Efforts to reduce manufacturing cost and negative environmental impacts have seen the mixture of natural fibre with synthetic fibre in composite structures. However, there are limited studies on the notch effect and fibre orientation on mechanical properties of hybrid fibre metal laminate (FML). In this study, tensile properties of FML with notch and different fibre orientation were investigated. The hybrid FML incorporated with kenaf fibre at the middle layer was compared with FML with three layers of E-glass fibre. Kenaf fibre and E-glass fibre used were in plain woven form. The FML in 2/1 configuration was manufactured through hot press manufacturing method to bond layers of annealed aluminium 5052 to the composite. Tensile test was conducted in a quasi-static manner according to ASTM E8. The results showed FML with three layers of glass fibre exhibited higher tensile strength compared with hybrid FML. However, the introduction of kenaf fibre in hybrid FML reduces the notch and fibre orientation sensitivity compared with glass fibre reinforced FML.
Fibre metal laminates, fibre orientation, hybrid, mechanical properties, notch effect
This paper is aimed at examining the use of blended learning and how it affects students' score in examination. Basic Movement Therapy (BMT) Digital Learning was constructed and developed based on multimedia design guidelines. A quasi-experimental design using two groups with pre-test post-test approach was used. A total of 103 students from the Universiti Kuala Lumpur, RCMP (Royal College Medical, Perak) were divided in two groups. The Control group received standard teaching sessions (N=51). The Treatment group received the same standard sessions but additionally used BMT Digital Learning application (N=52). Written test on basic movement therapy was done by students before and after intervention. Statistically significant better scores for the treatment group were noted. The results suggest that the use of BMT Digital Learning application was suitable for practical procedure purposes.
Basic movement therapy, blended learning, digital learning resource, education, therapy
Remanufacturing of used-products is becoming an important activity in many production companies. This paper reviews key remanufacturing process, highlights eight unique characteristics of remanufacturing process environment and proposes a generic conceptual remanufacturing process model that considers the presence and interactions of these eight features. The generic conceptual model could be modified to suit remanufacturing process of any given used products to be remanufactured. Future research can modify the generic remanufacturing model to suit used automotive parts remanufacturing with unique characteristics and apply simulation technique to model and analyse the corresponding remanufacturing process.
Sarawak has experienced several earthquakes of local origin and was also affected by long-distance earthquake that originated from Southern Philippine and the Straits of Macassar, Sulu Sea and Celebes Sea. The objectives for this study were to conduct site specific ground response analysis and develop design response spectra for Bakun area by using 1-D equivalent linear ground response analysis. The site characterisation was carried out utilising the soil profile and soil property data of the selected site. Local surface fault ruptures were investigated for possible hazards due to intraplate earthquakes. Earthquake ground motion records were selected based on characteristics of the controlling earthquakes for an area and the maximum magnitude faults were considered for risk assessment. The site-specific response spectra represent the predicted surface ground motions that reflect the levels of strong motion amplitude and frequency content at a particular site. The site-specific ground response analysis for Bakun site found that the peak ground acceleration at bedrock was amplified from 0.16 g to 0.33 g at the ground surface
Earth ground motions, frequency, peak ground acceleration, risk assessment, site specific ground response spectra
Sustainability is an important factor in designing vernacular architecture, including vernacular palace architecture; the latter refers to low-rise buildings similar to Traditional Malay Houses (TMH). However, the Istana Lama Seri Menanti is a 4-storey mid-rise vernacular palace which was designed with sustainability in mind. This mid-rise element of the palace communicates the vernacular architecture of TMH in Negeri Sembilan whereas sustainable designs are factored in environmentally friendly materials, construction methods, and the environmental impact of the building culturally and economically. This research was aimed at examining the sustainability approach of Istana Lama Seri Menanti as a mid-rise vernacular palace in the early 20th Century, and its impact on the current generation after 109 years. The research methodologies include case and precedent studies of vernacular palaces in Malaysia as well as interviews with experts in the field. In conclusion, the architectural sustainability of Istana Lama Seri Menanti had taken into account timber availability, consumption of naturally available resources, designs with minimal environmental impact and high cultural importance in the building design with the ultimate aim of conserving it for future generations.
