysis program with over 100 initial parameters. These results also indicate that the use of soils in geopolymer soil should have been limited. Additionally, increasing the sodium silicate in the alkaline liquid affected the geopolymerization reaction significantly. However, the suitable Si on the alkaline solution and soil should be limited.

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Optimization of Alkaline Activator/Fly ASH Ratio on the Compressive Strength of Manufacturing Fly ASH-BASED Geopolymer

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.110-116.734 ◽

2011 ◽

Vol 110-116 ◽

pp. 734-739 ◽

Cited By ~ 21

Author(s):

Mohd Mustafa Al Bakri Abdullah ◽

H. Kamarudin ◽

Omar A.K.A. Abdulkareem ◽

Che Mohd Ruzaidi Ghazali ◽

A.R. Rafiza ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Alkaline Solution ◽

Room Temperature ◽

High Strength ◽

Constant Ratio ◽

Optimum Amount ◽

Molar Ratios ◽

Naoh Solution ◽

Alkaline Activator

Fly ash and a mixture of alkaline activators namely sodium silicate (Waterglass) and sodium hydroxide (NaOH) solution were used for preparing geopolymer. The aim of this research is to determine the optimum value of the alkaline activator/fly ash ratio. The effect of the oxide molar ratios of SiO2/Al2O3, water content of the alkaline activator and the Waterglass% content were studied for each Alkaline activator/fly ash ratio. The geopolymers were synthesized by the activation of fly ash with alkaline solution at three different alkaline activator/fly ash ratios which were 0.3, 0.35, and 0.4 at a specific constant ratio of waterglass/NaOH solution of 1.00. The geopolymers were cured at 70°C for 24 h and cured to room temperature. Results revealed that the alkaline activator/fly ash ratio of 0.4 has the optimum amount of alkaline liquid, which shows the highest rate of geopolymerization compared to other ratios. A high strength of 8.61 MPa was achieved with 0.4 of activator/fly ash ratio and 14% of waterglass content.

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Assessment to the Solid to Liquid Ratios on the Soil Strength and Water Absorption of the Kedah’s Soil

Materials Science Forum ◽

10.4028/www.scientific.net/msf.841.59 ◽

2016 ◽

Vol 841 ◽

pp. 59-64 ◽

Cited By ~ 2

Author(s):

Hazamaah Nur Hamzah ◽

Mohd Mustafa Al Bakri Abdullah ◽

Cheng Yong Heah ◽

Mohd Remy Rozainy Arif Zainol ◽

Kamarudin Hussin

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Water Absorption ◽

Alkaline Solution ◽

Room Temperature ◽

Soil Stabilization ◽

Soft Soil ◽

Constant Ratio ◽

Liquid Ratio ◽

Naoh Solution

The purpose of this paper is to assess the solid to liquid ratios on the compressive strength and water absorption of Kedah’s soil by using geopolymerization method. Fly ash and soft soil were mixed with alkaline activators namely sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) for preparing stabilize the soil sample. The geopolymerization process for soil stabilization was synthesized by the activation of fly ash and soil with alkaline solution at four different solid to liquid ratios which were 1.5, 2.0, 2.5, and 3.0 at a specific constant ratio of Na2SiO3/NaOH solution of 0.5. The compressive strength up to 4.77 MPa was obtained at 3.0 of solid to liquid ratio and the water absorption has become increasingly lower to 2.28% as the ratio of solid to liquid increases in 7 days curing at room temperature.

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A Study of the Influence of FGD Gypsum Used as Cement Retarder on the Properties of Concrete

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.374-377.1311 ◽

2011 ◽

Vol 374-377 ◽

pp. 1311-1319

Author(s):

Peng Xuan Duan ◽

Ye Zhang ◽

Yuan Chao Miao ◽

Ying Li

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Portland Cement ◽

Ordinary Portland Cement ◽

Negative Influence ◽

Slag Cement ◽

Fgd Gypsum ◽

Cement Retarder ◽

Working Performance

This paper describes replacing natural gypsum with FGD gypsum as cement retarder, the influence on the working performance, compressive strength and admixture adaptability of concretes, which were prepared with fly ash cement, slag cement and ordinary Portland cement. The results indict the FGD gypsum instead of natural gypsum used as cement retarder has little difference on the working performance of concrete and additionally the FGD gypsum has no negative influence on the compressive strength and admixture adaptability of concretes.

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Compressive Strength of Geopolymer Concrete Composites: Modeling and Comprehensive Systematic Review

10.21203/rs.3.rs-611987/v1 ◽

2021 ◽

Author(s):

Hemn Unis Ahmed ◽

Azad A. Mohammed ◽

Ahmed S. Mohammed

Keyword(s):

Systematic Review ◽

Compressive Strength ◽

Fly Ash ◽

Sodium Hydroxide ◽

Sodium Silicate ◽

Alkaline Solution ◽

Construction Material ◽

Assessment Tools ◽

Curing Temperature ◽

Geopolymer Concrete

Abstract The growing concern about global climate change and its adverse impacts on societies is putting severe pressure on the construction industry as one of the largest producers of greenhouse gases. Given the environmental issues associated with cement production, geopolymer concrete has emerged as a sustainable construction material. Geopolymer concrete is cementless concrete that uses industrial or agro by-product ashes as the main binder instead of ordinary Portland cement; this leads to being an eco-efficient and environmentally friendly construction material. Compressive strength is one of the most important mechanical property for all types of concrete composites including geopolymer concrete, and it is affected by several parameters like an alkaline solution to binder ratio (l/b), fly ash (FA) content, SiO2/Al2O3 (Si/Al) of the FA, fine aggregate (F) and coarse aggregate (C) content, sodium hydroxide (SH) and sodium silicate (SS) content, ratio of sodium silicate to sodium hydroxide (SS/SH), molarity (M), curing temperature (T), curing duration (CD) inside the oven and specimen ages (A). In this regard, a comprehensive systematic review was carried out to show the effect of these different parameters on the compressive strength of the fly ash-based geopolymer concrete (FA-GPC). In addition, multi-scale models such as Artificial Neural Network (ANN), M5P-tree (M5P), Linear Regression (LR), and Multi-logistic Regression (MLR) models were developed to predict the compressive strength of FA-GPC composites. For the first time, in the modeling process, twelve effective parameters including l/b, FA, Si/Al, F, C, SH, SS, SS/SH, M, T, CD, and A were considered the modeling input parameters. Then, the efficiency of the developed models was assessed by various statistical assessment tools like Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the Coefficient of determination (R2). Results show that the curing temperature, sodium silicate content, and ratio of the alkaline solution to the binder content are the most significant independent parameters that influence on the compressive strength of the FA-GPC, and the ANN model has better performance for predicting the compressive strength of FA-GPC in compared to the other developed models.

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