Articles

  1. INFLUENCE OF MATRIC SUCTION ON INSTABILITY OF UNSATURATED SILTY SOIL IN UNCONFINED CONDITIONS Download Article

    Ali Murtaza Rasool and Jiro Kuwano
    • Article Type: Research Article
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    • Pages (1-7)
    • No of Download = 194

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    Rainfall has been recognized as one of the main causes of natural or manmade slope failure in many tropical areas of the world. In order to reduce and mitigate rainfall-induced slope failures, there is a need to develop an understanding of reduction in shear strength of soil due to water infiltration. This research aimed at understanding the influence of matric suction on water infiltration and transformation of shear strength in unsaturated soil in unconfined condition. In the present study, two types of test series have been performed using modern triaxial test apparatus: (1) shear-infiltration test, and (2) pre-wetting shear test. From test results, it was concluded that water infiltration causes the excessive deformations and softening which decreases the cohesion and hence reduces the shear strength of the soil. The more decrease in shear strength was witnessed in case of pre-wetting shear tests and maximum reduction observed was 85% against 36cm3 of infiltrated water.

  2. GEOTECHNICAL PROPERTIES OF RAW AND PROCESSED BAUXITE FROM BUKIT GOH, KUANTAN, PAHANG; IN ACCORDANCE WITH IMSBC CODE Download Article

    Muzamir Hasan, Ahmad Amirul Faez, M. Azizul Moqsud, Tam Weng Long and Phang Biao Yu
    • Article Type: Research Article
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    • Pages (8-13)
    • No of Download = 191

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    This research focuses on the differences of geotechnical properties between raw and processed
    Bukit Goh bauxite. As bauxite material has high clay content which mostly composed of silicate minerals, it has
    high risk to cause cargo liquefaction which in turn causes catastrophic incident. This paper includes the analysis
    of raw and processed bauxite where its fine particle contents has been minimized using beneficiation method to
    reduce the risk of liquefaction by referring to the International Maritime Solid Bulk Cargoes Code (IMSBC Code)
    standard. To analyse these characteristics of the bauxite, five samples were selected at Bukit Goh, Kuantan; three of the samples from the Bukit Goh mine and two samples from stock pile were tested to identify the bauxite geotechnical properties by referring to GEOSPEC 3: Model Specification for Soil Testing; particle size distribution, moisture content, specific gravity, morphological properties as well as its elemental and oxide properties. Laboratory tests involved including Small Pycnometer test, Dry Sieve test, X-ray fluorescence test (XRF) and Field emission scanning electron microscopy test (FESEM). The results show that average moisture content of raw bauxite is 24.81% which exceeded the recommended value of maximum 10% while the average moisture content of processed bauxite is only 6.69%. The average fine material for raw bauxite is 38.40% which should not be greater than 30% per IMSBC standard while for processed bauxite is 21.40%. In conclusion, the quality and safety of processed bauxite is better than raw bauxite.

  3. TOXICITY AND BIOEFFICACY OF WEED ESSENTIAL OILS AGAINST COWPEA BRUCHIDS AND THEIR EFFECT ON MUNGBEAN SEEDS Download Article

    Ruchuon Wanna and Perayos Khangkhun
    • Article Type: Research Article
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    • Pages (14-19)
    • No of Download = 200

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    These investigations aimed to determine toxicity and bioefficacy of weed essential oils Bitter bush (Eupatorium odoratum L.), Finger grass (Limnophila aromatica (Lamk.) Merr.), and Vietnamese mint (Polygonum odoratum) derived by hydrodistillation against cowpea bruchids, Callosobruchus maculatus (Fabricius) on stored mungbean. Experiments were assessed under laboratory conditions (30±2°C, 70-80%RH and 16L:8D photoperiods). Results showed that weed essential oils from Bitter bush, Finger grass and Vietamese mint leaves have contact toxicity on cowpea bruchids as shown by the impregnated filter paper test. LC50 values were 137.15, 225.17 and 99.12 ppm at 48 h after exposure, respectively. Fumigant toxicity by the fumigation method on cowpea bruchids showed all weed essential oils had high efficiency against the cowpea bruchids (100% of mortality). Repellency toxicity test showed that weed essential oils from Bitter bush, Finger grass and Vietnamese mint leaves have repellent toxicity on cowpea bruchids as LC50 values were 607.23, 141.93 and 109.81 ppm at 6 h after exposure, respectively. The potential of weed essential oils on reproduction of the cowpea bruchids female adults had strong repellent activity for egg laid on mungbean seeds, were 100% at 48 h. Three weed essential oils did not affect the seed germinating. These results suggested that essential oils from three weed plants could be used as potential control agents for cowpea bruchids, and the database can be used for active ingredient studies to develop commercial products in the future.

