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.

Cohesion of Composite Reinforcement Produced from Rovings with High Performance Concrete

2015 ◽  
Vol 732 ◽  
pp. 397-402 ◽  
Author(s):  
Tomáš Vlach ◽  
Magdaléna Novotná ◽  
Ctislav Fiala ◽  
Lenka Laiblová ◽  
Petr Hájek
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Tensile Load ◽  
Experimental Tests ◽  
Production Method ◽  
Concrete Cover ◽  
Thin Structures ◽  
Load Bearing Capacity ◽  
Technical Textiles ◽  
Composite Reinforcement

The reinforcement of concrete with composite technical textile creates a tensile load-bearing capacity. It allows the elimination of steel reinforcement and minimisation of concrete cover. Based on this, the concrete cover is designed with respect to the cohesion of reinforcement with concrete. By using of textile reinforcement very thin structures could be created. The aim of this paper was to determine the interaction conditions of carbon and basalt composite reinforcement in a matrix of epoxy resin with high performance concrete (HPC). The tensile strength of used composite reinforcement and the other mechanical parameters of HPC were determined by experimental tests. Experiments copied the production method of technical textiles. These two combinations of materials present the influence on the design of the structures with textile reinforcements.

The Effect of Surface Treatments of Textile Reinforcement on Mechanical Parameters of HPC Facade Elements

2016 ◽  
Vol 677 ◽  
pp. 203-206 ◽  
Author(s):  
Tomáš Vlach ◽  
Lenka Laiblová ◽  
Michal Ženíšek ◽  
Alexandru Chira ◽  
Anuj Kumar ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Cover ◽  
Silica Sand ◽  
Bending Test ◽  
Textile Reinforced Concrete ◽  
Modern Material ◽  
Significant Saving ◽  
Technical Textiles ◽  
Thin Elements

Development of extremely thin concrete structures and demand for extremely thin elements are the reason of using composite non-traditional materials as reinforcement. Steel reinforcement is not very chemically resistant and it limits the thickness because of the required concrete cover as protection. This is the reason why textile reinforced concrete (TRC) going to be very famous and modern material. TRC in combination with fine grain high performance concrete (HPC) allows a significant saving of concrete. Due to its non-corrosive properties of composite technical textiles it is possible to design very subtle structures and elements. TRC and HPC in general are developed at the Faculty of Civil Engineering and the Klokner Institute, CTU in Prague. This present paper investigates the cohesion influence of textile reinforcement on four point bending test. All small experimental panels were reinforced with the same 3D technical textile from AR-glass roving with different type of cover layer. Different conditions of interaction between technical textiles and HPC were ensured by modified surface using silica sand and silica flour.

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.

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.

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.

Shear behavior of large stud shear connectors embedded in ultra-high-performance concrete

2020 ◽  
Vol 23 (16) ◽  
pp. 3401-3414
Author(s):  
Yuqing Hu ◽  
Huiguang Yin ◽  
Xiaomeng Ding ◽  
Shuai Li ◽  
JQ Wang
Keyword(s):  
Numerical Analysis ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Slab ◽  
Shear Behavior ◽  
Shear Capacity ◽  
Ultra High Performance Concrete ◽  
Shear Connectors ◽  
Push Out ◽  
Static Shear

In this article, the static shear behavior of large-headed studs embedded in ultra-high-performance concrete was investigated by push-out test and numerical analysis. A total of nine push-out specimens with single and grouped studs embedded in ultra-high-performance concrete and normal strength concrete slabs were tested. In the testing process, only shank failure appeared without cracks occurring on the surface of ultra-high-performance concrete slab when the steel–ultra-high-performance concrete specimens reached ultimate shear capacity. The shear capacity of specimens with large studs embedded in ultra-high-performance concrete slab increased by 10.6% compared those in normal concrete, and the current design codes such as Eurocode4, AASHTO LFRD 2014, and GB50017-2003 all underestimate the shear capacity of such kind of steel–ultra-high-performance concrete composite structures according to experimental results. Numerical models were established using ABAQUS with introducing damage plasticity material model. The influence of stud diameter, concrete strength, thickness of clear cover, and spacing of studs on the static shear behavior was thoroughly investigated via parametric analysis. Based on the experimental and numerical analysis, the existence of wedge block and the decrease of axis force are beneficial for improving the shear capacity of stud shear connectors.

Effects of Fly Ash Particle Sizes on the Compressive Strength and Fracture Toughness of High Performance Concrete

2011 ◽  
Vol 284-286 ◽  
pp. 984-988
Author(s):  
An Shun Cheng ◽  
Yue Lin Huang ◽  
Chung Ho Huang ◽  
Tsong Yen
Keyword(s):  
Fracture Toughness ◽  
Particle Size ◽  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Bending Test ◽  
Strength Development ◽  
Particle Sizes

The study aims to research the effect of the particle size of fly ash on the compressive strength and fracture toughness of high performance concrete (HPC). In all HPC mixtures, the water-to-binder ratio selected is 0.35; the cement replacement ratios includes 0%, 10% and 20%; the particle sizes of fly ash have three types of passing through sieves No. 175, No. 250 and No. 325. Three-point-bending test was adopted to measure the load-deflection relations and the maximum loads to determine the fracture energy (GF) and the critical stress intensity factor (KSIC). Test results show that adding fly ash in HPC apparently enhances the late age strengths of HPC either for replacement ratio of 10% or 20%, in which the concrete with 10% fly ash shows the higher effect. In addition, the smaller the particle size is the better the late age concrete strength will be. The HPC with the finer fly ash can have higher strength development and the values of GF and KSIC due to the facts of better filling effect and pozzolanic reaction. At late age, the GF and KSIC values of concrete with 10% fly ash are all higher than those with 20% fly ash.

scholarly journals Damage Assessment using Acoustic Emission on Concrete Beam

2020 ◽  
Vol 9 (3) ◽  
pp. 2977-2981
Keyword(s):  
Acoustic Emission ◽  
Damage Assessment ◽  
High Performance ◽  
High Performance Concrete ◽  
Bending Test ◽  
Ultra High Performance Concrete ◽  
Reliable Technique ◽  
Damage Level ◽  
Three Point Bending ◽  
Selection Of

The selection of reliable technique for damage assessment is important in civil engineering structure. The present study proposed Acoustic emission (AE) technique by using the fundamental AE parameter to evaluate damage accumulated on Ultra High-Performance Concrete (UHPC) specimens. The UHPC beam with dimension of 515 mm x 98 mm x 98 mm was tested under three-point bending test with stepwise flexural load. In order to detect and to collect the AE data, Micro-SAMOS (μ-SAMOS) digital AE system and R6I sensors type were used while data analyses were carried out using AEwin software. The damage level that take place during increasing static loading on tested concrete beams and the mechanism was successfully evaluated using the AE technique.

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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