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Dynamic modulus of elasticity and compressive strength evaluations of modified reactive powder concrete (MRPC) by non-destructive ultrasonic pulse velocity method

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JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 2022年第2期21卷 490-499页

作者： Ghaffari Moghaddam, Farid Akbarpour, Abbas Firouzi, Afshin Islamic Azad Univ Sci & Res Branch Dept Civil Engn Tehran Iran Islamic Azad Univ South Tehran Branch Dept Civil Engn Tehran Iran

This study investigates the method of ultrasonic pulse velocity technique as a non-destructive test for concrete to estimate the mechanical properties of RPC, modified reactive powders concrete (MRPC). This study is based on data obtained from the experimental investigation done in this work and comparison with the data of previous works. After conducting pulse velocity tests on cubic samples, the relationship between pulse velocity, elastic modulus and compressive strength of samples was obtained with an acceptable approximation. Also, the validity of the proposed relation ACI 363.1 and four distinguished researchers regarding the calculation of RPC, MRPC elastic modulus and its comparison with the dynamic elasticity modulus (ASTM C 597) with respect to different materials and mix designs. The dynamic modulus of elasticity (Ed) increased on average by 19% over the modulus of elasticity (Ec). Given the lack of research on the relationship between the parameters mentioned in the MRPC, the present study is an exploratory research concerned with the relationship of these methods. Also, two new models are presented for relating these parameters.

关键词： Modified reactive powder concrete (MRPC) compressive strength sustainability modulus of elasticity pulse velocity non-destructive testing

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Low strength concrete: Stress-strain curve, modulus of elasticity and tensile strength

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STRUCTURES 2022年 38卷 1615-1632页

作者： Ispir, Medine Ates, Ali Osman Ilki, Alper Istanbul Tech Univ Dept Civil Engn TR-34469 Istanbul Turkey Gazi Univ Fac Technol Dept Civil Engn TR-06560 Ankara Turkey

Material characterization of low strength concrete has significant importance for structural/ seismic performance assessments of existing low-quality structures. The main objectives of this study are to characterize the compressive and tensile behaviors of low strength concrete (LSC). For this purpose, an extensive experimental database is formed by collecting available test results and by conducting new tests. The database combines the compression or splitting tension test results of 165 standard concrete cylinders with the compressive strengths ranging from 3.9 to 20.3 MPa. Firstly, the test results are presented by plotting compressive stress-axial strain curves and by calculating moduli of elasticity, axial strains at peak stresses, ultimate axial strains, and tensile strengths. Secondly, the predictive capabilities of available expressions are demonstrated by comparing them with the corresponding experimental results. Thirdly, simple regression analyses are conducted to define the compressive stress-axial strain curves, and the relationships between compressive, tensile strengths, and elastic modulus. Finally, the prediction capabilities of the proposed expressions are evaluated considering the tests, which were not used to establish the proposed expressions and conducted by other researchers. The comparisons show that the proposed expressions can predict the low strength concrete characteristics with good accuracy.

关键词： Low strength concrete modulus of elasticity Tensile strength Stress -strain curve

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Evaluation of the Use of Cellulose, Latex and Metakaolin in the Production of Cement Composites with Low Water Absorption and High modulus of elasticity

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JOURNAL OF NATURAL FIBERS 2022年第4期19卷 1566-1579页

作者： Dos Santos, Lara Cristina Peres Ferreira, Rondinele Alberto Dos Reis Motta, Leila Aparecida De Castro Pasquini, Daniel De Oliveira, Andrielli Morais Univ Fed Uberlandia Civil Engn Sch Uberlandia MG Brazil Univ Fed Uberlandia Chem Inst Uberlandia MG Brazil Univ Fed Goias Civil Engn Sch Goiania Go Brazil