  4. SAFETY AND EFFICIENCY FOR WEEDING WORK AND LEVEE SLOPE’S FORM REQUIRED FOR MOWING MACHINES ON PADDY FIELDS IN STEEP SLOPING AREAS IN JAPAN Download Article

    Yoshiyuki Uchikawa, Masami Matsui, Teruo Arase and Takahiro Tamura
    • Article Type: Research Article
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    • Pages (20-24)
    • No of Download = 167

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    In Japan, land readjustment projects have standardized and expanded the design and size of rice paddy fields. These projects have simultaneously promoted the conversion of levee slopes into stable inclines by expanding the difference in levels between paddy fields, which has expanded levee slopes, i.e. the weeding area. Continuous weeding work is required to prevent erosion and the collapse of steep levee slopes, and serious accidents sometimes occur in the weeding work using brush cutters on such slopes. Brush cutters have been popular for weeding work, but mowing machines are increasingly popular for reasons of safety and work efficiency. However, the levee form was designed based on the assumption of using brush cutters, which recommends small horizontal standing places both at the middle and the bottom of the slope. Therefore, it is necessary to examine whether the form of the levee slope is suitable for mowing machines. We conducted weeding work experiments in two types of levee slopes (with and without standing places) using two types of weeding equipment (mowing machines and brush cutters), and the flora of the levee slopes and the working stress on operators were investigated. Our conclusions are that (1) mowing machines are safer and more efficient than brush cutters and (2) the conventional levee form with standing places will also be effective for mowing machines.

  5. OPTIMAL RESTORATION STRATEGY OF A WATER PIPELINE NETWORK IN SURIGAO CITY, PHILIPPINES Download Article

    Agnes Garciano, Lessandro Estelito Garciano, Renan Ma. Tanhueco and Taze Jared Abubo
    • Article Type: Research Article
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    • Pages (25-29)
    • No of Download = 170

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    Quick recovery of water services immediately after an earthquake is critical. This is to minimize hazards to environmental sanitation and consequent health problems caused by the lack of potable water supply. It is necessary therefore that water lifeline operators establish restoration strategies to deal with damage scenarios in their respective concession areas specifically during extreme seismic events. The recent 6.7 magnitude earthquake in Surigao City due to the movement of the Philippine Fault Zone: Surigao segment underscored this need. However due to the complexity of the network a systematic restoration sequence that minimizes restoration time and maximizes delivery of water service should be employed. In this research, the authors employed Horn’s algorithm to determine the optimal restoration strategy of a pipeline network in Surigao City, Philippines. The repair sequence starts with the determination of a minimal spanning tree of the given pipeline network. The water source is designated as the root of this tree while the nodes represent the water demand at specific areas. The edges of the tree structure representing the pipelines connect the nodes. The assigned numeric value or weight of an edge (link) denotes the time to repair that specific pipeline. This value is a function of the length of the pipeline. The results show that an optimal job sequence may be carried out by considering maximal ratios of expanding family trees within the network. A least penalty function is a consequence of the optimal repair job sequence.

  6. AN INVESTIGATION ON THE STRENGTH OF AXIALLY LOADED COLD-FORMED STEEL Z-SECTIONS Download Article

    James Matthew L. De Jesus and Bernardo A. Lejano
    • Article Type: Research Article
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    • Pages (30-36)
    • No of Download = 201

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    Cold-formed steel (CFS) provides high strength-to-weight ratios that prove efficient in the construction of steel structures. CFS Z-section members exhibit buckling failures that may be difficult to predict due to complexity in geometry. There exists a gap in experimental and computational studies done in the Philippines regarding the structural performance of locally-produced CFS members. The objective of this study is to investigate the load-carrying capacity of Z-section CFS members when subjected to axial compression using experimental and computational methods. The study considers a total of 180 member samples with one section shape, six different lengths and six different thicknesses. Experimentally, the CFS members were subjected to compression loads using a standing steel frame with a hydraulic jack, a load cell and 4 displacement transducers to record the parameters needed for the investigation. High-speed video recordings were used to verify the different failure modes. These are then compared to computational results as per the National Structural Code of the Philippines (NSCP). Furthermore, the study also provides a comparison of experimental and computational results with Finite Element Method (FEM) using ANSYS. The main failure modes were torsional-flexural and distortional buckling. Torsional-flexural buckling was observed in 74.01% of the samples. Although 72.88% of the failure modes were predicted correctly, it was found that the provisions in the NSCP in predicting the strength of the member were relatively high with respect to the experimental and FEM results. This means that the predicted strength was non-conservative. It was also found that a modification factor of 0.52 can be used to achieve similar results between the predicted and actual strength of the member.

