EXPERIMENTAL DETERMINATION OF THE STRESS EVOLUTION IN A PREBENT STEEL VERY HIGH-PERFORMANCE CONCRETE BEAM BY MEANS OF AN ACTIVE STRESSMETER

2009 ◽  
Vol 33 (2) ◽  
pp. 34-42 ◽  
Author(s):  
S. Staquet ◽  
E. Merliot ◽  
C. N’Guyen Van Phu ◽  
F. Derkx ◽  
F. Toutlemonde
Keyword(s):  
Experimental Determination ◽  
High Performance ◽  
Concrete Beam ◽  
High Performance Concrete ◽  
Stress Evolution ◽  
Very High

Autogenous Shrinkage in Plain Cement Mixtures

2008 ◽  
Vol 400-402 ◽  
pp. 137-143 ◽  
Author(s):  
Vinod Rajayogan ◽  
Obada Kayali
Keyword(s):  
Experimental Determination ◽  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Basic Mechanism ◽  
Realistic Model ◽  
Test Method ◽  
Ongoing Research ◽  
Cement Mixtures

Determination of a realistic model for the estimation of autogenous shrinkage in plain cement mixtures has been an ongoing research among researchers in high performance concrete. While no standard test method exists for the determination of autogenous shrinkage, various researchers have designed different test methods for measurement of autogenous shrinkage. Current study involved the experimental determination of autogenous shrinkage using the test method developed by O.M.Jensen and co-workers, complimented with non-contact eddy current sensors. Measurements were conducted from as early as 1.5 hours from the time of casting. The samples were placed in a constant temperature chamber and the temperature of the sample was also monitored using a thermocouple. The study was carried out on plain cement mixtures at three water cement ratios of 0.25, 0.32 and 0.38. Measurements were also conducted on simple sealed prismatic samples but these measurements could only be collected after 24 hours of casting. The work is supplemented with CEMHYD3D simulations of the samples at similar water-cement ratios under sealed conditions so as to understand the development of the microstructure of the cement responsible for autogenous shrinkage. While experimental determination of internal relative humidity is quite difficult, data regarding chemical shrinkage, amount of water left and the development of the discontinuous capillary network from the simulations help to understand the determined experimental values of autogenous shrinkage. A detailed explanation on the causes of autogenous shrinkage and the basic mechanism responsible for it has been presented.

Bestimmung der Dauerhaftigkeit von Hochleistungsbeton mit Hilfe des CDF-Tests / Determination of the durability of high performance concrete by means of CDF-test

1999 ◽  
Vol 5 (1) ◽  
pp. 29-40
Author(s):  
R. Krumbach ◽  
U. Schmelter ◽  
K. Seyfarth
Keyword(s):  
Frost Resistance ◽  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Strength Concrete ◽  
Factors Influencing

Abstract Variable obsen>ations concerning frost resistance of high performance concrete have been made. The question arises which are the decisive factors influencing durability under the action of frost and de-icing salt. The proposed experiments are to be carried out in cooperation with F.A.- Finger - Institute of Bauhaus University Weimar. The aim of this study is to determine possible change of durability of high strength concrete, and to investigate the origin thereof. Measures to reduce the risk of reduced durability have to be found.

Roof Structural System Study with Use of UHPC

2017 ◽  
Vol 259 ◽  
pp. 70-74
Author(s):  
Milan Holý
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Construction Materials ◽  
High Strength ◽  
Structural System ◽  
Total Load ◽  
Dominant Component ◽  
Industrial Buildings ◽  
Normal Strength ◽  
Very High

This paper deals with the roof structural system using prestressed girders made of ultra-high performance concrete (UHPC). One of the aims of this study is to verify whether the option of the UHPC girders could be under certain boundary conditions competitive with the commonly used construction materials. Due to its high strength, UHPC enables the design of the structural elements with the high load bearing capacity and with smaller slenderness compared to normal strength concrete elements. The price of UHPC is currently still very high compared to the normal strength concretes or steel. Therefore, its use for the usual designed structures does not recently seem too economically attractive. The effect of material savings is nonnegligible in the case, that a self-weight of the structure forms dominant component of the total load. In addition to the high strength, UHPC has very high resistance to environmental influences. It is therefore likely, that UHPC could be advantageously applied e.g. for the roofing of industrial buildings of chemical plants with high aggressive environments, because there are high demands on the life cycle of the structure.

