Isothermal Strength Development Models of Ultra-High-Performance Concrete

2020 ◽  
Vol 117 (1) ◽  
Author(s):  
Thomas E. Allard ◽  
Matthew W. Priddy ◽  
Isaac L. Howard ◽  
Jay Shannon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Strength Development ◽  
Ultra High Performance Concrete ◽  
Development Models

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.

Experimental Tests of the UHPC in Triaxial Compression

2013 ◽  
Vol 486 ◽  
pp. 78-83 ◽  
Author(s):  
Filip Vogel ◽  
Radoslav Sovják ◽  
Marcel Jogl
Keyword(s):  
Power Law ◽  
High Performance ◽  
High Performance Concrete ◽  
Triaxial Compression ◽  
Experimental Tests ◽  
Strength Development ◽  
Ultra High Performance Concrete ◽  
Permissible Stress ◽  
Triaxial Strength ◽  
Stress Surface

An experimental study of the ultra high performance concrete (UHPC) subjected to triaxial compression is presented in this paper. The examined ultra high performance concrete was developed at the Faculty of Civil Engineering at CTU in Prague from the components locally available in the Czech Republic without using any special mixing technique or curing procedure. The uniaxial compressive strength was determined to be 123 MPa and 149 MPa for cylinders and cubes, respectively. Behaviour of the UHPC in triaxial compression was investigated in two different ways. In the first way cylinders were tested in triaxial chamber. The cylinders were 200 mm high and 100 mm in diameter. The cylinders were tested in triaxial chamber under lateral stresses equaled to 10, 20 and 30 MPa. The second way of testing UHPC in the triaxial compression was a triaxial loading machine where cubes were tested. The size of the cubes was 100 mm. The cubes were tested under the lateral stresses equaled to 15, 30, 60 and 90 MPa. Two equations for both cylinders and cubes showing the strength development were provided using power law regressions. The difference between triaxial strength development of cubes and cylinders was slight. The results obtained in this study were in good agreement with the results gained from the literature. It was experimentally verified that the strength development of the UHPC under different levels of the confinement pressure is not linear and tends to follow the power law function. In addition it was stated that the permissible stress surface of the UHPC falls below the permissible stress surface of the normal strength concretes, especially within the higher confinement pressures.

scholarly journals Development of CORPS-STIF 1.0 with application to ultra-high performance concrete (UHPC)

2021 ◽  
Author(s):  
Isaac Howard ◽  
Thomas Allard ◽  
Ashley Carey ◽  
Matthew Priddy ◽  
Alta Knizley ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Strength Development ◽  
Mass Concrete ◽  
Ultra High Performance Concrete ◽  
Time Step ◽  
Integrated Framework ◽  
Scale Structures ◽  
Predictive Software ◽  
The Heat Transfer Coefficient

This report introduces the first release of CORPS-STIF (Concrete Observations Repository and Predictive Software – Structural and Thermodynamical Integrated Framework). CORPS-STIF is envisioned to be used as a tool to optimize material constituents and geometries of mass concrete placements specifically for ultra-high performance concretes (UHPCs). An observations repository (OR) containing results of 649 mechanical property tests and 10 thermodynamical tests were recorded to be used as inputs for current and future releases. A thermodynamical integrated framework (TIF) was developed where the heat transfer coefficient was a function of temperature and determined at each time step. A structural integrated framework (SIF) modeled strength development in cylinders that underwent isothermal curing. CORPS-STIF represents a step toward understanding and predicting strength gain of UHPC for full-scale structures and specifically in mass concrete.

scholarly journals TRIAXIAL COMPRESSIVE STRENGTH OF ULTRA HIGH PERFORMANCE CONCRETE

2013 ◽  
Vol 53 (6) ◽  
pp. 901-905 ◽  
Author(s):  
Radoslav Sovják ◽  
Filip Vogel ◽  
Birgit Beckmann
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Triaxial Compression ◽  
Material Design ◽  
Triaxial Tests ◽  
Strength Development ◽  
Ultra High Performance Concrete ◽  
Triaxial Compressive Strength ◽  
Compressive Strength Development

The aim of this work is to describe the strength of Ultra High Performance Concrete (UHPC) under triaxial compression. The main goal is to find a trend in the triaxial compressive strength development under various values of confinement pressure. The importance of triaxial tests lies in the spatial loading of the sample, which simulates the real loading of the material in the structure better than conventional uniaxial strength tests. In addition, the authors describe a formulation process for UHPC that has been developed without using heat treatment, pressure or a special mixer. Only ordinary materials available commercially in the Czech Republic were utilized throughout the material design process.

scholarly journals Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2950
Author(s):  
Nankyoung Lee ◽  
Yeonung Jeong ◽  
Hyunuk Kang ◽  
Juhyuk Moon
Keyword(s):  
High Temperature ◽  
Silica Fume ◽  
High Performance ◽  
Structural Modification ◽  
Cement Hydration ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Ultra High Performance Concrete

This study investigated the heat-induced acceleration of cement hydration and pozzolanic reaction focusing on mechanical performance and structural modification at the meso- and micro-scale. The pozzolanic reaction was implemented by substituting 20 wt.% of cement with silica fume, considered the typical dosage of silica fume in ultra-high performance concrete. By actively consuming a limited amount of water and outer-formed portlandite on the unreacted cement grains, it was confirmed that high-temperature curing greatly enhances the pozzolanic reaction when compared with cement hydration under the same environment. The rate of strength development from the dual reactions of cement hydration and pozzolanic reaction was increased. After the high-temperature curing, further strength development was negligible because of the limited space availability and preconsumption of water under a low water-to-cement environment. Since the pozzolanic reaction does not directly require the anhydrous cement, the reaction can be more easily accelerated under restrained conditions because it does not heavily rely on the diffusion of the limited amount of water. Therefore, it significantly increases the mean chain length of the C–S–H, the size of C–S–H globules with a higher surface fractal dimension. This finding will be helpful in understanding the complicated hydration mechanism of high-strength concrete or ultra-high performance concrete, which has a very low water-to-cement ratio.

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