  7. INVESTIGATION OF THE EFFECTS OF DIFFERENT NATURAL FIBERS ON THE STRENGTH OF COMPRESSED STABILIZED EARTH BLOCKS (CSEB) Download Article

    Bernardo A. Lejano and Kyle Solomon D. Pineda
    • Article Type: Research Article
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    • Pages (37-43)
    • No of Download = 200

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    This study investigates the most effective combination of natural fibers (namely coconut coir, abaca, and maguey) used as reinforcement for Compressed Stabilized Earth Blocks (CSEB). Portland cement and 0.25% fibers by weight were used to stabilize and reinforce CSEB, respectively. The blocks were made primarily with Manila soil and were formed using hand-pressed machine. CSEB without fibers were first tested with varying cement contents of 6%, 8%, 10%, and 12% by weight. This was examined to determine the practical cement content (PCC). Three strength tests namely dry compressive strength, wet compressive strength, and flexural strength were conducted on CSEB at PCC with different fiber combinations of coir, abaca, and maguey fibers to determine the mix producing maximum strength. The highest dry compressive strength was obtained with 100% maguey fiber; the highest wet compressive strength was obtained with 100% abaca fiber; while the highest flexural strength was obtained with 17% coir fiber, 17% abaca fiber, and 67% maguey fiber. Using the Response Surface Methodology (RSM), the maximum strengths were predicted as follows: 100% maguey for dry compressive strength, 100% abaca for wet compressive strength, and 38.4% abaca and 61.6% maguey for flexural strength. However, the optimal mix of CSEB for three the strength tests consists of CSEB with 42.5% abaca and 57.5% maguey. The fibers were found to improve the performance of the block such as the strength and post-crack behavior. Furthermore, the performances of a wall made of fiber-reinforced and unreinforced CSEB were investigated. The test results showed a 33.79% increase in load carrying capacity of the fiber-reinforced wall compared to unreinforced wall.

  8. REVIEWS ON THE APPLICABILITY OF CONSTRUCTION AND DEMOLITION WASTE AS LOW-COST ADSORBENTS TO REMOVE-HEAVY METALS IN WASTEWATER Download Article

    G.M.P. Kumara, Takashi Saito, Shingo Asamoto and Ken Kawamoto
    • Article Type: Research Article
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    • Pages (44-51)
    • No of Download = 213

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    Removal of heavy metals from wastewater is of special concern due to the persistence of heavy metals in the environment. The industrial discharge of heavy metals adversely affects soil and water resources, aquatic organisms, and ecosystem integrity. In addition, high concentrations of heavy metals are detected in solid waste landfill leachate in many developing countries due to non-segregated waste dumping. At present, various kinds of adsorbents such as activated carbon, biomass resources, geomaterials, and industrial waste products are used to treat heavy metal-contaminated water. However, the use of construction and demolition waste (CDW) and its recycled materials to treat heavy metal-contaminated water has not been fully examined. Because the generation of CDW is increasing due to rapid urbanization and a high demand for construction, the wise use of CDW and its recycled materials is necessary. This paper reviews journal articles published from 2004 to 2016 that studied the applicability of low-cost CDW adsorbents to remove heavy metals from wastewater. In particu-lar, it summarizes results on using CDW and recycled materials such as cement, concrete, and brick compared to those from various other adsorbents such as biosorbents, geomaterials, and their industrial products. The poten-tial applicability of CDW and its recycled materials as heavy-metal adsorbents was examined based on a com-parison table listing material properties, test conditions, and measured adsorption properties.

  9. SHEAR BOND STRENGTH OF FA-PC GEOPOYLMER UNDER DIFFERENT SAND TO BINDER RATIOS AND SODIUM HYDROXIDE CONCENTRATIONS Download Article

    Tanakorn Phoo-ngernkham, Sakonwan Hanjitsuwan, Satakhun Detphan, Jaksada Thumrongvut,Cherdsak Suksiripattanapong, Nattapong Damrongwiriyanupap, Prinya Chindaprasirt and Shigemitsu Hatanaka
    • Article Type: Research Article
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    • Pages (52-57)
    • No of Download = 165

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    This paper presents the effects of sand to binder (S/B) ratio and sodium hydroxide (NaOH) concentration on setting time, compressive strength, and shear bond strength of fly ash (FA)-Portland cement (PC) geopolymer binder. Geopolymer binder is manufactured from FA and PC at the ratio of 90:10 by weight of binder. The liquid alkali solution used in this study are sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions. The Na2SiO3/NaOH ratio of 2.0, liquid alkali solution/binder ratio of 0.60, and curing at ambient temperature are fixed in all mixes. The differences in NaOH concentrations of 5, 10 and 15M and S/B ratios of 1.00, 1.25 and 1.50 has been investigated. Test results show that the differences of NaOH concentration and S/B ratio has an effect on setting time, compressive strength and shear bond strength of FA-PC geopolymer mortar. The setting time of mortars are obviously decreased with increasing of S/B ratio whereas the setting time of mortars are obviously increased with increasing of NaOH concentration. The compressive and shear bond strengths of mortars increase as increasing of both S/B ratio and NaOH concentration up to a threshold limit. The highest slant shear strength between Portland cement concrete substrate and FA-PC geopolymer mortar is found in the mortar with 1.25 S/B ratio and 10M NaOH concentration which gives 24.1 MPa.

