• Advances in concrete construction
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• v.5 no.6
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• pp.575-586
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• 2017

The disposal of polythene waste and fly ash is causing serious threat to the environment. Aim of this study is to decrease environmental pollution by using polythene waste and fly ash in concrete. In this study, cement was partially replaced with 0%, 5%, 10%, 15% and 20% fly ash (by weight) and plastic waste was added in shredded form at 0.6% by weight of concrete. The specimens were prepared for the concrete mix of M25 grade and water to cementitious material ratio (w/c) was maintained as 0.45. Fresh concrete property like workability was examined during casting the specimens. Hardened properties were found out by carrying out the experimental work on cubes, cylinders and beams which were cast in laboratory and their behavior under test were observed at 7 & 28 days for compressive strength and at 28 days for density, flexural strength, dynamic modulus of elasticity, abrasion resistance, water permeability and impact resistance. Overall results of this study show that addition of 0.6% (by weight of the concrete) plastic waste with 10% (by weight of cement) replacement of cement by fly ash result an improvement in properties of the concrete than conventional mix.

• Structural Engineering and Mechanics
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• v.78 no.3
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• pp.319-332
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• 2021

The wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridges, as well as in the building construction for the design of wood concrete floor systems. The authors of this paper has been working for the past few years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors, this assembling technique does ensure an almost perfect connection between wood and concrete. This paper presents a careful theoretical investigation into interfacial stresses at the level of the two interfaces in composite wooden beam- reinforced concrete slab strengthened by external bonding of prestressed composite plate under a uniformly distributed load. The model is based on equilibrium and deformations compatibility requirements in all parts of the strengthened composite beam, i.e., the wooden beam, RC slab, the CFRP plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the CFRP- wooden-concrete hybrid structures.

• Advances in concrete construction
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• v.16 no.5
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• pp.255-267
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• 2023

The production of ultra-early-strength concrete (UESC) traditionally involves complexity or necessitates high-temperature curing conditions. However, this study aimed to achieve ultra-early-strength performance solely through room-temperature curing. Experimental results demonstrate that under room-temperature (28℃) curing conditions, the concrete attained compressive strengths of 20 MPa at 4 hours and 69.6 MPa at 24 hours. Additionally, it exhibited a flexural strength of 7.5 MPa after 24 hours. In contrast, conventional concrete typically reaches around 20.6 MPa (3,000 psi) after approximately 28 days, highlighting the rapid strength development of the UESC. This swift attainment of compressive strength represents a significant advancement for engineering purposes. Small amounts of steel fibers (0.5% and 1% by volume, respectively) were added to address potential concrete cracking due to early hydration heat and enhance mechanical properties. This allowed observation of the effects of different volume contents on ultra-early-strength fiber-reinforced concrete (UESFRC). Furthermore, the compressive strength of 0.5% and 1% UESFRC increased by 16.3% and 31.3%, respectively, while the flexural strength increased by 37.1% and 47.9%. Moreover, toughness increased by 58.2 and 69.7 times, respectively. These findings offer an effective solution for future emergency applications in public works.

• Advances in concrete construction
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• v.6 no.6
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• pp.645-658
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• 2018

Despite being one of the most abundantly used construction materials because of its exceptional properties, concrete is susceptible to deterioration and damage due to various factors particularly corrosion, improper loading, poor workmanship and design discrepancies, and as a result concrete structures require retrofitting and strengthening. In recent times, Fiber Reinforced Polymer (FRP) composites have substituted the conventional techniques of retrofitting and strengthening of damaged concrete. Most of the research studies related to concrete strengthening using FRP have been performed on undamaged test specimens. This contribution presents the results of an experimental study in which concrete specimens were damaged by mechanical loading and elevated temperature in laboratory prior to application of Carbon Fiber Reinforced Polymer (CFRP) sheets for strengthening. The test specimens prepared using concrete of target compressive strength of 28 MPa at 28 days were subjected to compressive and splitting tensile testing up to failure and the intact pieces of the failed specimens were collected for the purpose of repair. In order to induce damage as a result of elevated temperature, the concrete cylinders were subjected to $400^{\circ}C$ and $800^{\circ}C$ temperature for two hours duration. Concrete cylinders damaged under compressive and split tensile loads were re-cast using concrete and rich cement-sand mortar, respectively and then strengthened using CFRP wrap. Concrete cylinders damaged due to elevated temperature were also strengthened using CFRP wrap. Re-cast and strengthened concrete cylinders were tested in compression and splitting tension. The obtained results revealed that re-casting of specimens damaged by mechanical loadings using concrete & mortar, and then strengthened by single layer CFRP wrap exhibited strength even higher than their original values. In case of specimens damaged by elevated temperature, the results indicated that concrete strength is significantly dropped and strengthening using CFRP wrap made it possible to not only recover the lost strength but also resulted in concrete strength greater than the original value.