In this work, the aim was to study the influence of cellulose Kraft pulps, natural rubber latex, and metakaolin in the optimization of the values of flexural strength and water absorption of cementitious composites through the design of experiments (central composite design) at 28 days of age. According to the design of experiments, the composite with 1.252% cellulose, 1.126% latex and 37.06% metakaolin presented the optimized value of the modulus of elasticity (21.89 GPa). In addition, an increase in the values of modulus of elasticity for composites with lower cellulose contents was observed. Latex and metakaolin provided small variations in the modulus of elasticity. For water absorption, only cellulose exhibited significant interference. Thus, lower values of water absorption were found for lower concentrations of cellulose. The optimized composite that showed less water absorption was with 1.5% cellulose, 0.02% latex, and 4% metakaolin, with 10.28% absorption. In view of the results obtained, it was concluded that the use of central composite design, the molding method adopted, and the limits of constituents used allowed the optimization the values studied responses (modulus of elasticity, and absorption).

关键词： Absorption cement composites modulus of elasticity natural rubber latex optimization

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Effect of Waste Clay Brick on the modulus of elasticity, Drying Shrinkage and Microstructure of Metakaolin-Based Geopolymer Concrete

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ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022年第10期47卷 12671-12683页

作者： Ahmed, Mahmood F. Khalil, Wasan, I Frayyeh, Qais J. Minist Educ Gen Directorate Educ Anbar Prov Hit 31007 Iraq Univ Technol Baghdad Civil Engn Dept Baghdad 10066 Iraq

This study focuses on utilization of clay brick waste as constituents for metakaolin-based geopolymer concrete (MK-Gpc), and the evaluation of their effect on the modulus of elasticity, shrinkage behavior and microstructure feature. To conduct this experimental study, two groups of MK-Gpc mixtures made with varying contents and forms of brick wastes were prepared, tested and compared with control mix (zero waste content). In first group, clay brick powder was substituted at doses of 10%, 15% and 20% by weight of metakaolin, while the second group consisted of waste clay brick aggregate (BA) as a partial replacement of natural coarse aggregate (NCA) by volume level of 10%, 20% and 30%. It was found that static modulus of elasticity of control mix dropped up to 47% and 56% for specimens with 20%BP and 30%BA, respectively. Test results indicated that the usage of BP increases drying shrinkage of MK-Gpc at early age and tends to decline after 28-day curing. The incorporation of 20%BA showed an adverse effect on shrinkage at all ages while the inclusion of 10% and 30%BA improved the drying shrinkage. The scanning electron microscopy (SEM) images revealed various microstructure features that include porous, microcrack structure and interface bonding zone between geopolymers and recycled waste aggregate, which represent the key factors that are having effects on the MK-Gpc properties.

关键词： Geopolymer concrete Metakaolin Waste clay brick modulus of elasticity Drying shrinkage

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modulus of elasticity predictions through LSBoost for concrete of normal and high strength

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MATERIALS CHEMISTRY AND PHYSICS 2022年 283卷 126007-126007页

作者： Zhang, Yun Xu, Xiaojie North Carolina State Univ Raleigh NC 27695 USA

In the past, empirical equations and some statistical regression approaches have been developed to estimate the modulus of elasticity of concrete. These methods aim at facilitating the application and design of concrete. But the accuracy and stability of these equations and models need further improvements. In this study, the leastsquares boosting model is developed to predict the elastic modulus based on compressive strength for normaland high-strength concrete. The model is highly accurate and stable, generates better predictions than other models reported in the literature, and thus is promising as a fast, robust, and low-cost tool for elastic modulus estimations.