  10. INFLUENCE OF SEAWATER ON THE STRENGTH OF RC BEAMS AND CORROSION BEHAVIOR OF STEEL Download Article

    Bernardo A. Lejano and Cheryl Lyne C. Roxas
    • Article Type: Research Article
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    • Pages (58-64)
    • No of Download = 143

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    The effects of seawater on the strength performance of reinforced concrete (RC) beams were investigated. Four RC beams measuring 150 x 200 x 800 mm were constructed. Two beams were constructed with concrete mixed with freshwater and the other two were constructed with seawater. Center point loading test was conducted on the beams specimens. Load, deflection, and strain of each beam were monitored and recorded. It was found that the difference between the strength test values obtained by using freshwater and seawater were minimal. However, formation of rust in steel when seawater was used was very evident. Hence, the effects of seawater on the corrosion behavior of steel were investigated. Mortar specimens with cold-joint were used as medium to facilitate the investigation of corrosion. Ordinary Portland cement (OPC) Type 1 was used as binder for the mortar and was partially replaced with fly ash at 30% and 50%. Rectangular prism specimens of dimensions 40mm by 40mm by 160mm were cast for macrocell corrosion measurements and compressive strength determination. From the test results, the following were observed: (a) Specimens with fly ash were observed to have lower corrosion rates compared with the ones without fly ash; (b) Specimens mixed with freshwater resulted to the higher strength both at 7th-day age and 28th-day age; (c) Regardless of the type of water used in making the mortar, specimens cured in seawater achieved higher later strength values.

  11. OPTIMUM USE OF GEOGRID IN THE UNBOUND GRANULAR LAYER FOR THE PAVEMENT CONSTRUCTION Download Article

    Aung Aung Soe, Jiro Kuwano, Ilyas Akram and Takaya Kogure
    • Article Type: Research Article
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    • Pages (65-70)
    • No of Download = 172

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    The benefits of using geogrid for the pavement construction have been reported by many researchers. The well-known benefits are base course reduction and rut-depth reduction. Currently, the available information is still limited for the geogrid-stabilized pavement construction. In this study, the benefits of geogrid stabilization were investigated through series of laboratory test. Base-course thickness and reinforcement position of geogrid were considered as the control parameters and their influences were analyzed on the surface and subgrade deformations. The tests were performed in a rigid square-tank, and the subgrade and base course were modelled by using the fine and coarse silica sands. Triangular geogrid was used for the reinforcement. Cyclic loading was applied with the variable steps of loading ranging from 100 kPa to 550 kPa. From the test results, it was realized that the surface deformation was mainly contributed from the subgrade deformation in the thin base-course sections. In contrast, the base-course deterioration dominated and resulted in severe surface deformation in the thick base-course sections. This severe deformation was effectively reduced when geogrid location was shifted to the upward position inside base course layer. However, this geogrid position has negligible influence on the subgrade deformation, which is considerably affected by the base-course thickness. In all test cases, a progressive loss in base course thickness was noticed under high footing pressure. This loss is smaller in the thin section, compared to thick one. Test results revealed that the benefit of geogrid stabilization is more obvious in the thin section.

  12. EXPERIMENTAL STUDY ON MECHANICAL BEHAVIOUR OF CONCRETE BEAMS WITH SHREDDED PLASTICS Download Article

    Richard M. De Jesus, Emmanuel Bastian Pelaez and Moises Carll Cañeca
    • Article Type: Research Article
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    • Pages (71-75)
    • No of Download = 142

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    In recent years, more attention is being paid to alternative disposal of wastes to lessen the harmful impact of these wastes to the environment. In the construction industry, alternative disposal of waste comes in the form of utilization of waste as a substitute construction material. Plastic, typically in the form of plastic bags and bottles, is one of the most abundant wastes in Manila, and, also among the most problematic when it comes to disposal due to its non-biodegradable nature. Hence, more attention is given to alternative use of plastics as a substitute material in construction. In this study, experimental investigation was conducted to assess the performance of concrete beams with shredded plastics, sourced out locally, as a supplementary material. Strength properties of a concrete beam, in terms of compression, tension, and flexure, were investigated for both plain concrete and concrete with shredded plastics. Results showed that concrete with shredded plastics were slightly higher than that of plain concrete in terms of tension and compression strength. Flexural strength of concrete with shredded plastic, also showed higher strength than that of plain concrete. Additionally, this study showed the applicability of elastic flexural theory to concrete beams with plastics.

