scholarly journals High-volume Fly Ash Concrete for Pavements Findings: Volume 1

2021 ◽  
Author(s):  
Aniruddha Baral ◽  
◽  
Jeffrey Roesler ◽  
M. Ley ◽  
Shinhyu Kang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Air Entrainment ◽  
High Volume ◽  
Mix Design ◽  
Hydration Reaction ◽  
Index Test ◽  
Fly Ash Concrete ◽  
High Volume Fly Ash ◽  
Foam Index

High-volume fly ash concrete (HVFAC) has improved durability and sustainability properties at a lower cost than conventional concrete, but its early-age properties like strength gain, setting time, and air entrainment can present challenges for application to concrete pavements. This research report helps with the implementation of HVFAC for pavement applications by providing guidelines for HVFAC mix design, testing protocols, and new tools for better quality control of HVFAC properties. Calorimeter tests were performed to evaluate the effects of fly ash sources, cement–fly ash interactions, chemical admixtures, and limestone replacement on the setting times and hydration reaction of HVFAC. To better target the initial air-entraining agent dosage for HVFAC, a calibration curve between air-entraining dosage for achieving 6% air content and fly ash foam index test has been developed. Further, a digital foam index test was developed to make this test more consistent across different labs and operators. For a more rapid prediction of hardened HVFAC properties, such as compressive strength, resistivity, and diffusion coefficient, an oxide-based particle model was developed. An HVFAC field test section was also constructed to demonstrate the implementation of a noncontact ultrasonic device for determining the final set time and ideal time to initiate saw cutting. Additionally, a maturity method was successfully implemented that estimates the in-place compressive strength of HVFAC through wireless thermal sensors. An HVFAC mix design procedure using the tools developed in this project such as the calorimeter test, foam index test, and particle-based model was proposed to assist engineers in implementing HVFAC pavements.

scholarly journals Effect of AEA-SP Dosage Sequence on Air Entrainment in FA Concrete

2019 ◽  
Vol 61 (2) ◽  
pp. 1-21
Author(s):  
Andrei Shpak ◽  
Stefan Jacobsen
Keyword(s):  
Fly Ash ◽  
Air Entrainment ◽  
High Volume ◽  
Parameter Control ◽  
Laboratory Measurements ◽  
Fly Ash Concrete ◽  
Air Content ◽  
High Volume Fly Ash ◽  
Foam Index ◽  
Concrete Image

Abstract Laboratory measurements show that varying the dosage sequence of air-entraining agent and co-polymer in the mix (SP added before, after or together with AEA) greatly affects air entrainment in fresh and hardened fly ash concrete. Image analysis shows a somewhat lower specific surface when SP is added together with AEA. Foam Index measurements on the same binder materials, admixtures, and dosage sequences were therefore found less useful for studying the effect of admixture combinations. Obtaining a certain air content using the experience with AEA-SP dosage was found to be an untrivial task if there is a lack of parameter control. Finally, examples of successful mixing procedure for air entrainment in a series of high-volume fly ash concrete are shown.

scholarly journals Late Age Dynamic Strength of High-Volume Fly Ash Concrete with Nano-Silica and Polypropylene Fibres

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 243 ◽  
Author(s):  
Mohamed H. Mussa ◽  
Ahmed M. Abdulhadi ◽  
Imad Shakir Abbood ◽  
Azrul A. Mutalib ◽  
Zaher Mundher Yaseen
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Elevated Temperatures ◽  
High Volume ◽  
Nano Silica ◽  
Polypropylene Fibres ◽  
Fly Ash Concrete ◽  
High Volume Fly Ash ◽  
Dynamic Compressive Strength ◽  
Curing Age

The dynamic behaviour of high-volume fly ash concrete with nano-silica (HVFANS) and polypropylene fibres at curing ages of 7 to 90 days was determined by using a split Hopkinson pressure bar (SHPB) machine. At each curing age, the concrete samples were laboratory tested at different temperatures conditions under strain rates reached up to 101.42 s−1. At room temperature, the results indicated that the dynamic compressive strength of plain concrete (PC) was slightly higher than HVFANS concrete at early curing ages of 7 and 28 days, however, a considerable improvement in the strength of HVFANS concrete was noted at a curing age of 90 days and recorded greater values than PC owing to the increase of fly ash reactivity. At elevated temperatures, the HVFANS concrete revealed a superior behaviour than PC even at early ages in terms of dynamic compressive strength, critical strain, damage and toughness due to increase of nano-silica (NS) activity during the heating process. Furthermore, equations were suggested to estimate the dynamic increase factor (DIF) of both concretes under the investigated factors.

