On the Properties of Ultra High Strength Concrete With Particular Reference to Heat of Hydration

1984 ◽  
Vol 42 ◽  
Author(s):  
Leif Aarsleff ◽  
Jorn Bredal-Jorgensen ◽  
Ervin Poulsen
Keyword(s):  
Thermal Stress ◽  
Cross Section ◽  
High Strength Concrete ◽  
High Strength ◽  
Heat Of Hydration ◽  
Compression Tests ◽  
Thin Sections ◽  
Strength Concrete ◽  
Penetration Tests ◽  
Cement Compounds

AbstractIt has been observed that the heat of hydration for concrete under practical conditions not only depends on the type of cement and the content of cement and silica fume in the concrete but also depends on the w/c-ratio of the concrete. On.microscopic examination of concrete having low w/c-ratio it has been observed that the cement compounds are left partly unhydrated. However, the unhydrated cement compounds exist for all values of the w/c-ratio, but appear to increase with decreasing value of the w/c-ratio, particularly when w/c < 0.35.This fact wIll influence the present way of estimating the heat of hydration when a thermal stress analysis is to be carried out for an ultra high strength concrete in order to prevent the concrete from crackling due to temperature differences across a massive cross-section.The tests are carried out with concrete having a compression strength greater than 100 MPa (∼ 14,000 psi). In order to obtain samples drilled from the same casting for compression tests, microscopic investigatlon, penetration tests and freezing/thawing-investigation rather large specimens are used. A very effective insulation of the concrete is provided, and the temperature of the concrete is recorded by thermo-couples.The structure of the cement paste is studied using petrographical examination of thin-sections and polished samples. The tests on penetration and freezing/thawing are not dealt with in this paper.

Aseismic Performance Analysis of High-Strength Concrete Circular Pier

2013 ◽  
Vol 431 ◽  
pp. 161-166
Author(s):  
Kang Qi
Keyword(s):  
Reinforced Concrete ◽  
Performance Analysis ◽  
Cross Section ◽  
High Strength Concrete ◽  
Bending Strength ◽  
Bending Moment ◽  
High Strength ◽  
Strength Concrete ◽  
Strength And Ductility

Circular pier are widely used in bridge substructure. Strength and ductility are two important indicators reflect its aseismic performance. Based on the analysis of complete bending moment-curvature curve curvature, bending strength and ductility on reinforced concrete circular pier cross-section, this paper analyzes the aseismic performance of high-strength concrete circular pier. And it can provide reference for using high strength concrete more reasonable.

Failure Probability of Short High-Strength Concrete Tied Columns

2003 ◽  
Vol 19 (2) ◽  
pp. 299-309
Author(s):  
Wen-Yao Lu ◽  
Ing-Juang Lin
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Failure Probability ◽  
High Strength Concrete ◽  
High Strength ◽  
Concrete Columns ◽  
Monte Carlo Technique ◽  
Strength Model ◽  
Strength Concrete ◽  
High Strength Concrete Columns

ABSTRACTThis paper aims to investigate the failure probability of short high-strength concrete tied columns using the Monte Carlo technique. The random variables considered in this study are the strength of concrete, the strength of steels, the cross-section dimensions, the location of the steel reinforcement, the variability of strength model and the loads. The results show that the failure probabilities of high-strength concrete columns designed according to the ACI Code are relatively high. The current ACI Code may not be conservative for design of short high-strength concrete tied columns.

scholarly journals Non-linear Analysis of Slender High Strength Concrete Column

2019 ◽  
Vol 5 (7) ◽  
pp. 1440-1451
Author(s):  
Ernesto Fenollosa ◽  
Iván Cabrera ◽  
Verónica Llopis ◽  
Adolfo Alonso
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Axial Force ◽  
High Strength Concrete ◽  
Bending Moment ◽  
High Strength ◽  
Concrete Columns ◽  
Strength Concrete ◽  
The Moment ◽  
High Strength Concrete Columns

