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CONTENTS
Volume 8, Number 1, August 2019
 

Abstract
The possibility of using recycled coarse glass aggregates as a substitute for natural crushed stone are relatively limited. In order to promote it for engineering application, this paper reports the effect of coarse glass aggregate on mechanical behavior of concrete. The coarse aggregates are substituted for coarse glass aggregate (CGA) as 0%,20%,40%,60%,80% and 100%.The results show that increasing the coarse glass aggregate content cause decrease in compressive strength, the elastic modulus, the splitting tensile strength, the flexural strength. An equation is presented to generate the relationship between cube compressive strength and prism compressive strength, the relationship between cube compressive strength and elastic modulus, the relationship between cube compressive strength and splitting tensile strength, the relationship between cube compressive strength and flexural strength of coarse glass concrete.

Key Words
coarse glass aggregate; concrete; mechanical behavior; relation

Address
Lan-lan Yan: Faculty of Science, East China University of Technology, Nanchang 330013, China
Jiong-Feng Liang: Faculty of Civil & Architecture Engineering, East China University of Technology, Nanchang 330013, China

Abstract
This paper describes an experimental investigation on hybrid fiber reinforced concrete (HYFRC) beams. And the main aim of this present paper is to examine the dynamic characteristics and damage evaluation of undamaged and damaged HYFRC beams under free-free constraints. In this experimental work, totally four RC beams were cast and analyzed in order to evaluate the dynamic behavior as well as static load behavior of HYFRCs. Hybrid fiber reinforced concrete beams have been cast by incorporating two different fibers such as steel and polypropylene (PP). Damage of HYFRC beams was obtained by cracking of concrete for one of the beams in each set under four-point bending tests with different percentage variation of damage levels as 50%, 70% and 90% of maximum ultimate load. And the main dynamic characteristics such as damping, fundamental natural frequencies, mode shapes and frequency response function at each and every damage level has been assessed by means of non-destructive technique (NDT) with hammer excitation. The fundamental natural frequency and damping values obtained through dynamic tests for HYFRC beams were compared with control (reference) RC beam at each level of damage which has been acquired through static tests. The static experimental test results emphasize that the HYFRC beam has attained higher ultimate load as compared with control reinforced concrete beam.

Key Words
composite materials; compressive strength; fiber-reinforced concrete; non-destructive testing; vibration

Address
Radhika Sridhar and Ravi Prasad: Department of Civil Engineering, National Institute of Technology, Warangal, India

Abstract
The rich recipe of ultra high performance concrete (UHPC) offers the higher mechanical, durability and dense microstructure property. The variable like cement/sand ratio, amount of supplementary cementitious material, water/binder ratio, amount of fiber etc. alters the UHPC hardened properties to any extent. Therefore, to understand the effects of these variables on the performance of UHPC, inevitably a stage-wise development is required. In the present experimental study, the effect of sand/cement ratio, the addition of finer material (fly ash and quartz powder) and, hybrid fiber on the fresh, compressive and microstructural property of UHPC is evaluated. The experiment is conducted in three phases; the first phase evaluates the flow value and strength attainment of ingredients, the second phase evaluates the efficiency of finer materials (fly ash and quartz powder) to develop the UHPC and the third phase evaluate the effect of hybrid fiber on the flow value and strength of ultra high performance hybrid fiber reinforced concrete (UHP-HFRC). It has been seen that the addition of fly ash improves the flow value and compressive strength of UHPC as compared to quartz powder. Further, the usage of hybrid fiber in fly ash contained matrix decreases the flow value and improves the strength of the UHP-HFRC matrix. The dense interface between matrix and fiber and, a higher amount of calcium silicate hydrate (CSH) in fly ash contained UHP-HFRC is revealed by SEM and XRD respectively. The dense interface (bond between the fiber and the UHPC matrix) and the higher CSH formation are the reason for the improvement in the compressive strength of fly ash based UHP-HFRC. The differential thermal analysis (DTA/TGA) shows the similar type of mass loss pattern, however, the amount of mass loss differs in fly ash and quartz powder contained UHP-HFRC.

