scholarly journals Behavior of High Strength Concrete Subjected to Elevated Temperature

2019 ◽  
Vol 9 (2) ◽  
pp. 2997-3000
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
High Strength ◽  
Air Cooling ◽  
Split Tensile Strength ◽  
Strength Concrete ◽  
Hardened Properties ◽  
Compressive Strength Of Concrete

The High strength concrete defined as per IS 456 as the concrete having characteristic compressive strength more than 65 MPa. The concrete when subject to fire i.e. elevated temperatures loses its properties at a rapid rate. In the present investigation, ordinary vibrated concrete of M90 grade was developed as per the IS 10262. The hardened properties of concrete like compressive strength and split tensile strength were determined for concrete at ordinary temperature. The concrete specimens were subjected to elevated temperatures of 400oC, 600 oC, and 800 oC and then the specimens were brought to room temperature under different cooling regimes like air cooling and water quenching. The compressive residual strength of concrete was determined and a typical compared was made with the control specimen. The decrease in compressive strength of concrete at 800 oC was high compared to that at 400 oC.

scholarly journals Effect of Steel Fiber Aspect Ratio on the Properties of High Strength Self Compacting Concrete

2019 ◽  
Vol 9 (2) ◽  
pp. 2938-2941
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Steel Fibers ◽  
Self Compacting Concrete ◽  
Split Tensile Strength ◽  
Strength Concrete ◽  
Fiber Aspect Ratio ◽  
Aspect Ratios ◽  
Hardened Properties

The High strength concrete defined as per IS 456 as the concrete having characteristic compressive strength more than 65 MPa. The self-compacting concrete has lot of advantages including concreting at congested reinforcement locations, better finish, good compaction etc. The inclusion of fibers in the concrete mix decreases the brittle nature of concrete thereby the ductility increases. Different types of fibers are available for inclusion in concrete like steel, glass, polypropylene, basalt, etc. In the present investigation, high strength concrete having characteristic strength of 90 MPa was developed and hooked ended steel fibers are used and the hardened properties are determined. Steel fibers having diameter of 1 mm and lengths of 25 and 50 mm were added to concrete in 0.125%, 0.25% and 0.5% by volume of concrete. Three hardened properties compressive strength, split tensile Strength and flexural strength were determined. Out of the two lengths of fiber i.e with two aspect ratios, the fiber with 50 mm length yielded better results.

Effect of Chopped Basalt Fiber on the Fresh and Hardened Properties of Fly Ash High Strength Concrete

2014 ◽  
Vol 567 ◽  
pp. 381-386 ◽  
Author(s):  
Nasir Shafiq ◽  
Muhd Fadhil Nuruddin ◽  
Ali Elheber Ahmed Elshekh ◽  
Ahmed Fathi Mohamed Salih
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Progressive Increase ◽  
Test Results ◽  
Strength Concrete ◽  
Hardened Properties ◽  
Chopped Basalt Fiber

In order to improve the mechanical properties of high strength concrete, HSC, several studies have been conducted using fly ash, FA. Researchers have made it possible to achieve 100-150MPa high strength concrete. Despite the popularity of this FAHSC, there is a major shortcoming in that it becomes more brittle, resulting in less than 0.1% tensile strain. The main objective of this work was to evaluate the fresh and hardened properties of FAHSC utilizing chopped basalt fiber stands, CBFS, as an internal strengthening addition material. This was achieved through a series of experimental works using a 20% replacement of cement by FA together with various contents of CBFS. Test results of concrete mixes in the fresh state showed no segregation, homogeneousness during the mixing period and workability ranging from 60 to 110 mm. Early and long terms of compressive strength did not show any improvement by using CBFS; in fact, it decreased. This was partially substituted by the effect of FA. Whereas, the split and flexural strengths of FASHC were significantly improved with increasing the content of CBFS as well as the percentage of the split and flexural tensile strength to the compressive strength. Also, test results showed a progressive increase in the areas under the stress-strain curves of the FAHSC strains after the CBFS addition. Therefore, the brittleness and toughness of the FAHSC were enhanced and the pattern of failure moved from brittle failure to ductile collapse using CBFS. It can be considered that the CBFS is a suitable strengthening material to produce ductile FAHSC.

