scholarly journals Effect of Temperature and Age of Concrete on Strength – Porosity Relation

10.14311/516 ◽  
2004 ◽  
Vol 44 (1) ◽  
Author(s):  
T. Zadražil ◽  
F. Vodák ◽  
O. Kapičková
Keyword(s):  
Compressive Strength ◽  
Effect Of Temperature

The compressive strengths of unsealed samples of concrete at the age of 180 days and have been measured at temperatures 20 °C, 300 °C, 600 °C and 900 °C. All of tests were performed for cold material. We compared our results with those obtained in [10] for the same type of concrete (age 28, resp. 90 days and measured at temperature ranging from 20 °C to 280 °C). Dependencies of compressive strength and porosity were correlated together and compared for the samples of age 28, 90 and 180 days. Behaviour of concrete of the age 90, resp. 180 days confirms generally accepted hypothesis that with increasing porosity strength of the concrete decreases. It has to be stressed out, howerer, that concrete samples of the age 28 days exhibit totally opposite dependency. 

scholarly journals Temperature Effect on the Compressive Behavior and Constitutive Model of Plain Hardened Concrete

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2801 ◽  
Author(s):  
Ayman El-Zohairy ◽  
Hunter Hammontree ◽  
Eddie Oh ◽  
Perry Moler
Keyword(s):  
Experimental Data ◽  
Compressive Strength ◽  
Temperature Effect ◽  
Modulus Of Elasticity ◽  
Constitutive Models ◽  
Ultimate Strain ◽  
Effect Of Temperature ◽  
Hardened Concrete ◽  
Compressive Behavior ◽  
Stress Strain

Concrete is one of the most common and versatile construction materials and has been used under a wide range of environmental conditions. Temperature is one of them, which significantly affects the performance of concrete, and therefore, a careful evaluation of the effect of temperature on concrete cannot be overemphasized. In this study, an overview of the temperature effect on the compressive behavior of plain hardened concrete is experimentally provided. Concrete cylinders were prepared, cured, and stored under different temperature conditions to be tested under compression. The stress–strain curve, mode of failure, compressive strength, ultimate strain, and modulus of elasticity of concrete were evaluated between the ages of 7 and 90 days. The experimental results were used to propose constitutive models to predict the mechanical properties of concrete under the effect of temperature. Moreover, previous constitutive models were examined to capture the stress–strain relationships of concrete under the effect of temperature. Based on the experimental data and the proposed models, concrete lost 10–20% of its original compressive strength when heated to 100 °C and 30–40% at 260 °C. The previous constitutive models for stress–strain relationships of concrete at normal temperatures can be used to capture these relationships under the effect of temperature by using the compressive strength, ultimate strain, and modulus of elasticity affected by temperature. The effect of temperature on the modulus of elasticity of concrete was considered in the ACI 318-14 equation by using the compressive strength affected by temperature and the results showed good agreement with the experimental data.

Experimental Study on the Strength and Deformation Quality of Granite with Effect of High Temperature

2012 ◽  
Vol 226-228 ◽  
pp. 1275-1278 ◽  
Author(s):  
Xiao Li Xu ◽  
Feng Gao
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
High Temperature ◽  
Reference Value ◽  
Effect Of Temperature ◽  
Rock Crystal ◽  
Brittle Ductile Transition ◽  
Strength And Deformation ◽  
Temperature Strain

Experiments on granite under uniaxial compression at high temperature of 25~850°C and after high temperature of 25~1300°C were conducted to study the effect of temperature on rock strength and deformation quality. The results show that: (1) Fitting curves between temperature strain and thermal expansion coefficient with temperature are closely first order growth exponential function relation at high temperature. Temperature strain has mutagenicity after high temperature, which can not reflect rock deformation law at high temperature exactly. (2)Mechanical properties of granite weak continuously at high temperature. Compressive strength and elastic modulus show second order attenuation trend of exponential law. But mechanical properties show mutation state after high temperature, which is closely related to the alteration of rock crystal form and brittle-ductile transition. Regression curves between compressive strength and elastic modulus with temperature are closely polynomial curve. The results reflect the fundamental regulation of granite’s interior structure changing under the action of different temperature, which will provide some reference value to rock engineering involved in high temperature.

scholarly journals Penggunaan Menthol untuk Bahan Konsolidan Cagar Budaya Arang

2019 ◽  
Vol 13 (1) ◽  
pp. 3-11
Author(s):  
Moh Habibi ◽  
Dimas Arif Primanda Aji ◽  
Rifqi Kurniadi Suryanto ◽  
Riyanto Prasetiya Lambang ◽  
Arif Gunawan
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Water Content ◽  
Morphological Characteristic ◽  
Solidification Process ◽  
Effect Of Temperature ◽  
Durability Testing ◽  
Site Test ◽  
Excavation Site ◽  
Shape And Size