This paper describes the state-of-the-art of green airport infrastructure in Colombia. It is aimed at identifying opportunities for public-private investment in this type of projects which constitute a growing global trend in the air transport industry. The study provides an insight into the green airport infrastructure industry in Colombia based on available literature. The relation to green airport infrastructure projects and Public-Private Partnerships were also analysed. Findings reveal that green airport infrastructure ensures compliance with the COP21 commitments and the Kyoto protocol.
Airport management, Colombia, concessions, green airport infrastructure, public-private partnerships
In the area of sustainable development, construction waste is an important issue that must be tackled responsibly. It is an assortment of waste, at the stage of construction. This paper assesses waste minimisation or reduction measures and such practices in the Kuala Lumpur construction industry. A structured questionnaire survey was conducted to obtain contractors' views on 25 waste minimisation measures discussed in literature. Data was analysed using frequency analysis method and average index analysis method. The results showed that adoption of proper site management techniques is widely practised. The adoption of these waste minimisation measures could lead cost savings to the construction industry and prevent environmental degradation.
Construction industry, Kuala Lumpur, measures, waste minimisation
Sungai Sarawak is the most important river in Sarawak. This study was aimed at assessing water quality in the selected stations from Satok bridge to the downstream, Muara Tebas, located along Sungai Sarawak. Water quality trend analysis was conducted to determine the correlation between the water quality parameters. Trend analysis was carried out using Mann-Kendall Test because data collected was non-parametric. Next, Spearman rank was used in order to determine the correlation between parameters. The results obtained and the observation made in this study reveals that the trend exists only for Chemical Oxygen Value (COD). But there are trends for Biochemical Oxygen Demand, (BOD), Dissolved Oxygen (DO), Total Suspended Solid (TSS), Ammoniacal Nitrogen (NH4N) and Turbidity to decrease or increase with no trends between 2007 and 2011. The correlation between parameters is not very strong because there are many determinants of water quality parameters. The result from this study would provide useful information for water quality management in order to maintain and improve the water quality of Sungai Sarawak.
Correlation, management trends analysis, water quality
Rapid urbanisation and industrialisation have had an adverse and deep impact on the environment contributing to global warming and climate change. These thermal environmental problems can be even more challenging to people living in regions with warm and humid climatic conditions throughout the year, such as Malaysia. This paper analyses wind characteristics and outdoor thermal comfort index at the hottest temperatures based on data recorded hourly between 2012 and 2014 for two cities in East Malaysia, namely Kuching (Sarawak) and Kota Kinabalu (Sabah). Wind characteristics were analysed using only wind velocity and direction, while the level of outdoor thermal comfort was measured using Universal Thermal Climate Index (UTCI). The results showed that hourly average wind velocities for Kuching and Kota Kinabalu were 1.84 m/s and 2.15 m/s respectively while the highest average wind velocities was 10.1 m/s and 12.4 m/s respectively. No wind movement (i.e. 0 m/s) was recorded for both locations. The prevailing annual wind flow is generally from South-Southeast (150°) in Sarawak and from East-Southeast (110°) in Sabah. It was also found that both Kuching and Kota Kinabalu experienced strong and extreme heat stress conditions with UTCI levels of 44.8°C and 49.8°C respectively. Thus, it can be concluded that, East Malaysia faces strong and extreme heat stress conditions. This study is an original contribution on the subject of outdoor thermal environment in Malaysia, Further research to better understand outdoor thermal environmental problems is recommended.
This paper describes the culture of Traditional Malays, in particular the use of sustainable furniture inside a Traditional Malay House (TMH). The sample houses for this study were retrieved from archived reports, from the Centre for Built Environment in the Malay World (KALAM), Universiti Teknologi Malaysia (UTM). Data collected were analysed using Componential Analysis for the presence of components (based on drawings of archival reports as well as photographic evidence from site visits). The findings showed that the Malays used a variety ofsustainable furniture in their houses. Additionally, their homes had built-in furniture, which indicated the houses were pre-designed based on its user.