Properties of High Strength Concrete with Calcined Diatomaceous Earth as Cement Replacement under Compression

2020 ◽  
Vol 402 ◽  
pp. 7-13
Author(s):  
Muttaqin Hasan ◽  
Aris Muyasir ◽  
Taufiq Saidi ◽  
Husaini ◽  
Raudha Azzahra
Keyword(s):  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
High Strength Concrete ◽  
Diatomaceous Earth ◽  
High Strength ◽  
Compression Load ◽  
Strength Concrete ◽  
Cement Replacement ◽  
Concrete Mixtures ◽  
Compressive Strength Of Concrete

In this research, calcined diatomaceous earth from Aceh Besar, Indonesia was used as cement replacement in producing high strength concrete. Four concrete mixtures in which the percentage of cement replacement of 0%, 5%, 10% and 15% by weight were studied. Four cylinder-specimens with 100 mm diameter and 200 mm high were prepared for each mixture. The compression load was applied on the specimens at the age of 28 days until the specimens failed. The mixture without calcined diatomaceous earth was more workable than that with diatomaceous earth. The compressive strength of concrete with diatomaceous earth in this study was almost the same for all mixture. However, those compressive strength was lower than the compressive strength of concrete without calcined diatomaceous earth for about 14.6%. Modulus of elasticity of high strength concrete decreased with increasing of cement replacement percentage.

Structural Behavior of RC Cylinders Confined with High Strength Transverse Reinforcement

2010 ◽  
Vol 163-167 ◽  
pp. 1321-1324
Author(s):  
Sang A. Cha ◽  
Cho Hwa Moon ◽  
Sang Woo Kim ◽  
Kil Hee Kim ◽  
Jung Yoon Lee
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Yield Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Structural Behavior ◽  
Transverse Reinforcement ◽  
Strength Concrete ◽  
High Rise ◽  
Compressive Strength Of Concrete

The number of high-rise reinforced concrete (RC) buildings is steadily increasing since 1980’s. The use of high strength concrete is indispensible for high-rise RC construction to ensure sufficient strength of the structure. The effect of high strength concrete can be significantly improved by the use of high strength and large size reinforcing bars. The yield strength of transverse reinforcement is limited in the current design codes to prevent possible sudden concrete failure due to over reinforcement. This paper presents the effects of the yield strength of transverse reinforcement and compressive strength of concrete on the structural behavior of reinforced concrete cylinders. Two parameters were considered in this investigation: compressive strength of concrete and the yield strength of transverse reinforcement (472MPa, 880MPa, and 1,430 MPa). Analytical and experimental results indicated that the structural behavior of RC cylinders confined with high strength transverse reinforcement is strongly influenced by compressive strength of concrete.

scholarly journals The Use of Fly Ash as Additive Material to High Strength Concrete

2018 ◽  
Vol 20 (2) ◽  
pp. 65-70
Author(s):  
Endah Kanti Pangestuti ◽  
Sri Handayani ◽  
Mego Purnomo ◽  
Desi Christine Silitonga ◽  
M. Hilmy Fathoni
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength Concrete ◽  
Building Materials ◽  
High Strength ◽  
Coal Waste ◽  
Normal Concrete ◽  
Strength Concrete ◽  
Concrete Mixtures ◽  
Compressive Strength Of Concrete

