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CONTENTS
Volume 10, Number 2, August 2020
 

Abstract
Basalt fiber is an eco-friendly fiber and comparatively newer to the world of fiber-reinforced polymer (FRP) composites. A limited number of studies have been reported in the literature on the strengthening of reinforced concrete (RC) beams with basalt fiber reinforced polymer (BFRP). The present experimental work explores the feasibility of using the BFRP strips for shear strengthening of the RC beams. The strengthening schemes include full wrap and U-wrap. A simple mechanical anchorage scheme has been introduced to prevent the debonding of U-wrap as well as to utilize the full capacity of the BFRP composite. The effect of varying shear span-to-effective depth (a/d) ratio on the behavior of shear deficient RC beams strengthened with BFRP strips under different schemes is examined. The RC beams were tested under a four-point loading system. The study finds that the beams strengthened with and without BFRP strips fails in shear for a/d ratio 2.5 and the enhancement of the shear capacity of strengthened beams ranges from 5% to 20%. However, the strengthened beams fail in flexure, and the control beam fails in shear for a higher a/d ratio, i.e., 3.5. The experimental results of the present study have been compared with the analytical study and found that the latter gives conservative results.

Key Words
basalt fiber reinforced polymer (BFRP); reinforced concrete beams; shear strengthening; mechanical anchorage system; shear span to depth ratio

Address
S. Kar and K.C. Biswal: Department of Civil Engineering, National Institute of Technology, Rourkela, Odisha - 769008, India

Abstract
In this study eleven beam of steel fibre-reinforced concrete were tested on concentrated load in order to evaluate the shear strength and deformation of the beams after burning. Variables considered in the test include spaces of shear reinforcement (stirrups) and temperature (normal temperature at 38oC, 300oC, 600oC and 900oC). The steel fiber used is set at 0.5% of the concrete volume. The phenomenon of the test results shows that although the beams were tested to achieve shear failure, the fact that all the tested beams did not encounter any shear failure. It has shown the influence of steel fibers and stirrups that plays a role in determining the mode of collapse. The concrete shear capacity of steel fibrous concrete beams installed with stirrups in altered spacing variations is not significantly different from each other, while beam deformability increases when the space stirrups are reduced. Furthermore, models of the developed-steel fibrous shear strength are compared and discussed with experimental results.

Key Words
shear; ductility; beams; steel fiber; stirrups; temperatures

Address
Antonius, Rinda Karlinasari, Aref Widhianto: Department of Civil Engineering, Universitas Islam Sultan Agung, Semarang, Indonesia
Purwanto: Department of Civil Engineering, Universitas Semarang, Semarang, Indonesia

Abstract
This paper presents experimental results on bond-slip behavior of steel reinforced high-strength concrete (SRHC) after exposure to elevated temperatures. Three parameters were considered in this test: (a) high temperatures (i.e., 20oC, 200oC, 400oC, 600oC, 800oC); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 SRHC specimens subjected to high temperatures were designed for push out test. The load-slip curves at the loading end and free end were obtained, the influence of various variation parameters on the ultimate bond strength and residual bond strength was analyzed, in addition, the influence of elevated temperatures on the invalidation mechanism was researched in details. Test results show that the shapes of load-slip curves at loading ends and free ends are similar. The ultimate bond strength and residual bond strength of SRHC decrease first and then recover partly with the temperature increasing. The bond strength is proportional to the concrete strength, and the bond strength is proportional to the anchoring length when the temperature is low, while the opposite situation occurs when the temperature is high. What\'s more, the bond damage of specimens with lower temperature develops earlier and faster than the specimens with higher temperature. From these experimental findings, the bond-slip constitutive formula of SRHC subjected to elevated temperatures is proposed, which fills well with test data.