  13. NON-LINEAR APPROACHES TO THE RESPONSE OF BRICK MASONRY WALL TO LATERAL LOADING Download Article

    Miroslav Mynarz and Lucie Mynarzova
    • Article Type: Research Article
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    • Pages (76-82)
    • No of Download = 178

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    The response of brick masonry wall subjected to lateral loading is presented in this paper. Modelling and analysis of masonry seems to be complicated due to two-component material with different properties and dimensions. Out-of-plane loading adds another issue to be solved. Therefore, it is necessary to perform a calibration to evaluate the dynamic properties of the structure. The response of the finite element model is improved by predicting the parameter by performing a non-linear structural analysis. The deformations obtained numerically were compared to that of experimental observations. The experiments were carried out in one of the experimental galleries in the limestone pit. The study deals with the response of the masonry separating walls at various thicknesses, mechanical properties or loading. This contribution compares the effect of variability of particular parameters to the response of the walls. The results could be used for explosion prevention and protection; masonry buildings are taking into account considering the danger of explosion of natural gas or other items. For favourable design or assessment of masonry wall exposed to the out-of-plane load, which involves also explosion, it is possible to calculate the structure using some finite element model.

  14. MACROCELL CORROSION ASSESSMENT OF STEEL IN COLD-JOINTED CONCRETE MIXED AND CURED IN SEAWATER Download Article

    Cheryl Lyne C. Roxas and Bernardo A. Lejano
    • Article Type: Research Article
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    • Pages (83-89)
    • No of Download = 202

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    Previous research works have been devoted to developing sustainable construction materials. This is due to the potential risk of global warming resulting from the abuse and misuse of natural resources. Therefore, this study aims to address this through the use of abundant and by-product resources in the production of concrete, like seawater and fly ash. If these materials were proven comparable to conventional materials, then problems on freshwater scarcity, fluctuating supply of cement and associated pollutants from its production can be addressed. This research specifically concentrates on the effects of varying water to cement ratios and fly ash content on the macrocell corrosion behavior of steel in cold-jointed concrete. Ordinary Portland cement in concrete was partially replaced with fly ash at 30% and 50%. Water to cement (w/c) ratios of 0.30, 0.35, 0.40, 0.45, 0.55 and 0.60 were tested. Rectangular prism specimens were cast to monitor the macrocell corrosion activity of the reinforcements. Results have shown an increasing trend of corrosion rate with increasing w/c ratios regardless of mixing water, with specimens mixed with seawater having higher values compared to freshwater. Generally, the 0.30 w/c ratio resulted to the lowest corrosion susceptibility. In terms of fly ash content, it was found that corrosion rate decreases with increasing fly ash percentage. Fly ash decreases the permeability of concrete, thus making it less exposed to aggressive environments. Cold-joints showed evident corrosion effects as external elements may penetrate through these planes of weakness in the concrete.

  15. A REVISIT TONICOLL HIGHWAY EXCAVATION IN SINGAPORE Download Article

    Samal Hama Salih, Mohammad Mirza Hassan, Jim Shiau and Zakaria Hossain
    • Article Type: Research Article
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    • Pages (90-96)
    • No of Download = 211

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    This paper demonstrates the use of explicit finite difference program FLAC to numerically simulate staged braced excavation involving various stages of excavation and strutting. The short term undrained condition is considered in the analyses. A FISH script is developed, with automatic mesh generation capacity, to study the behavior of wall deformation and ground settlement during the stages of construction. The numerical model is developed using the case study of Nicoll Highway in Singapore. Both the geotechnical design and the causes of failure of the Nicoll Highway excavation are re-visited through extensive comparisons with existing published data. It is considered as a successful development with the main purpose in mind to develop a numerical model for the analysis of staged excavation in the construction of underground basements. The success of the development is to be used in assisting other design projects in the future.

  16. UTILIZATION OF POLYPROPYLENE TO SUBSTITUTE BITUMEN FOR ASPHALT CONCRETE WEARING COURSE (AC-WC) Download Article

    Emenda Sembiring, Harmein Rahman and Yoanne Maretha Siswaya
    • Article Type: Research Article
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    • Pages (97-102)
    • No of Download = 167

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    In this study, Polypropylene (PP) plastics waste with various concentrations of 0.5%, 0.8%, and 1% were investigated to substitute bitumen’s mass. The mixing of plastics and asphalt was conducted by wet method, which added PP plastic into the asphalt when being heated so it produced a homogeneous mixture. Then, AC-WC mixture was made with bitumen contents of 5%, 5.5%, 6%, 6.5%, and 7%. Each mixture was carried out in triplicate for every plastic’s concentrations. Five parameters of mixtures were tested by Marshall Method, as follows: VIM, VMA, VFA, stability, and flow. Then, all the parameters were plotted in bar chart to determine an OBC (optimum bitumen content). Changes in rheological properties after the addition of PP plastics occurs which indicates the increasing of viscosity, softening point, flash point, and the decreasing of density, penetration and solubility. Based on Marshall Test, the OBC for asphalt pen 60/70 was 5.4% while the OBC with PP plastic content of 0.5%, 0.8% and 1%, consecutively, were 5.41%, 5.43% and 5.45%. Despite the increasing of OBC, this substitution of bitumen to plastics has some advantages such as increasing stability and remaining strength index (RSI), reducing plastic waste generation and asphalt cost. However, it has disadvantages such as it consumes more energy and it increases gas emission.