This article shows the influence of axial force eccentricity on high strength concrete columns design. The behavior of columns made of normal, middle and high strength concrete with slenderness values between 20 and 60 under an eccentric axial force has been studied. Structural analysis has been developed by means of software which considers both geometrical and mechanical non-linearity. The sequence of points defined by increasing values of axial force and bending moment produced by eccentricity has been represented on the cross-section interaction diagram until failure for each tested column. Then, diagrams depicting the relationship between failure axial force and column's slenderness have been drawn. The loss of bearing capacity of the member for normal and middle strength columns when compared with the bearing capacity of their cross-section is more noticeable as axial force eccentricity assumes higher values. However, this situation reverses for high strength columns with high slenderness values. On the basis of results obtained, the accuracy level for the moment magnifier method was checked. Despite the good concordance in most of the cases, it was verified that the moment magnifier method leads to excessively tight results for high strength concrete columns with high slenderness values. In these specific cases, a coefficient which amends the column rigidity is proposed so as to obtain safer values.

Analysis of Post-Combustion High-Strength Concrete Compressive Strength Using Polypropylene Fibers

2020 ◽  
Vol 26 (1) ◽  
pp. 118-127
Author(s):  
Teuku Budi Aulia ◽  
Muttaqin Muttaqin ◽  
Mochammad Afifuddin ◽  
Zahra Amalia
Keyword(s):  
Compressive Strength ◽  
Thermal Stress ◽  
Silica Fume ◽  
High Temperatures ◽  
High Strength Concrete ◽  
High Strength ◽  
Polypropylene Fibers ◽  
Concrete Compressive Strength ◽  
Strength Concrete ◽  
Maximum Value

High-strength concrete is vulnerable to high temperatures due to its high density. The use of polypropylene fibers could prevent structure explosion by forming canals due to melted fibers during fire, thus release its thermal stress. This study aims to determine the effect of polypropylene fibers on compressive strength of high-strength concrete after combustion at 400ºC for five hours. High-strength concrete was made by w/c-ratio 0.3 with cement amount 550 kg/m3 and added with silica fume 8% and superplasticizer 4% by cement weight. The variations of polypropylene fibers were 0%, 0.2% and 0.4% of concrete volume. The compression test was carried out on standard cylinders Ø15/30 cm of combustion and without combustion specimens at 7 and 28 days. The results showed that compressive strength of high-strength concretes without using polypropylene fibers decreased in post-combustion compared with specimens without combustion, i.e., 0.81% at 7 days and 23.42% at 28 days. Conversely, the use of polypropylene fibers can increase post-combustion compressive strength with a maximum value resulted in adding 0.2% which are 25.52% and 10.44% at 7 and 28 days respectively. It can be concluded that the use of polypropylene fibers is effective to prevent reduction of high-strength concrete compressive strength that are burned at high temperatures.

Seismic behavior of large-size encased cross-section steel-reinforced high-strength concrete circular columns

Structures ◽  
2021 ◽  
Vol 34 ◽  
pp. 1169-1184
Author(s):  
Hongying Dong ◽  
Xu Liang ◽  
Wanlin Cao ◽  
Huazhen Guo ◽  
Fei Yin
Keyword(s):  
Cross Section ◽  
High Strength Concrete ◽  
Seismic Behavior ◽  
High Strength ◽  
Strength Concrete ◽  
Large Size

scholarly journals Fibrous Reinforcing System to Increase the Shear Resistance of High Strength Concrete

2008 ◽  
Vol 587-588 ◽  
pp. 887-891
Author(s):  
Simão Santos ◽  
Joaquim Barros ◽  
Lúcio Lourenço
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Shear Resistance ◽  
Shear Loading ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Experimental Program ◽  
Compression Tests ◽  
Strength Concrete ◽  
High Strength Fiber