Key Words
steel reinforced high strength concrete; elevated temperatures test; P-S curve; bond strength calculation; constitutive

Address
Zongping Chen: College of Civil Engineering and Architecture, Guangxi University, 530004 Nanning, P.R. China; Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Nanning 530004, Guangxi, P.R. China
Ji Zhou, Xinyue Wang: College of Civil Engineering and Architecture, Guangxi University, 530004 Nanning, P.R. China

Abstract
This study explores the feasibility of granite waste aggregate (GWA) as a partial replacement of natural fine aggregate (NFA) in binary blend self-compacting concrete (SCC) prepared with fly ash. Total of nine SCC mixtures were prepared wherein one was Ordinary Portland cement (OPC) based control SCC mixture and remaining were fly ash based binary blend SCC mixtures which included the various percentages of GWA. Fresh properties tests such as slump flow, T500, Vfunnel, J-ring, L-box, U-box, segregation resistance, bleeding, fresh density, and loss of slump flow (with time) were conducted. Compressive strength and percentage of permeable voids were evaluated in the hardened state. All the SCC mixtures exhibited sufficient flowability, passing ability, and resistance to segregation. Besides, all the binary blend SCC mixtures exhibited lower fresh density and bleeding, and better residual slump (up to 50% of GWA) compared to the OPC based control SCC mixture. Binary blend SCC mixture incorporating up to 40% GWA provided higher compressive strength than binary blend control SCC mixture. The findings of this study encourage the utilization of GWA in the development of binary blend SCC mixtures with satisfactory workability characteristics as a replacement of NFA.

Key Words
fly ash; granite waste aggregate; self-compacting concrete; fresh properties; bleeding; loss in slump flow; compressive strength

Address
Abhishek Jain, Rajesh Gupta: Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, Rajasthan, India
Sandeep Chaudhary: Discipline of Civil Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552, India

Abstract
In the present study, a mechanical model is applied to account the effects of the surrounding viscoelastic media on the buckling behavior of single microfilament within the cell. The model immeasurably associates filament\'s bending rigidity, neighboring system elasticity, and cytosol viscosity with buckling wavelengths, buckling growth rates and buckling amplitudes of the filament. Cytoskeleton components in living cell bear large compressive force and are responsible in maintaining the cell shape. Actually these filaments are surrounded by viscoelastic media consisting of other filaments network and viscous cytosole within the cell. This surrounding, viscoelastic media affects the buckling behavior of these filaments when external force is applied on these filaments. The obtained results, indicate that the coupling of viscoelastic media with the viscous cytosol greatly affect the buckling behavior of microfilament. The buckling forces increased with the increase in the intensity of surrounding viscoelastic media.

Key Words
microfilaments; viscoelastic media; buckling; compressive loads; amplitudes

Address
Mohamed A. Khadimallah: Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 11942, Saudi Arabia
Muhammad Safeer: Department of Mathematics, University of Azad Jammu and Kashmir, Muzaffarabad, 1300, Azad Kashmir, Pakistan; Department of Mathematics University of Poonch Rawalwkot 12350 Azad Kashmir, Pakistan
Muhammad Taj: Department of Mathematics, University of Azad Jammu and Kashmir, Muzaffarabad, 1300, Azad Kashmir, Pakistan
Hamdi Ayed: Department of Civil Engineering, College of Engineering, King Khalid University, Abha, Kingdom of Saudi Arabia; Higher Institute of Transport and Logistics of Sousse, University Sousse, Tunisia
Muzamal Hussain: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Souhail Mohamed Bouzgarrou: Civil Engineering Department, Faculty of Engineering, Jazan University, Kingdom of Saudi Arabia
S.R. Mahmoud: GRC Department, Faculty of Applied studies, King Abdulaziz University, Jeddah, Saudi Arabia
Manzoor Ahmad: Department of Mathematics University of Poonch Rawalwkot 12350 Azad Kashmir, Pakistan
Abdelouahed Tounsi: Materials and Hydrology Laboratory University of Sidi Bel Abbes, Algeria Faculty of Technology Civil Engineering Department; Department of Civil and Environmental Engineering, King Fahd University of Petroleumand Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
An experimental study on the stress-strain relation of PVC-CFRP confined reinforced concrete columns subjected to eccentric compression was carried out. Two parameters, such as the CFRP strips spacing and eccentricity of axial load, were considered. The experimental results showed that all specimens failed by compressive yield of longitudinal steel bar and rupture of CFRP strips. The bearing capacity of specimen decreases as the eccentricity or the CFRP strips spacing increases. The stressstrain relation of specimens undergoes two stages: parabolic and linear stages. In the parabolic stage, the slope of stress-strain curve decreases gradually as the eccentricity of axial loading increases while the CFRP strips spacing has little effect on the slope of stress-strain curve. For the linear stage, the slope of stress-strain curve decreases as the eccentricity of axial load or the CFRP strips spacing increases. A model for predicting the stress-strain relation of columns under eccentric compression is proposed and it agrees well with various test data.

