Engineering Commons^™

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

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 …

Benefits Of Geopolymer Concrete-Filled Frp Beams And Its Flexural Behavior, Wahid Ferdous, Allan Manalo, Amar Khennane, Obada Kayali

Wahid Ferdous

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

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

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

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

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 …

Agricultural Wastes As Aggregate In Concrete Mixtures – A Review, Hilmi Mahmud

Hilmi Mahmud

Concrete is the most widely used construction material. With the ever-increasing industrialization and urbanization, huge amounts of natural resources are required to make concrete. This, in turn, means that large volumes of natural resources and raw materials are being used for concrete production around the world. To eliminate or minimize the negative environmental impact of the concrete industry and promote environmental sustainability of the industry, the use of wastes from industry as materials for concrete making is considered as an alternative solution for preventing the excessive usage of raw materials. The wide availability of agricultural wastes make them a suitable …