• Structural Engineering and Mechanics
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• v.41 no.2
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• pp.231-242
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• 2012

This research work aims to develop an optimal design using Finite Element (FE) and Genetic Algorithm (GA) methods to replace the traditional concrete and timber material by a Synthetic Polyurethane fibre glass composite material in railway sleepers. The conventional timber railway sleeper technology is associated with several technical problems related to its durability and ability to resist cutting and abrading action of the bearing plate. The use of pre-stress concrete sleeper in railway industry has many disadvantages related to the concrete material behaviour to resist dynamic stress that may lead to a significant mechanical damage with feasible fissures and cracks. Scientific researchers have recently developed a new composite material such as Glass Fibre Reinforced Polyurethane (GFRP) foam to replace the conventional one. The mechanical properties of these materials are reliable enough to help solving structural problems such as durability, light weight, long life span (50-60 years), less water absorption, provide electric insulation, excellent resistance of fatigue and ability to recycle. This paper suggests appropriate sleeper design to reduce the volume of the material. The design optimization shows that the sleeper length is more sensitive to the loading type than the other parameters.

• Advances in concrete construction
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• v.10 no.1
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• pp.71-79
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• 2020

Ultra-high-performance concrete (UHPC) is recognized as a promising material in future civil engineering projects due to its outstanding mechanical and durability properties. However, the lack of local UHPC materials and official standards, especially for prestressed UHPC structures, has limited the application of UHPC. In this research, a large-scale prestressed bridge girder composed of nonproprietary UHPC is produced and investigated. This work has two objectives to develop the mixing procedure required to create UHPC in large batches and to study the flexural behavior of the prestressed girder. The results demonstrate that a sizeable batch of UHPC can be produced by using a conventional concrete mixing system at any precast factory. In addition, incorporating local aggregates and using conventional mixing systems enables regional widespread use. The flexural behavior of a girder made by this UHPC is investigated including flexural strength, cracking pattern and development, load-deflection curve, and strain and neutral axis behaviors through a comprehensive bending test. The experimental data is similar to the theoretical results from analytical methods based on several standards and recommendations of UHPC design.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.113-116
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• 2007

This is a research for evaluated recycled glass powder to add asphalt concrete filler. To make a comparative study, Mechanical performance of lime stone and slag dust Mixtures was evaluated according to test procedure. Lab. performance tests included marshall stability, indirect tensile strength, resilient modulus and wheel tracking. Water resistance tests were evaluated by marshall strength ratio and tensile strength ratio. In conclusion, Results of mechanical performance showed that recycled glass powder mixtures were equivalent to conventional mixtures. Especially, result of tensile strength ratio tested recycled glass powder mixtures was superior to conventional mixtures.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.885-890
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach. Pseudo dynamic tests of four full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, three test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.43-45
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• 2011

As technologies evolve, building large concrete structures ever built, but due to lack of maintenance after completion of concrete corrosion, leaks, and preparedness from the problem that is an urgent need. In particular, water-resistant variety of concrete structures. How the concept applies to the most important public drinking water purification and drinking water that is draining the production and storage, and distribution as the structure cause damage to the structure when the contaminated water is supplied to each home that can harm the health of citizens is the cause. Therefore, the correct choice of materials, and thorough a lot of investment in construction and maintenance should have. In this study, unlike conventional water-proof materials, methods, and in other reactions easily than conventional poly-urea resins have good physical performance and chemical resistance, high performance polyurea resin performance review of the physical infrastructure of the country for the longevity of would like to make long-term durability.

• Resources Recycling
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• v.9 no.3
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• pp.37-45
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• 2000

This paper presents the experimental test results on moisture and freeze-thaw resistance of hot mix crumb rubber modified (CRM) asphalt concrete mixture. To compare the differences in mechanical properties of conventional and CRM asphalt concretes, various tests were conducted under different moisture conditions and freeze-thaw cycles. Marshall mix design was also performed to determine the optimum asphalt contents for the both asphalt concrete mixtures. Test results revealed that the moisture and freeze-thaw resistance of CRM asphalt mixture was superior to the conventional asphalt concrete. As a result, it is considered that the utilization of waste tires in asphalt pavements has the potential of minimizing the damage due to the moisture and freeze-thaw.