Activator-related effects of sodium hydroxide storage solution in standard testing of fly ash geopolymer mortars for alkali–silica reaction

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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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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Effect of NaOH and Water Contents on Solidification of Sodium Silicate Free Geopolymer

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.625.3 ◽

2014 ◽

Vol 625 ◽

pp. 3-6 ◽

Cited By ~ 1

Author(s):

Ahmer Ali Siyal ◽

Lukman Ismail ◽

Zakaria Man ◽

Khairun Azizi Azizli

Keyword(s):

Fourier Transform ◽

Infrared Spectroscopy ◽

Fly Ash ◽

Portland Cement ◽

Sodium Hydroxide ◽

Fourier Transform Infrared Spectroscopy ◽

Setting Times ◽

Behavior Study ◽

Class F Fly Ash ◽

Water Contents

Geopolymers are fast setting binder materials possessing strength comparable with Portland cement. In this study solidification and bonding behavior of sodium hydroxide activated class F fly ash geopolymers were determined. Solidification was determined using Vicat apparatus and bonding behavior study was carried out using Fourier transform infrared spectroscopy (FTIR). The decrease in solidification time from 105 minutes to 90 minutes was observed when Na/Al ratio increased from 1 to 1.4. By changing liquid to solid (L/S) ratio from 0.154 to 0.231 initial and final setting times found to increase. FTIR results showed main peaks at 1000 cm-1and 1432 cm-1due to asymmetric stretching of Al-O/ Si-O bonds.

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Durability of blended cement against sodium sulphate attack and alkali-silica reaction

10.32920/ryerson.14662332.v1 ◽

2021 ◽

Author(s):

Giri Raj Adhikari

Keyword(s):

Fly Ash ◽

Silica Fume ◽

Alkali Silica Reaction ◽

Sulphate Attack ◽

Ternary Blends ◽

Replacement Level ◽

Fly Ashes ◽

Study Results ◽

High Calcium ◽

High Calcium Fly Ash

Blended cements were studied for their efficacy against sulphate attack and alkali-silica reaction using six different types of fly ashes, a slag, a silica fume and four types of General Use Portland cement of different alkalinity. The study results showed that low calcium fly ash, silica fume and ground granulated blast furnace slag enhanced the sulphate resistance of cement with increased efficacy with the increase in the replacement level. However, slag and silica fume, especially at low replacement levels, exhibited increased rate of expansion beyond the age of 78 weeks. On the contrary, high calcium fly ashes showed reduced resistance to sulphate attack with no clear trend between the replacement level and expansion. Ternary blends consisting of silica fume, particulary in the amount of 5%, high calcium fly ashes and General Use (GU) cement provided high sulphate resistance, which was attributable to reduced permeability. In the same way, some of ternary blends consisting of slag, high calcium fly ash and GU cement improved sulphate resistance. Pre-blending optimum amount of gypsum with high calcium fly ash enhanced the latter's resistance to sulphate attack by producing more ettringite at the early stage of hydration. In the context of alkali-silica reaction permeability was found to be a contributing factor to the results of the accelerated mortar bar test. High-alkali, high-calcium fly ash was found to worsen the alkali silica reaction when used in concrete containing some reactive aggregates. Ternary blend of slag with high calcium fly ash was found to produce promising results in terms of counteracting alkali-silica reaction.

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Characterization and Performance of Mechanical Properties of GGBS Based Geo Polymer Mortars

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d8997.118419 ◽

2019 ◽

Vol 8 (4) ◽

pp. 8336-8342

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Fly Ash ◽

Sodium Hydroxide ◽

Construction Industry ◽

Research Paper ◽

Setting Times ◽

And Performance ◽

Creep And Shrinkage

From decades it has been recognized that Geopolymer will considerably replace the role of cement in the construction industry. In general, Geopolymer exhibits the property of the peak compressive strength, minimal creep and shrinkage. In this current research paper, Geopolymer mortar is prepared by using GGBS and Fly ash. The mix proportions are of (100-60)%GGBS with Fly ash by 10% replacement. The alkali activators Na0H and Na2Sio3 are used in the study for two different molarities of 4&8. The ratio to Sodium silicates to sodium hydroxide is maintained from 1.5, 2, 2.5 & 3 were used. Mortars are prepared and studied the effect of molarities of alkali activators in their setting times and strengths

