scholarly journals Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4102
Author(s):  
Jan Stindt ◽  
Patrick Forman ◽  
Peter Mark
Keyword(s):  
Heat Treatment ◽  
High Performance ◽  
High Performance Concrete ◽  
Treatment Time ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Shrinkage Strain ◽  
Temperature Treatment ◽  
Production Flow ◽  
Steel Fibres

Resource-efficient precast concrete elements can be produced using high-performance concrete (HPC). A heat treatment accelerates hardening and thus enables early stripping. To minimise damages to the concrete structure, treatment time and temperature are regulated. This leads to temperature treatment times of more than 24 h, what seems too long for quick serial production (flow production) of HPC. To overcome this shortcoming and to accelerate production speed, the heat treatment is started here immediately after concreting. This in turn influences the shrinkage behaviour and the concrete strength. Therefore, shrinkage is investigated on prisms made from HPC with and without steel fibres, as well as on short beams with reinforcement ratios of 1.8% and 3.1%. Furthermore, the flexural and compressive strengths of the prisms are measured directly after heating and later on after 28 d. The specimens are heat-treated between 1 and 24 h at 80 °C and a relative humidity of 60%. Specimens without heating serve for reference. The results show that the shrinkage strain is pronouncedly reduced with increasing temperature duration and rebar ratio. Moreover, the compressive and flexural strength decrease with decreasing temperature duration, whereby the loss of strength can be compensated by adding steel fibres.

Investigation of Grouted Coupler Connection Details for Accelerated Bridge Construction

2021 ◽  
pp. 036119812199939
Author(s):  
Brent Phares ◽  
Yoon-Si Lee ◽  
Travis K. Hosteng ◽  
Jim Nelson
Keyword(s):  
Crack Width ◽  
High Performance ◽  
Static Load ◽  
High Performance Concrete ◽  
Precast Concrete ◽  
Chloride Penetration ◽  
Load Testing ◽  
Test And Evaluation ◽  
Load Tests ◽  
Precast Elements

This paper presents a laboratory investigation on the performance of grouted rebar couplers with the connection details similar to those utilized on the precast concrete elements of the Keg Creek Bridge on US 6 in Iowa. The testing program consisted of a series of static load tests, a fatigue test, and evaluation of the chloride penetration resistance of laboratory specimens. The goal of this testing was to evaluate the ability of the grouted rebar couplers to develop flexural capacity at the joint between the precast elements as well as the durability of the connection. For structural load testing, seven full-scale specimens, each with #14 epoxy-coated rebars spliced by epoxy-coated grouted couplers, were fabricated and tested in three different loading cases: four-point bending, axial tension plus bending, and a cyclic test of the system in bending. The static load testing demonstrated that the applied axial load had a minimal effect on the formation of cracks and overall performance of the connection. When ultra-high performance concrete was used as a bedding grout, the initiation of crack was slightly delayed but no considerable improvement was observed in the magnitude of the crack width during loading or the crack closure on unloading. The results of the seventh specimen, tested in fatigue to 1 million cycles, showed little global displacement and crack width throughout the test, neither of which expanded measurably. No evidence of moisture or chloride penetration was detected at the grouted joint during the 6-month monitoring.

Study on corrosion effect of high-performance concrete under the action of sulfate and chlorine

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940054 ◽  
Author(s):  
Rongrong Yin ◽  
Jie Hu ◽  
Yu Liu ◽  
Qing Wu ◽  
Chenchen Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Growth Stage ◽  
High Performance Concrete ◽  
Slow Growth ◽  
Concrete Strength ◽  
Corrosion Damage ◽  
Chloride Salt ◽  
Single Action ◽  
Two Stages

The thickness of corroded concrete layer and the compressive strength of prisms under the action of sulfate and chloride salt were investigated by ultrasonic test and compression test, respectively. The results show that under the single action of sulfate, the strength of concrete experienced two stages: a slow growth stage and a rapid descent stage. Correspondingly, under the combined action of sulfate and chloride, the concrete strength experienced another two stages: a slow growth stage and a slow degradation stage. The existence of chloride inhibited the corrosion damage of concrete in a certain extent. It was found that higher concentration of chlorine salt would lead to a stronger inhibition effect. A good consistency was observed among corrosion layer thickness, compressive strength and X-ray diffraction results. The inhabitation of chloride to the sulfate corrosion of concrete was proved.

scholarly journals Tests of Residual Shear Transfer Strength of Concrete Exposed to Fire

2018 ◽  
Vol 64 (2) ◽  
pp. 187-199
Author(s):  
Muhaned A. Shallal ◽  
Aqil Mousa K. Al Musawi
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Real Life ◽  
Shear Plane ◽  
Concrete Cover ◽  
Experimental Program ◽  
Fire Exposure ◽  
Structural Components ◽  
Shear Transfer

AbstractReinforced concrete is one of the most widely used structural components about which much scientific research has been conducted; however, some of its characteristics still require further research. The main focus of this study is the effect of direct fire on the shear transfer strength of concrete. It was investigated under several parameters including concrete strength, number of stirrup legs (the steel area across the shear plane), and fire duration. The experimental program involved the testing of two sets (groups) of specimens (12 specimens each) with different concrete strengths. Each set contained specimens of two or four stirrup legs exposed to direct fire from one side (the fire was in an open area to simulate a real-life event) for a duration of one, two, and three hours. The results of the comparison showed the importance of using high-performance concrete (instead of increasing the number of stirrup legs) to resist shear stress for the purpose of safety. A significant reduction in shear strength occurred due to the deterioration of the concrete cover after three hours of direct fire exposure.

Research and Applying Evolution of High Efficient Water-Reducing Agent for High Performance Concrete

2012 ◽  
Vol 610-613 ◽  
pp. 573-576
Author(s):  
Zheng Jun Wang ◽  
Jia Bin Liang
Keyword(s):  
High Performance ◽  
Lightweight Concrete ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Reducing Agent ◽  
Mass Concrete ◽  
Green Concrete ◽  
High Efficient ◽  
Strength And Durability

This paper discusses the development of water-reducing agent and the present situation of the application of high performance concrete. The traditional concrete will be substituted by high performance concrete, green concrete. In the course of appearance of high performance and green, concrete admixtures plays an extremely important role. Concrete water-reducing agent is admixture of the main part. In the case of keeping liquidity, it can make water consumption reduce, so the concrete strength and durability can be improved. It is applicable to all kinds of industrial and civil construction engineering, and it can be applied to different strength grade of concrete. It has important significance for mass concrete engineering, marine building facilities, and component and product of high strength lightweight concrete.

scholarly journals Experimental Evaluation of Nano Silica Effects to High Performance Concrete Strength in Early Age

2020 ◽  
Vol 869 ◽  
pp. 032011
Author(s):  
Van-Thuc Ngo ◽  
Tien-Thanh Bui ◽  
Thanh-Quang-Khai Lam ◽  
Thi-Thu-Nga Nguyen ◽  
Van-Hau Nguyen
Keyword(s):  
Experimental Evaluation ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Early Age ◽  
Nano Silica
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