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Influence of Nano-Materials on Mechanical and Permeation Characteristics of high strength concrete

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Journal of Wuhan University of Technology(Materials Science) 2022年第3期37卷 416-422页

作者： K V S Gopala Krishna Sastry M Srinivasula Reddy A Ravitheja Civil Engineering G Pulla Reddy Engineering CollegeKurnoolAPIndia SVR Engineering College NandyalAndhra PradeshIndia

Efforts have been made to evaluate the influences of the addition of nanoparticles on the strength,durability and mineralogical changes of high strength concrete(HSC).Therefore,mixes were prepared for conventional concrete mix(CCM)of M80 ***,various mixes were prepared by replacing cementitious materials initially with 1%Nano-CaCO_(3)(NC),2%NC,3%NC in the CCM,and then 1%NC and Nano-SiO_(2)(NS)NS,2%NC and NS,3%NC and NS(NC and NS were in equal proportion)in the *** developed concretes were then evaluated for mechanical properties,permeation characteristics,and mineralogical *** the studies,it is found that the concrete at 2%NCS possesses superior mechanical and superior permeation characteristics of all the mixes.A clear variation in the mineralogical structure with the addition of nanoparticles has been observed.

关键词： high strength concrete nano silicon dioxide nano calcium carbonate mechanical properties permeation properties

Behavior of high strength concrete Filled Square Steel Tube Stub Columns with Inner CFRP Tube Under Biaxial Eccentric Compression

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Computer Modeling in Engineering & Sciences 2021年第4期127卷 273-290页

作者： Zhijian Yang Guochang Li Yan Lang Zengmei Qiu School of Civil Engineering Shenyang Jianzhu UniversityShenyang110168China Department of Building Engineering Suqian CollegeSuqian223800China

This paper studies the contribution of CFRP(carbon fiber-reinforced polymer)to the mechanical behavior of high strength concrete-filled square steel tube(HCFST)under biaxial eccentric *** new type of composite member is composed of an inner CFRP tube and an outer steel tube with concrete filled in the two *** finite element analysis was made by ABAQUS on the behavior of high strength concrete filled square steel tubular columns with inner CFRP circular tube subjected to bi-axial eccentric *** results obtained from the finite element analysis were verified with the experimental *** addition,the load-deflection curves in the whole process were calculated and analyzed,which can be divided into three segments:Elastic phase,plastic phase,descending *** on the load-deflection curves,the stresses analysis on the core concrete,CFRP tube and steel tube were *** confinement effect of the CFRP tube improves the ductility of HCFST-CFRP stub *** ratio and eccentricity affect the ultimate bearing capacity of HCFST stub ***,a calculation formula of ultimate bearing capacity was proposed in the paper.

关键词： CFRP tube concrete-filled square steel tube high strength concrete bi-axial bending stub column

Mechanical Properties and Flowability of high strength concrete Incorporating Ground Granulated Blast-furnace Slag

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Journal of Wuhan University of Technology(Materials Science) 2001年第3期16卷 42-45页

作者：姚武 State Key Lab. of concrete Mat. Res. Tongji University Shanghai 200092 China

The high strength concrete(HSC)was produced by partially replacingthe normal portland cement with special ground granulatedblast-furnace slag(GGBS)ranging up to 60/100. The effects of the GGBSon the flowabilityand mechanical properties of HSC were studied. Thehydration process and microstructure char- acteristics wereinvestigated by X-ray diffraction(XRD)and scanning microscopy(SEM),respectively. The test results indicate that the GGBS has especiallysupplementary effect on water reducing and excellent property Ofbetter control of lump loss.

关键词： high strength concrete mechanical property flowability

Influence of MB-value of Manufactured Sand on the Shrinkage and Cracking of high strength concrete

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Journal of Wuhan University of Technology(Materials Science) 2009年第2期24卷 321-325页

作者：王稷良 Key Laboratory of Road Structure and Material Ministry of Communications (Beijing) Research Institute of Highway Ministry of Communication

The relation between methylene blue （MB） value of MS and its limestone dust content and clay content was investigated. The effects of MB value ranging from 0.35 to 2.5 on the workability of fresh concrete and crack propagation characteristics at the age of 24 hours, and effects on the mechanical properties, dry shrinkage of the harden concrete were tested. The experimental results show that the MB value is not related with the limestone dust content of MS, but in direct proportion to clay content. With the increase of MB value, the concrete workability decreases, and the flexural strength and 7 d compressive strength reduce markedly, whearas the 28 d compressive strength is not affected. When the MB-value is less than or equal to 1.35, the change of the MB-value has a little influence on early plastic cracking and dry shrinkage property of concrete, but when the MB-value is more than 1.35, the tendency of plastic cracking and dry shrinkage is remarkable.

关键词： manufactured sand methylene blue value high strength concrete anti-cracking shrinkage

Effects of Curing Conditions on strength Development of high strength concrete

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China Ocean Engineering 1997年第1期12卷 99-108页

作者： Cai, YB Kwan, KH UNIV HONG KONG DEPT CIVIL & STRUCT ENGNHONG KONGHONG KONG

This paper presents the results of a series of studies on the influence of curing conditions on the strength development of high strength concrete. The 1-, 3-, 7-, 14- and 28-day strengths of four different mixes of Grade 75 similar to 80 concrete, with or without pulverized fuel ash and/or condensed silica fume, under five different curing regimes were investigated. It is revealed that the curing conditions have significant influence on both the short term and long term strength development of the concrete and that concrete mixes of the same grade but containing different mineral admixtures show distinct favour for a curing regime. These results will be helpful for evaluating suitable curing methods for high strength concrete with different mix proportions.