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Non-Destructive Test on Granite Powder Concrete

International Journal of Emerging Trends in Engineering Research ◽

10.30534/ijeter/2021/03942021 ◽

2021 ◽

Vol 9 (4) ◽

pp. 357-360

Keyword(s):

Fly Ash ◽

Sodium Hydroxide ◽

Silica Fume ◽

Ambient Air ◽

Rebound Hammer ◽

Primary Parameter ◽

Exploratory Investigation ◽

Granite Powder ◽

Test Outcomes ◽

Non Destructive

This paper presents a definite exploratory investigation on penetrability qualities of granite powder (GP) concrete. The primary parameter researched in this investigation was M30 and M60 grades concrete with substitution of sand by GP of 0, 25,50 and 100 and concrete as fractional supplanting with super plasticiser, fly ash, slag and silica fume. The antacid arrangement utilized for present examination is the mix of sodium hydroxide and sodium silicate arrangement. The test example was 50 mm (thick) x 100 mm (diameter) cylinder shapes heat-relieved at 60°C in an oven. The variety was concentrated on the examples exposed to ambient air just as oven heat relieving. non-destructive tests on cylinders with the help of rebound hammer for a time of 28, 56, 90, 180 and 365 days. The test outcomes show that the substitution of rock and incomplete substitution of admixtures display better execution

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Physical, Mechanical and Micro-Structural Properties of F Type Fly-Ash Based Geopolymeric Bricks Produced by Pressure Forming Process

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.69.69 ◽

2010 ◽

Vol 69 ◽

pp. 69-74 ◽

Cited By ~ 14

Author(s):

Ömer Arıöz ◽

Kadir Kilinç ◽

Mustafa Tuncan ◽

Ahmet Tuncan ◽

Taner Kavas

Keyword(s):

Heat Treatment ◽

Compressive Strength ◽

Fly Ash ◽

Sodium Hydroxide ◽

Sodium Silicate ◽

Heat Treatment Temperature ◽

Treatment Duration ◽

Treatment Temperature ◽

Alumino Silicate ◽

Heat Treatment Duration

Geopolymer is a new class of three-dimensionally networked amorphous to semi-crystalline alumino-silicate materials, and first developed by Professor Joseph Davidovits in 1978. Geopolymers can be synthesized by mixing alumino–silicate reactive materials such as kaolin, metakaolin or pozzolans in strong alkaline solutions such as NaOH and KOH and then cured at room temperature. Heat treatment applied at higher temperatures may give better results. Depending on the mixture, the optimum temperature and duration vary 40-100 °C and 2-72 hours, respectively. The properties of geopolymeric paste depend on type of source material (fly ash, metakaolin, kaolin), type of activator (sodium silicate-sodium hydroxide, sodium silicate-potassium hydroxide), amount of activator, heat treatment temperature, and heat treatment duration. In this experimental investigation, geopolymeric bricks were produced by using F-type fly ash, sodium silicate, and sodium hydroxide solution. The bricks were treated at various temperatures for different hours. The compressive strength and density of F-type fly ash based geopolymeric bricks were determined at the ages of 7, 28 and 90 days. Test results have revealed that the compressive strength values of F-type fly ash based geobricks ranged between 5 and 60 MPa. It has been found that the effect of heat treatment temperature and heat treatment duration on the density of F-type fly ash based geobricks was not significant. It should be noted that the spherical particle size increased as the heat treatment temperature increased in the microstructure of F-type fly ash based geobricks treated in oven at the temperature of 60 °C for 24 hours.

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