Analysis of the Cementitious and Pozzolanic Properties of a Silico-Aluminous (Class F) Fly Ash

1985 ◽  
Vol 65 ◽  
Author(s):  
Andre Carles-Gibergues ◽  
Pierre-Claude Aitcin
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Chemical Composition ◽  
Pure Water ◽  
Mineralogical Composition ◽  
Pozzolanic Reaction ◽  
Strength Increase ◽  
Lime Water ◽  
Physico Chemical ◽  
Class F

ABSTRACTA silico-aluminous (Class F) French fly ash has been studied during the last ten years. While over this period the fly ash was produced from different bituminous coals, it has demonstrated high constancy in terms of its chemical and physical composition as well as cementitious properties. The first part of this paper gives a complete physico-chemical characterization of this fly ash, including chemical composition, mineralogical composition of its crystallized fraction, chemical composition of its glass, grain-size distribution, specific surface area, and bulk density. The second part deals with physico-chemical experiments performed to determine the cementitious components of this fly ash through its dissolution in pure water and in lime water. The lime water experiment was also carried out on a washed sample containing few residual sulfates. This series of experiments demonstrates the importance of sulfates in this particular fly ash, especially during the early stages of hydration. Their action results in the formation of ettringite. The cementitious role of these sulfates has been confirmed by comparing the compressive strength of mortar cubes containing washed and nonwashed fly ash. After 7 days, mortar cubes made with this fly ash showed a slight compressive strength increase when compared to a reference mix containing the same amount of quartz. This compressive strength increase can be related to the formation of C-S-H due to the pozzolanic reaction. After 8 months, the pozzolanic reaction had consumed most of the lime generated by the hydration of C2S and C3S, so that practically no portlandite remained in the mortar.

scholarly journals Thermal, Physico-Chemical, and Mechanical Behaviour of Mass Concrete with Hybrid Blends of Bentonite and Fly Ash

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 60 ◽  
Author(s):  
Muhammad Ahad ◽  
Muhammad Ashraf ◽  
Rabinder Kumar ◽  
Mukhtar Ullah
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Thermal Stresses ◽  
Thermo Gravimetric Analysis ◽  
Xrd Analysis ◽  
Pozzolanic Reaction ◽  
Pulse Velocity ◽  
Mass Concrete ◽  
Gravimetric Analysis ◽  
Physico Chemical

Mass concrete has been commonly known for its thermal stresses which arise due to the entrapment of hydration temperature susceptible to thermal cracking. The utilization of mineral additives is a promising and widely adopted technique to mitigate such effects. This paper presents the thermal, physico-chemical, mechanical, and morphological behaviour of mass concrete with blends of bentonite (BT) and fly ash (FA). Apart from the rise in temperature due to hydration, the compressive strength, ultrasonic pulse velocity (UPV), differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) analysis, and microstructure were studied. The results of this study revealed that the substitution of BT and FA significantly improved the compressive strength and development rate of UPV in the mass concrete samples. The FA concrete (FC) specimen presented the lowest temperature during the peak hours compared to all other concrete mixes studied in this research. Bentonite concrete (BC) was also found to be more effective in controlling the escalation of temperature in mass concrete. Scan electron microscopy (SEM) micrographs presented partially reacted FA particles in a mix. XRD and DTA analysis indicated that the concentration of calcium hydroxide (CH) declined by substituting FA and BT, specifically in ternary blends, which was due to the dilution effect and consumption of CH through the pozzolanic reaction.

scholarly journals The Use of Borax in Deterring Flash Setting of High Calcium Fly Ash Based Geopolymer

2016 ◽  
Vol 857 ◽  
pp. 416-420 ◽  
Author(s):  
Antoni ◽  
Stephen Wibiatma Wijaya ◽  
Juan Satria ◽  
Agung Sugiarto ◽  
Djwantoro Hardjito
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Fly Ash ◽  
Chemical Composition ◽  
Setting Time ◽  
Chemical Properties ◽  
Physico Chemical ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Positive Effect

Geopolymer that was made with high CaO content fly ash was found to have higher compressive strength than the low CaO fly ash, using the same mixture composition. This effect could be due to the physico-chemical properties of the fly ash, in respect to its particle size or the chemical composition. Although it was not widely published, the occurrence of flash setting of geopolymer was known to occur when using high CaO content fly ash as the precursor. Geopolymer paste may solidify within minutes after the addition of alkali activators, making it very difficult to cast in big volume. This paper investigate the effect of borax addition to the high calcium fly ash-based geopolymer mixture to reduce the occurrence of flash setting. It was found that the setting time can be extended significantly, with the addition of 5% borax, by mass, of fly ash. The addition of borax also have positive effect on increasing the compressive strength of geopolymer.

scholarly journals Feasibility of Pulverized Oyster Shell as a Cementing Material

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Chou-Fu Liang ◽  
Hung-Yu Wang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Oyster Shell ◽  
Pozzolanic Reaction ◽  
Compaction Process ◽  
Lower Strength ◽  
Compacted Soil ◽  
Cementing Material ◽  
Unconfined Strength ◽  
Strength Variance

This research intends to study the cementing potential of pulverized oyster shell, rich in calcium, when mixed with fly ash and soil. Cylindrical compacted soil and cubic lime specimens with different proportions of the shells and fly ash are made to study the strength variance. Soil, which is classified as CL in the USCS system, commercialized pulverized oyster shell, F-type fly ash, and lime are mixed in different weight percentages. Five sample groups are made to study the compressive strength of soil and lime specimens, respectively. The lime cubes are made with 0.45 W/B ratio and the cylindrical soils are compacted under the standard Procter compaction process with 20% moisture content. The results show that increment of shell quantity result to lower strength on both the soil and lime specimens. In a 56-day curing, the compressive strength of the lime cubes containing fly ash increases evidently while those carrying the shell get little progress in strength. The soil specimens containing fly ash gradually gain strength as curing proceeds. It suggests that mixtures of the shell and fly ash do not process any Pozzolanic reaction nor help to raise the unconfined strength of the compacted soil through the curing.

