Siti Hawa Hamzah

Bonding Strength of Expanded Polystyrene (EPS) Beads Enhanced with Steel Fiber in Reinforced Lightweight Concrete (LWC)

Lightweight concrete (LWC) is one of the favourable concrete to be used as it has low density with acceptable high strength, high durability, and toughness. In order to produce LWC, it is required special material such as expanded polystyrene (EPS) beads and steel fiber to be added into the design mix concrete. As known, EPS beads have zero strength. Meanwhile, the significant of steel fiber is to reduce micro and macro crack propagation. Therefore, pull out test were carried out to measure the bond strength between reinforcement bar and three series of concrete mix design which are normal concrete, EPS-LWC and EPS-LWC enhanced with steel fiber. Concrete adhesion and bearing deformation of reinforcing bar against the concrete are the two main mechanisms that influence the strength of bond in the steel reinforced concrete. Deformation will increase when the bonding stress increase. Normal concrete series shows the higher average bonding stress which is 531.22 kPa compared to others series concrete mix. Meanwhile, bonding stress of EPS-LWC mix is 174.54 kPa which is higher than EPS-LWC enhanced with steel fiber mix. Even though the present of the steel fibre can increase the strength of the LWC, but it effects to the bonding strength between reinforcement steel rod and concrete. There are two improtant factor in bonding determination which are volume fraction and aspect ratio of the steel fiber. Segregation will increase when the aspect ratio of steel fiber increased. Besides, the workability becomes low. This present study used types of hooked end steel fiber with 60 mm length and aspected ratio is 0.75. While the size of the cylindrical is 300 mm x 150 mm. The position of the steel fiber in the specimens is too compact and presenting the air voids. Consequently weaken the bonding strength between concrete and reinforcement bar.

Crack Behaviour of Retrofitted Pre-Tensioned Concrete Beam

Crack is a common cause of the degradation of concrete and may affect its structural durability. In order to ensure the bridge is safe utilized in anticipated period of their future service, a proper maintenance process and procedure should be taken. Therefore in this study, static load test were performed on a pre-tensioned (PRT) concrete beam to investigate crack behaviour before and after retrofitting process as well as to determine the effectiveness of the retrofitting method. A control beam named PRTB1 will fully loaded until fail to determine its maximum load capacity and critical load of the beam. Hence another beam named PRTB-FRP will be loaded until it reached it critical load capacity before retrofitted using Fiber Reinforced Polymer (FRP) plates located beneath the centre of the beam. After the retrofitting process PRTB-FRP will be put again under the static load. The load capacity of PRTB-FRP increased compared to PRTB1 with some improvement in crack propagation behaviour after retrofitted.

Harmonic Formulation of Prestressed Concrete Sleeper Subjected to Freight Train

In Malaysia, rail transportation has become an integral part of the society. It can be seen by the effort of the Malaysia Government to improve the rail system by laying new route, provide new type of trains and others. For transporting goods, Malaysian rail authorities (Keretapi Tanah Melayu Berhad) used 22 coaches so-called freight train becoming one of the most popular transportation in delivery goods. In the past, wood is commonly used as a material in sleeper’s manufacturing but nowadays, prestressed concrete sleeper starts to capture their name in the industry in producing more quality sleeper as one of railway track components. This study will be focusing on determination of constant amplitude for 22 coaches, cyclic counting strain and calculation of frequency of strain on prestressed sleeper subjected to freight train. Rainflow cyclic counting method is used to determine the constant amplitude, cycle and frequency for each parts of train body. By using rainflow method and formulas, average number of cycle and frequency is obtained. From the obtained results, the individual PCS have to endure a maximum frequency and number of cycles of 11.91 Hz and 1.39 s, respectively. The outcome of this study will have a formulation of the freight train that is currently being used in Malaysia.