  17. IDENTIFICATION OF POTENTIAL SITES FOR HARVESTING TIDAL CURRENT POWER IN KELIAN CAPE, KELABAT BAY, AND LARANTUKA STRAIT Download Article

    Harman Ajiwibowo, Kanisius S. Lodiwa, Munawir B. Pratama and Andojo Wurjanto
    • Article Type: Research Article
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    • Pages (103-111)
    • No of Download = 195

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    Harvesting of power from tidal currents is part of an emerging effort to capture energy from renewable sources, as non-renewable energy resources are depleted. The Indonesian government plans to develop tidal energy power generators in several areas and is conducting assessments in Bangka Belitung province at two locations in Kelian Cape and Kelabat Bay and in the province of East Nusa Tenggara at Larantuka Strait. Three potential locations namely Kelian Cape, Kelabat Bay, and Larantuka Strait, is assessed. Field measurements, numerical modeling, and potential site analysis are carried out. Both tidal elevation and tidal current validation between field measurement data and numerical modeling results are carried out and show good agreement. MIKE 3 (licensed) is used for the modeling process. The Kelian Cape model presents three potential sites at Kelian Cape, with a maximum velocity of 1.4 m/s. The Kelabat Bay model gives five potential sites, located at the bay’s narrowest point, with a maximum velocity of 1.15 m/s. The Larantuka Strait model gives four potential sites in the narrowest area, with a maximum velocity of 2.5 m/s. Larantuka Strait is found to have the most potential for harvesting of tidal current power, as the current velocity at Larantuka Strait is higher, meaning that turbine devices with higher cut-in speeds are suitable. In Kelian Cape and Kelabat Bay, devices with low cut-in speed such as the Gorlov Helical Turbine or Sabella Turbine are required.

  18. THE EFFECT OF MATRIC SUCTION ON THE SHEAR STRENGTH OF UNSATURATED SANDY CLAY Download Article

    Heni Pujiastuti, Ahmad Rifa’i, Agus Darmawan Adi and Teuku Faisal Fathani
    • Article Type: Research Article
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    • Pages (112-119)
    • No of Download = 204

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    The shear strength parameters of the soil is the key engineering property required for the design of geotechnical structures and stability analysis. The shear strength of an unsaturated soil is controlled by matric suction. This research examined the effect of matric suction on the shear strength behavior of sandy clay using a series of experimental tests in the laboratory. The contact filter paper method was used to measure matric suction and the SoilVision knowledge-based system was used to give an approximation of the entire soil water characteristic curve (SWCC). The shear strength of the unsaturated sandy clay was examined using a series of unconsolidated undrained (UU) triaxial tests to identify the relationship between shear strength, cohesion, internal friction angle, and matric suction. The result shows that the shear strength of the soil increases as matric suction increases. It was found that when the matric suction is smaller than air entry value (AEV), the shear strength of the soil increases as matric suction increases and the increment is linear because the soil is in saturated conditions. At a certain matric suction value (on soil samples occurred at 40-600 kPa matric suction values), there is a significant increase in the shear strength of soil associated with the inter-particle force produced due to negative pore water pressure. Furthermore, at a high matric suction, the relationship between shear strength and matric suction tend to be stable as in a low water content, the matric suction is not transmitted effectively to the contact point of soil particles.

  19. CHARACTERISTICS OF POLYCYCLIC AROMATIC HYDROCARBON FORMATION DURING SMOKING Download Article

    Haruki Shimazu, Tsuyoshi Yata and Naoto Ozaki
    • Article Type: Research Article
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    • Pages (120-127)
    • No of Download = 209

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    This study examines the concentrations of polycyclic aromatic hydrocarbons (PAHs) in cigarettes and sidestream cigarette smoke. All 16 gas-phase PAHs and fourteen particulate-phase PAHs were determined in sidestream cigarette smoke for four brands of cigarettes. The median total of gas-phase and particulate-phase PAH concentrations after two cigarettes were smoked were 79.6 ng/m3 and 10.0 ng/m3, and the concentrations were several times higher than before smoking. Median PAH increases in the air samples were 1050 ng per cigarette for gas-phase PAHs and 228 ng per cigarette for particulate-phase PAHs. Gas–particle partition coefficients (Kp) of PAHs in air samples before and after smoking were correlated with the subcooled liquid vapor pressures (PLº) of PAHs. The slopes of log-log plots of Kp versus PLº before and after smoking were -0.270 and -0.575, respectively. PAH partitioning between the gas and particle phases after smoking was closer to equilibrium state because the slope was closer to -1. Furthermore, all 16 PAHs were determined in the cigarettes. The medians of total PAH concentrations in the four brands of cigarettes were 353 ng/g before smoking and 1130 ng/g after smoking. Median PAH increase in the cigarette samples during smoking was 1410 ng per cigarette. The relationships in the concentration of the between total suspended particulate (TSP) and total particulate-phase PAHs, and between total gas-phase PAHs and total particulate-phase PAHs were significantly positive. These findings imply that lowering the amount of TSP generated will lower the amounts of PAHs generated.

