Microstructural properties and compressive strength of fly ash-based geopolymer cement immersed in CO2-saturated brine at elevated temperatures

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

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Research on Mechanical Performance & Behaviour of Geopolymer Concrete Subjected to Elevated Temperatures

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.b1001.0882s819 ◽

2019 ◽

Vol 8 (2S8) ◽

pp. 883-887

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Silica Fume ◽

Elevated Temperatures ◽

Mechanical Performance ◽

Geopolymer Concrete ◽

Sem Images ◽

Before And After ◽

Alkaline Conditions ◽

Compressive Strength Of Concrete

The investigative studies on mechanical performance & behaviour, of Geopolymer Concrete (GPC) before and after the exposure to elevated temperatures (of 200 0 C -1000 0 C with an increment of 100 0 C). Indicate that the GPC Specimens Exhibited better Compressive strength at higher temperatures than that of those made by regular OPC Concrete with M30 Grade. The chronological changes in the geopolymeric structure upon exposure to these temperatures and their reflections on the thermal behaviour have also been explored. The SEM images indicate GPC produced by fly ash , metakaolin and silica fume, under alkaline conditions form Mineral binders that are not only non-flammable and but are also non-combustible resins and binders. Further the Observations drawn disclose that the mass and compressive strength of concrete gets reduced with increase in temperatures.

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Mechanical and microstructural properties of high calcium fly ash one-part geopolymer cement made with granular activator

Heliyon ◽

10.1016/j.heliyon.2019.e02255 ◽

2019 ◽

Vol 5 (9) ◽

pp. e02255 ◽

Cited By ~ 7

Author(s):

Bashar S. Mohammed ◽

Sani Haruna ◽

M.M.A. Wahab ◽

M.S. Liew ◽

Abdulrahman Haruna

Keyword(s):

Fly Ash ◽

Microstructural Properties ◽

High Calcium ◽

High Calcium Fly Ash ◽

Geopolymer Cement ◽

Mechanical And Microstructural Properties

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Effect of cooling methods on residual compressive strength and cracking behavior of fly ash concretes exposed at elevated temperatures

Fire and Materials ◽

10.1002/fam.2276 ◽

2014 ◽

Vol 40 (2) ◽

pp. 335-350 ◽

Cited By ~ 10

Author(s):

Faiz U. A. Shaikh ◽

Vanissorn Vimonsatit

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Elevated Temperatures ◽

Cracking Behavior ◽

Residual Compressive Strength ◽

Cooling Methods

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EFFECT OF MIXING PROPORTION ON COMPRESSIVE STRENGTH OF FLY-ASH BASED GEOPOLYMER PASTE AND MORTAR USING TAGUCHI’S METHOD

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2015.72 ◽

2015 ◽

Vol 2 (1) ◽

Author(s):

Sajid Khan Afridi ◽

Vanissorn Vimonsatit

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Elevated Temperatures ◽

Three Dimensional ◽

Silica Content ◽

Polymeric Chain ◽

Low Carbon ◽

Solid Ratio ◽

Mix Proportion ◽

Alkali Activated

Alkali activated pozzolan are known low carbon cementitious binders which can be used to replace cement. The material is also known as geopolymer because of its three dimensional polymeric chain and ring like structure consisting silica and alumina. A common type of pozzolan used is fly ash because of its rich silica content; therefore the term alkali activated fly-ash based binders is adopted. Despite much research and development of this material, there is no specific standard for design mix proportion. This research used the Taguchi’s design of experiment method to determine the optimum mix proportion of alkali activated fly ash based cement paste and mortar. Four factors were considered in the tests, silica fume, sand to cementitious ratio, liquid to solid ratio, and percentage of superplasticiser. Tests were conducted on the 9 batches of alkali activated fly-ash based paste and mortar samples to determine the compressive strength under ambient condition. Tests were also conducted to determine the residual strength of the samples after exposed to elevated temperatures. ANOVA analysis of the test results revealed the main factors contribution on the tested properties and led to the determination of the optimum design proportion of the factors considered in these tests.

