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Full-Text Articles in Engineering
Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan
Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan
Anil Patnaik
A new type of enamel coated dowel bars for use as concrete pavements has been recently developed and implemented. A gradual deterioration of such bars can occur due to corrosion occurring at locations of the fine microscopic cracks and other defects in the coating. The results of a study aimed at evaluating and understanding the corrosion resistance of such dowel bars is presented and comparisons made with corresponding epoxy-coated dowel bars. Identical defects were introduced onto the surface of the dowel bars with the two types of coatings. The extrinsic influence of environment and resultant corrosion based on type, location …
Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan
Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan
Robert Y. Liang
A new type of enamel coated dowel bars for use as concrete pavements has been recently developed and implemented. A gradual deterioration of such bars can occur due to corrosion occurring at locations of the fine microscopic cracks and other defects in the coating. The results of a study aimed at evaluating and understanding the corrosion resistance of such dowel bars is presented and comparisons made with corresponding epoxy-coated dowel bars. Identical defects were introduced onto the surface of the dowel bars with the two types of coatings. The extrinsic influence of environment and resultant corrosion based on type, location …
Evaluating Waste Concrete For The Treatment Of Acid Sulphate Soil Groundwater From Coastal Floodplains, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, Laura Banasiak
Evaluating Waste Concrete For The Treatment Of Acid Sulphate Soil Groundwater From Coastal Floodplains, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, Laura Banasiak
Laura J Banasiak Dr
The treatment of acidic groundwater generated from acid sulphate soil (ASS) terrain is a challenging environmental issue in coastal floodplains of Australia. In this study, a laboratory column experiment was conducted to assess the performance of waste concrete for treating the acidic groundwater leachate from ASS terrain of the Shoalhaven region of NSW. The groundwater was highly acidic (pH of 2.5–3.5) and contained elevated concentrations of iron (10–90 mg/L) and aluminium (30–45 mg/L). Passage of the acidic groundwater through the column filled with waste concrete resulted in a significant improvement in water quality. Reduction in the concentration of iron and …
Armouring By Precipitates And The Associated Reduction In Hydraulic Conductivity Of Recycled Concrete Aggregates Used In A Novel Prb For The Treatment Of Acidic Groundwater, Punyama Pathirage, Buddhima Indraratna, Long Nghiem, Laura Banasiak, Gyanendra Regmi
Armouring By Precipitates And The Associated Reduction In Hydraulic Conductivity Of Recycled Concrete Aggregates Used In A Novel Prb For The Treatment Of Acidic Groundwater, Punyama Pathirage, Buddhima Indraratna, Long Nghiem, Laura Banasiak, Gyanendra Regmi
Laura J Banasiak Dr
Acidic groundwater generated from acid sulphate soil (ASS) is a major geo-environmental problem in Australia. A permeable reactive barrier (PRB) with recycled concrete aggregates as the reactive material has received considerable attention as an innovative, cost effective technology for passive treatment of acidic groundwater in ASS terrain. Laboratory column experiments conducted at the University of Wollongong investigated the acid neutralisation behaviour of recycled concrete and its potential to remove dissolved aluminium (Al) and iron (Fe). The recycled concrete effectively treated the acidic groundwater, resulting in near-neutral effluent pH and complete removal of Al and Fe. However, armouring of the concrete …
Thin Conductive Concrete Overlay For Bridge Deck Deicing And Anti-Icing, Sherif Yehia, Christopher Tuan
Thin Conductive Concrete Overlay For Bridge Deck Deicing And Anti-Icing, Sherif Yehia, Christopher Tuan
Christopher Y. Tuan