Malay culture, sustainable furniture, traditional Malay furniture, traditional Malay house, traditional Malays
Prolonged drought conditions have adverse environmental and socio-economic impacts due to unmet water demands. Defining drought is difficult because of its onset and ending time. Therefore, characterisation of drought is essential for drought management operations. Thus, drought indices come in handy and are a practical approach to assimilate large amounts of data into quantitative information which can then be applied for drought forecasting, declaring drought levels, contingency planning and impact assessments. This study analyses drought events using indices, namely SPI and Deciles Index, computed with DrinC software program but are not popular in Malaysia. It is observed that both indices are identical and suitable for drought occurrences.
DrinC, drought, indices, Malaysia, SPI & DI, water
An e-learning website is very useful, especially for students and lecturers, as this platform is very efficient for blended learning. Thus, the main objective of this research was to determine the user expectations of e-learning websites of comprehensive universities through localisation based on user preferences. This research showed how users interact with e-learning websites and indicated the patterns that can be used as standard guidelines to design the best e-learning websites. It was found localisation of e-learning websites was scarce and slow interaction with e-learning websites has inconvenienced users. Additionally, too many web objects on the user interface of e-learning websites have a tendency to confuse users. A mixed method approach was used I this study, namely content analysis (qualitative) and localisation (quantitative). Thus, this research contributes to knowledge by guiding users on localising their web objects according to their preferences and hopefully allow for an easy and quick information search for e-learning websites.
E-learning, localisation, user expectations, web objects
The major aim of this research was to investigate the addition of BPSC on the physical and rheological properties of asphalt binder. In this study, addition of five different percentages of BPSC compositions were studied, namely (2, 4, 6 and 8%). The impact of modifier on the rheological and physical properties was determined using conventional tests, such as softening point, ductility and penetration, and measurements from a dynamic shear rheometer. Based on the results, it was observed that the addition of BPSC has a significant impact on the rheological properties of asphalt binder and would improve rutting resistance at high temperatures. Meanwhile, results related to physical properties indicated that a decrease in penetration and increase in softening points results in stiffness of BPSC. The results showed that BPSC reduced temperature susceptibility and increased stiffness and elastic behaviour in comparison to unmodified asphalt binder. This means BPSC would increase the resistance of permanent deformation (rutting). Finally, BPSC could be considered as an appropriate additive to modify the properties of asphalt binder.
Bus services usually tend to be irregular and their level of irregularity depends on various factors, such as crowding level, terminal departure behaviour, passengers' behaviour, operator behaviour, traffic and weather condition and etc. High-frequency bus routes have shorter headways (usually headway less than 10 to 15 minutes) and higher passenger demand compared with normal routes. Therefore, level of irregularity can be even higher in bus service at high-frequency operation. Running time variability comes from both systematic changes in ridership and traffic levels at different times of the day, which can be accounted for in service planning, and the inherent stochasticity of homogeneous periods, which must be dealt with through real-time operations control. This study evaluated impact of ridership changes and traffic condition through time of the day on running time variability, using Automatic Vehicle Location system (AVL) and Automatic Fare Collection system (AFC). All data extracted and collected from RapidKL Company for route U32, which is a high-frequency route in downtown of Kuala Lumpur. Descriptive analysis on data showed a high variation in running times, especially in morning peak hours. A liner regression model also proved than crowding level (extracted from AFC data), number of stops and congestion zones have relatively high impact on running time variation.
AFC, AVL, bus service, high-frequency, running time, variability
Strength and durability are important characteristics of concrete and desired engineering properties. Exposure to aggressive environment threatens durability of concrete. Previous studies on bio-concrete using several types of bacteria, including sulphate reduction bacteria (SRB), had to increase durability of concrete have shown promising results. This study used mixtures designed according to concrete requirement for sea water condition with SRB composition of 3%, 5% and 7% respectively. The curing time were 28, 56 and 90 days respectively. The mechanical properties, namely compressive strength and water permeability, were tested using cube samples. The results showed compressive strength had higher increase than the control at 53.9 Mpa. The SRB with 3%composition had maximum water permeability. Thus, adding SRB in concrete specimens improves compressive strength and water permeability. This is particularly suitable for applications using chloride ion penetration (sea water condition) where corrosion tends to affect durability of concrete constructions.
