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CONTENTS
Volume 12, Number 4, October 2021
 


Abstract
Polymer Concrete (PC) is a composite material made by fully replacing the cement hydrate binders of conventional cement concrete with polymer binders or liquid resins. As expected, the physico-mechanical properties of PC concrete are governed by the composition of the PC mixture. The present study aims to examine the effect of the aggregate type and of the addition of steel fibers on the mechanical properties of PC. In particular, two PC concrete mixtures, using granite or silica aggregates, have been developed and the effect of the addition of steel fibers has been investigated. The PC mixtures are characterized by mechanical tests such as the compression test, the flexural test, the splitting tensile test and the estimation of the energy absorption. The results of this study demonstrate a relative superiority, in terms of mechanical properties, of the PC made with granite aggregates as compared to that of the silica aggregate mixture. Moreover, the addition of steel fibers on PC mixtures showed a significant increase of the compressive toughness, of the splitting tensile and of the flexural strength, whereas the Young

Key Words
aggregates; mechanical properties; polymer concrete; polyester resin; steel fibers

Address
Panagiotis G. Asteris: Computational Mechanics Laboratory, School of Pedagogical and Technological Education, Heraklion, GR 14121, Athens, Greece
Hamid Naseri: Department of Civil Engineering, Faculty of Engineering, Urmia University, 5756151818 Urmia, Iran
Mohsen Hajihassani: Department of Civil Engineering, Faculty of Engineering, Urmia University, 5756151818 Urmia, Iran
Mehdi Kharghani: Department of Civil Engineering, Faculty of Engineering, Islamic Azad University, Science and Research Branch of Tehran, Iran
Constantin E. Chalioris: Department of Civil Engineering, School of Engineering, Democritus University of Thrace, Xanthi, 67100, Greece

Abstract
The paper presents the study of concrete made with supplementary cementitious materials such as Fly Ash (FA) and Ultra Fine Slag (UFS). Ordinary Portland Cement (OPC) is partially replaced with 20%, 30%, and 40% of FA by weight of cementitious content in three FA binary combinations. OPC is further replaced with 5%, 10%, 15%, and 20% of UFS to all three binary combinations forming twelve ternary combinations. The paper assesses workability, strength behaviour, chloride migration, water permeability, and cost aspect of all mixes. The results indicate that the use of FA binary combinations improves the workability but mechanical and durability properties are compromised. In case of FA-UFS ternary combinations, the compressive, flexural, and split tensile strengths have been observed to improve up to 36%, 13%, and 22%, respectively. Chloride migration and water permeability of ternary mix improve by 92% and 94% compared to reference concrete. An optimization technique using Taguchi-grey relational analysis (GRA) suggested that a ternary combination with 55% OPC, 30% FA, and 15% UFS qualify as an optimum mix combination.

Key Words
fly ash; grey relational analysis; optimization method; replacement of ordinary Portland cement; ultra-fine slag

Address
Vinay Mohan Agrawal: Civil Engineering Department, Goa College of Engineering, Goa University, Goa, India; National Institute of Construction Management and Research, Goa, India
Purnanand P. Savoikar: Civil Engineering Department, Goa College of Engineering, Goa University, Goa, India

Abstract
In recent years, Fibers Reinforced Polymer (FRP) bars with high tensile strength and lightness have been developed as an alternative to steel bars and it is important to know the durability performance of these bars against environmental effects. In this study, experimental studies were conducted to evaluate the durability performance of FRP bars produced with various fibers. Five environmental conditions representing humidity, sea water, hot air, cold air and concrete pore water to which the bars may be exposed were created and aramid, glass and carbon fiber FRP bars were exposed to these environments. After conditioning, the water absorption, mass loss and tensile strength of the samples were determined. At the end of the study, it was determined that Glass Fiber Reinforced Polymer (GFRP) bars were greatly affected by the presence of water, Aramid Fiber Reinforced Polymer (AFRP) bars were sensitive to high temperatures, and Carbon Fiber Reinforced Polymer (CFRP) bars showed good performance in all environmental conditions.

Key Words
FRP bar; durability; strength and mass loss; alkaline solution; sea water; temperature; humidity

Address
Ferhat Aydin: Civil Engineering, Faculty of Technology, Sakarya University of Applied Sciences
Şeymanur Arslan: Civil Engineering, Faculty of Engineering Arcitercture and Design, Bartin University

Abstract
A vast amount of natural resources are required to produce concretes due to industrialisation and urbanisation, indicating that large quantities of raw materials are being utilised worldwide. The use of industrial wastes as an aggregate in concrete is highly recommended to promote sustainable development by reducing the consumption of natural resources. Agricultural wastes are available in large amounts, thereby making them an acceptable and reliable solution for aggregate in concrete. In this study, natural aggregates, such as coconut shell and oil palm shell, were replaced with normal coarse aggregate. The properties of concrete, such as workability, density, compressive strength in different curing regimes, splitting tensile strength, Young

Key Words
agricultural waste; curing; drying shrinkage; mechanical properties; structural lightweight aggregate concrete

Address
Alireza Javadi Pordesari: Department of Civil Engineering, Faculty of Engineering, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
Payam Shafigh: Centre for Building, Construction and Tropical Architecture (BuCTA), Faculty of Built Environment, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
Zainah Ibrahim: Department of Civil Engineering, Faculty of Engineering, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
Muhammad Aslam: Department of Civil Engineering, School of Engineering and Technology,Institute of Southern Punjab, 60000 Multan, Pakistan