Concrete bridge decks are prone to ice accumulation. Bridge decks freeze before the roads approaching them freeze, making wintry highway travel treacherous. Road salts and deicing chemicals are effective for ice removal but cause damage to concrete and corrosion of reinforcing steel in concrete bridge decks. The resulting rapid degradation of existing concrete pavements and bridge decks is a major concern to transportation and public-works officials. The use of insulation materials for ice control and electric or thermal heating for deicing have been attempted, with unsatisfactory results. Conductive concrete is a cementitious admixture containing electrically conductive components to attain high …
Flexural Behavior Of Concrete-Filled Circular Steel Tubes Under High-Strain Rate Impact Loading, Yaohua Deng, Christopher Tuan
Flexural Behavior Of Concrete-Filled Circular Steel Tubes Under High-Strain Rate Impact Loading, Yaohua Deng, Christopher Tuan
Christopher Y. Tuan
Nine simply supported circular steel concrete-filled tubes (CFTs), two circular steel posttensioned concrete-filled tubes (PTCFTs), and one circular steel fiber–reinforced concrete-filled tube (FRCFT) have been tested in an instrumented drop-weight impact facility. The weight and the height of the drop-weight were varied to cause failure in some test specimens. The failure modes and local damages in those specimens have been investigated extensively. Failure in the steel tubes was commonly tensile facture or rupture along the circumference. Concrete core in the impact area commonly crushed under compression and cracked under tension. The use of prestressing strands and steel fibers significantly restrained …
Conductive-Concrete Overlays - An Innovative Solution For Bridge Deck Deicing, Sherif Yehia, Christopher Tuan
Conductive-Concrete Overlays - An Innovative Solution For Bridge Deck Deicing, Sherif Yehia, Christopher Tuan
Christopher Y. Tuan
Bridge decks are prone to ice accumulation, making winter travel treacherous. Road salts and some other deicing chemicals are cost effective, but may cause surface scaling, reinforcing-steel corrosion, or both. Another alternative is a thin, conductive-concrete overlay that, when connected to a power source, can generate enough heat through electrical resistance to prevent ice formation on the deck or melt ice after it forms. Using a conductive concrete overlay provides an environment-friendly deicing method that would prolong bridge service life by significantly reducing the use of road salt and deicing chemicals. When used on pedestrian bridges, sidewalks, and driveways, it …
Evaluation Of Use Of Lithium Nitrate In Controlling Alkali-Silica Reactivity In Existing Concrete Pavement, Christopher Tuan, Hoasu Sun
Evaluation Of Use Of Lithium Nitrate In Controlling Alkali-Silica Reactivity In Existing Concrete Pavement, Christopher Tuan, Hoasu Sun
Christopher Y. Tuan
This study presents the findings from a 2-year field trial in which lithium nitrate was applied at a rate of 0.006 gal/ft2 twice a year on an existing concrete pavement in Norfolk, Nebraska, in an attempt to arrest ongoing alkali-silica reaction (ASR) distress. Various destructive and nondestructive means were used to measure the effectiveness of the treatments. Concrete cylinders were cored for petrographic examination and split tension testing. Powder samples were taken to determine the lithium content. Nondestructive evaluations used crack mapping, a Schmidt hammer, a velocity meter, and an impact echo apparatus. The amount of lithium that penetrated into …
Electrical Resistance Heating Of Conductive Concrete Containing Steel Fibers And Shavings, Christopher Tuan
Electrical Resistance Heating Of Conductive Concrete Containing Steel Fibers And Shavings, Christopher Tuan
Christopher Y. Tuan
Conductive concrete is a category of concrete containing electrically conductive components to attain stable and high electrical conductivity. Due to its electrical resistance and impedance, a thin conductive concrete overlay can generate enough heat to prevent ice formation on a bridge deck when connected to a power source. Steel fibers and steel shavings were used for the conductive materials in this study. A conventional concrete slab, 1.2 x 3.6 m (4 x 12 ft), has been constructed with a 9 cm (3.5 in.) conductive concrete overlay for conducting deicing experiments in the natural environment. The conductive concrete mixture was developed …
Bond Strength And Transfer Length Of Pre-Tensioned Bridge Girders Cast With Self-Consolidating Concrete, Amgad Girgis, Christopher Tuan
Bond Strength And Transfer Length Of Pre-Tensioned Bridge Girders Cast With Self-Consolidating Concrete, Amgad Girgis, Christopher Tuan
