DST Consulting Engineers Inc.

Thunder Bay, Canada

DST Consulting Engineers Inc.

Thunder Bay, Canada
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Disfani M.M.,Swinburne University of Technology | Arulrajah A.,Swinburne University of Technology | Suthagaran V.,Coffey Geotechnics | Bo M.W.,DST Consulting Engineers Inc.
Resources, Conservation and Recycling | Year: 2013

An innovative research study was undertaken to characterize the settlement characteristics of aged wastewater biosolids to facilitate its long-term settlement prediction when used as fill material in road embankment applications. Settlement can be sub-divided into compression due to consolidation and deformation attributed to biodegradation. Results of an extensive geotechnical laboratory evaluation including compaction characteristics, shear strength parameters, coefficient of consolidation, compression index, swell index and coefficient of secondary consolidation were used to predict the consolidation settlement of biosolids in road embankments. Other relevant parameters for biodegradation settlement prediction, such as organic content, pH and electrical conductivity of the biosolids were also determined. The biodegradation induced settlement of a road embankment built with aged biosolids was subsequently analyzed by applying an analytical method used previously for municipal solid waste landfills. The adopted model shows that the rate of biodegradation settlement reduces with the reduction in pH values of biosolids. The model also suggests that the time taken for full process of biodegradation decreases dramatically with pH value of the biosolids between 0 and 6 and then increases exponentially with pH value of the biosolids between 8 and 14. A framework has been developed to predict the total settlement of wastewater biosolids in road embankments for end-users. © 2013 Elsevier B.V. All rights reserved.


Arulrajah A.,Swinburne University of Technology | Ali M.M.Y.,Swinburne University of Technology | Disfani M.M.,Swinburne University of Technology | Piratheepan J.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc.
Journal of Materials in Civil Engineering | Year: 2013

Laboratory and field experiments were undertaken to investigate the possible application of recycled crushed glass blended with crushed basaltic waste rock as a footpath base material. The laboratory experimental program included basic and specialized geotechnical tests including particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio (CBR), Los Angeles abrasion, pH, organic content, and triaxial shear tests. A field demonstration footpath comprising two sections of recycled glasswaste rock blends with 15% and 30% recycled glass content and a third control section with only waste rock was subsequently constructed on the basis of the outcomes of the initial laboratory tests. Subsequently field tests with a nuclear density gauge and Clegg impact hammer were undertaken, as well as laboratory testing of field samples to assess the geotechnical performance of the trial sections. The field and laboratory test results indicated that adding crushed glass may improve the workability of the crushed waste rock base material but subsequently results in lower shear strength. The blend with 15% glass content was found to be the optimum blend, in which the material presented good workability and also had sufficiently high base strength. Higher recycled glass content (30%) resulted in borderline, though still satisfactory, performance. The research findings indicate that recycled crushed glass in blends with crushed waste rock is a potential alternative material to be used in footpath bases. A separate study is recommended to evaluate the environmental risks associated with the usage of these recycled materials. © 2013 American Society of Civil Engineers.


Arulrajah A.,Swinburne University of Technology | Piratheepan J.,Swinburne University of Technology | Disfani M.M.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc.
Journal of Materials in Civil Engineering | Year: 2013

A comprehensive laboratory evaluation of the geotechnical and geoenvironmental properties of five predominant types of construction and demolition (C&D) waste materials was undertaken in this research study. The C&D materials tested were recycled concrete aggregate (RCA), crushed brick (CB), waste rock (WR), reclaimed asphalt pavement (RAP), and fine recycled glass (FRG). The geotechnical assessment included particle size distribution, particle density, water absorption, compaction, Los Angeles abrasion, postcompaction sieve analysis, flakiness index, hydraulic conductivity and California bearing ratio (CBR) tests. Shear strength properties of the materials were studied through a series of triaxial tests. Consolidated drained triaxial tests undertaken on the recycled materials indicated that the recycled materials had a drained cohesion ranging from 41 kPa to 46 kPa and a drained friction angle ranging from 49° to 51°, with the exception of FRG and RAP. The response of the materials under repeated load was investigated using repeated load triaxial (RLT) tests. The RLT testing results indicated that RCA, WR, and CB performed satisfactorily at 98% maximum dry density and at a target moisture content of 70% of the optimum moisture content under modified compaction. The geoenvironmental assessment included pH value, organic content, total and leachate concentration of the material for a range of contaminant constituents. In terms of usage in pavement subbases, RCA and WR were found to have geotechnical engineering properties equivalent or superior to that of typical quarry granular subbase materials. CB at the lower target moisture contents of 70% of the OMC was also found to meet the requirements of typical quarry granular subbase materials. The properties of CB, RAP, and FRG, however, may be further enhanced with additives or mixed in blends with high quality aggregates to enable their usage in pavement subbases © 2013 American Society of Civil Engineers.


