• Title/Summary/Keyword: Engineering Properties of concrete

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Mechanical properties of SFRHSC with metakaolin and ground pumice: Experimental and predictive study

  • Saridemir, Mustafa;Severcan, Metin Hakan;Celikten, Serhat
    • Steel and Composite Structures
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    • v.23 no.5
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    • pp.543-555
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    • 2017
  • The mechanical properties of steel fiber reinforced high strength concrete (SFRHSC) made with binary and ternary blends of metakaolin (MK) and ground pumice (GP) are investigated in this study. The investigated properties are ultrasonic pulse velocity (Upv), compressive strength (fc), flexural strength (ff) and splitting tensile strength (fst) of SFRHSC. A total of 16 steel fiber reinforced concrete mixtures were produced by a total binder content of 500kg/m3 for determining the effects of MK and GP on the mechanical properties. The design fc was acquired from 70 to 100 MPa by using a low water-binder ratio of 0.2. The test results exhibit that high strength concrete can be obtained by replacing the cement with MK and GP. Besides, correlations between these results are executed for comprehending the relationship between mechanical properties of SFRHSC and the strong correlations are observed between these properties. Moreover, two models in the gene expression programming (GEP) for predicting the fc of SFRHSC made with binary and ternary blends of MK and GP have been developed. The results obtained from these models are compared with the experimental results. These comparisons proved that the results of equations obtained from these models seem to agree with the experimental results.

Modeling of chloride diffusion in a hydrating concrete incorporating silica fume

  • Wang, Xiao-Yong;Park, Ki-Bong;Lee, Han-Seung
    • Computers and Concrete
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    • v.10 no.5
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    • pp.523-539
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    • 2012
  • Silica fume has long been used as a mineral admixture to improve the durability and produce high strength and high performance concrete. And in marine and coastal environments, penetration of chloride ions is one of the main mechanisms causing concrete reinforcement corrosion. In this paper, we proposed a numerical procedure to predict the chloride diffusion in a hydrating silica fume blended concrete. This numerical procedure includes two parts: a hydration model and a chloride diffusion model. The hydration model starts with mix proportions of silica fume blended concrete and considers Portland cement hydration and silica fume reaction respectively. By using the hydration model, the evolution of properties of silica fume blended concrete is predicted as a function of curing age and these properties are adopted as input parameters for the chloride penetration model. Furthermore, based on the modeling of physicochemical processes of diffusion of chloride ion into concrete, the chloride distribution in silica fume blended concrete is evaluated. The prediction results agree well with experiment results of chloride ion concentrations in the hydrating concrete incorporating silica fume.

An experimental study on engineering properties of concrete containing fly-ash, slag powder and limestone powder (석회석미분말을 사용한 4성분계 콘크리트의 공학적 특성에 관한 실험적 연구)

  • Hong, Ji-Hoon;Yum, Jun-Haun;Kim, Jung-Bin;Jeong, Yong;Lee, Seong-Yeun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.561-564
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    • 2006
  • This study is aimed for investigating the engineering properties of concrete containing fly ash, slag powder and limestone powder. The results of this study are as follows; As limestone powder is incresed, slump, air loss and strength is reduced, variation ratio of length is reduced, dynamic modulus of elasticity and neutralization depth is incresed.

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Impact Echo Test for the Dynamic Characteristics of a Vibration-Mitigated Concrete Structure

  • Chung, Young-Soo;Park, Young-Goo
    • KCI Concrete Journal
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    • v.14 no.1
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    • pp.23-29
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    • 2002
  • Recent construction activities have given rise to civil petitions associated with vibration-induced damages or nuisances. To mitigate unfavorable effects of construction activities, the measures to reduce or isolate from vibration need to be adopted. In this research, a vibration-mitigated concrete, which is one of the active measures for reducing vibration in concrete structures, was investigated. Concrete was mixed with vibration-reducing materials (i.e. latex, rubber power, plastic resin, and polystyrofoam) to reduce vibration and tested to evaluate dynamic material properties and structural characteristics. Normal and high strength concrete specimens with a certain level of damage were also tested for comparisons. In addition, recycling tires and plastic materials were added to produce a vibration-reducing concrete. A total of 32 concrete bars and eight concrete beams were tested to investigate the dynamic material properties and structural characteristics. Wave measurements on concrete bars showed that vibration-mitigated concrete has larger material damping ratio than normal or high strength concrete. Styrofoam turned out to be the most effective vibration-reducing mixture. Flexural vibration tests on eight flexural concrete beams also revealed that material damping ratio of the concrete beams is much smaller than structural damping ratio for all the cases.