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Effect of nano silica and fine silica sand on compressive strength of sodium and potassium activators synthesised fly ash geopolymer at elevated temperatures

Fire and Materials ◽

10.1002/fam.2496 ◽

2017 ◽

Vol 42 (3) ◽

pp. 324-335 ◽

Cited By ~ 3

Author(s):

Faiz Shaikh ◽

Sharany Haque

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Elevated Temperatures ◽

Silica Sand ◽

Nano Silica ◽

Sodium And Potassium

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Effect of Elevated Temperatures on Mortar with Naturally Occurring Volcanic Ash and Its Blend with Electric Arc Furnace Slag

Advances in Materials Science and Engineering ◽

10.1155/2018/5324036 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 6

Author(s):

Nauman Khurram ◽

Kaffayatullah Khan ◽

Muhammad Umair Saleem ◽

Muhammad Nasir Amin ◽

Usman Akmal

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Volcanic Ash ◽

Elevated Temperatures ◽

Electric Arc Furnace ◽

Electric Arc ◽

Arc Furnace ◽

Test Results ◽

Electric Arc Furnace Slag ◽

Furnace Slag

The mechanical behavior of basaltic volcanic ash (VA) and fly ash (FA) as a cement replacement under elevated temperatures is mainly investigated in the current study. For this, cement content has been partially replaced with and without the presence of electric arc furnace slag (S). Four distinct ranges of temperatures (200°C, 400°C, 600°C, and 800°C) were selected, and the modified mixes were subjected to these gradually elevated temperatures. Samples were cured and cooled by using air- and water-cooling techniques. Test results were established by examining the sample weights and compressive strength before and after the exposure of each temperature level. The pozzolanic potential of volcanic ash and fly ash samples was identified using the strength activity index. After analyzing the test results, it has been found that there is a significant effect on the compressive strength of mortar mixes at the early ages of its strength gain. However, at the later ages of curing, samples modified with volcanic and fly ash with the presence of electric arc furnace slag have shown a better performance than control mix in terms of strength and weight loss.

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Mechanical and Microstructural Characterization of Quarry Rock Dust Incorporated Steel Fiber Reinforced Geopolymer Concrete and Residual Properties after Exposure to Elevated Temperatures

Materials ◽

10.3390/ma14226890 ◽

2021 ◽

Vol 14 (22) ◽

pp. 6890

Author(s):

Muhammad Ibraheem ◽

Faheem Butt ◽

Rana Muhammad Waqas ◽

Khadim Hussain ◽

Rana Faisal Tufail ◽

...

Keyword(s):

Mechanical Properties ◽

Weight Loss ◽

Compressive Strength ◽

Fly Ash ◽

Mechanical Strength ◽

Elevated Temperatures ◽

Strength Properties ◽

Steel Fibers ◽

Geopolymer Concrete

The purpose of this research is to study the effects of quarry rock dust (QRD) and steel fibers (SF) inclusion on the fresh, mechanical, and microstructural properties of fly ash (FA) and ground granulated blast furnace slag (SG)-based geopolymer concrete (GPC) exposed to elevated temperatures. Such types of ternary mixes were prepared by blending waste materials from different industries, including QRD, SG, and FA, with alkaline activator solutions. The multiphysical models show that the inclusion of steel fibers and binders can enhance the mechanical properties of GPC. In this study, a total of 18 different mix proportions were designed with different proportions of QRD (0%, 5%, 10%, 15%, and 20%) and steel fibers (0.75% and 1.5%). The slag was replaced by different proportions of QRD in fly ash, and SG-based GPC mixes to study the effect of QRD incorporation. The mechanical properties of specimens, i.e., compressive strength, splitting tensile strength, and flexural strength, were determined by testing cubes, cylinders, and prisms, respectively, at different ages (7, 28, and 56 days). The specimens were also heated up to 800 °C to evaluate the resistance of specimens to elevated temperature in terms of residual compressive strength and weight loss. The test results showed that the mechanical strength of GPC mixes (without steel fibers) increased by 6–11%, with an increase in QRD content up to 15% at the age of 28 days. In contrast, more than 15% of QRD contents resulted in decreasing the mechanical strength properties. Incorporating steel fibers in a fraction of 0.75% by volume increased the compressive, tensile, and flexural strength of GPC mixes by 15%, 23%, and 34%, respectively. However, further addition of steel fibers at 1.5% by volume lowered the mechanical strength properties. The optimal mixture of QRD incorporated FA-SG-based GPC (QFS-GPC) was observed with 15% QRD and 0.75% steel fibers contents considering the performance in workability and mechanical properties. The results also showed that under elevated temperatures up to 800 °C, the weight loss of QFS-GPC specimens persistently increased with a consistent decrease in the residual compressive strength for increasing QRD content and temperature. Furthermore, the microstructure characterization of QRD blended GPC mixes were also carried out by performing scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS).