Penelitian ini bertujuan untuk mengetahui efektivitas penggunaan menthol sebagai bahan konsolidasi sementara cagar budaya pada temuan ekskavasi yang rapuh. Pengujian yang dilakukan meliputi karakteristik morfologi menthol, penetrasi kering dan basah menthol pada ketiga jenis sampel (Arang, Bata, Batu), durabilitas konsolidasi sementara menthol pada sampel, dan kuat tekan. Hasil penelitian menunjukkan bahwa proses solidifikasi menthol dimulai pada bagian tepi dan membentuk bentukan seperti jarum (whisker). Penetrasi menthol pada sampel sangat dipengaruhi oleh bentuk dan ukuran partikel sampel serta kandungan air yang terdapat pada sampel. Untuk pengujian durabilitas, pengaruh suhu sangat besar terhadap durabilitas konsolidasi menthol. Semakin tinggi suhu lingkungan, maka semakin cepat pula proses sublimasi menthol. Hasil uji kuat tekan sangat dipengaruhi oleh ukuran partikel sampel, semakin kecil ukuran partikel sampel yang terkonsolidasi menthol, maka semakin tinggi pula nilai kuat tekan yang dihasilkan. Dari hasil penelitian ini dapat disimpulkan bahwa menthol dapat digunakan sebagai bahan konsolidan sementara cagar budaya arang. This study aims to determine the effectiveness of the use of menthol as temporary consolidant for fragile heritage findings on the excavation site. Test includes morphological characteristic of menthol, dray and wet penetration of menthol to three type of sample (charcoal, stone, and brick), durability, and compressive strength. The results show that the menthol solidification process starts at the edges and forms a shape like whiskers. Menthol penetration is strongly influenced by the shape and size of the sample and also water content in the samples. For durability testing, the effect of temperature is very significant on the durability of menthol consolidation. The higher the temperature, the faster the menthol sublimation process will be. Whereas for compressive strength is highly influenced by particle size of the consolidated sample, the smaller consolidated sample the higher compressive strength produced. From this study it can be concluded that menthol can be used as a temporary consolidant material for the fragile heritage findings.

scholarly journals Effect of Temperature on Concrete Carbonation Performance

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Peng Liu ◽  
Ying Chen ◽  
Zhiwu Yu ◽  
Rongling Zhang
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Strain Curve ◽  
Crystal Form ◽  
Surface Strain ◽  
Effect Of Temperature ◽  
Linear Segment ◽  
Hydration Products ◽  
Carbonation Depth ◽  
Before And After

In this study, the effect of temperature on macroperformance and microcharacteristic of carbonized concrete was investigated. The carbonation depth, compressive strength, and surface strain of concrete under different simulated environments for 28 d were measured. XRD and ESEM-EDS analysis were conducted to present the phase composition, types of hydration products, and microstructure characteristics of samples before and after carbonation. The results showed that the effects of temperature on carbonation depth, strain, and compressive strength were significant. There was a linear relation between temperature and carbonation depth as well as compressive strength of concrete. The effects of environment factors on concrete surface strain after carbonation manifested as the strain value and the slope of linear segment of strain curve. Significant differences of phase composition and hydration products were observed before and after the carbonation, which mainly manifested as attenuation and disappearance of diffraction peaks of hydration products. Temperature affects the crystal form of the carbonation products.

Effect of Temperature and Composition of Palm Oil Fuel Ash on Compressive Strength of Porcelain

2014 ◽  
Vol 660 ◽  
pp. 173-177 ◽  
Author(s):  
Mohamad Zaky Noh ◽  
Hassan Usman Jamo ◽  
Zainal Arifin Ahmad
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Palm Oil ◽  
Ball Mill ◽  
Effect Of Temperature ◽  
Mixed Powder ◽  
Palm Oil Fuel Ash ◽  
Fuel Ash ◽  
Substitute Material ◽  
Oil Fuel

The treated palm oil fuel ash (POFA) is used as a substitute material in producing an improved porcelain ceramics. Most of the POFA is posed as waste in landfills, causing environmental and other problems. The POFA is grounded in a ball mill until the particle size is reduced to about 50 μm. Then it is heated at a temperature of 600 oC for 1.5 h in an electric furnace. About 5 wt% to 25 wt% of POFA is used to substitute quartz in porcelain composition. The mixed powder is then pressed into pellets at pressure of 91 MPa. All the pellets are sintered at a temperature of 1000 oC, 1100 oC, 1200 oC and 1280 oC for 2.0 h soaking times. It is found that the highest compressive strength, 45 MPa is obtained at 15 wt% of POFA and sintered at 1100 oC. The improvement in the properties could be attributed to the changes in the microstructural features as a result of an increase in mullite and cristobalite simultaneously.

scholarly journals Behavior of HPC with Fly Ash after Elevated Temperature

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Huai-Shuai Shang ◽  
Ting-Hua Yi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Ultrasonic Velocity ◽  
High Performance ◽  
Elevated Temperatures ◽  
High Performance Concrete ◽  
Surface Characteristics ◽  
Effect Of Temperature ◽  
Cleavage Strength