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Experimental & numerical investigation of mechanical properties in steel fiber-reinforced UHPC

  • Dadmand, Behrooz;Pourbaba, Masoud;Sadaghian, Hamed;Mirmiran, Amir
    • Computers and Concrete
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    • v.26 no.5
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    • pp.451-465
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    • 2020
  • This paper presents experimental and numerical investigations on mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC) with four types of steel fibers; micro steel (MS), crimped (C), round crimped (RC) and hooked-end (H), in two fiber contents of 1% and 2% (by volume) and two lengths of 13 and 30 mm. Compression, direct tension, and four-point bending tests were carried out on four types of specimens (prism, cube, dog-bone and cylinder), to study tensile and flexural strength, fracture energy and modulus of elasticity. Results were compared with UHPC specimens without fibers, as well as with available equations for the modulus of elasticity. Specimens with MS fibers had the best performance for all mechanical properties. Among macro fibers, RC had better overall performance than H and C fibers. Increased fibers improved all mechanical properties of UHPFRC, except for modulus of elasticity, which saw a negligible effect (mostly less than 10%). Moreover, nonlinear finite element simulations successfully captured flexural response of UHPFRC prisms. Finally, nonlinear regression models provided reasonably well predictions of flexural load-deflection behavior of tested specimens (coefficient of correlation, R2 over 0.90).

Mechanical and durability properties of self-compacting concrete with blended binders

  • Xie, T.Y.;Elchalakani, M.;Mohamed Ali, M.S.;Dong, M.H.;Karrech, A.;Li, G.
    • Computers and Concrete
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    • v.22 no.4
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    • pp.407-417
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    • 2018
  • Over the past three decades, self-compacting concrete (SCC), which is characterized by its superior rheological properties, has been gradually used in construction industry. It is now recognized that the application of SCC using supplementary cementitious materials (SCM) is highly attractive and promising technology reducing the environmental impact of the construction industry and reducing the higher materials costs. This paper presents an experimental study that investigated the mechanical and durability properties of SCCs manufactured with blended binders including fly ash, slag, and micro-silica. A total of 8 batches of SCCs were manufactured. As series of tests were conducted to establish the rheological properties, compressive strength, and durability properties including the water absorption, water permeability, rapid chloride permeability and initial surface absorption of the SCCs. The influences of the SCC strength grade, blended types and content on the properties of the SCCs are investigated. Unified reactive indices are proposed based on the mix proportion and the chemical composition of the corresponding binders are used to assess the compressive strength and strength development of the SCCs. The results also indicate the differences in the underlying mechanisms to drive the durability properties of the SCC at the different strength grades.

Application Research on Mechanical Strength and Durability of Porous Basalt Concrete

  • Zhu, Yuelei;Li, Jingchun;Zhu, He;Jin, Long;Ren, Qifang;Ding, Yi;Li, Jinpeng;Sun, Qiqi;Wu, Zilong;Ma, Rui;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.32 no.3
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    • pp.115-124
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    • 2022
  • Porous basalt aggregate is commonly used in roadbed engineering, but its application in concrete has rarely been studied. This paper studies the application of porous basalt in concrete. Porous basalt aggregate is assessed for its effects on mechanical strength and durability of prepared C50 concrete; because it has a hole structure, porous basalt aggregate is known for its porosity, and porous basalt aggregates can be made full of water through changing the content of saturated basalt; after full-water condition is achieved in porous basalt aggregate mixture of C50 concrete, we discuss its mechanical properties and durability. The effects of C50 concrete prepared with basalt aggregate on the compressive strength, water absorption, and electric flux of concrete specimens of different ages were studied through experiments, and the effects of different replacement rates of saturated porous basalt aggregate on the properties of concrete were also studied. The results show that porous basalt aggregate can be prepared as C50 concrete. For early saturated porous basalt aggregate concrete, its compressive strength decreases with the increase of the replacement rate of saturated aggregate; this occurs up to concrete curing at 28 d, when the replacement rate of saturated basalt aggregate is greater than or equal to 40 %. The compressive strength of concrete increases with the increase of the replacement rate of saturated aggregate. The 28 d electric flux decreases with the increase of the replacement rate of saturated aggregate, indicating that saturated porous basalt aggregate can improve the chloride ion permeability resistance of concrete in later stages.