The evolution of 'sustainability' reflects a crucial change in global thinking, which is forcing firms to re-evaluate their approach in measuring organisational performance. The objectives of this study are to examine the extent of eco-innovation practices and their effects on sustainable business performance of chemical companies in Malaysia. The results show a moderate to a considerable extent of eco-innovation practices among the companies.
Chemical industry, eco-innovation, organisational performance, performance, sustainable performance
Algae biodiesel is undeniably very promising as an energy substitute for fossil fuel. It mass cultivation though requires huge capital investment. The aim of this study was to find a simple, inexpensive and tolerable media for algae growth. The optimal growth conditions for algae growth were studied. Botryococcus sp. was isolated from Sembrong Dam in Johor, Malaysia. In this study, two media were used, namely bold's basal medium (BBM) and synthetic media from nitrogen and phosphorus compound. The synthetic media consisted of ammonium chloride and monopotassium phosphate that were blended together and modified into desired ratios. The N: P ratio of 1.5:1 yielded the highest chlorophyll-a concentration and the optimal growth conditions of algae for both media were at 6000 Lux, pH 7 and 30 rpm. The BMM had the highest algae growth, 3.25 x 107cell/ml while the synthetic media yielded a maximum cell concentration of up to 1.025 x 107 cell/ml which is 68.5% lower compared with BBM. The findings of this study point to the importance of large scale production of algae useful for industrial production of biodiesel.
Lemongrass leaves are often under-utilised and unexploited. In this study, lemongrass leaves were used to produce water soluble essential oil using a steam distillation system. Water steam was passed through the lemongrass leaves which were placed and supported on a grid above the water in a distiller. The steam distillation system was fabricated and optimised using Response Surface Methodology (RSM). The maximum oil yield with optimal relative citral content is obtained at 6.69 of plant-to-water ratio, 26.68 minutes of distillation time using air-dried lemongrass leaves left under the shade for two days. At the optimum conditions, the predicted oil yield was 0.6719% of lemongrass (C. citratus) oil which contains 71.79% of citral content.
Malaysia has over 5 million hectares of land planted with palm oil, divided almost equally between peninsula Malaysia and East Malaysia. This paper presents a laboratory evaluation of the performance of the waste product palm kernel shell (PKS) in creating plant-based asphalt concrete (bio-asphalt concrete). PKS aggregate partially replaced granite aggregate in preparing the mixes (10%, 30%, and 100%) in the range of 5mm-14mm in ACW 14 mixed with 5% to 7% of bitumen content. 35 blows and 50 blows compaction of mixes was used to evaluate the potential of palm kernel shells in the preparation of bitumen to deal with light to medium traffic. Results showed that PKS aggregate can be used up to 30% PKS replacement for the light traffic design and only 10% PKS replacement was potential to be used in medium traffic design.
Bio-asphalt concrete, green aggregate replacement, oil palm, palm kernel shell
A combination of phosphoric acid (H3PO4) 20% v/v impregnation and carbonization method was employed to convert honeydew rind into activated carbons (ACPHDR) for Zn(II) and Cr(III) removal aqueous solution. The characterization of ACPDHR by N2 sorption, iodine number and Boehm analysis result 1272 m2/g surface area, 1174 mg/g and 1.13 mmol/g total acidic functional groups respectively. Fourier transform infrared (FTIR) and Field emission scanning electron microscopy-electron dispersed microscopy (FESEM-EDX) analysis of unloaded and metal-loaded carbon showed shifted of significance peaks and the changes of surface morphology of the sorbent. The adsorption was optimized at pH, shaking duration, initial metal concentration and mass of adsorbent of 5.5, 40 min and 500 mg/L, 0.4 g for Zn(II) and 4, 40 min, 1000 mg/L, 0.1 g for Cr(III) removal. It is concluded that the metal removal was influenced by pH solution, contact time, initial metal concentration and mass of adsorbent. The highest removal of Zn(II) and Cr(III) was observed at 84.24% and 90.10% respectively. Waste from honeydew will be benefited from this research which offer a cheaper alternative precursor to coal based activated carbons.
