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

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.

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.

scholarly journals Effect of Elevated Temperature on Alkali Activated Slag and Fly Ash based Geopolymer Concrete

2020 ◽  
Vol 9 (4) ◽  
pp. 1241-1250
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Flexural Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Geopolymer Concrete ◽  
Base Materials ◽  
Activated Slag ◽  
Alkali Activated

Activated Slag (AAS) and Fly Ash (FA) based geopolymer concrete a new blended alkali-activated concrete that has been progressively studied over the past years because of its environmental benefits superior engineering properties. Geopolymer has many favorable characteristics in comparison to Ordinary Portland Cement. Many base materials could be utilized to make geopolymer with the convenient concentration of activator solution. In this study, the experimental program composed of two phases; phase on divided into four groups; Group one deliberated the effect of sodium hydroxide molarity and different curing condition on compressive strength. Group two studied the effect of alkali activated solution (NaOH and Na2SiO3) content on compressive strength and workability. The effect of sand replacement with slag on compressive strength and workability was explained in group three. Group four studied the effect of slag replacement with several base materials Fly Ash (FA), Ordinary Portland Cement (OPC), pulverized Red Brick (PRB), and Meta Kaolin (MK). Phase two contains three mixtures from phase one which had the highest compressive strength. For each mixture, the fresh concrete test was air content. In addition the hardened concrete tests were the compressive strength at 3, 7, 28, 90, 180, and 365 days, the flexural strength at 28, 90, and 365 days, and the young's modulus at 28, 90, and 365 days. Moreover; the three mixtures were exposed to elevated temperature at 100oC, 300oC, and 600oC to study the effect of elevated temperature on compressive and flexural strength.

scholarly journals Alkali-Activated Hybrid Cements Based on Fly Ash and Construction and Demolition Wastes Using Sodium Sulfate and Sodium Carbonate

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7572
Author(s):  
William Valencia-Saavedra ◽  
Rafael Robayo-Salazar ◽  
Ruby Mejía de Gutiérrez
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Sodium Carbonate ◽  
Sodium Sulfate ◽  
Room Temperature ◽  
Ordinary Portland Cement ◽  
Mechanical Performance ◽  
Construction And Demolition Wastes ◽  
Alkali Activated

This article demonstrates the possibility of producing alkali-activated hybrid cements based on fly ash (FA), and construction and demolition wastes (concrete waste, COW; ceramic waste, CEW; and masonry waste, MAW) using sodium sulfate (Na2SO4) (2–6%) and sodium carbonate (Na2CO3) (5–10%) as activators. From a mixture of COW, CEW, and MAW in equal proportions (33.33%), a new precursor called CDW was generated. The precursors were mixed with ordinary Portland cement (OPC) (10–30%). Curing of the materials was performed at room temperature (25 °C). The hybrid cements activated with Na2SO4 reached compressive strengths of up to 31 MPa at 28 days of curing, and the hybrid cements activated with Na2CO3 yielded compressive strengths of up to 22 MPa. Based on their mechanical performance, the optimal mixtures were selected: FA/30OPC-4%Na2SO4, CDW/30OPC-4%Na2SO4, FA/30OPC-10%Na2CO3, and CDW/30OPC-10%Na2CO3. At prolonged ages (180 days), these mixtures reached compressive strength values similar to those reported for pastes based on 100% OPC. A notable advantage is the reduction of the heat of the reaction, which can be reduced by up to 10 times relative to that reported for the hydration of Portland cement. These results show the feasibility of manufacturing alkaline-activated hybrid cements using alternative activators with a lower environmental impact.

scholarly journals Effect of Ordinary Portland Cement and Water Glass on the Properties of Alkali Activated Fly Ash Concrete

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 40 ◽  
Author(s):  
Vytautas Bocullo ◽  
Danutė Vaičiukynienė ◽  
Ramūnas Gečys ◽  
Mindaugas Daukšys
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Water Glass ◽  
Ordinary Portland Cement ◽  
Reference Sample ◽  
Freeze And Thaw ◽  
Naoh Solution ◽  
Increased Strength ◽  
Alkali Activated

This research presents the influence of ordinary Portland cement (OPC) and/or water glass addition on fly ash alkali-activated mortar and concrete. The results show that fly ash (FA) concrete activated with a NaOH solution and water glass mixture had better resistance to freeze and thaw, carbonation, alkali-silica reaction (ASR) and developed higher compressive strength and static elastic modulus compared with the FA concrete activated only with an NaOH solution. The addition of OPC contributes to the development of a denser microstructure of alkali activated concrete (AAC) samples. In the presence of water glass and OPC, the compressive strength (52.60 MPa) of the samples increased more than two times as compared with the reference sample (21.36 MPa) without OPC and water glass. The combination of OPC and water glass showed the increased strength and enhanced durability of AAC. The samples were more resistant to freeze and thaw, ASR, and carbonation.

