Key Engineering Materials Vol. 879

Abstract: This paper investigates the effect of partial replacement of fly ash with sago pith waste ash and silica fume in fabricating the geopolymer mortar concrete. The mixtures of geopolymer mortar concrete were prepared by replacing sago pith waste ash and silica fume at 5% of total weight of fly ash. There were six specimens of geopolymer mortar cubes and bricks fabricated in this study. The specimens are tested with compressive strength test, rebound hammer test and ultrasonic pulse velocity test. The results from the tests are compared with some existing published works as to clarify the effect of replacing the fly ash with sago waste and silica fume on the strength of concrete. Comparisons had been made and concluded that the molarity of alkaline solution, Al₃O₂ and CaO influenced the development of compressive strength along the curing time of fly ash based geopolymer concrete.

Abstract: Currently, application of industrial waste or by-product in road construction industrials is a major interest by researchers, government officers and engineers. Coal ashes by-product from industrial parks negatively impact environment, costly in treatment, and require large ground for disposing areas. Therefore, this paper proposes on using the coal ash from furnace products of an industrial park in South of Vietnam to be incorporated into dense graded asphalt concrete using Nominal Maximum Aggregate Size 12.5mm. Laboratory performance tests including Marshall stability, indirect tensile strength, Cantabro loss, and dynamic fatigue test were conducted. The effects of coal ash contents in replacement of fine aggregate which is passing 4.75mm sieve from asphalt mixture into laboratory performance of mixture is also discussed in detail.

Abstract: Nowadays, road damage issue become the norm due to increment of traffic load and traffic volume. It shortens the service life of asphalt mixtures and increase the cost of maintenance. One way to reduce the issue is by using polymer additive in asphalt mixture. Treated Plastic is one type of polymer additive made of plastic bag (Polyethylene). The main purpose of this research is to determine the improvement of asphalt mixture’s performance incorporating Treated Plastic (TP) as additive in terms of stability, stiffness, fatigue cracking, stripping and rutting. The mechanical properties of asphalt mixes that include various percentages of TP (0%, 0.25%, 0.5%, 0.75%, 1%, 2% and 3%) were calculated and assessed with laboratory tests. 0.75% by weight of total mix of TP was found to be the optimum amount. The outcomes were analyzed by Marshall Stability and Flow, Resilient Modulus, Tensile Strength Ratio and Hamburg Wheel Tracker test. As the results shown, the addition of TP gave significant improvement to the stability and stiffness of asphalt mixture. 0.75% of TP was selected as the optimum percent content with percent improvement about 100, 73 and 25% for fatigue cracking, rutting and stripping resistance respectively. Hence, 0.75% of TP improved the resistance of rutting and stripping but susceptible to fatigue cracking.

Abstract: Flexible pavement failure has been a major problem encountered in various countries. Some common distress which had been listed are cracking and rutting. The causes of this distress are due to moisture, weak sub-grades and poor construction quality. High amount of distress in the pavement however is likely to cause dis-comfort for the passengers, higher accident rate and heavy traffic. Study suggested that, flexible pavement failure can be reduce, through maintenance of the wearing course of the pavement, improving the base, sub-base layer or the sub-grade soil underneath of the pavement. However, high production or material cost, high construction cost, excessive settlement, or weak inter-molecular bonds in the flexible pavement are some of the common problem encountered with the current improvement techniques. This significance difference of this review paper compare to other is that, in this review paper it focuses on the flexible pavement failure, the different types of improvement method currently applied. Consequently, it further recommend flexible pavement improvement method through by reducing the sub-base layer thickness and inclusion of light weight material in the sub-base layer so that, the settlement of the pavement is reduced.

Abstract: Steel bridge structure without intermediate bracing system (IBS) has been widely used in several countries and one of them is Japan. In this type of structure, the main steel girder is not reinforced by the stiffeners. The stiffness of the main girder is enhanced with steel plate directly welded to the top flange of the main girder, forming the “beams–system”. The reinforced concrete deck slab with the set of main girder and steel plate works compositely through steel shear connectors whose shape is C (channel) or I character. As for steel bridge structures, the main role of shear connectors is shear resistance between the concrete deck slab and steel girder plate in the exploitation stage. However, previous research has shown that the density of shear connectors influences on the stability as well as the stiffness of the bridge structure. Therefore, it has approved that this appurtenance is able to not only have the ability of shear resistance but also enhance the stiffness of the steel bridge structure which is particularly surveyed with the type of especial bridge structure – the steel bridge structure without IBS. Hence, the shear connectors in this kind of bridge structure are deliberately researched as an extra role in the construction stage. The following factors of the channel shape shear connectors would be researched for evaluating their impacting level on the stability of the special steel bridge structure: the properties (the length and the moment of inertia of the cross-section) and the density on the steel plate. Through the analysis of impacting level to the stability of three mentioned factors (the length and density of the shear connectors; the moment of inertia of the cross-section), the expected result is as following: 1) The minimum density of shear connectors is proposed. 2) The influence of the moment of inertia of the cross-section, the density, and the length on the stability is quite clear. 3) As for the economy, the optimal designed range among three factors is also suggested.