Key Words
Ultra High Performance Concrete (UHPC); Steel Fiber; Crimped Fiber; Hooked Fiber; Hybrid Fiber; Fly Ash; Quartz Powder

Address
Raju Sharma and Prem Pal Bansal: Civil Engineering Department, Thapar Institute of Engineering and Technology, 147001 Patiala, India

Abstract
The present investigation is mainly focused on studying the flexural behavior of reinforced geopolymer concrete (RGPC) beams under pure bending. In this study, copper slag (CS) was used as a partial replacement of fine aggregate. Sand and CS were blended in different proportions (100:0, 80:20, 60:40 and 40:60) (sand:CS) by weight. Fly ash and ground granulated blast furnace slag (GGBS) were used as binders and combination of sodium hydroxide (8M) and sodium silicate solution were used for activating the binders. The reinforcement of RGPC beam was designed as per guidelines given in the IS 456-2000 and tested under pure bending (two-point loading) after 28 days of ambient curing. After conducting two point load test the flexural parameters viz., moment carrying capacity, ultimate load, service load, cracking moment, cracking load, crack pattern and ultimate deflection were studied. From the results, it is concluded that RGPC beams have shown better performance up to 60% of CS replacement.

Key Words
reinforced geopolymer concrete beams; copper slag; two-point loading; flexural parameters

Address
C. Sreenivasulu: Department of Civil Engineering, Jawaharlal Nehru Technological University, Anantapur, India
J. Guru Jawahar: Department of Civil Engineering, Annamacharya Institute of Technology and Sciences, Tirupati, India
C. Sashidhar: Department of Civil Engineering, Jawaharlal Nehru Technological University, Anantapur, India

Abstract
Durability of strengthened reinforced concrete (RC) beams with CFRP sheets under wetting and drying cycles of magnesium sulfate attack is investigated in this research. Accordingly, 18 RC beams were designed and made where 10 of them were strengthened by CFRP sheets at their tension side. Magnesium sulfate attack and wetting and drying cycles with water and magnesium sulfate solution were considered as exposure conditions. Finally, flexural performance of the beams was measured before and after 5 months of exposure. Results indicated that the bending capacity of the strengthened RC beams was reduced about 10% after 5 months of immersion in the magnesium sulfate solution. Wetting and drying cycles of magnesium sulfate solution reduced the bending capacity of the strengthened RC beams about 7%. Also, flexural capacity reduction of the strengthened RC beams in water and under wetting and drying cycles of water was negligible.

Key Words
durability; reinforced concrete beams; strengthening; CFRP; sulfate attack; wetting and drying cycles

Address
Hamid Rahmani: Civil Engineering Department, University of Zanjan, University Blvd., Zanjan, Iran
Soha Alipour: Civil Engineering Department, Yasouj University, Daneshjoo Street, Yasouj, Iran
Ali Alipour Mansoorkhani: Civil Engineering Department, Yasouj University, Daneshjoo Street, Yasouj, Iran

Abstract
Portland cement pervious concrete has been expected to have good water permeability, mechanical properties and abrasion resistance at the same time when Portland cement pervious concrete is applied to the actual vehicle pavement. In this study, the coarse aggregate and cement were replaced by the fine aggregate and the silica fume to improve actual road performance Portland cement pervious concrete. The Mechanical properties, the water permeability and the abrasion resistance of Portland cement pervious concrete were investigated. The results show that the compressive strength, the flexural strength and the abrasion resistance are increased when the fine aggregate and the silica fume are added to Portland cement pervious concrete separately. However, the porosity and the water permeability are decreased simultaneously. With assistance of silica fume and fine aggregate simultaneously, Portland cement pervious concrete could achieve a higher strength. The compressive strength, the flexural strength and the abrasion resistance of Portland cement pervious concrete mixed with 5% fine aggregates and 8% silica fume are increased by 93.1%, 65% and 65.2%, respectively. The porosity and the water permeability are decreased by 22.4% and 85% when Portland cement pervious concrete is mixed with 5% fine aggregate and 8% silica fume. Therefore, the replacement ratio of the fine aggregates and the silica fume should be considered comprehensively and determined on the premise of ensuring the water permeability coefficient.