关键词： curing condition high strength concrete strength development mineral admixture mix proportion

Shear design of high strength concrete prestressed girders

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Frontiers of Structural and Civil Engineering 2014年第4期8卷 373-387页

作者： Emad L. LABIB Hemant B. DHONDE Thomas T. C. HSU Y. L. MO Oil Field Development Engineering LLC Houston TX 77079 USA Department of Civil Engineering VIIT University of Pune Pune 411007 India Department of Civil and Environmental Engineering University of Houston Houston TX 77004 USA

Normal strength prestressed concrete I-girders are commonly used as the primary superstructure components in highway bridges. However, shear design guidelines for high strength PC girders are not available in the current structural codes. Recently, ten 7.62 m （25 feet） long girders made with high strength concrete were designed, cast, and tested at the University of Houston （UH） to study the ultimate shear strength and the shear concrete contribution （Vc） as a function of concrete strength （f＇c）. A simple semi-empirical set of equations was developed based on the test results to predict the ultimate shear strength of prestressed concrete I-girders. The UH-developed set of equations is a function of concrete strength （√f＇c）, web area （bwd）, shear span to effective depth ratio （a/d）, and percentage of transverse steel （Pt）. The proposed UH-Method was found to accurately predict the ultimate shear strength of PC girders with concrete strength up to 117 MPa （17000 psi） ensuring satisfactory ductility. The UH-Method was found to be not as overly conservative as the ACI-318 （2011） code provisions, and also not to overestimate the ultimate shear strength of high strength PC girders as the AASHTO LRFD （2010） code provisions. Moreover, the proposed UH-Method was found fairly accurate and not exceedingly conservative in predicting the concrete contribution to shear for concrete strength up to 117 MPa （17000 psi）.

关键词： shear design high strength concrete prestressed girders full-scale tests

Structural Behavior of Continuous Prestressed Steel Fiber Reinforced high strength concrete Beam

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Journal of Southwest Jiaotong University(English Edition) 2008年第1期16卷 37-45页

作者：刘海波向天宇赵人达 School of Civil Engineering Southwest Jiaotong University

The flexural behaviors of continuous fully and partially prestressed steel fiber reinforced high strength concrete beams are studied by experiment and nonlinear finite element analysis. Three levels of partial prestress ratio （PPR） are considered, and three pairs of two-span continuous beams with box sections varying in size are designed. The major parameters involved in the study include the PPR and the fiber location. It is concluded that the prestressed high strength concrete beam exhibits satisfactory ductility; the influences of steel fiber on the crack behaviors for partially prestressed beams are not as obvious as those for fully prestressed ones; steel fibers can improve the structural stiffness after cracking for fully prestressed high strength concrete beams; the moment redistribution from mid-span to intermediate support in the first stage should be mainly considered in practical design.

关键词： high strength concrete Steel fiber reinforced concrete Prestressed concrete Continuous beam

Developing Sustainable high strength concrete Mixtures Using Local Materials and Recycled concrete

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Materials Sciences and Applications 2016年第2期7卷 128-137页

作者： Anthony Torres Alex Burkhart Department of Engineering Technology Texas State University San Marcos TX USA

This study presents the development of high strength concrete (HSC) that has been made more sustainable by using both local materials from central Texas and recycled concrete aggregate (RCA), which has also been obtained locally. The developed mixtures were proportioned with local constituents to increase the sustainable impact of the material by reducing emissions due to shipping as well as to make HSC more affordable to a wider variety of applications. The specific constituents were: limestone, dolomite, manufactured sand (limestone), locally available Type I/II cement, silica fume, and recycled concrete aggregate, which was obtained from a local recycler which obtains their product from local demolition. Multiple variables were investigated, such as the aggregate type and size, concrete age (7, 14, and 28-days), the curing regimen, and the water-to-cement ratio (w/c) to optimize a HSC mixture that used local materials. This systematic development revealed that heat curing the specimens in a water bath at 50℃ (122oF) after demolding and then dry curing at 200℃ (392oF) two days before testing with a w/c of 0.28 at 28-days produced the highest compressive strengths. Once an optimum HSC mixture was identified a partial replacement of the coarse aggregate with RCA was completed at 10%, 20%, and 30%. The results showed a loss in compressive strength with an increase in RCA replacement percentages, with the highest strength being approximately 93.0 MPa (13,484 psi) at 28-days for the 10% RCA replacement. The lowest strength obtained from an RCA-HSC mixture was approximately 72.9 (MPa) (10,576 psi) at 7-days. The compressive strengths obtained from the HSC mixtures containing RCA developed in this study are comparable to HSC strengths presented in the literature. Developing this innovative material with local materials and RCA ultimately produces a novel sustainable construction material, reduces the costs, and produces mechanical performance similar to prepackaged, comm

关键词： high strength concrete Sustainability Recycled concrete Aggregate Local Products Construction Materials

Behaviour of concrete Filled Steel Square-Tube Stub Column with Steel-Fiber Reinforced high strength concrete

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Behaviour of Concrete Filled Steel Square-Tube Stub Column w...