scholarly journals Study the Fire Resistance of Desert Sand Concrete (DSC) with Interface Phase through Uniaxial Compression Tests and Analyses

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Qian Zhang ◽  
Haifeng Liu ◽  
Qiang Liu ◽  
Jialing Che ◽  
Weiwu Yang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Fire Resistance ◽  
Elevated Temperatures ◽  
Fine Aggregate ◽  
Compression Tests ◽  
Desert Sand ◽  
Simulation Results

The shortage of sand resources and high-rise building fires are becoming increasingly prominent. Desert sand (DS) with smaller particles can effectively fill the concrete voids and further improve its working performance; it is used as a fine aggregate to produce concrete. This article studied the performance of desert sand concrete (DSC) against fire resistance by using mathematical modeling for simulation. The stress-strain curves of desert sand mortar (DSM) after elevated temperatures were tested, and the constitutive model was established. By comparing the experiment and simulation results, it was verified that the model is suitable to be adopted in this study. Data from experiment and past literature can serve as parameters for the subsequent simulation. The destruction process of DSC under uniaxial compression after elevated temperature was simulated by using ANSYS. The simulation results indicated that, after elevated temperature, compressive strength reduced with increase of interface thickness. The compressive strength of DSC had a substantially linear increase as the interface compressive strength increased. For two-grade coarse aggregate, the optimum volume content was 45%, and particle size of it showed a significant effect on the compressive strength of DSC. The DSM constitutive model and simulation results can provide a sound theoretical basis and technical support for DSC engineering applications.

scholarly journals Compressive Behaviour of Coconut Fibre (Cocos nucifera) Reinforced Concrete at Elevated Temperatures

Fibers ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 5 ◽  
Author(s):  
Gideon Bamigboye ◽  
Ben Ngene ◽  
Omotolani Aladesuru ◽  
Oluwaseun Mark ◽  
Dunmininu Adegoke ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Elevated Temperature ◽  
Fire Resistance ◽  
Elevated Temperatures ◽  
Cocos Nucifera ◽  
Fibre Content ◽  
Cement Concrete ◽  
The World ◽  
Coconut Fibre

Fire outbreaks in buildings have been a major concern in the world today. The integrity of concrete is usually questioned due to the fact that after these fire outbreaks the strength of the concrete is reduced considerably. Various methods have been adopted to improve the fire resistance property of concrete. This study focused on the use of coconut fibre to achieve this feat. In this study, varying percentages of treated and untreated coconut fibres were incorporated into concrete and the compressive strength was tested for both before heating and after heating. The percentages of replacement were 0.25, 0.5, 0.75 and 1% fibre content by weight of cement. Concrete cubes that had 0% fibre served as control specimens. After subjecting these concrete cubes to 250 °C and 150 °C for a period of 2 h, the compressive strength increased when compared to the control. The compressive strength increased up to 0.5% replacement by 3.88%. Beyond 0.5% fibre, the compressive strength reduced. Concrete having coconut fibre that had been treated with water also exhibited the highest compressive strength of 28.71 N/mm². It is concluded that coconut fibres are a great material in improving the strength of concrete, even after it was exposed to a certain degree of elevated temperature.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Isothermal Fatigue Behavior and Damage Modeling of a High Temperature Woven PMC

1999 ◽  
Vol 122 (1) ◽  
pp. 62-68 ◽  
Author(s):  
A. L. Gyekenyesi
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Stiffness Degradation ◽  
Fatigue Properties ◽  
Residual Compressive Strength ◽  
Stiffness Reduction ◽  
Fatigue Damage Accumulation ◽  
Strength Tests

This study focuses on the fully reversed fatigue behavior exhibited by a carbon fiber/polyimide resin woven laminate at room and elevated temperatures. Nondestructive video edge view microscopy and destructive sectioning techniques were used to study the microscopic damage mechanisms that evolved. The elastic stiffness was monitored and recorded throughout the fatigue life of the coupon. In addition, residual compressive strength tests were conducted on fatigue coupons with various degrees of damage as quantified by stiffness reduction. Experimental results indicated that the monotonic tensile properties were only minimally influenced by temperature, while the monotonic compressive and fully reversed fatigue properties displayed greater reductions due to the elevated temperature. The stiffness degradation, as a function of cycles, consisted of three stages; a short-lived high degradation period, a constant degradation rate segment covering the majority of the life, and a final stage demonstrating an increasing rate of degradation up to failure. Concerning the residual compressive strength tests at room and elevated temperatures, the elevated temperature coupons appeared much more sensitive to damage. At elevated temperatures, coupons experienced a much larger loss in compressive strength when compared to room temperature coupons with equivalent damage. The fatigue damage accumulation law proposed for the model incorporates a scalar representation for damage, but admits a multiaxial, anisotropic evolutionary law. The model predicts the current damage (as quantified by residual stiffness) and remnant life of a composite that has undergone a known load at temperature. The damage/life model is dependent on the applied multiaxial stress state as well as temperature. Comparisons between the model and data showed good predictive capabilities concerning stiffness degradation and cycles to failure. [S0742-4795(00)01001-2]