Effects of Fly Ash/Slag Ratio and Liquid/Binder Ratio on Strength of Alkali-Activated Fly Ash/Slag Mortars

2013 ◽  
Vol 377 ◽  
pp. 50-54 ◽  
Author(s):  
Mao Chieh Chi ◽  
Yen Chun Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
The Other ◽  
Factors Influencing ◽  
Binder Ratio ◽  
Alkali Activated ◽  
Significant Factors

The purpose of this study is to investigate the effects of fly ash/slag ratio and liquid/binder ratio on strength of alkali-activated fly ash/slag (AAFS) mortars. Three liquid/binder ratios of 0.35, 0.5 and 0.65 and three fly ash/slag ratios of 100/0, 50/50, and 0/100 were selected as variables to design and produce mixes of AAFS mortars. The compressive strength and flexural strength of alkali-activated fly ash/slag mortars were discussed and compared with reference mortars produced using ordinary Portland cement (OPC) mortars. Based on the results, both fly ash/slag ratio and the liquid/binder ratio are significant factors influencing the strengths of AAFS mortars. The strength of AAFS mortars except alkali-activated fly ash mortars is higher than that of OPC mortars. When the fly ash/slag ratio reaches 50/50, the AAFS mortars possesses the highest strength compared with the other mortars.

scholarly journals Effects of Water on Pore Structure and Thermal Conductivity of Fly Ash-Based Foam Geopolymers

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Yong Cui ◽  
Dongmin Wang
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Total Porosity ◽  
Mechanical And Thermal Properties ◽  
Practical Application ◽  
Pore Characteristics ◽  
Solid Ratio

The influence of the water-to-solid ratio (W/S) on the viscosity, pore characteristics, bulk density, compressive strength, and thermal conductivity of foamed fly ash-based geopolymers with thermal conductivity less than 0.065 W/(m·K) was investigated, and their properties and cost analysis were also compared with that of foamed ordinary Portland cement (OPC). When the W/S varied from 0.38 to 0.5, the apparent viscosity of geopolymer paste 15 min after the preparation decreased significantly from 168 Pa·s to 6 Pa·s. The increasing W/S ratio contributed to the rise of the number of microcapillaries (φ < 50 nm) and macrocapillaries (50 nm < φ < 50 μm) but contributed to the decline of artificial air pores (φ > 50 μm). The refinement of pore characteristics lowered the 28 d thermal conductivity of foamed geopolymers from 0.06 W/(m·K) to 0.048 W/(m·K). Although the slight increase of total porosity of foamed geopolymers from 89% to 92% with the increase of the W/S ratio weakened their 28 d compressive strength from 0.75 MPa to 0.45 MPa, this strength still meets the Ordinary Portland Cement (OPC) based Foam Insulation Board standard of JC/T2200-2013 (>0.4 MPa for 0.25 g/cm3). The production cost of foamed geopolymers was slightly higher by 1.1–1.5 times than that of foamed OPC. However, considering the more beneficial effect of environmental load reductions and better mechanical and thermal properties of foamed geopolymers than those of foamed OPC, slightly higher cost would be acceptable for practical application.

scholarly journals Design of High Volume CFBC Fly Ash Based Calcium Sulphoaluminate Type Binder in Mixtures with Ordinary Portland Cement

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5798
Author(s):  
Peeter Paaver ◽  
Oliver Järvik ◽  
Kalle Kirsimäe
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Building Materials ◽  
Ordinary Portland Cement ◽  
High Volume ◽  
Cementitious Materials ◽  
Fluidised Bed ◽  
Complete Replacement ◽  
Cfbc Fly Ash

Growing concerns on global industrial greenhouse gas emissions have boosted research for developing alternative, less CO2 intensive binders for partial to complete replacement of ordinary Portland cement (OPC) clinker. Unlike slag and pozzolanic siliceous low-Ca class F fly ashes, the Ca- and S-rich class C ashes, particularly these formed in circulating fluidised bed combustion (CFBC) boilers, are typically not considered as viable cementitious materials for blending with or substituting the OPC. We studied the physical, chemical-mineralogical characteristics of the mechanically activated Ca-rich CFBC fly ash pastes and mortars with high volume OPC substitution rates to find potential alternatives for OPC in building materials and composites. Our findings indicate that compressive strength of pastes and mortars made with partial to complete replacement of the mechanically activated CFBC ash to OPC is comparable to OPC concrete, showing compared to OPC pastes reduction in compressive strength only by <10% at 50% and <20% at 75% replacement rates. Our results show that mechanically activated Ca-rich CFBC fly ash can be successfully used as an alternative CSA-cement type binder.

COMPRESSIVE STRENGTH AND THERMAL CONDUCTIVITY OF WATER AND AIR CURED PORTLAND CEMENT-FLY ASH-SILICA FUME MORTARS

2018 ◽  
Vol 17 (9) ◽  
pp. 2023-2030
Author(s):  
Arnon Chaipanich ◽  
Chalermphan Narattha ◽  
Watcharapong Wongkeo ◽  
Pailyn Thongsanitgarn
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Silica Fume

Study on Waterproof and Water-Resistant Properties of Gypsum

2012 ◽  
Vol 476-478 ◽  
pp. 1585-1588
Author(s):  
Hong Pan ◽  
Guo Zhong Li
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Ordinary Portland Cement ◽  
Experimental Results ◽  
Softening Coefficient

The comprehensively modified effect of cement, VAE emulsion and self-made acrylic varnish on mechanical and water-resistant properties of gypsum sample was investigated and microstructure of gypsum sample was analyzed. Experimental results exhibit that absolutely dry flexural strength, absolutely dry compressive strength, water absorption and softening coefficient of gypsum specimen with admixture of 10% ordinary Portland cement and 6% VAE emulsion and acrylic varnish coated on its surface can respectively reach to 5.11MPa , 10.49 MPa, 8.32% and 0.63, respectively.

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