关键词： modulus of elasticity Concrete Compressive strength LSBoost Machine learning

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UHPC modulus of elasticity: Assessment and new developments using companion materials and structural data

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ENGINEERING STRUCTURES 2024年 310卷

作者： Cimesa, Milana Moustafa, Mohamed A. Univ Nevada Dept Civil & Environm Engn Reno NV 89557 USA

The determination of the concrete modulus of elasticity (MOE) plays a crucial role in the analysis and design of structural reinforced and prestressed concrete elements. Various empirical MOE prediction equations have been developed for UHPC. However, most of the existing models have been typically calibrated or developed based on data from one type of UHPC and material tests only. As such, no previous work looked at the MOE prediction equations validity at a large-scale structural level and for the different range of UHPC mixtures that span from economic or non-proprietary lower-end mixtures to robust carbon nanofiber (CNF)-enhanced and high-end mixtures. This research fills this knowledge gap by revisiting the topic of UHPC MOE prediction equations using exclusive companion datasets of materials and full-scale structural tests that also incorporate, for the first time, four different types of UHPC mixtures. In this study, MOE values are estimated from experimentally determined axial stiffness of 22 full-scale UHPC columns with varying cross-sections in conjunction with hundreds of cylinders. The study first compared cylinders and columns-based MOE values, then used the extensive experimental datasets to assess recent and relevant UHPC MOE prediction equations, including what has been proposed for the AASHTO UHPC Structural Design Guide. The results show that while some of the existing prediction models are accurate for traditional UHPC mixtures, all models consistently underestimate MOE for CNF-enhanced UHPC and overestimate it for economic UHPC mixtures with local sand and cement. The paper concludes with a recommendation to account for UHPC mixture type and proposes new modifications for adopting MOE prediction equations for all types of UHPC.

关键词： modulus of elasticity Cylinders Columns Large-scale testing Stiffness Emerging UHPC mixtures Axial behavior

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Modelling and optimization of long-term modulus of elasticity and Poisson's ratio of graphene oxide based engineered cementitious composites by using response surface methodology

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DIAMOND AND RELATED MATERIALS 2024年 143卷

作者： Bheel, Naraindas Mohammed, Bashar S. Univ Teknol PETRONAS Dept Civil & Environm Engn Tronoh 32610 Perak Malaysia

The lack of coarse aggregate is a prominent factor contributing to the relatively low modulus of elasticity (ME) seen in engineered cementitious composites (ECCs). In contrast, the accumulation of graphene oxide (GO) into cementitious composites has resulted in enhancements in their deformation characteristics. However, the ME and Poisson's ratio (PR) of ECC are influenced by the curing period, among several other factors. The objective of the experimental investigation is to examine the impact of GO on the long-term ME and PR of ECC, including different volume fractions of Polyvinyl Alcohol (PVA) fibre. Moreover, the cylindrical specimens (300 mm x 150 mm) were subjected to testing for the parameters ME and PR at two years after exposure to water. Besides, the testing was completed in accordance with the guidelines outlined in ASTM C496. It has been observed that the ME was recorded 30.20 GPa at 0.05 % of GO along with 1 % of PVA fibre which is greater than control mixture while the PR was noted by 0.17 at 0.05 % of GO along with 1 % of PVA which is 15 % lesser than control mixture after two years correspondingly. Based on the findings, the incorporation of GO and the extension of the curing period had a positive influence on the ME and PR of all specimens.

关键词： Graphene oxide Nanoparticles ECC modulus of elasticity Poisson 's ratio

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Effect of varying water cement ratio on modulus of elasticity of high-performance fibre-reinforced concrete (HPFRC)

Effect of varying water cement ratio on modulus of elasticit...

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International Conference on Advances in Construction Materials and Structures (ICCMS)

作者： Shelorkar, Ajay P. Jadhao, Pradip D. MVPSs KBT Engn Dept Civil Engn Nasik 422013 India KKW Inst Engn Educ & Res Dept Civil Engn Nasik 422003 India