Abstract. The use of coal waste (Fly Ash) is currently being developed in building materials technology, as a high-strength concrete mix material. This study aims to determine the strength of concrete by adding fly ash as a substitute for cement in high-strength concrete mixtures. This research was conducted with an experimental method to obtain results and data that would confirm the variables studied. The total number of specimens used in this study were 36 pieces with different sizes of cube tests which were 15 cm x 15 cm x 15 cm. A total of 36 concrete samples were used to test the compressive strength of concrete with a percentage of Fly Ash in  0% (normal concrete), 20%, 25% and 30% with a concrete treatment age of 7 days, 21 days and 28 days. A total of 12 more samples were used to test water absorption in concrete at 28 days of maintenance. Each percentage percentage of Fly Ash uses 3 concrete test samples. The increase in compressive strength occurs at 7, 21 and 28 days in concrete. However, the compressive strength of concrete produced by concrete using the percentage of Fly Ash is always lower than the value of normal concrete compressive strength. From testing the compressive strength of concrete at 28 days of treatment with content of 0%, 20%, 25% and 30% Fly Ash obtained results of 45.87 MPa, 42.67 MPa, 40.89 MPa, and 35.27 MPa respectively

scholarly journals Fire Performance of Heavyweight Self-Compacting Concrete and Heavyweight High Strength Concrete

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 822 ◽  
Author(s):  
Farhad Aslani ◽  
Fatemeh Hamidi ◽  
Qilong Ma
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Modulus Of Elasticity ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
High Strength ◽  
Self Compacting Concrete ◽  
Strength Concrete ◽  
Magnetite Content ◽  
Hardened State

In this study, the fresh and hardened state properties of heavyweight self-compacting concrete (HWSCC) and heavyweight high strength concrete (HWHSC) containing heavyweight magnetite aggregate with 50, 75, and 100% replacement ratio, and their performance at elevated temperatures were explored experimentally. For fresh-state properties, the flowability and passing ability of HWSCCs were assessed by using slump flow, T500 mm, and J-ring tests. Hardened-state properties including hardened density, compressive strength, and modulus of elasticity were evaluated after 28 days of mixing. High-temperature tests were also performed to study the mass loss, spalling of HWSCC and HWHSC, and residual mechanical properties at 100, 300, 600 and 900 °C with a heating rate of 5 °C/min. Ultimately, by using the experimental data, rational numerical models were established to predict the compressive strength and modulus of elasticity of HWSCC at elevated temperatures. The results of the flowability and passing ability revealed that the addition of magnetite aggregate would not deteriorate the workability of HWSCCs and they retained their self-compacting characteristics. Based on the hardened densities, only self-compacting concrete (SCC) with 100% magnetite content, and high strength concrete (HSC) with 75 and 100% magnetite aggregate can be considered as HWC. For both the compressive strength and elastic modulus, decreasing trends were observed by introducing magnetite aggregate to SCC and HSC at an ambient temperature. Mass loss and spalling evaluations showed severe crack propagation for SCC without magnetite aggregate while SCCs containing magnetite aggregate preserved up to 900 °C. Nevertheless, the mass loss of SCCs containing 75 and 100% magnetite content were higher than that of SCC without magnetite. Due to the pressure build-up, HSCs with and without magnetite showed explosive spalling at high temperatures. The residual mechanical properties analysis indicated that the highest retention of the compressive strength and modulus of elasticity after exposure to elevated temperatures belonged to HWSCC with 100% magnetite content.

scholarly journals Effect of Basalt Fibers on the Properties of High Strength Self-Compacting Concrete.

2019 ◽  
Vol 9 (1) ◽  
pp. 3995-3998
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Basalt Fibers ◽  
Self Compacting Concrete ◽  
Split Tensile Strength ◽  
Strength Concrete ◽  
Aspect Ratios ◽  
Slump Flow ◽  
Flow Test ◽  
Hardened Properties