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Effect of Dipotassium Hydrogen Phosphate and Calcium Nitrate on Strength and Microstructural Properties of Geopolymer Mortar

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.821.486 ◽

2019 ◽

Vol 821 ◽

pp. 486-492

Author(s):

Norbaizurah Rahman ◽

Amalina Hanani Ismail ◽

Andri Kusbiantoro

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Coal Fly Ash ◽

Setting Time ◽

Relevant Literature ◽

Calcium Nitrate ◽

Microstructural Properties ◽

Hydrogen Phosphate ◽

Strength Performance ◽

Dipotassium Hydrogen Phosphate

Adoption of coal fly ash (Class C) as the main source material for geopolymers would cause rapid setting to the fresh geopolymer mortar or concrete. This behaviour explained the limited application of this material in the construction industry. On the other hand, calcium nitrate (Ca (NO3)2) and dipotassium hydrogen phosphate (K2HPO4) are alternative admixtures that known to extend the setting time of fresh geopolymers. However, their effect on the strength and microstructural properties remain unclear due to the limitation of relevant literature from previous studies. Therefore, this study aims to investigate the effect of these admixtures in fly ash based geopolymer system, particularly to its strength performance. The effects of adding Ca (NO3)2 and K2HPO4 were evaluated at dosages of 0.5%, 1.5%, and 2.5% (by fly ash weight) in the geopolymer mixture, and samples were cured at room temperature. Hardened geopolymer specimens were measured for their compressive strength, porosity, and microstructural characteristic. The inclusion of 0.5% of alternative chemical reagents was found as the optimum proportion and able to enhance the compressive strength of the geopolymer mixtures. However, efflorescence was detected on the surface of the hardened specimen when K2HPO4 was included in its mixture. This phenomenon is influenced by the presence of monovalent and trivalent anions in the system namely nitrates and phosphates. In this study, each anion had a particular role in each stage of geopolymerisation, and determined the quality via crystal growth control and influenced the development of aluminosilicate structures.

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Behavior of HPC with Fly Ash after Elevated Temperature

Advances in Materials Science and Engineering ◽

10.1155/2013/478421 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 11

Author(s):

Huai-Shuai Shang ◽

Ting-Hua Yi

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Flexural Strength ◽

Ultrasonic Velocity ◽

High Performance ◽

Elevated Temperatures ◽

High Performance Concrete ◽

Surface Characteristics ◽

Effect Of Temperature ◽

Cleavage Strength

For use in fire resistance calculations, the relevant thermal properties of high-performance concrete (HPC) with fly ash were determined through an experimental study. These properties included compressive strength, cubic compressive strength, cleavage strength, flexural strength, and the ultrasonic velocity at various temperatures (20, 100, 200, 300, 400 and 500∘C) for high-performance concrete. The effect of temperature on compressive strength, cubic compressive strength, cleavage strength, flexural strength, and the ultrasonic velocity of the high-performance concrete with fly ash was discussed according to the experimental results. The change of surface characteristics with the temperature was observed. It can serve as a reference for the maintenance, design, and the life prediction of high-performance concrete engineering, such as high-rise building, subjected to elevated temperatures.

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