This experimental study investigates the outcome of varying water-cement ratios on the modulus of elasticity of HPFRC and the optimization of the water-cement ratio. This study compared modulus of elasticity by using LVDT, UPV and stress-strain relation graph and developed modulus of elasticity equation for HPFRC. The water-cement ratio is taken as the variable. This was accomplished by observing the casting of HPFRC with partial substitution by metakaolin and fly ash. To test the mechanical properties of HPFRC and NC (Normal concrete) specimens with variable water-cement ratios, such as compressive strength and modulus of *** to normal strength concrete, HPFRC (High-Performance Fibre-Reinforced Concrete) shows compressive strength increment and decreases trends in deformations before failure. Hook ended Steel fibre having a length of 50 mm and 0.75 mm diameter used with 2%, 3%, and 4% by volume. The variation of water-cement ratio used as 0.2,0.25,0.3,0.35, and 0.4. The super-plasticiser used was 1.5 percent for all mixes of HPFRC. The compressive strength and modulus elasticity of HPFRC were obtained higher values after 28 days for 2%, 3%, and 4% of fibre replacement with a w/c of 0.25 as 91.9, 94.8, 96.1 MPa and 40400, 42400, 43672 MPa, respectively. The dynamic modulus of elasticity and compressive strength of HPFRC had a significant relationship, with R2 = 0.8782. The findings of the HPRPC tests revealed a greater positive relationship between compressive strength and dynamic modulus of elasticity. Copyright (C) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Advances in Construction Materials and Structures.

关键词： Compression test hooked ended Steel fibre Super plasticiser High-performance fibre reinforced concrete W/C ratio modulus of elasticity

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Moisture Impact on Static and Dynamic modulus of elasticity in Structural Normal-Weight Concretes

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MATERIALS 2024年第15期17卷 3722页

作者： Domagala, Lucyna Marganska, Maria Miazgowicz, Marek Cracow Univ Technol Fac Civil Engn PL-31155 Krakow Poland

In the case of concrete built into a structure, the static secant modulus of elasticity (Ec,s) is often estimated based on its dynamic value (Ed) measured by the ultrasonic pulse velocity method instead of direct tests carried out on drilled cores. Meanwhile, the prevailing equations applied to estimate Ec,s often overlook the impact of concrete moisture. This study aimed to elucidate the moisture impact across two normal-weight structural concretes differing in compressive strength (51.6 and 71.4 MPa). The impact of moisture content was notably more evident only for the weaker concrete, according to dynamic modulus measurements. In other cases, contrary to the literature reports and expectations, this effect turned out to be insignificant. These observations may be explained by two factors: the relatively dense and homogeneous structure of tested concretes and reduced sensitivity of Ec,s measurements to concrete moisture condition compared to Ed measurements obtained using the ultrasonic method. Additionally, established formulas to estimate Ec,s were verified. The obtained modulus results tested under different moisture conditions of normal-weight concretes were also compared with those of lightweight aggregate concretes of identical volume compositions previously obtained in a separate study.

关键词： structural concrete normal-weight aggregate moisture content density ultrasonic pulse velocity compressive strength modulus of elasticity

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Evaluation of modulus of elasticity based on vibration modes identification using acoustic methods

Evaluation of modulus of elasticity based on vibration modes...

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37th Danubia Adria Symposium on Advances in Experimental Mechanics (DAS)

作者： Prezelj, Jurij Emri, Igor Nikonov, Anatolij Univ Ljubljana Fac Mech Engn Askerceva Ul 6 Ljubljana Slovenia Fac Ind Engn Novo mesto Segova Ul 112 Novo Mesto Slovenia

Paper presents an experimental methodology that allows the reconstruction of the modulus of elasticity of thin elastic plates based on vibration mode analysis using a simple microphone to locate nodes by exploiting the properties of an acoustic Very Near Field (VNF). The shape of the plate used in measurements was determined from analytical and FEM simulations of plate vibration under harmonic excitation. The measurements were carried out on a 4 mm thick aluminum plate with the dimensions 200 mm x 900 mm suspended with two elastic strings to achieve FFFF boundary condition. The results showed that the proposed methodology allows accurate prediction of modulus of elasticity for thin plates. In addition, it was found that reliable measurements can be performed at background noise levels (measured in 1/3 octave band) up to 40 *** (c) 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 37th Danubia Adria Symposium on Advances in Experimental Mechanics.

关键词： Acoustic field Sonic resonance modulus of elasticity Plates Vibrations

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