Key Words
PVC-CFRP confined concrete; eccentric compression; failure mode; stress-strain relation

Address
Feng Yu, Zhengyi Kong, Deguang Li: Department of Civil Engineering and Architecture, Anhui University of Technology, Ma\'anshan 243032, China
Quang-Viet Vu: Institute of Research and Development, Duy Tan University, Danang 550000, Vietnam

Abstract
This paper studies the influence of silica fume and Processed Quarry Fines (PQF) on the flexural behaviour of the reinforced concrete beams by experimental as well as numerical studies. The study has been shown that the incorporation of PQF can significantly increase the stiffness and the flexural strength of reinforced HPC beams. Also, the ultimate strength of specimens prepared with the 10% silica fume and 100% PQF are higher compared to conventional reinforced concrete specimen. Numerical analysis is performed to find the ultimate strength of HPC beams to compare with experimental results. Nonlinear behaviour of steel reinforcing bars and plain concrete is simulated using appropriate constitutive models and experimental results. The results indicate that the ultimate strength, deformed shape and crack patterns of reinforced HPC beams obtained through the Finite Element Analysis (FEA) are confirming with the experimental results.

Key Words
finite element analysis; flexural behavior; high performance concrete beams; manufactured sand; silica fume

Address
T. Shanmuga Priya: School of Civil Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, 6320142, India
R. Senthilkumar: Department of Civil Engineering, National Institute of Technology Tiruchirappalli, Tamil Nadu, 620015, India

Abstract
The main objective of this study is the assessment of the ability of limestone mortars to resist to different chemical attacks. The ability of polypropylene (PP) fibres waste used as reinforcement of these concrete materials to enhance their durability is also studied. Crushed sand 0/2 mm which is a fine limestone residue obtained by the crushing of natural rocks in aggregates industry is used for the fabrication of the mortar. The fibres used, which are obtained from the waste of domestic plastic sweeps\' fabrication, have a length of 20 mm and a diameter ranging between 0.38 and 0.51 mm. Two weight fibres contents are used, 0.5 and 1%. The durability tests carried out in this investigation included the water absorption by capillarity, the mass variation, the flexural and the compressive strengths of the mortar specimens immersed for 366 days in 5% sodium chloride, 5% magnesium sulphate and 5% sulphuric acid solutions. A mineralogical analysis by X-ray diffraction (XRD) and a visual inspection are used for a better examination of the quality of tested mortars and for better interpretation of their behaviour in different solutions. The results indicate that the reinforcement of limestone mortar by PP fibres waste is an excellent solution to improve its chemical resistance and durability. Moreover, the presence of PP fibres waste does not affect significantly the water absorption by capillarity of mortar nether its mass variation, when exposed to chloride and sulphate solutions. While in sulphuric acid, the mass loss is higher with the presence of PP fibres waste, especially after an exposure of 180 days. The results reveal that these fibres have a considerable effect of the flexural and the compressive behaviour of mortar especially in acid solution, where a reduction of strength loss is observed. The mineralogical analysis confirms the good behaviour of mortar immersed in sulphate and chloride solutions; and shows that more gypsum is formed in mortar exposed to acid environment causing its rapid degradation. The visual observation reveals that only samples exposed to acid attack during 366 days have showed a surface damage extending over a depth of approximately 300 um.

Key Words
fibre concrete; recycled polypropylene fibres; crushed sand; chemical attacks; capillarity; absorption, mechanical strength; expansive gel

Address
Khadra Bendjillali: Department of Civil Engineering, Laboratory of Structures Rehabilitation and Materials, University Amar Telidji, P.O. Box 37G, Route de Ghardaia, Laghouat 03000, Algeria
Bensaid Boulekbache: Department of Civil Engineering, Laboratory of Materials Sciences and Environment, University Hassiba Benbouali, Chlef, Algeria
Mohamed Chemrouk: Department of Structure and Materials, Laboratory of Buildings in the Environment, University of Sciences and Technology Houari Boumediene, Algiers, Algeria


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