scholarly journals The Role of HVFA Concrete in the Sustainability of the Urban Built Environment

2006 ◽  
Vol 1 (4) ◽  
pp. 129-140
Author(s):  
Mark Reiner ◽  
Kevin Rens ◽  
Anu Ramaswami
Keyword(s):  
Fly Ash ◽  
Built Environment ◽  
Portland Cement ◽  
Cost Reduction ◽  
Full Scale ◽  
Partial Replacement ◽  
Volume Percentage ◽  
Cement Replacement ◽  
Urban City ◽  
Full Scale Testing

Although fly-ash as a partial replacement for cement has been utilized for many years, its use has been almost exclusively used in low volume percentages such as 10% or 20% cement replacement. This paper looks at high volume percentage replacements from 40% to 70%. A mini-mix study revealed that 50% and 60% cement replacement percentages were the best candidates for full scale testing. The environmental benefits included a 25% reduction in smog, human health, and fossil fuel reduction compared to the same element built with 100% Portland cement mix. The economic benefits included a 15% capital cost reduction and a 20% life-cycle cost reduction when compared with a 100% Portland cement mix. Full scale testing included a complete mix design in addition to the construction of four concrete infrastructure products. The products built included an alley panel and curb and gutter sections in the City and county of Denver, a precast manhole and lid, and a twin tee prestressed girder. Although cement products are just one of many materials used in the construction of the built environment, its production has a large impact on the environment. Lowering the embodied energy of multiple types of construction materials will have a significant effect on sustainable urban development. Symbiotic recycling of waste material, such as fly ash in concrete, back into the built environment can help reduce materials on the input side and pollution on the output side of the bulk material flow of an urban city.

Macroscopic and Microscopic Properties of High Performance Concrete with Partial Replacement of Cement by Fly Ash

2019 ◽  
Vol 292 ◽  
pp. 108-113 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Roman Chylík ◽  
Zdeněk Prošek
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Partial Replacement ◽  
Experimental Program ◽  
Second Phase ◽  
Depth Of Penetration ◽  
Cement Replacement

The paper describes an experimental program focused on the research of high performance concrete with partial replacement of cement by fly ash. Four mixtures were investigated: reference mixture and mixtures with 10 %, 20 % and 30 % cement weight replaced by fly ash. In the first stage, the effect of cement replacement was observed. The second phase aimed at the influence of homogenization process for the selected 30% replacement on concrete properties. The analysis of macroscopic properties followed compressive strength, elastic modulus and depth of penetration of water under pressure. Microscopic analysis concentrated on the study of elastic modulus, porosity and mineralogical composition of cement matrix using scanning electron microscopy, spectral analysis and nanoindentation. The macroscopic results showed that the replacement of cement by fly ash notably improved compressive strength of concrete and significantly decreased the depth of penetration of water under pressure, while the improvement rate increased with increasing cement replacement (strength improved by 18 %, depth of penetration by 95 % at 30% replacement). Static elastic modulus was practically unaffected. Microscopic investigation showed impact of fly ash on both structure and phase mechanical performance of the material.

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 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.

High Dosage Type-C Fly Ash and Limestone in Sand-Gravel Concrete

1996 ◽  
Vol 1532 (1) ◽  
pp. 36-43
Author(s):  
Mohamed Nagib Abou-Zeid ◽  
John B. Wojakowski ◽  
Stephen A. Cross
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Concrete Beams ◽  
Partial Replacement ◽  
Equal Weight ◽  
Department Of Transportation ◽  
Fly Ash Concrete ◽  
Freeze And Thaw ◽  
Concrete Mixtures ◽  
Type C

Alkali-silica reactions are a major cause of concrete deterioration. The reactions can lead to severe damage that may ultimately endanger the performance and safety of concrete structures. The use of fly ash as partial replacement of Portland cement and the use of some limestone in concrete mixtures were considered as two potential approaches to minimize the severity of the problem. Sand-gravel concrete mixtures were prepared by replacing 15, 25, and 35 percent, by weight of Portland cement, with an equal weight of ASTM Type C fly ash. In those mixtures, either 30 percent or 50 percent of the total aggregate was limestone. Concrete beams were prepared and the wetting-and-drying test was performed in accordance with Kansas Department of Transportation (KDOT) specifications. Also, freeze-and-thaw testing of concrete beams were performed on some selected mixtures. Results indicate that most of the fly ash concrete mixtures with 30 percent limestone do not fulfill the requirements of the KDOT specifications. The fly ash mixtures with 50 percent limestone yield better results; most of them meet the specifications. Results also show that increasing the fly ash dosage does not seem as effective as introducing limestone for alleviating alkali-silica reaction problems.

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