Performance of carbon fibre reinforced polymer plate bonding system under various environmental conditions

The use of Carbon Fiber Reinforced Polymer (CFRP) as strengthening material for reinforced concrete and steel has been a focused of many researched around the world. Superior properties of the CFRP plate including lightweight, high tensile strength, and corrosion resistance make it a favorable material in strengthening of existing structures. The CFRP strengthening technique has been known to enhance the structural performance of the strengthened member. However, one of the main drawbacks is the long-term durability of the CFRP bonding system against various environmental conditions. This study evaluates the durability performance of the CFRP plate bonding system exposed to different environments. Experimental work was conducted in which the CFRP plate, adhesive coupons, and CFRP double lap shear samples were prepared and subjected to either continuous or wet-dry cycles in different exposures including plain water, salt water, acidic solution, and outdoor. The exposed samples were tested at different ages. The study found that the CFRP plate was quite durable and the change on the properties was negligible. However, the results indicated that exposure to different environments had affected the adhesive strength properties significantly with exposure to salt water was found to have the most degradation effect on the adhesive

Effects of palm oil clinker as coarse aggregates replacement in self curing concrete

Concrete, if properly design, can be one of the most durable material and widely used in construction due to its availability and good compressive strength. A good quality concrete can be produced not only through good design of concrete mix proportions but also good and proper curing process that ensure a complete hydration process of the cement. However, sometimes proper curing process was not provided during concreting on site due to various reasons. This study investigates the effects of 10 mm crushed Palm Oil Clinker (POC) as partial aggregates replacement to act as internal reservoirs in concrete to provide internal curing process of cement. This process or technique is also popularly known as self-curing process for concrete. The POC which has the density of 780 kg/m3 was used to replace 20% of the coarse aggregates. A water/cement ratio of 0.53 was used in the concrete mix design. Three different curing conditions were employed, namely, normal water curing, air curing and 7 days in water plus outside curing conditions. The workability of the POC and control concretes was determined through slump test. The concrete samples were tested for compression at the age of 3, 7 and 28 days while concrete prisms and cylindrical samples were tested at the age of 7 and 28 days. The experimental results show that the inclusion of POC was found to increase the workability of concrete by 27% but reduced the concrete compressive strength by about 6% compared with the control concrete. In addition, the flexural and tensile strengths of POC concrete were found to be less than the control concrete due to the properties of the POC which was lightweight and porous. The experimental results show that the porous structure of the POC aggregates can be utilised as water reservoir for the process of internal curing for the self-curing concrete

Flexural behaviour of concrete beams reinforced with glass fibre reinforced polymer bars

Corrosion of steel reinforcement is one of the main problems facing the construction industries throughout the world. Many methods have been used to minimize the problem but without success. Thus, more durable reinforcements are highly needed to replace conventional steel. Glass Fibre Reinforced Polymer (GFRP) bars provide a good alternative reinforcement due to its non-corrodible characteristic. This paper presents the flexural behaviour of concrete beams, each measuring 150 x 255 x 2400 mm and reinforced with GFRP and stainless steel bars. The performance of the beams was analysed in terms of their load carrying capacity, load-deflection, load-concrete strain, load-reinforcement strain, cracking and mode of failure. The experimental results show that beams reinforced with GFRP bars experienced lower ultimate load, lower stiffness, and larger deflection at the same load level compared with control beam. However, the performance of the GFRP reinforced concrete beams improved slightly when stainless steel mesh was used as shear reinforcement

Performance of externally bonded reinforced concrete structures using carbon fibre reinforced polymer in tropical climate

Strengthening of existing concrete structures may be necessary in order to overcome the increase in loading capacity and also environmental effect. Durability and ductility are essential to the long-term sustainable service life of FRP material and concrete structural members with FRP reinforcement. Structural reliability and durability implies good performance of material that are able to resist degradation and capable to avoid structural damage. The strengthening of concrete structures through the use of externally bonded FRP composite system raises concern on the durability of the FRP materials at two locations. The first ones is the durability of the FRP material itself and the other one the durability between FRP material and the concrete substrate. The renewal of structural inventory is best summarized into (i) rehabilitation that include the application to repair, strengthening and retrofit structures and (ii) new construction with all FRP or new (Van Den Einde et al., 2003). Tropical climate of countries which experience high average annual temperature, humidity, rainfall and relatively constant ultra violet ray (UV) may have detrimental effect on the usage of FRP composite either externally or internally retrofitted. The rainy season or the most rainfall is experienced by East Malaysia in the October through February with annual rainfall of 5080 mm compared to 2500 mm of annual rainfall for the Peninsular Malaysia. Even tough, the temperature is quite consistent throughout the year, the temperature records in Malaysia for the last fifty years has shown a warming trend (Zhao et al., 2005). The amount of information on the durability of FRP subjected to environmental condition especially in the tropical climate environment is still very limited in the literature. Concluded researches show inconsistencies in the results on the degradation effect. It is crucial to study the tropical climate effect of using FRP and its matrix material in structures element in order to gain acceptance in a country which is experiencing tremendous wet and dry cycle through rain, moisture and dry season. This is essential because many of the applications of FRP as strengthening or repair materials are for outdoor environment. However, there is another concern of using FRP as external strengthening materials which is interfacial fracture along the bonded joints that can limit the strengthening performance of FRP materials. It is essential for the long term behavior of the structural bonded joints in civil engineering structures be guaranteed between 50 to 100 years for the acceptance of this bonded system in the construction industry (Täljsten, 2006)

