scholarly journals Experimental Investigations on the Temperature Increase of Ultra-High Performance Concrete under Fatigue Loading

2019 ◽  
Vol 9 (19) ◽  
pp. 4087 ◽  
Author(s):  
Melchior Deutscher ◽  
Ngoc Linh Tran ◽  
Silke Scheerer
Keyword(s):  
Fatigue Strength ◽  
Heating Rate ◽  
Temperature Increase ◽  
High Performance ◽  
High Performance Concrete ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Maximum Temperature ◽  
Experimental Investigations ◽  
Resource Saving

Leaner, more filigree, and resource-saving constructions are the development goal of the in the building industry. In reinforced concrete construction, a ultra-high strength concrete was developed to achieve these goals. Due to its use and requirements, this very pressure-resistant material is no longer only exposed to static loads. In applications such as wide-span bridges, machine foundations and wind turbines, the susceptibility to vibration is also significant. Research into the fatigue behavior of the new building material is therefore very important. In this article we will discuss the effect of heating up of high performance concretes under fatigue stress. The thesis is that warming up, which was already observed by several research groups, has an influence on the fatigue strength. Changes in the strength of the concrete or residual stresses generated by heating can lead to early failure. The aim is to find the reasons for the heating and the grade of influence on the fatigue strength. A systematic test program was developed to investigate the influencing parameters maximum stress level, frequency, and maximum grain size of the concrete. Thirty fatigue tests were carried out; the results will be presented here. The influence on the temperature increase as well as on the heating rate for the individual parameters will be discussed. The results show that all three discussed parameters have a significant influence on the temperature rise. Whereas the maximum temperature reached depends strongly on the frequency, the other two parameters mainly influence the heating rate.

scholarly journals Experimental Investigations on Temperature Generation and Release of Ultra-High Performance Concrete during Fatigue Tests

2020 ◽  
Vol 10 (17) ◽  
pp. 5845
Author(s):  
Melchior Deutscher ◽  
Ngoc Linh Tran ◽  
Silke Scheerer
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Construction Material ◽  
Maximum Temperature ◽  
Experimental Investigations ◽  
Heating Process ◽  
Parameter Study ◽  
Ultra High Performance Concrete ◽  
Resource Saving ◽  
Premature Failure

Smarter, more filigree, and resource-saving buildings are the aim of developments in the construction industry. In reinforced concrete construction, ultra-high strength concretes have been developed to achieve these goals. Due to their use and requirements, these highly pressure-resistant materials are increasingly exposed to cyclically occurring and high-frequency loads. Examples of this are applications in long-span bridges or wind turbines. Research into the fatigue behaviour of the new construction material is therefore very important for the standardization and practical introduction of the high performance material. In this article, we want to investigate the heating process of ultra-high performance concrete (UHPC) under fatigue stress in more detail. In previous investigations in this project, an influence of the heating on the fatigue strength could be determined. A systematic parameter study has defined decisive load configurations for a maximum heating process. The aim is now to better understand the heating process. For this purpose, the temperature generation rate and the temperature release, which probably influences the overall temperature development, are investigated. A test program with eight experiments gives information about the temperature release during the experiment and the heating rate with and without pre-damage in the sample. In addition, the causes of failure caused by temperature are investigated with additional insulated tests. The results are presented, discussed, and conclusions are drawn in the article. For instance, fatigue damage affects the rate of temperature increase, but not the thermal conductivity of the material. In the different configurations, the test specimens essentially overlap at the maximum temperature reached in the inner test specimen. In addition to the assumed influence of the temperature gradients in the cross section as a cause of premature failure due to additional constraint stresses, the maximum temperature in particular turns out to be decisive, independent of the gradient.

Shear resistance of self-consolidating concrete beams — experimental investigations

2005 ◽  
Vol 32 (6) ◽  
pp. 1103-1113 ◽  
Author(s):  
M Lachemi ◽  
K M.A Hossain ◽  
V Lambros
Keyword(s):  
High Performance ◽  
Failure Modes ◽  
Coarse Aggregate ◽  
High Performance Concrete ◽  
Maximum Size ◽  
Shear Resistance ◽  
Resistance Mechanisms ◽  
Experimental Investigations ◽  
Self Consolidating Concrete ◽  
Aggregate Interlock

Self-consolidating concrete (SCC) is a new generation of high performance concrete known for its excellent deformability and high resistance to segregation and bleeding. Lack of information regarding in situ properties and structural performance of SCC is one of the main barriers to its acceptance in the construction industry. There is some concern among researchers and designers that SCC may not be strong enough in shear because of some uncertainties in mechanisms resisting shear — notably the aggregate interlock mechanism. Because of the presence of comparatively smaller amount of coarse aggregates in SCC, the fracture planes are relatively smooth as compared with normal concrete (NC) that may reduce the shear resistance of concrete by reducing the aggregate interlock between the fracture surfaces. The paper compares the shear resistance of SCC and NC based on the results of an experimental investigation on 18 flexurally reinforced beams without shear reinforcements. The test parameters include concrete type, maximum size of coarse aggregate, coarse aggregate content, and beam shear span-to-depth ratio. Shear strength, shear ductility, crack patterns, and failure modes of all experimental beams are compared to analyze the shear resistance mechanisms of SCC and NC beams in both pre- and post-cracking stages. The recommendations of this paper can be of special interest to designers considering the use of SCC in structural applications.Key words: self-consolidating concrete, shear resistance, shear resistance factor, aggregate interlock, dowel action.