  20. INVESTIGATION INTO POTENTIAL OF FLY ASH OBTAINED FROM COAL-BASED POWER PLANTS TO CONTRIBUTE TO SUSTAINABLE ENVIRONMENT Download Article

    M.S.A.M. Anik, M.R. Islam, M.A. Iqbal, K.M.S. Quader
    • Article Type: Research Article
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    • Pages (128-133)
    • No of Download = 199

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    The main objective of this study was to investigate the potential of using fly ash as a mineral filler in asphalt mixtures to reduce the amount of fly ash generated from coal-based power plants in Bangladesh requiring disposal. To achieve this, several mix designs which included fly ash were developed and compared with mixtures using cement as a mineral filler, with mixtures of cement and fly ash with different ratios considered and their performances evaluated. It was found that the design with a bitumen content and fly ash as a mineral filler was within the economical range and, when its Marshall stability and flow values were compared with those of cement, it was found to be satisfactory. Also, the moisture susceptibility of an asphalt mixture with fly ash was checked through immersion-compression tests and compared with that of one with cement as a mineral filler. As it was observed that fly ash generated from coal-fired power plants can reduce the damage caused to asphalt by moisture and is more cost-effective than conventional fillers, it is proposed that using it as a filler material in pavements could reduce the substantial damage suffered by the environment.

  21. DISTRIBUTED MODEL OF HYDROLOGICAL AND SEDIMENT TRANSPORT PROCESS IN MEKONG RIVER BASIN Download Article

    Zuliziana Suif, Chihiro Yoshimura, Nordila Ahmad and Sengheng Hul
    • Article Type: Research Article
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    • Pages (134-139)
    • No of Download = 171

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    Soil erosion and sediment transport have been modeled at several spatial and temporal scales, yet few models have been reported for large river basins (e.g., drainage areas > 100,000 km2). In this study, we propose a process-based distributed model for assessment of sediment transport at a large basin scale. A distributed hydrological model was coupled with a process-based distributed sediment transport model describing soil erosion and sedimentary processes at hillslope units and channels. The model was tested in Mekong River Basin (795,000 km2). The simulation over 10 years showed good agreement with the observed suspended sediment load in the basin. The average Nash–Sutcliffe efficiency (NSE) and average correlation coefficient (r) between the simulated and observed suspended sediment loads were 0.60 and 0.78 respectively. Sensitivity analysis indicated that the suspended sediment load is sensitive to soil detachability over land (Kf) in the Mekong River Basin. Overall, the results suggest that the present model can be used to understand and simulate erosion and sediment transport in large river basins such as Mekong River Basin.

  22. EVALUATION OF PIER-SCOUR PREDICTIONS FOR WIDE PIERS USING FIELD DATA Download Article

    Nordila Ahmad, Bruce W. Melville, Thamer Mohammad and Zuliziana Suif
    • Article Type: Research Article
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    • Pages (140-145)
    • No of Download = 177

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    Many research have been carried out and formulas derived to estimate wide pier scour equation. However, many of these formulas were derived using data from laboratory and very limited equation that had been developed were tested using data from field. The purpose of this paper is to evaluate the laboratory wide pier scour equation that proposed from the previous findings with field data set. Large number of field data from the literature were extracted and it consist both clear-water and live-bed scour. A technique for evaluating the quality of the data was created and tested to the data set. Three pier-scour equations of wide pier from the literature also used to analyze the performance of each equation. Comparisons of computed and measured scour depths show that the formula from the previous publication demonstrated the smallest discrepancy ratio and Root Mean Square Error value when compared with the large number of laboratory and data from field.