Abstract: Magnesium Oxide (MgO) board has been widely used in prefabricated lightweight steelframe wall systems and as the floor board covering component. It is a non-insulating sheathingboard product which consists of sustainable materials with the characteristics of fire resistance,weather-ability, strength, resistance to mold and mildew. Although MgO board has recentlyworldwide used in façade construction but the research data related to the laboratory work such asthe bending strength is still limited. The previous studies on the bending strength of MgO board arebased on various standards such as ASTM, JC688 and British Standard subjected to the productscharacteristics and patterns. Therefore, the bending strength values obtained were inconsistent andnot convincing. Thus, this paper aims to examine the bending strength of MgO board with threedifference thicknesses (6mm, 9 mm and 12 mm) based on BS EN 310:1993 subjected to threepoints bending test. The failure modes during three points bending test was observed and theexperimental results obtained were compared with the theoretical values and others relevantstandards. A total of thirty six specimens with twelve specimens for each thickness in two groupdirections namely longitudinal (length) and transverse (width) direction were tested. The specimenswere prepared based on BS EN 326-1:1994 and BS EN 325:2012. The maximum flexure load of thespecimens was recorded and arithmetic mean bending strength for each thickness was presented.The experimental results showed the tested MgO board was not achieved minimum bendingstrength for load bearing used. It is recommended to be used in non-load bearing façade claddingconstruction.

Abstract: Pipeline system is one of the essential infrastructures in oil and gas industries as it is used to transport oil and gas over long distance. However, pipelines will undergo damages and deteriorations after being used for some years, especially when corrosion occurs. Corrosive pipes will experience reduction in wall thickness resulted a lower remaining strength of the pipe, and consequently lead to failure once the remaining strength unable to withstand the desired operating pressure of the pipe. Therefore, additional strength from repairing job needs to be provided, for instance, by using fibre-reinforced polymer (FRP) composites. Unlike the corroded pipeline assessment codes, the pipeline repair codes that are used to design composite repair system of corroded pipe do not include the defect geometries such as defect length. In this study, burst pressure of the composite repaired pipeline with different defect lengths and the effect of the defect length upon the burst capacity of composite repaired pipe are investigated. The study is carried out by finite element analysis on various defective pipes with different defect length sizes. The results show that the difference of the burst pressure subjected to various defect lengths is 15.59% and this had proved that there is effect of defect length upon the burst capacity of composite repaired pipe. This finding can be very useful for optimizing the existing repair design.

Abstract: Recently, there are a lot of technological developments in the earthquake engineering field to reduce structural damage and one of them is a base isolation system. The base isolation system is one of the best technologies for the safety of human beings and properties under earthquake excitations. The aim of this paper is to review previous research works on simulation of base isolation systems for RC buildings and their efficiency in the safety of these buildings. Base isolation decouples superstructure from substructure to avoid transmission of seismic energy to the superstructure of RC buildings. The most effective way to assess the base isolation system for RC building under different earthquake excitations is by conducting experiment work that consumes more time and money. Many researchers had studied the behavior of base isolation system for structure through modeling the behavior of the base isolation in which base isolator is modeled through numerical models and validated through experimental works. Previous researches on the modeling of base isolation systems of structures had shown similar outcomes as the experimental work. These studies indicate that base isolation is an effective technology in immunization of structures against earthquakes.

Abstract: The models are predicting and analyzing on compressive and flexural testing by considering fiber reinforcement embedded in confinement concrete. In this work, steel 4340 fiber with high aspect ratio was developed in unique random spline shape and randomly disperse in confinement concrete. Fibers designed in 15.5mm of average length and amount were varied in range of 50 to 200 and 250 to 1000 for compressive and flexural testing, respectively. Both varied orientation and random dispersion of fiber were developed using MATLAB before embedded and analyzed in Ansys Workbench. The finite element model was validated in initial results on plain concrete prior study in influence of confining and fibers to structure. The model proposed showed that confining reinforcement increasing ductility and large deflections in structure testing. In addition, fibers as reinforcement slightly increases in strength for both compressive and flexural in certain number. These method reinforcement was help warning of failure prior to complete failure that use in construction material.

Abstract: This paper presents the predicted results of nonlinear time history analysis of 11 storey (G+10) Reinforced Concrete (RC) residential building under the effects of a strong earthquake. The paper includes studying the effects of using Lead Rubber Bearings (LRB) as base isolators to improve the performance of RC building to sustain the impact of an earthquake. It also includes the effects of the infill panels on the overall dynamic response of both fixed base and base-isolated buildings subjected to a strong earthquake. The main results that are presented in this study include the variation of roof acceleration, roof displacement, base shear with time. The effects of using LRB and including the infill panels on the storey drift are also presented. Maximum reduction in the story drift was obtained when infill panels are included in the analysis of the base isolated building. The inclusion of the infill panels has only marginal effects on the variation of roof displacement with time when the building is isolated by LRB. The main important improvements that emerged from using LRB as well as the infill panels in the analysis are the reduction of inelastic energy and upgrading the elastic one that is summed up along the period of the earthquake.