Flexural strength and behaviour of SFRSCC ribbed slab under four point bending

An experimental investigation was carried out to study the ultimate strength and behaviour of SFRSCC ribbed slab under four point bending. Comparison was been made between ribbed slab that was fully reinforced with steel fibres (SFWS) with conventionally reinforced concrete ribbed slab (CS and CRC). The volume fraction of the 35 mm hooked end steel fibres used in the mix was 1% (80 kg/m3) with the aspect ratio of 65. Three full scale slab samples with the dimension of 2.8 x 1.2 m with 0.2 m thickness was constructed for the purpose of this study. The slab samples was loaded until failure in a four point bending test. As a whole, based on the results, it can be concluded that the performance of the steel fiber reinforced samples (SFWS) was found to be almost equivalent to the conventionally reinforced concrete ribbed slab sample (CRC).An experimental investigation was carried out to study the ultimate strength and behaviour of SFRSCC ribbed slab under four point bending. Comparison was been made between ribbed slab that was fully reinforced with steel fibres (SFWS) with conventionally reinforced concrete ribbed slab (CS and CRC). The volume fraction of the 35 mm hooked end steel fibres used in the mix was 1% (80 kg/m3) with the aspect ratio of 65. Three full scale slab samples with the dimension of 2.8 x 1.2 m with 0.2 m thickness was constructed for the purpose of this study. The slab samples was loaded until failure in a four point bending test. As a whole, based on the results, it can be concluded that the performance of the steel fiber reinforced samples (SFWS) was found to be almost equivalent to the conventionally reinforced concrete ribbed slab sample (CRC).

Finite Element Analysis: Displacement of Eccentric Loaded SFRC Ribbed Wall Panel

This finite element study was carried out to investigate the steel fiber reinforced concrete with three (3) ribbed wall (SFRC-3RW) panel containing reinforced wire mesh (BRC) subjected to axial and eccentric loading, also its load bearing response behavior. A ribbed wall with steel reinforced was modeled with finite element analysis software LUSAS 14.7 using three dimensional modeling and nonlinear finite element analysis. The SFRC-3RW panel was subject to axial and eccentric loading to observe and investigate its buckling effect, the load bearing response behavior, and compare with SFRC plain wall (PW). The SFRC-3RW and PW was using concrete grade 30 with 0.5 % steel fiber content. The SFRC-3RW ultimate load bearing is 581 kN with maximum compression vertical and lateral displacement by 2.36 and 6.16 mm, respectively, compared to SFRC-PW with eccentric loading (SFRC-PWe) 577 kN with maximum compression vertical and lateral displacement by 2.31 and 8.24 mm. The reduction in concrete volume and ultimate load capacity were 20 and 0.33 % from SFRC-PWe in which SFRC-3RW save the concrete amount and gave higher load capacity compared to SFRCPWe. It can be concluded that the load bearing capacity for SFRC-3RW with BRC is acceptable and can withstand vertical pressure also reducing the amount of concrete usage.

Monitoring of Precast Prestressed Concrete Beam due to Static Load by Using Pundit Equipment

The vast growt of population now increases the usage of buildings and infrastructures especially for concrete bridge. Prestressed concrete was introduced to be used in most concrete bridge superstructures. Predetermination of concrete strength ensures the condition of precast prestressed concrete structures. Testing of precast concrete is crucial in order to find its capabilities before commencing construction. Conventional method of testing usually takes a lot of time and is very costly. The aim of this study is to find the speed of the sound wave passing through the precast prestressed concrete beam. This study also identifies the shear modulus and the elastic modulus of precast prestressed concrete beam after the application of bending test on the two rectangular beams of 4 m length each. The test result indicates the condition of the beam, before and after loading condition. The ultrasonic pulse velocity (UPV) method is an ideal tool to show whether concrete structure is in good condition. This method can be used for those still been constructed and on existing structures. Interpretation of velocities using UPV method could easily determine the grading in terms of its uniformity and strength. The velocities indicate the occurrence of voids inside the beam which relates to the tendency of initial failure. Decreases in ultrasonic waves speed over time can reveal the onset of damage before visible deficiencies become evident. This allows inspectors and engineers to implement repair recommendations before minor deficiencies become safety hazards.