Experimental investigations of aerogel-incorporated ultra-high performance concrete

2015 ◽  
Vol 77 ◽  
pp. 307-316 ◽  
Author(s):  
Serina Ng ◽  
Bjørn Petter Jelle ◽  
Linn Ingunn Christie Sandberg ◽  
Tao Gao ◽  
Ólafur Haralds Wallevik
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Experimental Investigations ◽  
Ultra High Performance Concrete

scholarly journals Effect of KyAl4(Si8-y) O20(OH)4 Calcined Based-Clay on the Microstructure and Mechanical Performances of High-Performance Concrete

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1152
Author(s):  
David O. Nduka ◽  
Babatunde J. Olawuyi ◽  
Olabosipo I. Fagbenle ◽  
Belén G. Fonteboa
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Attenuated Total Reflection ◽  
Maximum Temperature ◽  
Microstructural Properties ◽  
Calcined Clay ◽  
X Ray ◽  
Cement Replacement ◽  
Mechanical And Microstructural Properties

The work described in this paper has been performed to determine the potential use of meta-illite (KyAl4(Si8-y) O20(OH)4) calcined clay (MCC) as a supplementary cementitious material (SCM) in a binary Portland cement (PC) for high-performance concrete (HPC) production. To obtain the properties of the cementitious materials, the chemical composition, mineral phases, morphology, calcination efficiency and physical properties were quantitatively analysed using the advanced techniques of X-ray fluorescence (XRF), scanning electron microscopy/energy dispersive X-ray (SEM/EDX), X-ray diffraction (XRD), Fourier transform infrared/attenuated total reflection (FTIR/ATR), thermogravimetric analysis (TGA), laser particle sizing and Brunauer–Emmett–Teller (BET) nitrogen absorption method. The MCC’s effect on the workability and mechanical properties (compressive, splitting tensile and flexural strengths) and microstructure (morphology and crystalline phases) of hardened MCC-based HPCs were determined. The XRF result shows that the oxide composition of MCC confirmed the pozzolanic material requirements with recorded high useful oxides content. At the same time, the SEM image presents particles of broad, solid masses with a wider surface area of irregular shape. The XRD results show that the MCC was majorly an illite-based clay mineral calcined at a maximum temperature of 650 °C, as revealed by the TGA. The MCC addition increases the slump flow of HPCs at 5–15% cement replacement. The MCC incorporation at 10% cement replacement best improved the porosity of HPCs at a later age resulting in increased mechanical and microstructural properties of tested samples. Therefore, it is recommended that MCC addition within 10% cement replacement be adopted for low W/B Class I HPC at no deleterious results on mechanical and microstructural properties of the concrete.

Fatigue prediction model of ultra-high-performance concrete beams prestressed with CFRP tendons

2021 ◽  
pp. 136943322110623
Author(s):  
Rui Hu ◽  
Zhi Fang ◽  
Ruinian Jiang ◽  
Yu Xiang ◽  
Chuanle Liu
Keyword(s):  
Prediction Model ◽  
High Performance ◽  
High Performance Concrete ◽  
Fatigue Behavior ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Ultra High Performance Concrete ◽  
Flexural Fatigue ◽  
Reinforced Polymer ◽  
Fatigue Development

In the present paper, a comprehensive study on the flexural fatigue behavior of ultra-high-performance concrete (UHPC) beams prestressed with carbon-fiber-reinforced polymer (CFRP) tendons is reported. A total of two UHPC beams prestressed with CFRP tendons were experimentally investigated. On the basis of the fatigue constitutive model of the materials, a fatigue prediction model (FPM) was developed to simulate the flexural fatigue evolvement of the beams. The strain and stress in UHPC and CFRP tendons were calculated by the sectional stress analysis. The influence of steel fiber was considered in the formulae for the crack resistance and crack width, and the midspan deflection was calculated using the sum of deflection before cracking and increment after cracking. The obtained test results were used to verify the FPM. A parametric study was then conducted to analyze the fatigue development of such component, and a formula to predict the flexural fatigue life of UHPC beams under different fatigue loads was proposed.

Sign in / Sign up

Export Citation Format

Share Document