Christopher Y. Tuan
Self-consolidating concrete (SCC) is becoming increasingly popular in the precast/prestressed concrete industry in the United States. However, there have been concerns regarding the bond strength, transfer length, and development length of prestressing strands and mild steel reinforcement with SCC. Further, there are no design guidelines for using SCC. In this study, a literature survey on the bond strength of SCC was conducted. Moustafa pullout tests were performed to determine the bond strength of 0.6 in. (15.2 mm) pretensioning strands with sec. The transfer lengths of three pretensioned concrete bridge girders were measured using Demec points. Pullout tests were also performed …
A Neural Network Approach To Predict The Performance Of Recycled Concrete Used In Permeable Reactive Barriers For The Treatment Of Acidic Groundwater, B Guruprasad, Buddhima Indraratna, Long Nghiem, G Regmi
A Neural Network Approach To Predict The Performance Of Recycled Concrete Used In Permeable Reactive Barriers For The Treatment Of Acidic Groundwater, B Guruprasad, Buddhima Indraratna, Long Nghiem, G Regmi
Long D Nghiem
This study developed a neural network model for examining the performance of recycled concrete for the treatment of acidic groundwater. Concentrations of Al, Fe and Ca and alkalinity of the effluent were selected as the output parameters to simulate the performance of recycled concrete for neutralizing acidic groundwater. The input variables were the number of pore volumes, pH, oxidation reduction potential and the average hydraulic conductivity. Of the 658 experimental datasets available, 409 datasets were used for training, 184 datasets were used for validation, and the remaining datasets were used for cross-validation. The reported results indicate that the neural model …
Treatment Of Acidic Groundwater In Acid Sulfate Soil Terrain Using Recycled Concrete: Column Experiments, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, A. Golab, B Guru Prasad
Treatment Of Acidic Groundwater In Acid Sulfate Soil Terrain Using Recycled Concrete: Column Experiments, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, A. Golab, B Guru Prasad
Long D Nghiem
Acidic groundwater generated from pyrite oxidation in acid sulfate (AS) soil is a major geoenvironmental problem in Australia. This study aims to evaluate recycled concrete as a reactive material in permeable reactive barriers (PRBs) for the remediation of acidic groundwater in low-lying AS soil floodplains. Laboratory experiments were systematically conducted to investigate the acid neutralization behavior of recycled concrete and its potential to remove dissolved Al and Fe. The results confirmed that recycled concrete could effectively treat acidic groundwater from an AS soil terrain, resulting in near neutral effluent over a long period with complete removal of Al and Fe. …
Highly Linear, Wide-Dynamic-Range Multiple-Input Translinear Element Networks, Kofi Odame, Eric Mcdonald, Bradley Minch
Highly Linear, Wide-Dynamic-Range Multiple-Input Translinear Element Networks, Kofi Odame, Eric Mcdonald, Bradley Minch
Bradley Minch
In this paper, we propose a modification to the class of circuits known as multiple input translinear element (MITE) networks. Our proposed modification leads to a MITE network that is free from certain nonidealities encountered in previous implementations. Further, the new MITE network described here readily accommodates the use of bipolar junction transistors in the input and output stages, thus implying a significantly wider dynamic range than we can achieve using subthreshold MOSFETs.
A New Method Of Producing High Strength Oil Palm Shell Lightweight Concrete, Zamin Jumaat
A New Method Of Producing High Strength Oil Palm Shell Lightweight Concrete, Zamin Jumaat
Zamin Jumaat
This paper presents a new method to produce high strength lightweight aggregate concrete (HSLWAC) using an agricultural solid waste, namely oil palm shell (OPS). This method is based on crushing large old OPS. Crushed OPS are hard and have a strong physical bond with hydrated cement paste. The 28 and 56 days compressive strength achieved in this study were about 53 and 56 MPa, respectively. Furthermore, it was observed that it was possible to produce grade 30 OPS concrete without the addition of any cementitious materials. Compared to previous studies, significantly lower cement content was used to produce this grade …