Effect of Partial Replacement of Fly Ash by Metakaolin on Strength Development of Fly Ash Based Geopolymer Mortar

2017 ◽  
Vol 744 ◽  
pp. 131-135 ◽  
Author(s):  
Muhammad Zahid ◽  
Nasir Shafiq ◽  
Mohd Fadhil Nuruddin ◽  
Ehsan Nikbakht ◽  
Asif Jalal
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide Solution ◽  
Base Material ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Partial Replacement ◽  
Strength Development ◽  
Class C ◽  
Class F

This article aims to investigate the compressive strength variation by the addition of metakaolin as a substitute of fly ash in the fly ash based geopolymer mortar. Five, ten and fifteen percent by weight of fly ash was replaced by highly reactive metakaolin. Two type of fly ashes namely, ASTM class F and ASTM class C were used as a base material for the synthesis of geopolymer mortar. Eight molar sodium hydroxide solution mixed with sodium silicate solution was used as alkaline activator. For optimum geopolymerization, mortar was cured at sixty degree Celsius for twenty four hours duration. Results show different behavior of metakaolin replacement on compressive strength for two different types of fly ash based geopolymer mortar. Improvement in compressive strength was seen by addition of metakaolin in ASTM class F fly ash based geopolymer. On the other hand compressive strength was decreased abruptly in fly ash class C based geopolymer up to certain replacement level.

COMPRESSIVE STRENGTH OF GEOPOLYMER MORTAR USING GROUND FERRONICKEL SLAG AND FLY ASH

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jhutan Chandra Kuri ◽  
Md Nabi Newaz Khan ◽  
Prabir Kumar Sarker
Keyword(s):  
Stainless Steel ◽  
Compressive Strength ◽  
Fly Ash ◽  
Nickel Alloy ◽  
Strength Increase ◽  
Reaction Products ◽  
Huge Amount ◽  
Alkaline Activator ◽  
Ferronickel Slag

A huge amount of ferronickel slag is produced as a by-product of manufacturing ferronickel, which is used in stainless steel and nickel alloy. This paper presents the effect of using different percentages of ground ferronickel slag (GFNS) with fly ash (FA) on the workability and compressive strength of geopolymer mortar. A mixture of NaOH and Na2SiO3 solutions was used as the alkaline activator. It was found that the flow of fresh mortar decreased with the increase of GFNS content. This is attributed to the higher fineness and angular shape of GFNS particles as compared to spherical fly ash particles. The mortar cube specimens were heat-cured at 60 °C for 24 hours. The compressive strength of geopolymer mortar using 100% FA was 54 MPa and it increased by 17%, 21% and 36% for using 25%, 50% and 75% GFNS as fly ash replacement, respectively. The strength increase is attributed to the increase of Si/Al ratio by GFNS that favoured the production of alkali aluminosilicate reaction products.

Modified Plasters for Restoration and Finishing Works

2014 ◽  
Vol 923 ◽  
pp. 42-47 ◽  
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Roman Kotiv
Keyword(s):  
Compressive Strength ◽  
Chemical Composition ◽  
Cementitious Materials ◽  
Quality Parameters ◽  
Supplementary Cementitious Materials ◽  
Cement Matrix ◽  
Hydration Products ◽  
High Quality ◽  
Physico Chemical ◽  
White Portland Cement

The paper is devoted to the research and development of modified plasters for restoration and finishing works based on decorative multicomponent cements containing white Portland cement and supplementary cementitious materials (silica fume, metakaolin and fine ground limestone). This cements are similar to Roman cement by their chemical composition. The use of optimal granulometry of decorative multicomponent cements provide directed formation of microstructure of the cement matrix with the formation of stable hydration products. Compositions of modified plasters by the criterions of workability and compressive strength were designed. Physico-chemical modification of plaster by complex air-entraining admixture allows to obtain high-quality modified plasters with improved quality parameters.

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

2017 ◽  
Vol 733 ◽  
pp. 85-88 ◽  
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.

An Abrasion Damage of Fly Ash Concretes Previously Subjected to Scaling

2016 ◽  
Vol 258 ◽  
pp. 587-590
Author(s):  
Aneta Nowak-Michta
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Abrasion Resistance ◽  
Air Entrainment ◽  
Binder Ratio ◽  
Abrasion Damage ◽  
Water Binder Ratio ◽  
Class F

Effect of quantity and quality of fly ash and compressive strength of concretes with their addition on abrasion resistance previously subjected to scaling is analyzed in the paper. The abrasion resistance was measured in Böhme test according to EN 1338: 2005. The cement was replaced with 20, 35, and 50% of Class F siliceous fly ash in three categories of losses on ignition A, B and C by mass. The water-binder ratio, the air-entrainment and the workability of mixtures were maintained constant at 0.38, 4,5% and 150 mm respectively.Prior scaling causes a decrease in abrasion resistance of fly ash concretes. In addition, both quantitative and qualitative fly ash parameters and compressive strength have an influence on abrasion damage.

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