Abstract
The current study explores the empirical whole stress-strain curves detected from the axial compression test of the green concretes manufactured with two kinds of no-cement binders. The first one is the binder of alkali-activated material (AAM) with ground granulated blast furnace slag blending with Class F fly ash (FFA) and the second is a new hydraulic SFC binder produced by mixing ternary powders of slag (S), FFA (F), and circulating fluidized bed combustion fly ash (C). The performances of two green concretes were conducted and compared with that of the plain ordinary Portland cement (OPC) concretes with the equivalent 28-day compressive strengths graded at 30, 40, and 50 MPa. Experimental results showed that the AAM concretes had the energy absorption capacity lower than those of the SFC and OPC concretes because the descending parts of the whole stress-strain curves of the AAM concretes referred to the snap back mode different from the strain softening modes of those of the SFC and OPC concretes with the compressive strength graded at 30 or 40 MPa. Among three concretes with equivalent strength grades, the AAM concretes had the lowest elastic Young

Key Words
CFBC fly ash; fly ash; no-cement; stress-strain curve; slag

Address
Hoang Anh Nguyen: Department of Rural Technology, College of Rural Development, Can Tho University, Can Tho City 90000, Vietnam
Ta Peng Chang: Department of Civil and Construction Engineering, National Taiwan University of Science and Technology (NTUST) (Taiwan Tech), Taipei 106, Taiwan
Yu Hao Kuo: Department of Civil and Construction Engineering, National Taiwan University of Science and Technology (NTUST) (Taiwan Tech), Taipei 106, Taiwan
Jeng Ywan Shih: Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan

Abstract
Utilization, reduction and disposal of the pulp and paper industry waste (Hypo Sludge) are crucial from an environmental perspective. Hypo sludge, when disposed of as landfill, contributes to the groundwater contamination caused by the leachates. Hence, the utilization of hypo sludge from the paper industry in the construction applications promotes the development of sustainable concrete; reduces landfills, and creates an environment free from harmful wastes. In the present context, this research focused on the partial replacement of cement by hypo sludge. It was observed that even though the addition of 10% of hypo sludge was sufficient to produce sustainable concrete, there was a negative influence on the durability as more water absorption was observed due to the presence of high cellulose fibre content. Hence styrene-butadiene rubber (SBR) latex and basalt fibres were added to improve its durability and post cracking behaviour respectively. A significant improvement in the strength and durability was observed when 10% of hypo sludge as a cement replacement is used in combination with 0.25% of basalt fibres and 10% of SBR latex when compared with the conventional concrete. The micro structural studies revealed that SBR latex produced better consistency in the interaction among the phases of concrete.

Key Words
basalt fibre; durability; hypo sludge; styrene-butadiene rubber latex; sustainability

Address
Srividhya Sundaresan: Department of Civil Engineering, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025, Tamilnadu, India
Vidjeapriya Ramamurthy: Department of Civil Engineering, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025, Tamilnadu, India
Neelamegam Meyappan: Department of Civil Engineering, Easwari Engineering College, Ramapuram, Chennai 600089, Tamil Nadu, India

Abstract
Evaluating the impact of fly ash (FA) and micro-silica (MS) on the tensile (TS) and compressive strength (CS) of concrete in different ages provokes to find the effective parameters in predicting the CS and TS, which not only could be usable in the practical works but also is extensible in the future analysis. In this study, in order to evaluate the effective parameters in predicting the CS and TS of concrete containing admixtures and to present a fitted equation, the multivariate adaptive regression splines (MARS) method has been used, which could find a relationship between independent and dependent variables. Next, for optimizing the output equation, hybrid genetic algorithm (GA), particle swarm optimization (PSO), and grey wolf optimization (GWO) methods have been utilized to find the optimal conclusions. It could be concluded that for both predictions of CS and TS, all models have the coefficient of determination (R2) larger than 0.949 and 0.9138, respectively. Furthermore, between three hybrid algorithms, MARS-PSO could be proposed as the best model to obtain the most accuracy in the prediction of CS and TS. The usage of hybrid MARS-PSO techniques causes a noticeable improvement in the prediction procedure.

Key Words
compressive and tensile strength prediction; fly ash; GA; high strength concrete; MARS; micro-silica; PSO and GWO

Address
Hang Yin, Shuxian Liu, Shasha Lu, Wei Nie and Baoxin Jia: Liaoning Technical University, Xihe District, Fuxin City, Liaoning Province, China

Abstract
This paper introduces several new damage states for shear walls with flexural behavior damaged in an earthquake. These damage states are deducted by carefully interpretation of reported available test results of shear walls in the literature. Moreover, two methods for obtaining the plastic hinge modification factors of strength, stiffness and ductility capacity of the damaged shear walls with the flexural behavior are presented. A method based on secant stiffness at maximum displacement of each cycle of observed damage and the second method uses the reloading stiffness of the hysteresis curves consistent with damage levels. The later method introduced in this research is more reasonable for obtaining modification factors among the introduced methods. Using these factors, a reliable residual capacity for damaged structures can be assessed and the proper seismic retrofitting method can be followed. In this research, the effects of damages caused by various experimental tests have been studied on 43 reinforced concrete shear walls with flexural behavior. By introducing and describing the bending performance

Key Words
damaged wall; damage levels; evaluation; hysteresis curve; reinforced shear wall; modification factors; post-earthquake structure safety; visual damage states; wall bending performance

Address
Seyedmilad Komarizadehasl: Department of Civil and Environment Engineering, Universitat Politècnica de Catalunya, BarcelonaTech, C/Jordi Girona 1-3, 08034, Barcelona, Spain
Mohammad Khanmohammadi: School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran


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