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CONTENTS
Volume 6, Number 4, August 2018
 

Abstract
The study herein reports the impact of Steel Fiber (SF) and Ground Granulated Blast Furnaces slag (GGBFS) content on the fresh and hardened properties of fly ash (FA) based Self-Compacting Geopolymer Concrete (SCGC). Two series of self-compacting geopolymer concrete (SCGC) were formulated with a constant binder content of 450 kg/m3 and at an alkaline-to-binder (a/b) ratio of 0.50. Fly ash (FA) was substituted with GGBFS with the replacement levels being 0%, 25%, 50%, 75%, and 100% by weight in each SCGC series. Steel fiber (SF) wasn\'t employed in the assembly of the initial concrete series whereas, within the second concrete series, an SF combination was achieved by a constant additional level of 1% by volume. Fresh properties of mixtures were through an experiment investigated in terms of slump flow diameter, T50 slump flow time, V-funnel flow time, and L-box height ratio. Moreover, the mechanical performance of the SCGCs was evaluated in terms of compressive strength, splitting tensile strength, and fracture toughness. Furthermore, a statistical analysis was applied in order to judge the importance of the experimental parameters, like GGBFS and SF contents. The experimental results indicated that the incorporation of SF had no vital impact on the fresh characteristics of the SCGC mixtures whereas GGBFS aggravated them. However, the incorporation of GGBFS was considerably improved the mechanical properties of SCGCs. Moreover, the incorporation of SF with the total different quantity of GGBFS replacement has considerably increased the mechanical properties of SCGCs, by close to (65%) for the splitting strength and (200%) for compressive strength.

Key Words
Self-Compacting Geopolymer Concrete (SCGC); GGBFS; Steel Fiber (SF); fresh properties; mechanical properties

Address
Saad Al-Rawi and Nildem Taysi: Department of Civil Engineering, Gaziantep University, Gaziantep, Turkey

Abstract
In this paper, mechanical and short-term durability properties of fly ash and slag based geopolymer concretes (FAGPC-SGPC) were investigated. The alkaline solution was prepared with a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) for geopolymer concretes. Ordinary Portland Cement (OPC) concrete was also produced for comparison. Main objective of the study was to examine the usability of geopolymer concretes instead of the ordinary Portland cement concrete for structural use. In addition to this, this study was aimed to make a contribution to standardization process of the geopolymer concretes in the construction industry. For this purpose; SGPC, FAGPC and OPC specimens were exposed to sulfuric acid (H2SO4), magnesium sulfate (MgSO4) and sea water (NaCl) solutions with concentrations of 5%, 5% and 3.5%, respectively. Visual inspection and weight change of the specimens were evaluated in terms of durability aspects. For the mechanical aspects; compression, splitting tensile and flexural strength tests were conducted before and after the chemical attacks to investigate the residual mechanical strengths of geopolymer concretes under chemical attacks. Results indicated that SGPC (100% slag) is stronger and durable than the FAGPC due to more stable and strong cross-linked aluminasilicate polymer structure. In addition, FAGPC specimens (100% fly ash) showed better durability resistance than the OPC specimens. However, FAGPC specimens (100% fly ash) demonstrated lower mechanical performance as compared to OPC specimens due to low reactivity of fly ash particles, low amount of calcium and more porous structure. Among the chemical environments, sulfuric acid (H2SO4) was most dangerous environment for all concrete types.

Key Words
fly ash/slag based geopolymer concrete (FAGPC)/(SGPC); sulfuric acid; magnesium sulfate; sea water

Address
Ahmet Emin Kurtoglu: Department of Civil Engineering, Istanbul Gelisim University, Istanbul, Turkey
Radhwan Alzeebaree: Department of Civil Engineering, Duhok Polytechnic University, Duhok, Iraq; Department of Civil Engineering, Gaziantep University, Gaziantep, Turkey
Omar Aljumaili: Department of Civil Engineering, Gaziantep University, Gaziantep, Turkey
Anil Nis: Department of Civil Engineering, Istanbul Gelisim University, Istanbul, Turkey
Mehmet Eren Gulsan, Ghassan Humur. Abdulkadir Cevik: Department of Civil Engineering, Gaziantep University, Gaziantep, Turkey


Abstract
Portland cement pervious concrete (PCPC) is an effective pavement material to solve or reduce the urban waterlogging problems. The Mechanical properties, the permeability, the abrasion resistance and the frost resistance of PCPC without fine aggregate were investigated. The increase of porosity was achieved by fixing the dosage of coarse aggregate and reducing the amount of cement paste. The results show that the compressive strength and the flexural strength of PCPC decrease with the increase of porosity. The permeability coefficient and the wear loss of PCPC increase with the increase of the porosity. The compressive strength and the flexural strength of PCPC subjected to 25 freeze-thaw cycles are reduced by 13.7%-17.8% and 10.6%-18.3%, respectively. For PCPC subjected to the same freeze-thaw cycles, the mass loss firstly increases and then decreases with the increase of the porosity. The relative dynamic modulus elasticity decreases with the increase of freeze-thaw cycles. And the lower the PCPC porosity is, the more obvious the dynamic modulus elasticity decreases.