Mechanical Behavior of 2D C/SiC Composites at Elevated Temperatures under Uniaxial Compression

2011 ◽  
Vol 462-463 ◽  
pp. 1-6 ◽  
Author(s):  
Tao Suo ◽  
Yu Long Li ◽  
Ming Shuang Liu
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Carbon Fiber ◽  
Mechanical Behavior ◽  
Uniaxial Compression ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Carbon Matrix ◽  
Structural Applications ◽  
Sic Composites

As Carbon-fiber-reinforced SiC-matrix (C/SiC) composites are widely used in high-temperature structural applications, its mechanical behavior at high temperature is important for the reliability of structures. In this paper, mechanical behavior of a kind of 2D C/SiC composite was investigated at temperatures ranging from room temperature (20C) to 600C under quasi-static and dynamic uniaxial compression. The results show the composite has excellent high temperature mechanical properties at the tested temperature range. Catastrophic brittle failure is not observed for the specimens tested at different strain rates. The compressive strength of the composite deceases only 10% at 600C if compared with that at room temperature. It is proposed that the decrease of compressive strength of the 2D C/SiC composite at high temperature is influenced mainly by release of thermal residual stresses in the reinforced carbon fiber and silicon carbon matrix and oxidation of the composite in high temperature atmosphere.

Recycled Concrete Using Crushed Construction Waste Bricks Subject to Elevated Temperatures

2010 ◽  
Vol 152-153 ◽  
pp. 1-10
Author(s):  
Chung Ming Ho ◽  
Wei Tsung Tsai
Keyword(s):  
Compressive Strength ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
Plain Concrete ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Recycled Concrete ◽  
Fine Aggregate ◽  
Term Performance

The objectives of this paper are to find the compressive strength and ultrasonic pulse velocity (UPV) of recycled concrete with various percentages of natural fine aggregate replaced by Recycled brick fine aggregate (RBFA) as well as the residual strength and residual UPV of recycled concrete subjected to elevated temperatures. Experiment results showed that the compressive strength and UPV decreased as amount of RBFA in concrete increased, the long-term performance of compressive strength and UPV development increased as the RBFA content increased. The residual strength of recycled concrete increased slightly after heating to 300°C and the residual UPV of recycled concrete decreased gradually as the exposed temperature increased beyond 300°C. In the range of 580 -800°C, recycled concrete lost most of its original compressive strength and UPV. After subjected to the temperature of 800°C, compared to plain concrete, recycled concrete with 100% RBFA had a greater discount rate of compressive strength and UPV of the order of 5-15% and 6-10%. Regression analysis results revealed that the residual strength and residual UPV of recycled concrete had a high relevance after elevated temperatures exposure.

Strength Recovery of Lightweight Concrete under Elevated Temperature

2014 ◽  
Vol 905 ◽  
pp. 300-305
Author(s):  
Salim Barbhuiya ◽  
Tommy Lo ◽  
Shazim Memon ◽  
Hamid Nikraz
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Relative Humidity ◽  
Elevated Temperatures ◽  
Lightweight Concrete ◽  
Curing Conditions ◽  
Strength Recovery ◽  
Curing Methods ◽  
Limited Application ◽  
Water Curing

This research is aimed at investigating the effect of elevated temperature, curing duration and curing methods on the strength recovery of lightweight concrete. Concrete specimens were subjected to elevated temperatures ranging from 300 to 600°C in a controlled heating environment. The specimens were subjected to three types of curing conditions: continuous water curing at 27°C, curing in a relative humidity of 95% at 27°C and curing in water at 60°C for three days and then curing in water at 27°C. The curing duration ranged from 7 to 56 days. The results indicated that the re-curing of concrete for the recovery of compressive strength is most effective in the temperature range from 300 to 500°C. For temperatures outside the range of 300 to 500°C, re-curing was either not effective or had limited application.

scholarly journals Feasibility study of compost as a partial substitute for fine aggregate in concrete

2021 ◽  
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Elevated Temperature ◽  
Fine Particles ◽  
Strength Loss ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
Control Specimen ◽  
Sem Image ◽  
Significant Difference

Abstract In this study, vermicompost is replaced for fine aggregate in geopolymer concrete (GPC). Initially mix design is made for GPC and mix proportion is proposed. The vermicompost is replaced at 5%, 10%, 15% and 20% with M sand in GPC. Result indicates the 5% replacement with vermicompost based geopolymer concrete (GPVC) has the compressive strength of 32 N mm−2 (M30 grade) whereas the compressive strength of control specimen made with GPC is 37 N mm−2. Other replacement shows 21 N mm−2, 14 N mm−2 and 11 N mm−2 respectively. The 5% replaced concrete cubes and control specimen are tested at an elevated temperature of 200°C, 400°C, 600°C and 800°C and compared with the control specimen. There is no significant difference observed in weight lost at control (GPC) and GPVC specimen. An elevated temperature, the weight loss is almost 4% at 200°C because of expulsion of water from the concrete. Afterwards only 2% weight loss is observed in remaining elevated temperature. The compressive strength loss is observed at an elevated temperature in GPC and GPVC specimen because of thermal incompatibility between aggregate and the binder. EDX results show M sand and compost contains Si, Al, C, Fe, Ca, Mg, Na and K and it is similar in the elemental composition and SEM image confirms vermicompost contains fine particles.