Bond Strength of Bar Connector Performance in Male-Female Interlocking Panel (M-FiP)

In this paper, the bond strength characteristic between reinforcement bar and cement grout as a wet joint connection mechanism in male-female interlocking panel (M-FiP) was investigated. The bond strength result depended on cement grout strength respectively. Total eight (8) specimens were constructed with grout strength as variables. Recycled aggregate with size 10 and 20 mm has been used as replacement normal aggregate in concrete production Grade 30 of male and female panel. The 12 O reinforcement bar size was used and installed vertically for all M-FiP specimens. The test result demonstrated that the average bond strength for all different days with cement grout strength about 58.70, 64.50, 64.70, and 90.60 N/mm2 is 3.80, 3.93, 3.99, and 4.29 N/mm2, respectively. From this result, it can be seen that the bond strength was influenced by material strength that has been used surrounding the reinforcement bar. The percentage increment of bond strength in different cement grout strength is 3.4, 5, and 12.9 % when compared with bond strength for 7 day M-FiP specimens. The high strength of cement grout provided greater bearing resistance against slippage between cement grout key and steel reinforcement bar. In fact, longer development length embedded in cement grout added the numbers of key that resist the slippage and directly increased the bond strength. The pullout failure occurred to all M-FiP specimens when concrete surrounding steel reinforcement bar ribs or called as concrete key is weak and other concrete at surrounding steel reinforcement bar is strong.

Steel Fibre Reinforced Self-Compacting Concrete (SFRSC) performance in slab application: A review

The application of Steel Fibre Reinforced Self-compacting Concrete (SFRSC) in the construction of structural elements is seen as an alternative solution to the complication in placing the reinforcement and compaction of normally vibrated concrete. The main advantage of SFRSC is the ability to be properly poured in place, filling the formwork corners and small voids between reinforcement bars by means of its own weight. Many research had been done in exploring the structural performance of SFRSC due to the enhanced engineering and mechanical properties. The incorporation of steel fibres in the mix has been found to enhance the hardened properties of self-compacting concrete in terms of its tensile strength, ductility, toughness, energy absorption capacity and as well as fracture toughness. The objective of this paper is to review the work done by previous researchers on the performance of SFRSC in slab structures. The knowledge could be used as a guide in expanding the application of SFRSC as the main mate...

Bending Strength of Pre-tensioned (PRT) Concrete Beam

This paper presents a preliminary study on bending strength of pre-tensioned (PRT) concrete beam as the experiment result can be used in maintenance planning. The production of beam was according to BS8110, BS4449:2005 and BS5896 for concrete, reinforcement bar and strand, respectively. For the bending test, theoretically and practically was conducted in accordance to BS5400 standard. The result showed cracked beam retrofitted with fiber reinforced polymer (FRP) plate and carbon fiber reinforced polymer (CFRP) sheets are able to increase the bending strength of beam up to 43 and 42 %, respectively.

Shear Resistance Analysis of Rebar Connector in RC Stocky Wall Panel Using Lusas 3D Modelling

Reinforced concrete (RC) stocky wall panel is a new innovation to the construction industry. To-date, studies on the RC stocky wall panel are under progress. This paper is analyzed shear resistance of rebar connector in RC stocky wall panels using LUSAS 3D model. Four (4) number of model have been analyzed using finite element analysis with varies size of rebar connector which is T12, T16, T20 and T25. These models of RC stocky wall panel was constructed in same dimension, 125 mm × 1,000 mm × 500 mm (Thickness:Length:Height). This paper was concerned with a finite element model to determine the maximum deflection of the RC stocky wall panel in resisting lateral load. These four (4) models are being analyzed to observe its deflection, stress and strain. The result was illustrated and discussed in graphs namely stress-strain relationship and also load versus displacement contour. The size of rebar connectors are affected the shear resistance results in term of lateral deflection, stress and strain. From this study, it can be concluded that, the larger diameter of rebar size has give the less displacement in model.