Mechanical behavior of hybrid steel-PVA fibers reinforced reactive powder concrete

  • Poorhoseina, Reza;Nematzadeh, Mahdi
    • Computers and Concrete
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    • v.21 no.2
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    • pp.167-179
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    • 2018
  • Reactive powder concrete (RPC) is a type of ultra-high strength cement-based material with a dense microstructure, which is made of ultra-fine powders. RPC demonstrate a very brittle behavior, thus adding fibers improves its mechanical properties. In this study, it was attempted to investigate the effect of using steel and polyvinyl alcohol (PVA) fibers as well as their combination on the properties of RPC. In this regard, hooked-end crimped steel fibers together with short PVA fibers were utilized. Steel and PVA fibers were used with the maximum volume fraction of 3% and 0.75%, respectively, and also different combinations of these fibers were used with the maximum volume fraction of 1% in the concrete mixes. In total, 107 concrete specimens were prepared, and the effect of fiber type and volume fraction on the physico-mechanical properties of RPC including compressive strength, tensile strength, modulus of elasticity, density, and failure mode was explored. In addition, the effect of the curing type on the properties of compressive strength, modulus of elasticity, and density of RPC was evaluated. Finally, coefficients for conversion of cubic compressive strength to cylindrical one for the RPC specimens were obtained under the two curing regimes of heat treatment and standard water curing.

Characteristics of sustainable concrete incorporating recycled coarse aggregates and colloidal nano-silica

  • Mukharjee, Bibhuti Bhusan;Barai, Sudhirkumar V
    • Advances in concrete construction
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    • v.3 no.3
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    • pp.187-202
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    • 2015
  • The present study addresses about the development of sustainable concrete utilizing recycled coarse aggregates manufactured form waste concrete and colloidal Nano-Silica. Experimental investigations are carried out to determine compressive and tensile strength of concrete mixes designed with recycled coarse aggregates and different percentages of Nano-Silica. Moreover, water absorption, density and volume voids of concrete mixes are also examined to ascertain the influence of Nano-Silica on behavior of recycled aggregate concrete. The outcomes of the research depict that properties of concrete mixes are significantly affected with the introduction of recycled coarse aggregates in place of the natural coarse aggregates. However, the study reveals that the depletion of behavior of recycled aggregate concrete could be restored with the incorporation of little amount (3%) of Nano-Silica.

Prediction of fly ash concrete compressive strengths using soft computing techniques

  • Ramachandra, Rajeshwari;Mandal, Sukomal
    • Computers and Concrete
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    • v.25 no.1
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    • pp.83-94
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    • 2020
  • The use of fly ash in modern-day concrete technology aiming sustainable constructions is on rapid rise. Fly ash, a spinoff from coal calcined thermal power plants with pozzolanic properties is used for cement replacement in concrete. Fly ash concrete is cost effective, which modifies and improves the fresh and hardened properties of concrete and additionally addresses the disposal and storage issues of fly ash. Soft computing techniques have gained attention in the civil engineering field which addresses the drawbacks of classical experimental and computational methods of determining the concrete compressive strength with varying percentages of fly ash. In this study, models based on soft computing techniques employed for the prediction of the compressive strengths of fly ash concrete are collected from literature. They are classified in a categorical way of concrete strengths such as control concrete, high strength concrete, high performance concrete, self-compacting concrete, and other concretes pertaining to the soft computing techniques usage. The performance of models in terms of statistical measures such as mean square error, root mean square error, coefficient of correlation, etc. has shown that soft computing techniques have potential applications for predicting the fly ash concrete compressive strengths.