scholarly journals Tensile Performance, Lap-Splice Length and Behavior of Concretes Confined by Prefabricated C-FRCM System

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Donguk Choi ◽  
Sorrasak Vachirapanyakun ◽  
Munckhtuvshin Ochirbud ◽  
Undram Naidangjav ◽  
Sangsu Ha ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Plain Concrete ◽  
Tensile Tests ◽  
Fine Aggregate ◽  
Compression Tests ◽  
Carbon Fabric ◽  
Direct Tension ◽  
Lap Splice ◽  
Nominal Strength ◽  
Tensile Performance

AbstractResults of an experimental study aimed to evaluate tensile performance, lap-splice length of carbon fabric-reinforced cementitious matrix system (C-FRCM), and performance of concretes confined by C-FRCM are presented. Green high-strength mortar was used in this study which actively utilized recycled fine aggregate and fine waste glass powder to partially substitute cementitious binder. Test plans were developed in due consideration of prefabricated C-FRCM for strengthening concrete columns: 14 tensile tests, 12 lap-splice tests, and 6 uniaxial compression tests of plain concrete specimens confined by C-FRCM were performed. Test variable for the tensile test was number of fabric layers (one or two layers). Nominal strength of the C-FRCM with two fabric layers was 11.0 MPa while it was 7.4 MPa with one fabric layer in tension. Full strength of the carbon fabric was developed in all tensile tests while the C-FRCM with two fabric layers (with axial fiber amount = 0.59% by vol.) showed pseudo-ductile behavior. From the lap-splice tests in direct tension, an increased lap-splice length was required for the double fabrics over that for the single fabrics. The required splice length was about 170 mm for the single fabrics and it was about 310 mm for the double fabrics. Plain concrete cylinders and prismatic specimens were laterally confined by C-FRCM and subjected to uniaxial compression. All test results showed strain-softening behavior. Compressive strength increased by 10–41% while ductility also increased by 6–45% indicating applicability of the prefabricated type C-FRCM in the future.

scholarly journals The effect of elevated temperature on the lightweight concrete containing waste PET aggregate

2018 ◽  
Vol 6 (3) ◽  
pp. 1-14
Author(s):  
Semiha Akçaözoğlu
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Structural Integrity ◽  
Elevated Temperatures ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
Lightweight Aggregate ◽  
Unit Weight ◽  
Residual Compressive Strength ◽  
Flexural Tensile Strength

In this study, the effect of waste PET as lightweight aggregate (WPLA) replacement with conventional aggregate on the some physical and mechanical properties and residual compressive strength of concrete was investigated. For this purpose, five different mixtures were prepared (the reference mixture and four WPLA mixtures including 30%, 40%, 50% and 60% waste PET aggregate by volume). The fresh and dry unit weights, compressive strengths, flexural-tensile strengths, water absorption and porosity ratios of the mixtures were measured. In addition the specimens exposed to elevated temperatures at 150, 300 and 450 °C and the residual compressive strengths were measured. Test results indicated that the unit weight, compressive strength and flexural-tensile strength of the specimens decreased as the amount of WPLA increased in concrete. After exposing to elevated temperature, WPLA mixtures retained their structural integrity and compressive strengths at 150 °C and 300 °C. However there was a significant decrease in the residual compressive strength values of WPLA mixtures at 450 °C.

scholarly journals Uniaxial Compression Behavior of Cement Mortar and Its Damage-Constitutive Model Based on Energy Theory

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1309 ◽  
Author(s):  
Yunliang Tan ◽  
Qingheng Gu ◽  
Jianguo Ning ◽  
Xuesheng Liu ◽  
Zhichuang Jia ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Uniaxial Compression ◽  
Loading Rate ◽  
Cement Mortar ◽  
Axial Stress ◽  
Great Influence ◽  
Strain Curve ◽  
Compression Tests ◽  
Whole Process ◽  
Damage Constitutive Model

The mechanical properties of mortar materials in construction are influenced both by their own proportions and external loads. The trend of the stress–strain curve in cracks compaction stage has great influence on the relationship between the strength and deformation of cement mortar. Uniaxial compression tests of mortar specimens with different cement–sand ratios and loading rates were carried out, and the stored and dissipated energies were calculated. Results indicated that the elastic modulus and strength of mortar specimens increase with the cement–sand ratio and loading rate. The energy dissipation shows good consistency with the damage evolution. When the loading rate is less than 1.0 mm/min, most of the constitutive energy at the peak point is stored in the specimen and it increase with cement–sand ratio. A simple representation method of axial stress in cracks compaction stage was proposed and an energy-based damage constitutive model—which can describe well the whole process of cement mortar under uniaxial compression—was developed and verified.

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