scholarly journals SETTING TIMES OF PORTLAND CEMENT–METAKAOLIN–FLY ASH BLENDS / PORTLANDCEMENČIO, METAKAOLINO IR LAKIŲJŲ PELENŲ MIŠINIŲ RIŠIMOSI TERMINAI

2011 ◽  
Vol 17 (1) ◽  
pp. 55-62 ◽  
Author(s):  
David Snelson ◽  
Stan Wild ◽  
Martin O’Farrell
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Partial Replacement ◽  
Setting Times ◽  
Pozzolanic Materials

In the present study two pozzolanic materials are used, Metakaolin (MK) and Fly Ash (PFA), as binary and ternary partial replacement binders with Portland cement (PC) to investigate their effect on standard consistence and setting times of paste. To maintain standard consistency for MK–PC pastes increasing w/b ratios are required with increasing MK levels, whereas PFA has little influence on consistency. For binary MK–PC pastes there are substantial increases in initial and final setting times at 5% MK followed by decreases at 10 and 15% MK before further increases at 20% MK. For binary PFA–PC pastes however setting times increase at approximately the same rate up to 30% PFA and then increase more sharply between 30% PFA and 40% PFA. In general the effects of both PFA and MK on consistency and setting times in binary pastes are reflected in the behaviour of the ternary pastes although the two pozzolans do not behave completely independently of each other. The different ways in which the two pozzolans influence setting times is explained in terms of differences in their pozzolanic activities and in the manner in which they influence the availability of water for hydration. Santrauka Šiame tyrime naudojamos dvi pucolaninės medžiagos—metakaolinas (MK) ir lakieji pelenai (PFA), kaip dviejų ir trijų komponentų dalinio pakeitimo rišikliai su portlandcemenčiu (PC), siekiant ištirti jų poveikį standartinėms konsistencijoms ir reguliuoti mišinio kietėjimo laiką. Siekiant išlaikyti standartinę MK–PC mišinio konsistenciją, didinant vandens ir rišamųjų medžiagų santykius, reikia didinti MK lygį, nes PFA turi mažai įtakos konsistencijai. Dviejų komponentų MK–PC mišiniams svarbu padidinti pradinius ir galutinius kietėjimo laikus 5% MK, po sumažėjimo 10 ir 15% MK, prieš tolesnį padidinimą 20% MK. Dviejų komponentų PFA–PC mišinių kietėjimo laikui padidinti maždaug tokiomis pačiomis normomis iki 30% PFA ir tuomet didinti atsargiau tarp 30% PFA ir 40% PFA. Apskritai PFA ir MK poveikis konsistencijai ir kietėjimo laikui abiejuose mišiniuose matomas iš trijų mišinio komponentų elgsenos, nors du pucolanai nėra visiškai nepriklausomi vienas nuo kito. Kiti būdai, kuriais du pucolanai daro įtaką kietėjimo laikui, yra pristatyti kalbant apie jų pucolaninės veiklos skirtumus ir jų elgseną, kurios metu jie daro įtaką vandens galimybei hidratuotis.

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

2014 ◽  
Vol 625 ◽  
pp. 3-6 ◽  
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.

Influence of Fly Ash and Basalt Fibers on Strength and Chloride Penetration Resistance of Self-Consolidating Concrete

2016 ◽  
Vol 866 ◽  
pp. 3-8 ◽  
Author(s):  
Osama Ahmed Mohamed ◽  
Waddah Al Hawat
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Strength Properties ◽  
Chloride Penetration ◽  
Partial Replacement ◽  
Basalt Fibers ◽  
Self Consolidating Concrete ◽  
Chloride Penetration Resistance ◽  
Hardened Properties

Fly ash is a sustainable partial replacement of Portland cement that offers significant advantages in terms of fresh and hardened properties of concrete. This paper presents the findings of a study that aims at assessing the durability and strength properties of sustainable self-consolidating concrete (SCC) mixes in which Portland cement was partially replaced with 10%, 20%, 30%, and 40% fly ash. The study confirms that replacing Portland cement with fly ash at all of the percentages studied improves resistance of concrete to chloride penetration. The 40% fly ash mix exhibited the highest resistance to chloride penetration compared to the control mix. Despite the relative drop in compressive strength after 7 days of curing, the 28-day compressive strength of 40% SCC mix reached 55.75 MP, which is very close to the control mix. The study also confirms that adding 1%, 1.5%, and 2% basalt fibers, respectively, to the 40% fly ash mix improves the resistance to chloride penetration compared to the mix without basalt fibers.