Heavy metals, honeydew rind, impregnated, low cost adsorbent, phosphoric acid
Ordinary Portland Cement (OPC) is widely used by the construction industry. Research to find the precise proportion of cement replacement material which can be used to produce a product called Ternary Blended Cement (TBC) is not new. The objective of this study is to determine the effect of POFA and SF as TBC on the heat of hydration and compressive strength of mortar. Before producing TBC, specimens using BBC is required. Mix design proportion for POFA and SF are 5%, 10%, 15%, and 20%. Mix design proportion TBC are chose from the highest compressive strength value achieved at 7 days of curing. This research found the heat of hydration of TBC containing 20% POFA and 5% SF is high in the beginning to drop at the end of hydration process in addition to producing lower compressive strength.
BBC, compressive strength, heat of hydration, OPC, POFA, SF, TBC
Seismic surface waves are a non-destructive technique used to obtain the dynamic properties of soil by measuring the shear wave velocity and calculating the shear modulus of soil. The shear modulus is one of the parameters to measure the stiffness of materials. This study evaluates soil profiles and the position of the sensor while conducting measurements of two, soil profiles, i.e. lateral and vertical non-homogeneities, using a continuous surface wave analysis (CSW) and multi-channel analysis of surface waves (MASW). Results showed the dispersive curve demonstrated an increased shear wave velocity with increasing depth for the sensor pair measurements on the clay (between columns), and decreased shear wave velocity with increasing depth for the sensor pair measurements on the column. In both instances the surface wave velocity results influenced by the depth and size of the wavelength, indicating that depth and wavelength controlled the volume of measurement in an elliptical shape. Therefore, the shear wave velocities and thus stiffness measured from the surface wave velocity techniques are represented the volume of soil measured across the sensor length.
Continuous surface wave analysis, multi-channel analysis of surface wave, seismic surface wave testing, site investigation
Concrete and masonry waste are the main types of waste typically generated at a construction project. There is a lack of studies in the country regarding the cost implication of managing these types of construction waste To address this need in Malaysia, the study is carried out to measure the disposal cost of concrete and masonry waste. The study was carried out by a site visit method using an indirect measurement approach to quantify the quantity of waste generated at the project. Based on the recorded number of trips for waste collection, the total expenditure to dispose the waste were derived in three construction stages. Data was collected four times a week for the period July 2014 to July 2015. The total waste generated at the study site was 762.51 m3 and the cost incurred for the 187 truck trips required to dispose the waste generated from the project site to the nearby landfill was RM22,440.00. The findings will be useful to both researchers and policy makers concerned with construction waste.
Construction project, cost analysis, concrete and masonry waste, indirect measurement, sustainable
The design and build concept has become a popular contract system. It requires the owner and contractor to identify, analyse and manage risks and search for the best solutions to improve performance. The objective of this paper is to identify the project manager's perception of risk factors associated with the design and build project in Malaysia. A total of 100 usable questionnaires were received and analysed using mean ranking and factor analysis. The results show that three most risky factors are: "client financial capability", "inadequate cash flow by contractor", and "lack of payment (delayed progress payment by owner to the contractor)". Risk can be grouped into 12 categories, namely: (1) lack of management competency; (2) lack of contractor experience; (3) political issues; (4) lack of standardized system; (5) unpredictable issues; (6) lack of client experience; (7) safety issues; (8) lack of teamwork; (9) poor supervision by client; (10) lack of client information; (11) material availability; and (12) design error.
The building sector consumes about forty percent of world energy, making energy efficiency in existing buildings an important issue. This study has been undertaken to investigate energy consumption of a building that has been redesigned to incorporate energy efficient features. It was found that the introduction of energy efficient features has helped to achieve savings up to 46% of the total spent on energy particularly based on electricity bills.
