Utilization of off-specification fly ash in preparing ultra-high-performance concrete (UHPC): Mixture design, characterization, and life-cycle assessment

2022 ◽  
Vol 180 ◽  
pp. 106136
Author(s):  
Jiang Du ◽  
Zhuo Liu ◽  
Christos Christodoulatos ◽  
Matthew Conway ◽  
Yi Bao ◽  
...  
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Mixture Design ◽  
Ultra High Performance Concrete

scholarly journals Ultra-high-performance concrete with local high unburned carbon fly ash

DYNA ◽  
2021 ◽  
Vol 88 (216) ◽  
pp. 38-47
Author(s):  
Joaquín Abellán García ◽  
Nancy Torres Castellanos ◽  
Jaime Antonio Fernandez Gomez ◽  
Andres Mauricio Nuñez Lopez
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Unburned Carbon ◽  
High Tech ◽  
Ultra High Performance Concrete ◽  
Conventional Concrete ◽  
The Cost

Ultra-high-performance concrete (UHPC) is a kind of high-tech cementitious material with superb mechanical and durability properties compared to other types of concrete. However, due to the high content of cement and silica fume used, the cost and environmental impact of UHPC is considerably higher than conventional concrete. For this reason, several efforts around the world have been made to develop UHPC with greener and less expensive local pozzolans. This study aimed to design and produce UHPC using local fly ash available in Colombia. A numerical optimization, based on Design of Experiments (DoE) and multi-objective criteria, was performed to obtain a mixture with the proper flow and highest compressive strength, while simultaneously having the minimum content of cement. The results showed that, despite the low quality of local fly ashes in Colombia, compressive strength values of 150 MPa without any heat treatment can be achieved.

Study on Interfacial Properties of Ultra-High Performance Concrete Containing Steel Slag Powder and Fly Ash

2011 ◽  
Vol 194-196 ◽  
pp. 956-960 ◽  
Author(s):  
Yan Zhou Peng ◽  
Kai Chen ◽  
Shu Guang Hu
Keyword(s):  
Fly Ash ◽  
Bond Strength ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Slag ◽  
Interfacial Zone ◽  
Ultra High Performance Concrete ◽  
Slag Powder ◽  
Steel Slag Powder

The interfacial properties of reactive powder concretes (RPCs), other known as ultra-high performance concrete (UHPC), containing steel slag powder and ultra fine fly ash are studied in this paper. The microstrctural characterization of interfacial transition zones (ITZs), including the aggregate-cement paste interfacial zone and the steel fiber-paste interfacial zone, is investigated by SEM. The microhardness of the aggregate-paste ITZ and the steel slag-paste ITZ is studied and the bond strength of steel fiber in matrix is tested through fiber pullout tests. The results indicate that the microhardness of the steel slag-paste ITZ is slightly higher than that of the aggregate-paste ITZ, which implies the advantage of the substitution of quartz powder with steel slag powder in preparation of RPCs to some degrees. Moreover, the hardness of these two ITZs is higher than that of the hardened paste. A certain amount of hydration products has been observed exsiting on the surface of steel fiber by SEM and the bond strength of steel fiber-martix is up to 9.3MPa. These interfical properties are definitely critical to obtain high performance of UHPCs containing steel slag powder and fly ash.

Mixture design methods for ultra-high-performance concrete - a review

2021 ◽  
Vol 124 ◽  
pp. 104242
Author(s):  
Min Zhou ◽  
Zemei Wu ◽  
Xue Ouyang ◽  
Xiang Hu ◽  
Caijun Shi
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Mixture Design ◽  
Design Methods ◽  
Ultra High Performance Concrete

scholarly journals Compressive Strength Development of High-Volume Fly Ash Ultra-High-Performance Concrete under Heat Curing Condition with Time

2020 ◽  
Vol 10 (20) ◽  
pp. 7107
Author(s):  
Pham Sy Dong ◽  
Nguyen Van Tuan ◽  
Le Trung Thanh ◽  
Nguyen Cong Thang ◽  
Viet Hung Cu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
High Volume ◽  
Strength Development ◽  
Ultra High Performance Concrete ◽  
Heat Curing ◽  
Compressive Strength Development ◽  
Curing Condition

This research investigated the effect of fly ash content on the compressive strength development of ultra-high-performance concrete (UHPC) at different curing conditions, i.e., the standard curing condition and the heat curing. A total of 20 mixtures were prepared to cast specimens to measure the compressive strength at different ages from 3 days to 180 days. Additionally, 300 specimens were prepared to estimate the appropriate heat curing period at the early ages in terms of enhancing the 28-day compressive strength of UHPC with high content of fly ash (FA). From the regression analysis using test data, empirical equations were formulated to assess the compressive strength development of UHPC considering the FA content and maturity function. Test results revealed that the preference of the addition of FA for enhancing the compressive strength of UHPC requires the early heat curing procedure which can be recommended as at least 2 days under 90 °C. Moreover, the compressive strength of UHPC with FA under heat curing mostly reached its 28-day strength within 3 days. The proposed models based on the fib 2010 model can be a useful tool to reliably assess the compressive strength development of UHPC with high-volume fly ash (HVFA) (up to 70% fly ash content) under a heat curing condition that possesses a different performance from that of normal- and high-strength concrete. When 50% of the cement content was replaced by FA, the embodied CO2 emission for UHPC mixture reduced up to approximately 50%, which is comparable to the CO2 emission calculated from the conventional normal-strength concrete.

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