Disfani M.M.,Swinburne University of Technology | Arulrajah A.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc. | Hankour R.,Geocomp Corporation
Waste Management | Year: 2011

A comprehensive suite of geotechnical laboratory tests was undertaken on samples of recycled crushed glass produced in Victoria, Australia. Three types of recycled glass sources were tested being coarse, medium and fine sized glass. Laboratory testing results indicated that medium and fine sized recycled glass sources exhibit geotechnical behavior similar to natural aggregates. Coarse recycled glass was however found to be unsuitable for geotechnical engineering applications. Shear strength tests indicate that the fine and medium glass encompass shear strength parameters similar to that of natural sand and gravel mixtures comprising of angular particles. Environmental assessment tests indicated that the material meets the requirements of environmental protection authorities for fill material. The results were used to discuss potential usages of recycled glass as a construction material in geotechnical engineering applications particularly road works. © 2011 Elsevier Ltd.


Arulrajah A.,Swinburne University of Technology | Piratheepan J.,Swinburne University of Technology | Disfani M.M.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc.
Journal of Materials in Civil Engineering | Year: 2013

Results of an extensive series of repeated load triaxial tests performed on three major recycled construction and demolition (C&D) materials at various moisture contents and stress levels were analysed to ascertain their performance in pavement subbases. The development of the resulting permanent deformation that accumulates with the repeated loading and the determination of resilient modulus by two phases of the test are described. The experimental study shows that the C&D materials perform satisfactorily at a moisture content of about 70% of their optimum moisture contents. Furthermore, the C&D materials also satisfy the two-parameter and three-parameter models. The results of this study indicate that, at a density ratio of 98% compared to maximum dry density obtained in the modified proctor test and with moisture contents in the range of 65-90% of the optimum moisture content, most of the recycled C&D materials produce comparatively smaller permanent strain and greater resilient modulus than natural commonly used granular subbase materials in pavement subbase applications. © 2013 American Society of Civil Engineers.


Rahman M.A.,Swinburne University of Technology | Arulrajah A.,Swinburne University of Technology | Piratheepan J.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc. | Imteaz M.A.,Swinburne University of Technology
Journal of Materials in Civil Engineering | Year: 2014

Extensive amounts of natural quarry aggregates are currently being used in road and pavement applications. The use of construction and demolition (C&D) materials such as recycled concrete aggregate (RCA), crushed brick (CB), and reclaimed asphalt pavement (RAP) as an alternative to quarry aggregates has generated interest in recent years, particularly as a pavement base or subbase material. However, the resilient moduli responses and performance of these C&D materials reinforced with geogrids under repeated loads have yet to be established. This research investigates the resilient moduli (MR) and permanent deformation characteristics of C&D materials reinforced with biaxial and triaxial geogrids with the use of repeated load triaxial (RLT) equipment. The effects of varying deviatoric stress on the resilient modulus of unreinforced and geogrid-reinforced C&D materials were also investigated. Regression analyses of resilient modulus test results were performed using the two- and three-parameter models. The MR properties of the geogrid-reinforced RCA and CB were found to be higher than that of the respective unreinforced material. The MR value of RCA+biaxial increased by 24% and of RCA+triaxial increased by 34% when compared with unreinforced RCA. The permanent deformation value obtained from RCA+biaxial decreased by 29% and of RCA+triaxial decreased by 36% when compared with unreinforced RCA. The MR value of CB+biaxial increased by 16% and of CB+triaxial increased by 55% when compared with unreinforced CB. The permanent deformation value decreased by 29 and 37% for CB+biaxial and CB+triaxial, respectively, when compared with unreinforced CB material. The incorporation of geogrids had significant effects on the resilient modulus and permanent deformation characteristics of C&D materials. The three-parameter resilient moduli model was found to provide a good fit for the geogrid-reinforced C&D materials. © 2014 American Society of Civil Engineers.