Key Words
Portland cement pervious concrete; fine aggregate; silica fume; water permeability; strength; porosity

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

Abstract
Chloride corrosion has become the main factor of reducing the service life of reinforced concrete structures. The object of this paper is to propose a theoretical model that predicts the service life of chloride-corrosive concrete under fatigue load. In the process of modeling, the concrete is divided into two parts, microcrack and matrix. Taking the variation of mcirocrack area caused by fatigue load into account, an equation of chloride diffusion coefficient under fatigue load is established, and then the predictive model is developed based on Fick\'s second law. This model has an analytic solution and is reasonable in comparison to previous studies. Finally, some factors (chloride diffusion coefficient, surface chloride concentration and fatigue parameter) are analyzed to further investigate this model. The results indicate: the time to pit-to-crack transition and time to crack growth should not be neglected when predicting service life of concrete in strong corrosive condition; the type of fatigue loads also has a great impact on lifetime of concrete. In generally, this model is convenient to predict service life of chloride-corrosive concrete with different water to cement ratio, under different corrosive condition and under different types of fatigue load.

Key Words
fatigue load; Chloride induced corrosion; microcrack area; fatigue damage; service life

Address
Tao Yang: School of Transportation, Southeast University, Southeast Unveristy Road 2#, Nanjing, Jiangsu, China; School of Material Science and Engineering, Chang\'an University, Nanerhuan Road Mid-Section, Xi\'an, Shannxi, China
Bowen Guan: School of Material Science and Engineering, Chang\'an University, Nanerhuan Road Mid-Section, Xi\'an, Shannxi, China
Guoqiang Liu, Jing Li, Yuanyuan Pan, Yanshun Jia and Yongli Zhao: School of Transportation, Southeast University, Southeast Unveristy Road 2#, Nanjing, Jiangsu, China

Abstract
This paper investigates the effect of recycled glass powder (RGP) on flowing properties of self-compacting mortars (SCMs) containing different ratios of fillers and superplasticizer dosages. Fly ash (FA), nano-silica (NS), micro-silica (MS), metakaolin (MK) and rice husk ash (RHA) are used as fillers and their synergistic effect with RFP is studied. The effects of fillers and high-range water reducer (HRWR) on flowing ability of mortars are primarily determined by slump flow and Vfunnel flow time tests. The results showed that for composites with a higher RGP content, the mortar flowing ability increased but tended to decrease when the composites containing 10% MK or 5% RHA. However, the flowing ability of samples incorporating 5% RGP and 10% SF or 25% FA showed an opposite result that their slump flow spread decreased and then increased with increasing RGP content. For specimens with 3% NS, the influence of RGP content on flowing properties was not significant. Except RHA and MS, the fillers studied in this paper could reduce the dosage of HRWR required for achieving the same followability. Also, the mixture parameters were determined and indicated that the flowability of mixtures was also affected by the content of sand and specific surface area of cement materials. It is believed that excess fine particles provided ball-bearing effect, which could facilitate the movement of coarse particles and alleviate the interlocking action among particles. Also, it can be concluded that using fillers in conjunction with RGP as cementitious materials can reduce the material costs of SCM significantly.

Key Words
recycled glass powder; Rheological properties; self-compacting mortar; cementitious materials

Address
Pedram Alipour: Department of Civil Engineering, Islamic Azad University-UAE Branch, P.O. Box 502321, Dubai, UAE
Maryam Namnevis, Behzad Tahmouresi: Department of Civil Engineering, University of Guilan, P.O. Box 4199613776, Rasht, Iran
Ehsan Mohseni, Waiching Tang: School of Architecture and Built Environment, the University of Newcastle, Callaghan, NSW 2308, Australia


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