Phosphogypsum — Fly ash cementitious binder — Its hydration and strength development

A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

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Strength Development and Elemental Distribution of Dolomite/Fly Ash Geopolymer Composite under Elevated Temperature

Materials ◽

10.3390/ma13041015 ◽

2020 ◽

Vol 13 (4) ◽

pp. 1015 ◽

Cited By ~ 4

Author(s):

Emy Aizat Azimi ◽

Mohd Mustafa Al Bakri Abdullah ◽

Petrica Vizureanu ◽

Mohd Arif Anuar Mohd Salleh ◽

Andrei Victor Sandu ◽

...

Keyword(s):

Elevated Temperature ◽

Fly Ash ◽

Portland Cement ◽

Ordinary Portland Cement ◽

Raw Materials ◽

Liquid Sodium ◽

Strength Development ◽

Elemental Distribution ◽

Distribution Analysis ◽

Geopolymer Composites

A geopolymer has been reckoned as a rising technology with huge potential for application across the globe. Dolomite refers to a material that can be used raw in producing geopolymers. Nevertheless, dolomite has slow strength development due to its low reactivity as a geopolymer. In this study, dolomite/fly ash (DFA) geopolymer composites were produced with dolomite, fly ash, sodium hydroxide, and liquid sodium silicate. A compression test was carried out on DFA geopolymers to determine the strength of the composite, while a synchrotron Micro-Xray Fluorescence (Micro-XRF) test was performed to assess the elemental distribution in the geopolymer composite. The temperature applied in this study generated promising properties of DFA geopolymers, especially in strength, which displayed increments up to 74.48 MPa as the optimum value. Heat seemed to enhance the strength development of DFA geopolymer composites. The elemental distribution analysis revealed exceptional outcomes for the composites, particularly exposure up to 400 °C, which signified the homogeneity of the DFA composites. Temperatures exceeding 400 °C accelerated the strength development, thus increasing the strength of the DFA composites. This appears to be unique because the strength of ordinary Portland Cement (OPC) and other geopolymers composed of other raw materials is typically either maintained or decreases due to increased heat.

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The Effect on Cement Mortar and Concrete by Admixture of Spray Drying Absorption Products

MRS Proceedings ◽

10.1557/proc-178-267 ◽

1989 ◽

Vol 178 ◽

Author(s):

Kirsten G. Jeppesen

Keyword(s):

Grain Size ◽

Fly Ash ◽

Cement Mortar ◽

Setting Time ◽

Mineralogical Composition ◽

Cement Clinker ◽

Strength Development ◽

Fall Meeting ◽

Freeze Thaw ◽

Spray Dried

AbstractSpray dried absorption products (SDA) having special characteristics are used as substitutes for cement in the preparation of mortars; the qualities of the resulting mixed mortars are described. Conditions are described for mortar mixes, data for which were presented at the MRS Fall Meeting 1987.The influence of the composition of the SDA on water requirement and setting time has been studied. A full scale project involving 3 precast, reinforced concrete front-elements containing 20 and 30 wt.% SDA is described. Strength development, mineralogical composition and corrosion were monitored for two years.A non-standard freeze-thaw experiment was performed which compares mortars containing SDA and fly ash (FA) and also shows the effect of superplasticizer.The possibility of improving the SDA by grinding has been tested and a limited improvement has been found. The strength of the mixed mortars seems slightly influenced by the grain size of SDAGypsum (CaSO4·2H2O), synthetic calcium-sulphite (CaSO3·½H2O) and 2 SDAs have been used as retarders for cement clinker. Mortar test prisms have been cast and comparative strengths after curing for 3 years are reported

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Hydration and strength development of binder based on high-calcium oil shale fly ash

Cement and Concrete Research ◽

10.1016/s0008-8846(99)00139-8 ◽

1999 ◽

Vol 29 (11) ◽

pp. 1713-1719 ◽

Cited By ~ 6

Author(s):

C Freidin

Keyword(s):

Fly Ash ◽

Oil Shale ◽

Strength Development ◽

High Calcium

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Determination of optimal microwave curing cycle for fly ash mortars

Canadian Journal of Civil Engineering ◽

10.1139/l07-132 ◽

2008 ◽

Vol 35 (4) ◽

pp. 349-357 ◽

Cited By ~ 6

Author(s):

İlker Bekir Topçu ◽

Mehmet Uğur Toprak ◽

Devrim Akdağ

Keyword(s):

Fly Ash ◽

Processing Parameters ◽

Microwave Energy ◽

Strength Prediction ◽

Strength Development ◽

Microwave Curing ◽

Optimal Processing ◽

Cement Mortars ◽

Curing Cycle

Microwave energy can accelerate the hydration of cement, which results in the rapid strength development of concrete. In this paper, prediction of later age compressive strength of fly ash cement mortars, based on the accelerated strength of mortars cured with microwave energy, was investigated. To accelerate curing properly, optimal processing parameters of microwave curing (MC) on Portland cement mortars (CM) and fly ash cement mortars (FA) were first determined and then were applied to mortars. The possible early ages for the strength prediction were found to be at 6 and 8 h for CM and FA, respectively. The error percentages for prediction of CM were ±2.22% and 2.91% for 7 and 28 d, respectively. Error percentages for FA, on the other hand, were ±4.36% and 5.20% for 7 and 28 d, respectively.

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