Key Words
Portland cement pervious concrete (PCPC); porosity; physical properties; freeze-thaw cycles

Address
Wuman Zhang, Honghe Li and Yingchen Zhang: Department of Civil Engineering, School of Transportation Science and Engineering, Beihang Univerisity, Beijing, 100191, China

Abstract
This experimental work aims at developing and investigating a lightened concrete by the addition of treated straws. The used formulation is based on that of an ordinary concrete which is composed of sand and gravel as the main aggregates. The properties of the straws are improved by using one of two treatments before their use: the hot water and bitumen. Henceforth, the main objective of this study is to assess the mechanical characteristics of different formulations with different compositions and treatments on straws. The obtained results have shown that the addition of straws improves its lightness property. However, it decreases the compressive and flexural strengths as well as decreases the modulus of elasticity and increases the dimensional variations. Set into comparison to the concrete with untreated straws, the treatment of straws by hot water or by bitumen improves most of the characteristics.

Key Words
concrete; straw; treatment; mechanical properties

Address
Zied Kammoun: de Tunis El Manar, Ecole Nationale d\'Ingenieurs de Tunis, LR11ES16 Laboratoire de Materiaux,
Optimisation et Energie pour la Durabilite, 1002, Tunis, Tunisia; Universite de Carthage, Institut Suprieur des Technologies de l\'Environnement de l\'Urbanisme et du Batiment, 2 Rue de l\'Artisanat Charguia 2, 2035 Tunis, Tunisia
Abderraouf Trabelsi: Universite de Tunis El Manar, Ecole Nationale d\'Ingnieurs de Tunis, LR-03-ES05 Laboratoire de Génie Civil, 1002, Tunis, Tunisia; Academie Militaire, Département Genie Civil, Fondouk Jadid, Tunisia

Abstract
Geopolymer concrete is a fastest developing field of research for utilizing industrial and agro waste materials as an alternative for Portland cement based concrete. Geopolymers are formed by the alkaline activation of aluminosilicates rich materials termed as geopolymerization. The process of geopolymerization requires elevated temperature curing which restricts its application to precast industry. This review summarizes the work carried out on developing the geopolymer concrete with the addition of various mineral admixtures at ambient curing temperature conditions. An overview of studies promoting the geopolymer concrete in general building construction is presented. Literature study revealed that geopolymer concrete with the addition of admixtures can exhibit desirable properties at ambient temperature conditions.

Key Words
geopolymer concrete; ambient curing; admixtures; compressive strength; durability

Address
Bharat Bhushan Jindal: Department of Civil Engineering, M. M. University, Ambala, Haryana, India

Abstract
The study evaluates properties of brick having coal ash and explores the possibility of utilization of coal bottom ash and coal fly ash as an alternative raw material in the production of coal ash bricks. Lower cement content was used in the investigations to attain appropriate strength and prohibit high carbon content that is cause of environmental pollution. The samples use up to 7% of cement whereas sand was replaced with bottom ash. Bricks were tested for compressive strength, modulus of rupture, ultrasonic pulse velocity (UPV), water absorption and durability. The results showed mix proportions of bottom ash, fly ash and cement as 1:1:0.15 i.e., M-15 achieved optimum values. The coal ash bricks were well bonded with mortar and could be feasible alternative to conventional bricks thus can contribute towards sustainable development.

Key Words
coal fly ash; coal bottom ash; brick; sand; cement; compressive strength; masonry prism

Address
Deepankar Kumar Ashish: Department of Civil Engineering, Punjab Engineering College, Chandigarh 160-012, India; Department of Civil Engineering, Maharaja Agrasen Institute of Technology, Maharaja Agrasen University, Baddi 174-103, India
Surender Kumar Verma: Department of Civil Engineering, Punjab Engineering College, Chandigarh 160-012, India
Joginder Singh: Department of Civil Engineering, Punjab Engineering College, Chandigarh 160-012, India
Namesh Sharma: Department of Civil Engineering, Maharaja Agrasen Institute of Technology, Maharaja Agrasen University, Baddi 174-103, India


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