scholarly journals Effect of Copolymer Latexes on Physicomechanical Properties of Mortar Containing High Volume Fly Ash as a Replacement Material of Cement

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
El-Sayed Negim ◽  
Latipa Kozhamzharova ◽  
Yeligbayeva Gulzhakhan ◽  
Jamal Khatib ◽  
Lyazzat Bekbayeva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Fly Ash ◽  
Setting Time ◽  
High Volume ◽  
Physicomechanical Properties ◽  
Partial Replacement ◽  
Setting Times ◽  
High Volume Fly Ash ◽  
Scanning Electron

This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes.

scholarly journals Coal gasification ash and Weathered fly ash, as partial replacement of Portland cement – effect on selected durability properties of concrete

2018 ◽  
Vol 199 ◽  
pp. 02021
Author(s):  
Dikeledi Maboea ◽  
Mike Otieno
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Coal Gasification ◽  
Partial Replacement ◽  
Low Grade ◽  
Durability Properties ◽  
Cement Specimen

This study uses Sasol ashes as cement extenders to contribute to the technology of partially replacing Portland cement by mass. There are two types of Sasol ashes; coal gasification ash (CGA) and weathered fly ash (WFA) produced from low grade coal. These ashes are disposed of by Sasol with no specific utilisation. In this investigation, PC will be partially replaced by mass with WFA, CGA and FA at 10%, 15% and 30% proportions for each type of ash. The durability indices will be measured and compared for all blended specimen (PC/WFA, PC/CGA and PC/FA). A 100% Portland cement specimen will be used as a control. The durability properties will be used to determine the potential of Sasol ashes being used as a cement extender.

scholarly journals AN INVESTIGATION ON THE PARTIAL REPLACEMENT OF PORTLAND CEMENT WITH KOSOVO FLY ASH IN CEMENT MORTARS

2017 ◽  
Vol 3 (3) ◽  
pp. 125-141
Author(s):  
Erion Luga ◽  
◽  
Alban Paja ◽  
Cengiz Duran Atis ◽  
◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Partial Replacement ◽  
Cement Mortars

scholarly journals Partial replacement and addition of fly ash in Portland cement: influences on carbonation and alkaline reserve

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Marcelo Henrique Farias de Medeiros ◽  
Janderson William Raisdorfer ◽  
Juarez Hoppe Filho ◽  
Ronaldo Alves Medeiros-Junior
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Partial Replacement ◽  
Alkaline Reserve

Combination of Various Admixtures as Partial Replacement for Portland Cement and the Influence on the Final Concrete Properties

2014 ◽  
Vol 1000 ◽  
pp. 20-23
Author(s):  
Klára Křížová ◽  
Rudolf Hela
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Partial Replacement ◽  
Concrete Properties

The article discusses the physical mechanical concrete properties of five different concrete recipes. The objective of the composition of the concrete is to use the lowest quantity of Portland cement by adding additives (fly ash, slag and limestone) and the various combinations.

The Development of Slurry Seal Design with Ordinary Portland Cement Replacement by Low Calcium Fly Ash

2015 ◽  
Vol 776 ◽  
pp. 24-29 ◽  
Author(s):  
Ary Setyawan ◽  
D. Sarwono ◽  
M.S. Adnan
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Indirect Tensile Strength ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Low Calcium ◽  
Indirect Tensile ◽  
Slurry Seal

Slurry Seal is an impermeable non-structural thin layer that is used for pavement maintenance consisting of a cold laid mixture of asphalt emulsion with continuous graded fine aggregate, mineral filler, water and other added ingredients. Ordinary Portland Cement (OPC) as the main filler in the application of slurry seal. Due to the relatively high cement prices and the pollution control for the environment; it is required to maintain the quality of the slurry by using a combination of OPC and LCFA (Low Calcium Fly Ash). This research was conducted to determine the value of consistency, setting time and indirect tensile strength (ITS) of slurry seal containing LCFA. A consistency testing used to obtain optimum moisture content to produce the sample for the rest of the test. The results show that with the addition of 5% water for pre-wetting and subsequently 10% of water content, the mixture provide appropriate consistency as required by highways standard. The time settings also meet the requirements of highways standard between 15 to 720 minutes for all types of mixtures. The mixture with composition of 50% OPC and 50% LCFA is considered as an ideal mixture at the optimum density value of 1.769 g/cm3, porosity of 9.55% and the indirect tensile strength of 30.99 kPa. It could be concluded that fly ash can be used as OPC partial replacement and enhance the properties on slurry seal application.

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