Arulrajah A.,Swinburne University of Technology | Piratheepan J.,Swinburne University of Technology | Aatheesan T.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc.
Journal of Materials in Civil Engineering | Year: 2011

This paper presents the findings of a laboratory investigation of the characterization of recycled crushed brick and an assessment of its performance as a pavement subbase material. The properties of the recycled crushed brick were compared with the local state road authority specifications in Australia to assess its performance as a pavement subbase material. The experimental program was extensive and included tests such as particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio, Los Angeles abrasion loss, pH, organic content, static triaxial, and repeated load triaxial tests. California bearing ratio values were found to satisfy the local state road authority requirements for a lower subbase material. The Los Angeles abrasion loss value obtained was just above the maximum limits specified for pavement subbase materials. The repeat load triaxial testing established that crushed brick would perform satisfactorily at a 65% moisture ratio level. At higher moisture ratio levels, shear strength of the crushed brick was found to be reduced beyond the acceptable limits. The results of the repeat load triaxial testing indicate that only recycled crushed brick with a moisture ratio of around 65% is a viable material for usage in pavement subbase applications. The geotechnical testing results indicate that crushed brick may have to be blended with other durable recycled aggregates to improve its durability and to enhance its performance in pavement subbase applications. © 2011 American Society of Civil Engineers.


Arulrajah A.,Swinburne University of Technology | Piratheepan J.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc. | Sivakugan N.,James Cook University
Canadian Geotechnical Journal | Year: 2012

This paper presents the findings of a laboratory investigation on the characterization of recycled crushed brick when blended with recycled concrete aggregate and crushed rock for pavement sub-base applications. The engineering properties of the crushed brick blends were compared with typical state road authority specifications in Australia for pavement sub-base systems to ascertain the potential use of crushed brick blends in these applications. The experimental programme included particle-size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio (CBR), Los Angeles abrasion, pH, organic content, and repeated load triaxial tests. Laboratory tests were undertaken on mixtures of 10%, 15%, 20%, 25%, 30%, 40%, and 50% crushed brick blended with recycled concrete aggregate or crushed rock. The research indicates that up to 25% crushed brick could be safely added to recycled concrete aggregate and crushed rock blends in pavement sub-base applications. The repeated load triaxial test results on the blends indicate that the effects of crushed brick content on the mechanical properties in terms of permanent deformation and resilient modulus of both the recycled concrete aggregate and crushed rock blends were marginal compared to the effects on dry density and moisture content.


Disfani M.M.,Swinburne University of Technology | Arulrajah A.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc. | Sivakugan N.,James Cook University
Journal of Cleaner Production | Year: 2012

Recycled crushed glass is the main by-product of the glass recycling industry. Insufficient knowledge of the geotechnical characteristics of recycled glass and its environmental risks are the primary barriers in its application in road works. An extensive suite of geotechnical and environmental tests were undertaken on two common types of recycled crushed glass (fine recycled glass and medium recycled glass) to study the potential of using them in road works as alternatives to natural aggregates. Recycled glass was found to exhibit either equivalent or superior workability, hydraulic conductivity and shear strength to natural aggregates within the same soil classification and demonstrated the potential to substitute natural sand and gravel mixtures in a range of road applications. To address the environmental concerns of using recycled glass in road work applications, a comprehensive series of chemical and environmental tests including total and leachate concentration for a range of contaminant constituents including heavy metals and aromatic hydrocarbons were carried out. Test results were compared with environmental protection authorities' requirements and indicated that no leaching hazard will be experienced during the service life of recycled glass in road work applications. Other possible environmental risks along with health and safety precautions and management suggestions have also been discussed. © 2011 Elsevier Ltd. All rights reserved.


Arulrajah A.,Swinburne University of Technology | Ali M.M.Y.,Swinburne University of Technology | Piratheepan J.,Swinburne University of Technology | Bo M.W.,DST Consulting Engineers Inc.
Journal of Materials in Civil Engineering | Year: 2012

This paper presents the findings of an extensive laboratory investigation on the geotechnical properties of waste excavation rock in pavement subbases. The waste excavation rock used in this study originated from "basalt floaters," or surface excavation basalt rock (basalt). Traditionally, this material would have been disposed as waste, often into landfill. The engineering properties of the crushed basaltic waste rock were compared with the local road authority specifications to assess its performance as a pavement subbase material. The experimental program was extensive and included tests such as particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio, Los Angeles abrasion loss, pH, organic content, static triaxial, and repeated load triaxial tests. The Los Angeles abrasion loss value obtained indicated that the crushed basaltic waste rock is durable. California bearing ratio values were found to satisfy the local state road authority requirements for a subbase material. Repeated load triaxial testing established that the crushed basaltic waste rock would perform satisfactorily as a pavement subbase material in the field. The results of the laboratory testing undertaken in this research indicated that crushed basaltic waste excavation rock satisfied the criteria for use in pavement subbase applications. © 2012 American Society of Civil Engineers. © ASCE /JULY 2012.

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