Behavior of palm oil fuel ash and metakaolin ternary blend cement mortar at elevated temperatures

This study examines the effect of a ternary blend of palm oil fuel ash (POFA) and metakaolin (MK) on the behavior of cement mortar exposed to elevated temperatures. The ternary blend was produced by combining 10% POFA and 10% MK by weight as a substitute to cement. Three additional samples which include plain portland cement (OPC), 20% MK binary and 20% POFA binary were also produced for comparison. Compressive strengths and ultrasonic pulse velocities of the mortar samples after heating to temperatures of 200, 400, 600, and 800°C for 2 h were assessed. Furthermore, X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy analysis were carried out to examine the microstructure of the samples. The results show that the compressive strength and microstructure of mortar exposed to elevated temperatures improved with the simultaneous use of POFA and MK compared to plain OPC mortar and when POFA or MK is singly used. The ternary blend of cement/POFA/MK can, therefore, be used as a fire resistant material

Assessment of bridge management system in Iran

The road and railroad networks are the most important elements of the infrastructure system and bridges are the main connective parts. Moreover, bridges are considered as important points in critical arteries. If the bridges deteriorate, because of aging, fatigue, loading, weather conditions, natural disaster and etc. repair works will be more expensive than maintenance works. The available budget for rehabilitation and maintenance usually is not enough for holding the system in a certain condition level its whole life. In our country bridge maintenance isn't important as their construction. Bridge maintenance authorities haven't any serious view towards prevention maintenance, and while there isn't any structural failure, they don't take any effective measures. Nowadays, in developed country and even some developing countries, all of the bridges are evaluated and maintained by Bridge Management System (BMS). Bridge management system has a specific principle and plenty of developed software for it. Hence, for deployment of this system, it's necessary to plan a specific program with reasonable time table in order to prevent the disadvantages of these national assets. In this paper, a study has been conducted about implementation of BMS in IRAN that present accomplished activities and then evaluate the process and finally significant strategies and executive suggestion have been mentioned

Flexural behaviour of steel fibre reinforced concrete slabs

Concrete is a material that is good in compression but weak in tension. Enhancing the tensile properties of concrete will lead to its greater application in construction. It was reported that improvement in the mechanical properties of reinforced concrete structure can be done by the inclusion of short fibres. Steel fibres have been reported to be able to increase the toughness, abrasion, impact resistances and allow for decrease in concrete slab thickness. This paper focuses on a study conducted in the laboratory to investigate the behaviour of steel fibre reinforced concrete slab. Four reinforced concrete slabs with different parameters to be studied were cast and tested to failure. The concrete slabs cast consist of slab with reinforcement bar R-150, slab with reinforcement bar R-300 and 1% dosage of steel fibres, slab with 1% dosage of steel fibres, and one plain concrete slab. All the slabs cast having the overall size of 100 x 500 x 1000 mm, and tested to failure under four point loading. The behaviour of the concrete slabs was studied through their ultimate load, load deflection characteristic upon loading, cracking history, and mode of failure. The results indicated that the inclusion of steel fibres can increased the ultimate load of the sample and its ability to absorb more energy after cracking, i.e. the toughness, compared with the control slab. It also shows that the use of steel fibres can reduce to some extent the total area of steel reinforcement required in reinforced concrete slab such for ground slab application

Introduction to civil engineering materials

xii+215hlm.;26c

Experimental study on compressive strength of Interlocking Hollow Block System (IHBS) using fly ash

Interlocking Hollow Block System (IHBS) is a reasonable solution for conventional block masonry due to its structural ability and building capability. In addition, economic and ecological building of brickwork can be achieved by incorporating fly ash into IHBS. The main aim of the research is to produce interlocking compressed hollow block that satisfy the standard requirement as in Eurocode 6. The study is essentially divided into 2 phases, block production and block compression testing. This paper studies on the compressive strength of interlocking hollow clay block with various compositions including laterite soil, cement, sand and fly ash. The optimum mix design is achieved with minimum compressive strength of 7 MPa, which comply with the standard BS 5628-1:1992 Code of practice for Use of masonry – Part 1: Structural use of unreinforced masonry. Test result on addition of fly ash revealed that the optimum fly ash content was 2% with the highest compressive strength of 10 MPa. The results of this study show that the proposed block mixture meets the standard strength requirements and the structural performance of the masonry block is improved by adding fly ash into the mix design

Degree of hardening of epoxy-modified mortars without hardener in tropical climate curing regime

Previous studies show that the epoxy resin will harden in the presence of calcium hydroxide from cement hydration process under steam curing. In this study, commercially available epoxy resin without any hardener was used as a polymeric admixture to prepare epoxy-modified mortars subjected to dry, and 5 day wet followed by dry curing in tropical environment. The mortars were prepared with a mass ratio of cement to fine aggregate 1:3, water-cement ratio of 0.48 and epoxy content of 5, 10, 15 and 20% of the cement. The tests conducted were workability, setting time, compressive strength, flexural strength, and degree of hardening of epoxy resin. The results of the study show that the optimum epoxy content that produced the highest strength was 10% under wet-dry curing. However, the degree of epoxy hardening starts to decrease with an increase in epoxy content above 10%. It was also found that a significant improvement in strength development is achieved along with additional dry curing period due to gradually hardening reaction of epoxy resin with cement hydrates