The available research has evidenced that discrete steel fibers can increase significantly the shear resistance of High Strength Concrete (HSC) structural elements when High Strength Fiber Reinforced Concrete (HSFRC) is designed in such way that fiber reinforcing mechanisms are optimized. In general, the increase of the concrete compressive strength is associated to an increase of its compactness, resulting benefits in terms of durability, but a strong concern emerges related to the integrity of this material, since it fails in a too brittle mode when submitted to high temperatures. To contribute for the knowledge about the benefits provided by discrete steel fibers when added to HSC applied to laminar structures, an experimental program composed of slab strips submitted to shear loading configuration was carried out. Uniaxial compression tests with cylinders of 150 mm diameter and 300 mm height, and bending tests with 600×150×150 mm3 beams were executed to assess the compression and bending behavior of the developed HSFRC. To evaluate the influence of the percentage of fibers in the shear resistance of laminar structures, three point loading tests with slab strips of 800×170×150 mm3 dimensions were performed. Taking the obtained experimental results, the applicability of the formulation proposed by RILEM TC 162-TDF was evaluated. Test results showed that, even with relative low dosages of steel fibers, the increment in shear resistance was significantly increased. The main obtained results in the research program are presented and discussed in this paper.

scholarly journals Experimental Study of High Strength Concrete By Alccofine and Bagasse Ash

2021 ◽  
Vol 889 (1) ◽  
pp. 012058
Author(s):  
Harshdeep Vani ◽  
Kaamun ◽  
Sahil Arora
Keyword(s):  
Experimental Study ◽  
Prestressed Concrete ◽  
High Strength Concrete ◽  
Nuclear Power ◽  
Cement Content ◽  
High Strength ◽  
Heat Of Hydration ◽  
Fine Aggregate ◽  
Strength Concrete ◽  
The Cost

Abstract The use of concrete is increasing day to day very rapidly. The lesser the cross-section higher will be the grade of concrete. High-grade concrete is generally used in the nuclear power plant or precast prestressed concrete. The higher the cement content high will be the occurrence of the defect due to heat of hydration in the concrete. This paper deals with the experimental study of high-strength concrete which can be prepared by using the cement content less than the required quantity by using any other supplementary material. Like Alccofine and bagasse ash. Alccofine is costlier than cement which increases the cost of concrete to adjust that cost of concrete the bagasse ash is been used in the place of fine aggregate.

Moment-Curvature Relationship Analysis of High-Strength Concrete Shear Wall

2013 ◽  
Vol 368-370 ◽  
pp. 1539-1546
Author(s):  
Can Song ◽  
Feng Li ◽  
Hua Jing Zhao
Keyword(s):  
Cross Section ◽  
High Strength Concrete ◽  
Shear Failure ◽  
Bending Moment ◽  
Shear Walls ◽  
High Strength ◽  
Shear Wall ◽  
Skeleton Curve ◽  
Strength Concrete ◽  
Relationship Analysis

In order to improve the lateral deformation capacity of the high strength concrete shear wall, partially confined end-zones are usually set in the both ends of the shear wall cross-section. According to the experimental results of 15 high strength concrete shear walls with flexural (flexural-shear) failure, the moment - curvature skeleton curve of this shear wall cross-section is simplified as four linear through cracking point, yield point, peak point and ultimate point. Based on the plane-section assumption, the bending moment and curvature expressions at cracking, yield, peak and ultimate state are derived. At the same time, the effect of partially confined end-zones on peak and ultimate moment-curvature are taken into account. The analysis results show that, the calculated values are in good consistent with the experimental data.

Experimental Study on the Bearing Capacity and Ductility of High Strength Concrete Columns Wrapped with CFRP Cloth

2012 ◽  
Vol 166-169 ◽  
pp. 1333-1336
Author(s):  
Zhong Jun Hu ◽  
Yan Xu
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
High Strength Concrete ◽  
High Strength ◽  
Concrete Columns ◽  
Compression Tests ◽  
Strength Concrete ◽  
Axial Compressive Strength ◽  
High Strength Concrete Columns ◽  
Strength And Ductility

By the axial compression tests on a total of 19 high strength concrete columns wrapped with CFRP cloth, the influence of shape section and different layers on the axial compressive strength and ductility is studied. The experimental results indicated: high strength concrete columns wrapped with CFRP in increasing the bearing capacity and ductility of concrete columns is still valid, its effect on the improvement of ductility is much greater than its capacity.

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