For use in fire resistance calculations, the relevant thermal properties of high-performance concrete (HPC) with fly ash were determined through an experimental study. These properties included compressive strength, cubic compressive strength, cleavage strength, flexural strength, and the ultrasonic velocity at various temperatures (20, 100, 200, 300, 400 and 500∘C) for high-performance concrete. The effect of temperature on compressive strength, cubic compressive strength, cleavage strength, flexural strength, and the ultrasonic velocity of the high-performance concrete with fly ash was discussed according to the experimental results. The change of surface characteristics with the temperature was observed. It can serve as a reference for the maintenance, design, and the life prediction of high-performance concrete engineering, such as high-rise building, subjected to elevated temperatures.

scholarly journals Temperature Effect on Mechanical Properties and Damage Identification of Concrete Structure

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Yubo Jiao ◽  
Hanbing Liu ◽  
Xianqiang Wang ◽  
Yuwei Zhang ◽  
Guobao Luo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Temperature Effect ◽  
Modulus Of Elasticity ◽  
Damage Identification ◽  
Coupling Effect ◽  
Concrete Slab ◽  
Splitting Tensile Strength ◽  
Effect Of Temperature

Static and dynamic mechanical properties of concrete are affected by temperature effect in practice. Therefore, it is necessary to investigate the corresponding influence law and mechanism. This paper demonstrates the variation of mechanical properties of concrete at temperatures from −20°C to 60°C. Temperature effects on cube compressive strength, splitting tensile strength, prism compressive strength, modulus of elasticity, and frequency are conducted and discussed. The results indicate that static mechanical properties such as compressive strength (cube and prism), splitting tensile strength, and modulus of elasticity have highly linear negative correlation with temperature; this law is also applied to the first order frequency of concrete slab. The coupling effect of temperature and damage on change rate of frequency reveals that temperature effect cannot be ignored in damage identification of structure. Mechanism analysis shows that variation of elastic modulus of concrete caused by temperature is the primary reason for the change of frequency.

The Effect of Temperature on Tensile and Compressive Strengths and Young's Modulus of Oil Shale

1979 ◽  
Vol 19 (05) ◽  
pp. 301-312 ◽  
Author(s):  
P.J. Closmann ◽  
W.B. Bradley
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Young’S Modulus ◽  
Oil Shale ◽  
Room Temperature ◽  
Young's Modulus ◽  
Effect Of Temperature ◽  
Triaxial Tests ◽  
Process Conditions ◽  
Decomposition Pressure

Abstract The analysis of underground oil-shale recovery processes requires knowledge of the mechanical properties of oil shale at various temperatures. The tensile strength, compressive strength, and Young's modulus are of special importance. The variation of these properties with temperature is important when assessing the strength of underground columns and confining walls for process cavities. This paper presents the results of an experimental study to quantify this temperature dependence. We found that both tensile and compressive strengths of oil shale show a marked decrease in strength as temperature increased, for a given richness. For example, for 15.6 gal/ton oil shale, the tensile strength at 400 deg. F is only 28% of its room temperature value. For 19.2 gal/ton shale, the compressive strength at 400 deg. F with 500-psi confining pressure is 43% of its value at room temperature. At a given temperature, both the tensile and compressive strengths decrease as richness increases, although the rate of decrease diminishes at richnesses of about 42 gal/ton and higher. Equations are developed to permit estimates of the various parameters involved. The compressive Young's moduli show a considerable decrease with temperature. At 400 deg. F the modulus is reduced to 51% of its room temperature value. Introduction In-situ processes for recovery of oil from nahcolite-bearing oil shale usually involve some heating or pyrolysis of the shale. Wet processes (steam, hot water) also involve dissolution of nahcolite to generate pore space and to create permeability. If the leaching of nahcolite is conducted at a sufficiently high temperature, some stress will develop in the rock beyond the heated cavity boundary because of CO2 generation and possibly water vapor, as follows. 2NaHCO3 goes to Na2CO3 + H2O + CO2. When the decomposition pressure of nahcolite is high enough, the rock tends to fracture ("popcorn effect"). Rubbling of the formation then can occur. To predict conditions suitable for fracturing and rubbling, we need to know how the rock tensile strength varies with temperature. McLamore measured the oil-shale tensile strength as a function of orientation of stress. So far as we know, no measurements of tensile strength as a function of temperature have been reported for oil shale. We also need to know the variation of nahcolite decomposition pressure with temperature. This pressure variation was measured by Templeton. The variation of Young's modulus, compressive strength, and Poisson's ratio also have been reported for various richnesses. Logan and Heard studied the compressive Young's modulus and thermal expansion as functions of richness. Compressive strength of oil shale has been studied extensively. This parameter was measured as a function of oil-shale richness for various confining pressures in triaxial tests at temperatures up to 300 deg. C (572 deg. F). The effect of temperature on rocks other than oil shale has also been studied. Knowledge of the compressive strength is important when assessing the possibility of failure of underground supporting walls in mines or with process cavities. Since the reacted oil shale probably will support the walls or the roofs of the process cavities very little, the strength of the supporting walls and roof under process conditions will determine the tendency for subsidence or intercavity communication. SPEJ P. 301^

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