Cost saving, energy efficiency, green building, greenhouse gases, Malaysia
Computer games are often considered a teaching and learning tool as it is generally appealing to students. In this preliminary study, we investigate students' perceptions of engaging game design in Learning of Historical Patriotic Heroes. In total, 33 students were involved in this study. The data was examined using standard descriptive statistical approaches. The results of the study indicated that the majority of the respondents are interested in the idea of Learning of Historical Patriotic Heroes through game approach. Hopefully, the outcome of this preliminary study will underline the need for developing a rigorous engaging game design for education.
Engagement, game design, historical patriotic heroes, students' perceptions
Sawdust is considered a waste material and a number of innovative ways are being taken to mitigate its effects on the environment. The use of sawdust as additional admixture in cement-sand brick production is an alternative option to mitigate the problem. In this study, three different types of cement-sand brick mixture in proportion of 1%, 2% and 3% of sawdust added to the normal mixture are prepared. Compression test was conducted on the brick mixture and results indicated 1% sawdust satisfy the Class 1 loadbearing brick whilst the 2% sawdust is slightly above the minimum required strength of 5.2 MN/m2 for an ordinary quality brick set by the Standards MS 76:1972. Thus, the use of sawdust as admixture in cement-sand brick should not exceed 3%.
This paper presents a development of an expert system to be used as an advisory in finding the solution to problems which are normally solved by human experts. The E-ACTIVETRANS is developed to help young engineers/planners in designing a new cycle lane in urban areas and also to help in reallocation of an existing roadway space for cycle lanes. This system has three sub-systems: Planning on Strategies to Shift from Passive Transportation to Active Transportation, Design on Bicycle Facilities and Examples of Successful Implementation. This paper focuses on the design of bicycle facilities whereby the prototype was developed based on data acquired from the domain experts who are involved in bicycle facility module design, as well as the initial text analysis obtained during the domain familiarisation stage. The validation of the system was performed through a comparison of knowledge content in E-ACTIVETRANS based on expert opinion. The average level of acceptance is 91 percent which validates the system and knowledge of the experts.
Bicycle facilities, E-ACTIVETRANS, expert system, human experts
The volume of waste generated from surface coating industries is of global concern. The disposal of this waste in the form of effluent has put enormous pressure on land and also poses as a health hazard when it leaches into soil and underground water. The study aims to examine the utilization of vinyl acetate effluents from water based paint factories as an admixture in concrete. Concrete specimens containing 0%, 2.5%, 5% and 10% of vinyl acetate effluents by weight of cement were prepared. The specimens were tested for drying shrinkage for 28 days and porosity was tested using mercury intrusion porosimetry. Findings show that concrete containing various proportions of vinyl acetate effluents manifests higher shrinkage behaviour compared to the control item. An investigation of pore size distribution reveals that polymer effluents have particles size larger than 50 nm which are categorize as macroporous in accordance to IUPAC classification. It can be concluded that adding polymer vinyl acetate effluents affects concrete deformation due to the condition of its pore structures. The utilization of this material may provide beneficial effect in terms of the durability performance of concrete and minimize environmental pollution.
The waiting time can be reduced by providing information on bus arrival time. The absence of this information leads to long waiting time and affects passengers' planning travel time. Although the waiting period that is longer or shorter is subjective to each passenger, without information on bus arrival times, the uncertain passenger arrival time may cause difficulties to determine realistic waiting time. This study concentrates on the optimal design of the waiting time from the passengers' arrival time at random. The survey data were observed from one bus stop encoded as ALMD stop in Putrajaya. This stop has no mechanism for real bus arrival information, which raises issue of inconsistent bus arrival times to bus passengers. To analyze the problems, the combination of mathematics and response surface methodology-central composite design applications is used to design optimum waiting time. The design of arrival time was set up into two interval minutes: between 0-29 and 30-59 minutes, which was considered as the random arrival time of passengers. The modification on intervals for waiting time was designed between 0 and 15 minutes to meet the criteria of headway, one bus within 30 minutes. The design outputs resulted in a mathematical model for waiting time and optimization value. The results generated an optimum waiting time of 8.7 minutes for the first passenger and 13.81 minutes for the next passenger, which were the best times with respect to the bus operation headway.