Effects of Compressive Strength and Carbonation of HCSA Amount on High Volume Fly Ash Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 333-337
Author(s):  
Juan Hong Liu ◽  
Fang Fang Hou ◽  
Shao Min Song ◽  
Bo Ya Jia
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Internal Structure ◽  
High Volume ◽  
Carbonation Depth ◽  
Fly Ash Concrete ◽  
Resistance Increase ◽  
Expansive Concrete ◽  
High Volume Fly Ash ◽  
Carbonation Resistance

In this article, the effects of compressive strength and carbonation depth of HCSA mixing amount on high volume fly ash concrete have been investigated. Besides, the effects of compressive strength and carbonation depth of the fly ash amount on HCSA expansive concrete have been also analyzed. The results show that proper HCSA mixing amount can improve the compressive strength and anti-carbonation resistance. On the condition of 55% mixing amount of fly ash and 6% HCSA, the compressive strength for 28 days enhanced 8MPa, the carbonation depth decreased by 0.7mm, at the age of 70, the strength increased by 12MPa and the depth reduced 1.7mm; when the mixing amount of HCSA reaches 10%, the internal structure of concrete would be destroyed; In the case of 6% HCSA amount, the compressive strength and anti-carbonation resistance decreases with the increase of fly ash mixing amount. While comparing to the concrete without HCSA, the compressive strength and anti-carbonation resistance increase obviously.

scholarly journals Early-age Properties of High-volume Fly Ash Concrete Mixes for Pavement: Volume 2

2021 ◽  
Author(s):  
Aniruddha Baral ◽  
◽  
Jeffery Roesler ◽  
Junryu Fu ◽  
◽  
...  
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
High Volume ◽  
Early Age ◽  
X Ray ◽  
Fly Ash Concrete ◽  
Setting Times ◽  
Chemical Admixtures ◽  
High Volume Fly Ash ◽  
Foam Index

High-volume fly ash concrete (HVFAC) is more cost-efficient, sustainable, and durable than conventional concrete. This report presents a state-of-the-art review of HVFAC properties and different fly ash characterization methods. The main challenges identified for HVFAC for pavements are its early-age properties such as air entrainment, setting time, and strength gain, which are the focus of this research. Five fly ash sources in Illinois have been repeatedly characterized through x-ray diffraction, x-ray fluorescence, and laser diffraction over time. The fly ash oxide compositions from the same source but different quarterly samples were overall consistent with most variations observed in SO3 and MgO content. The minerals present in various fly ash sources were similar over multiple quarters, with the mineral content varying. The types of carbon present in the fly ash were also characterized through x-ray photoelectron spectroscopy, loss on ignition, and foam index tests. A new computer vision–based digital foam index test was developed to automatically capture and quantify a video of the foam layer for better operator and laboratory reliability. The heat of hydration and setting times of HVFAC mixes for different cement and fly ash sources as well as chemical admixtures were investigated using an isothermal calorimeter. Class C HVFAC mixes had a higher sulfate imbalance than Class F mixes. The addition of chemical admixtures (both PCE- and lignosulfonate-based) delayed the hydration, with the delay higher for the PCE-based admixture. Both micro- and nano-limestone replacement were successful in accelerating the setting times, with nano-limestone being more effective than micro-limestone. A field test section constructed of HVFAC showed the feasibility and importance of using the noncontact ultrasound device to measure the final setting time as well as determine the saw-cutting time. Moreover, field implementation of the maturity method based on wireless thermal sensors demonstrated its viability for early opening strength, and only a few sensors with pavement depth are needed to estimate the field maturity.

scholarly journals Mix design of high-volume fly ash ultra high performance concrete

2021 ◽  
Vol 15 (4) ◽  
pp. 197-208
Author(s):  
Nguyen Van Tuan ◽  
Pham Sy Dong ◽  
Le Trung Thanh ◽  
Nguyen Cong Thang ◽  
Yang Keun Hyeok
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Fly Ash ◽  
Co2 Emissions ◽  
High Performance ◽  
High Performance Concrete ◽  
High Volume ◽  
Mix Design ◽  
Ultra High Performance Concrete ◽  
High Volume Fly Ash

The addition of supplementary cementitious materials (SCMs) to replace cement, especially with a high volume (> 50%), is an effective way to reduce the environmental impact due to the CO2 emissions generated in the production of ultra-high performance concrete (UHPC). Unfortunately, no official guidelines of UHPC using a high volume of SCMs have been published up to now. This paper proposes a new method of mix design for UHPC using high volume fly ash (HVFA), that is referred to the particle packing optimization of the Compressive Packing Model proposed by F. de Larrard. This proposed method also considers the heat treatment curing duration to maximize the compressive strength of HVFA UHPC. The experimental results using this proposed mix design method show that the optimum fly ash content of 50 wt.% of binder can be used to produce HVFA UHPC with a compressive strength of over 120 MPa and 150 MPa under standard curing and heat treatment, respectively. Moreover, the embodied CO2 emissions of UHPC reduces 56.4% with addition of 50% FA.

scholarly journals A Review on Early Age and Long-term Compressive Strength of High-volume Fly Ash Concrete

2018 ◽  
Vol 207 ◽  
pp. 01004
Author(s):  
Mu Li
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Volume ◽  
Partial Replacement ◽  
Early Age ◽  
Fly Ash Concrete ◽  
Power Stations ◽  
High Volume Fly Ash ◽  
Curing Age

Fly ash is a by-product of the combustion of the coal-fired electric power stations, and disposal of fly ash has been one of the environmental challenges. Much of the studies have been focused on the mechanical property of fly ash concrete. It is no doubt that the use of high-volume fly ash as a partial replacement of cement is also one of the effect way to utilize fly ash. It is known that the compressive strength of fly ash concrete is lower than that of ordinary concrete at early age, especially for high-volume fly ash concrete. It is urgent for engineers to consider the compressive strength of high-volume fly ash concrete at different curing age. In this review, the compressive strength of high-volume fly ash concrete in various literature was reported and then analyzed. Furthermore, the proposal of the utilization of high-volume fly ash concrete is provided.

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