Concrete having characteristics strength of more than 65 MPa is categorized as high-strength concrete according to IS 456. The high strength concrete is more brittle compared to ordinary strength concrete and inclusion of fibers can increase the ductility of concrete. In the present study, high strength self-compacting concrete of characteristic strength of 90 MPa was developed as per the guidelines of EFNARC. Basalt fibers were considered to investigate its influence on the properties of high strength self compacting concrete. Three aspect ratios of 230, 530 and 600 were considered and are added in proportions of 0.1% and 0.4% by volume of concrete. The properties of concrete determine were fresh and hardened. Fresh properties such as slump flow test, V-funnel test, V-funnel T5 minutes and L-box test were determined as per EFNARC. Also, hardened properties such as compressive strength, split tensile strength and flexural strength were determined. A typical comparison on the effect of aspect ratio of basalt fibers and the dosage on the properties of concrete were determined. From the results, the optimum dosage of fibers was determined.

scholarly journals Effect of size and shape of specimen on compressive strength of glass fiber reinforced concrete (GFRC)

2011 ◽  
Vol 9 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Rao Krishna ◽  
Rathish Kumar ◽  
B. Srinivas
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Glass Fiber ◽  
High Strength Concrete ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Strength Concrete ◽  
Size And Shape ◽  
Glass Fiber Reinforced ◽  
Compressive Strength Of Concrete

Concrete is a versatile material with tremendous applications in civil engineering construction. Structural concrete elements are generally made with concrete having a compressive strength of 20 to 35 MPa. Lately, there is an increase in use of high strength concrete (HSC) in major construction projects such as high-rise buildings, and bridges involving members of different sizes and shapes. The compressive strength of concrete is used as the most basic and important material property in the design of reinforced concrete structures. It has become a problem to use this value as the control specimen sizes and shapes are different from country to country. In India, the characteristic compressive strength is usually measured based on 150 mm cubes [1]. But, the ACI code of practice specifies the design compressive strength based on the standard 150x300 mm cylinders [2]. The use of 100x200 mm cylinders gained more acceptance as the need to test high strength concrete increases [3]. In this context the size and shape of concrete becomes an important parameter for the compressive strength. In view of the significance of compressive strength of concrete and due to the fact that the structural elements of different sizes and shapes are used, it is proposed to investigate the effect of size and shape of the specimen on the compressive strength of concrete. In this work, specimens of plain as well as Glass Fiber Reinforced Concrete (GFRC) specimens are cast in order to carry out a comparative study.

scholarly journals Physical and Mechanical Properties of High-Strength Concrete Modified with Supplementary Cementitious Materials after Exposure to Elevated Temperature up to 1000 °C

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 532 ◽  
Author(s):  
Jianwei Zhou ◽  
Dong Lu ◽  
Yuxuan Yang ◽  
Yue Gong ◽  
Xudong Ma ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Physical Properties ◽  
Water Absorption ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
High Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Concrete

This paper presents the experimental findings of a study on the influence of combining usage of supplementary cementitious materials (SCMs) on the performance of high-strength concrete (HSC) subjected to elevated temperatures. In this study, four types of HSC formulations were prepared: HSC made from cement and fly ash (FA), HSC made from cement and ultra-fine fly ash (UFFA), HSC made from cement and UFFA-metakaolin (MK), and HSC made from cement and FA-UFFA-MK. Mechanical and physical properties of HSC subjected to high temperatures (400, 600, 800, and 1000 °C) were studied. Furthermore, the relation between residual compressive strength and physical properties (loss mass, water absorption, and porosity) of HSC was developed. Results showed that the combined usage of SCMs had limited influence on the early-age strength of HSC, while the 28-d strength had been significantly affected. At 1000 °C, the residual compressive strength retained 18.7 MPa and 23.9 MPa for concretes containing 30% UFFA-5% MK and 10% FA-20% UFFA-5% MK, respectively. The specimen containing FA-UFFA-MK showed the best physical properties when the temperature raised above 600 °C. Combined usage of SCMs (10% FA-20% UFFA-5% MK) showed the lowest mass loss (9.2%), water absorption (10.9%) and porosity (28.6%) at 1000 °C. There was a strongly correlated relation between residual strength and physical properties of HSC exposed to elevated temperatures.

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