Bus passengers, design wait time, random arrival time, response surface methodology-central composite design (rsm-ccd), stop
High strength concrete (HSC) has lower ductility, but higher in strength compared to normal strength concretes. The strength and ductility of HSC can be improved by applying external confinement, such as steel strapping tensioning technique (SSTT). However, SSTT was literately reported effective in confining circular specimens, but the effectiveness of SSTT on square cross section specimens are yet well investigated. This study focuses on HSC square cross section specimens with different corner ratio, which were right angle and rounded corner. In addition, the effect of different number of layer of steel straps confining around the specimens under optimum lateral pre-tensioning stress also been investigated. The number of layers was fixed to two layers and four layers. Fifteen HSC specimens with dimension of 88 mm x 88 mm x 200 mm, which consist of three unconfined specimens, six right angle specimens, and six rounded corner specimens were prepared and tested monotonically to failure. The experimental results show that the strength and ductility of HSC improved significantly by using rounded corner confined specimens and higher number of layer of confinements. This is due to more uniform confining pressure was exerted on entire surface of rounded corner confined specimens. The strength and ductility of the specimens can be improved up to 53.7% and 207.5% respectively
The importance of the performance of concrete cannot be neglected since it is the early indicator of its physical and mechanical properties. It became more important when material with different physical properties than normal material such as rubber tire was used as concrete constituent. This paper presented apart of research result conducted on mortar and concrete with crumb rubber. Crumb rubber was replaced at 10%, 15% and 20% as sand replacement by volume. In addition, ordinary Portland cement was added to silica fume at 10% and 15% by weight. The properties measured in this study are air content and workability test. As for workability, superplasticizers were constantly used at 1% dosage for all mortar mixture, and 0.5% to 0.7% for concrete mixture. The air content was set at 4% to 6% and mortar flow test was conducted on a steel plate, shocked 15 times in 15 seconds and concrete slump test was carried out using slump cone equipment. Pressure method was used to measure air content. All mixes were done in a controlled room temperature. Results showed that when CR was added in the mixture segregation was observed in mortar requiring a high dose of superplasticizer to be added to improve the workability while air-modifying agent was used to reduce the mortar air content. In concrete mixture, low dosage of superplasticizers was required for workability and air-entrained agent was injected into the mixture to increase the air content between 4%-6%.
Air content, concrete slump, crumb rubber, mortar flow
Congenital talipes equinovarus (CTEV) or clubfoot is a complex deformity of the foot that is characterised by four main deformities; forefoot cavus and adductus, hindfoot varus and ankle equinus. Currently, the Ponseti method is the most general and recognized treatment with a high success rate of over 90%. The treatment involves gentle manipulation and serial casting. However, the casting method could create complications for the patients such as soft-tissue damage and inconvenience in following the treatment schedule especially for those living far away from hospital. The aim of this research is to develop an adjustable corrective device for clubfoot treatment based on the techniques in the Ponseti method and at the same time attempt to eliminate the side-effects. The prototype consists of six adjustable movements from six different mechanisms to correct the four deformities. The prototype was developed using 3D printing method and the main material used is polylactic acid (PLA), rubber, aluminium and cotton fabric with sponge. The total weight of the prototype is around 300 g.
3D printing, clubfoot, CTEV, design and fabrication, Ponseti method
Concrete durability determines service life of structures. It can though, be weakened by aggressive environmental conditions. For instance, bio-corrosion process is due to the presence and activity of microorganisms which produce sulphuric acid to form sulphate deterioration of concrete materials. The problems related to durability and repair systems are due to lack of suitable concrete materials. The use bacteria for concrete repairing and plugging of pores and cracking in concrete has been recently explored. Previous studies had proved the possibility of using specific bacteria via bio concrete as a sustainable method for improving concrete properties. Thus, lack of information on the application of bio concrete exposed to extreme condition was the motivation for this research.
Bacteria concrete, bio-concrete, concrete properties, durability, sea water