The Determination of Frost Resistance on Ultra High Performance Concrete

2014 ◽  
Vol 1025-1026 ◽  
pp. 1005-1009 ◽  
Author(s):  
Michaela Kostelecká ◽  
Jiří Kolísko
Keyword(s):  
Frost Resistance ◽  
High Performance ◽  
High Performance Concrete ◽  
Silica Sand ◽  
Ultra High Performance Concrete ◽  
Concrete Technology ◽  
Normal Concrete ◽  
Different Types ◽  
High Range

The ultra high performance concrete (UHPC) has very special properties that are expressively different of normal concrete. Due to its high compression strength greater than 150 MPa, tensile strength greater than 20 MPa and improved durability, these represent significant advances in concrete technology. These materials include Portland cement, silica fume, quartz flour, fine silica sand, high-range water-reducer, water and either steel or organic fibres. Depending on the type of fibres used can influence the compressive strength. The article describes the tests of frost resistance on UHPC plates with different types of textiles armatures. The aim of the testing is describe influence of textiles armatures in UHPC matrix in extreme conditions.

Comparison of Different Methods for Determination of Modulus of Elasticity of Composite Reinforcement Produced from Roving

2014 ◽  
Vol 1054 ◽  
pp. 104-109 ◽  
Author(s):  
Tomáš Vlach ◽  
Lenka Laiblová ◽  
Alexandru Chira ◽  
Magdaléna Novotná ◽  
Ctislav Fiala ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
High Performance ◽  
High Performance Concrete ◽  
Traditional Approach ◽  
Tensile Modulus ◽  
Bending Test ◽  
Thin Structures ◽  
Technical Textiles ◽  
Composite Reinforcement

Currently, high performance concrete (HPC) is becoming more and more popular mainly because of its great mechanical parameters. As in the case of ordinary power concrete (OPC) it is necessary to improve the load bearing capacity with using of reinforcement. The present age calls for using of very thin structures for reasons of both environmental parameters and visual quality. Based on this fact, reinforcement start to use durable composite materials, such as technical textiles made of them. Element of HPC with this type of reinforcement is called textile reinforced high performance concrete (TRHPC). It is impossible to use the traditional approach for usually used steel reinforcement if we want to design these extra-thin structures. Modeled structures are very sensitive for input parameters and the development of standards for TRC material lags. The present study is focused on the different method of approach for the determination of tensile modulus of composite reinforcement. Three used methods are compared with each other using numerical analysis of four point bending test of façade element for one type of used reinforcement. Curves from numerical analysis are finally compared with the curve from real experiment and based on this the final evaluation is generated.

scholarly journals State of the Art: Mechanical Properties of Ultra-High Performance Concrete

2017 ◽  
Vol 3 (3) ◽  
pp. 190-198 ◽  
Author(s):  
Mohamadtaqi Baqersad ◽  
Ehsan Amir Sayyafi ◽  
Hamid Mortazavi Bak
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
State Of The Art ◽  
High Strength ◽  
Structural Members ◽  
Ultra High Performance Concrete ◽  
Conventional Concrete ◽  
The Past ◽  
Very High

During the past decades, there has been an extensive attention in using Ultra-High Performance Concrete (UHPC) in the buildings and infrastructures construction. Due to that, defining comprehensive mechanical properties of UHPC required to design structural members is worthwhile. The main difference of UHPC with the conventional concrete is the very high strength of UHPC, resulting designing elements with less weight and smaller sizes.  However, there have been no globally accepted UHPC properties to be implemented in the designing process. Therefore, in the current study, the UHPC mechanical properties such as compressive and tensile strength, modulus of elasticity and development length for designing purposes are provided based on the reviewed literature. According to that, the best-recommended properties of UHPC that can be used in designing of UHPC members are summarized. Finally, different topics for future works and researches on UHPC’s mechanical properties are suggested.

scholarly journals Optimum Dose of Binary Admixtures in Self Compacting Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 103-108
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Optimum Dose ◽  
Replacement Level ◽  
Self Compacting Concrete ◽  
Pozzolanic Material ◽  
Time Flow ◽  
Day By Day

Self Compacting Concrete (SCC) is a high performance concrete and is becoming popular day by day in the field of construction. Generally, the quantity of binder is more in SCC than the normal concrete. The application of pozzolanic material is found successful in such type of concrete. Generally, Ordinary Portland Cement (OPC) is replaced with Fly Ash (FA). In this paper, the results of an experimental programme to evaluate the performance of SCC are presented and optimum dose of binary admixture was found. For the determination of the optimum dose, concrete cubes of 100mm sizes were cast. The replacement level of OPC by FA was varied as- 5, 10, 15 and 20%, by mass. The OPC was also replaced separately by Metakaolin (MK) - 5, 10, 15 and 20%, by mass. Further, the OPC was replaced by the binary admixture (FA+MK). The workability and strength of SCC of grade M25 (Referral concrete- RC) and the concrete using the binary admixtures were studied. All SCC mixes were tested for workability as recommended by EFNARC i.e. Slump flow, T50 time flow, V-funnel, L-box, U-box and J-ring. The workability of SCC mix increases with FA and decreases gradually as MK content is increased. The optimum replacement level of OPC by binary admixture is 25% (FA-15% + MK-10%) with respect to compressive strength. The water absorption of cubes was also examined. It is concluded that a high strength and economical SCC could be developed by incorporation of FA and MK.

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