  23. A BASIC STUDY ON FLUID PREDICTION OF MORTAR WITH VARIOUS POWDERS Download Article

    Yuki Takagi, Koji Takasu, Hidehiro Koyamada and Hiroki Suyama
    • Article Type: Research Article
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    • Pages (146-150)
    • No of Download = 191

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    In the field of concrete, Fly ash and crushed stone powder which are by-product powders and limes stone powder are used as admixture materials for concrete from the viewpoint of environmental load. Then we should use by-product powders as materials of the concrete as a substitute of fine aggregate. Therefore, it is necessary to predict fluidity of the concrete with powders in large quantities. In this study, we tried a fluid evaluation of mortar with various by-products powders and a fluid prediction by grasping a fluid tendency of mortar with various powders as a part of fine aggregate, and adopted the thickness of a surplus water film theory and the relative flow area ratio as an evaluation index. We clarified when used by-product powders as a part of fine aggregate, we can use excess water film for an index. But the value of the relative flow area ratio was different because of the same thickness of a surplus water film depending on the kind of the powder. It was thought that the fluidity of mortar was able to predict by applying the correction value proposed by this study in various mixtures that used the by-product powder.

  24. CHARACTERIZATION OF CERIUM OXIDE-CHITOSAN NANOCOMPOSITE–MODIFIED SCREEN PRINTED CARBON ELECTRODE AND APPLICATION IN MELATONIN DETERMINATION Download Article

    Pachanuporn Sunon, Porntip Wongkaew, Jeffrey Johns and Nutjaree Johns
    • Article Type: Research Article
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    • Pages (151-157)
    • No of Download = 213

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    A simple and effective modification of the working screen printed carbon electrode (SPCE) surface has been developed with a mixture of chitosan biopolymer and nano cerium oxide at 1:1 composition for the detection of melatonin, a circadian rhythm regulation hormone. The fabricated electrode was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrophotometer (EDS), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Electro-oxidation behaviors of melatonin were extensively observed by differential pulse voltammetric(DPV) analysis. The experimental results demonstrated that the modified cerium oxide-chitosan screen printed carbon electrode (SPCE-Chi-CeO2) exhibited satisfactorily improvement in the electrochemical current sensitivity.Alinear calibration curve for melatonin was obtained in the concentration range from 0-10 μg/ml with a detection limit of 0.18 μg/ml based on DPV measurement. Good selectivity was also obtained in an interference study with some other closely structural related compounds such as tryptophan and serotonin. Thus this modification strategy was proved to be a suitable tool for the simple, fast, sensitive and selective determination of melatonin.

  25. EVALUATION OF ATTENUATION OF ULTRASONIC WAVE IN AIR TO MEASURE CONCRETE ROUGHNESS USING AERIAL ULTRASONIC SENSOR Download Article

    Seiya Nagaoka, Islam Mohammad Raihanul, Kenji Okajima, Ryoei Ito, Ken Watanabe and Tetsu Ito
    • Article Type: Research Article
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    • Pages (158-163)
    • No of Download = 54

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    In Japan, the total length of the main concrete agriculture irrigation canals is estimated to be about 50,000 km. These canals deteriorate over time and most of the canal surface has become rough. One method of measurement of the roughness of the concrete surface is by the aerial ultrasonic sensor. As far as the literature is concerned, no study of the use of 42-kHz sensors for the evaluation of ultrasonic attenuation during air propagation has been conducted. The aim of this study is to evaluate and correct the attenuated values of an ultrasonic wave. In this paper, the reflected wave of the ultrasonic wave was measured under different conditions of temperature, humidity, and atmospheric pressure with a smooth board and a rough board. These were corrected by using the ISO9613-1 equation. It is concluded that the relative error of the corrected value is small when compared with the measured value. The results of this study reveal that correction using the ISO9613-1 equation for attenuation of the 42-kHz ultrasonic wave is an effective method.

  26. IMPACT OF AGRICULTURAL WATER ALLOCATION ON THE ECOSYSTEMS IN THE INNER NIGER RIVER DELTA Download Article

    Barry Kassambara, Homayoon Ganji and Takamitsu Kajisa
    • Article Type: Research Article
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    • Pages (164-170)
    • No of Download = 31

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    The Niger River is a lifeline for humans and biodiversity in Africa’s Sahelian region. Owing to climate change and population increase over the past three decades, the inhabitants of the Sahel have witnessed that their ecosystem is under threat, and a significant reduction of its resources has occurred, particularly in the Inner Niger Delta. In the recent years, because of the Malian government’s policy of developing large-scale irrigation, a sustained rate of expansion of around 5,000 ha of new reclamation area has been seen each year in Office du Niger located upstream of the Inner Delta. The expansion of annual rice double cropping and sugarcane cultivation constitute the main factors for the reduction of the water resources downstream in this Delta. This paper analyzes the hydrological impacts of this large-scale irrigation and crop pattern on the floodplain of the Inner Delta during high-flow and low-flow periods. The study results indicated that despite the rainfall and recent increases in upstream flows of the Niger River, the flooded area size has reduced. We could confirm that the annual average water-withdrawal proportion barely changed during the high-flow period but changed significantly during the low-flow period when the size of the paddy rice and sugarcane area increased. Therefore, changing the crop pattern toward vegetables instead of paddy rice and sugarcane during the low-flow period might be a solution.