M. M. Disfani

Recycled crushed glass in road work applications

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.

Laboratory evaluation of the use of cement-treated construction and demolition materials in pavement base and subbase applications

AbstractConstruction and demolition (C&D) materials constitute a major proportion of waste materials present in landfills worldwide. With the scarcity of high-quality quarry aggregates, alternative materials, such as C&D materials, are increasingly being considered as a replacement for traditional road-construction materials, particularly as the sustainable usage of these C&D materials has significant environmental benefits. In this research, an extensive laboratory evaluation was carried out to determine the engineering properties of cement-treated C&D materials. The C&D materials investigated were reclaimed asphalt pavement (RAP), recycled concrete aggregate (RCA), and crushed brick (CB). The geotechnical properties of cement-treated C&D materials were evaluated to assess their performance in pavement base/subbase applications. The effect of curing duration on the strength of the C&D materials was analyzed by conducting unconfined compression strength and repeated load triaxial tests. The RAP required 2...

Reclaimed Asphalt Pavement and Recycled Concrete Aggregate Blends in Pavement Subbases: Laboratory and Field Evaluation

In recent years, efforts have been made to incorporate reclaimed asphalt pavement (RAP) into pavement base or subbase applications by means of cement binder stabilization. This approach, however, may not be an environmentally friendly solution due to the high carbon footprint involved in the production of Portland cement. Recycled concrete aggregate (RCA), on the other hand, has been widely accepted in pavement applications. The sustainable solution of blending RAP with RCA was investigated in this research in an attempt to facilitate the usage of this blend as an alternative pavement subbase material. An extensive suite of geotechnical laboratory tests was undertaken on RAP with contents of 100, 50, 30 and 15% in blends with RCA. Results of the research study indicated that RAP/RCA blends with a low 15% RAP content meet the repeated load triaxial requirements for use in pavement subbase layers. Results of field performance of a pavement subbase constructed with untreated 100% RAP, at a private haul road field-demonstration site, confirmed that it had insufficient strength requirements to meet local road-authority pavement-subbase requirements. RAP and RAP/RCA blends, although found in this study to be not fully compliant with the local road-authorities requirements, could be potentially considered for lower traffic usage, such as haul roads and footpaths.

Geotechnical Performance of Recycled Glass-Waste Rock Blends in Footpath Bases

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 glass-waste 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.

Select chemical and engineering properties of wastewater biosolids

The select chemical and engineering characteristics of biosolids produced at a wastewater treatment plant in Eastern Australia were investigated to assess its suitability as structural fill material in road embankments. Results of comprehensive set of geotechnical experimentation including compaction, consolidation, creep, hydraulic conductivity and shear strength tests implied that biosolids demonstrate behavior similar to highly organic clays with a higher potential for consolidation and settlement. Results of chemical study including heavy metals, dichloro diphenyl trichloroethane (and derivatives) and organochlorine pesticides, indicate that biosolids samples are within the acceptable limits which allows their usage under certain guidelines. Results of tests on pathogens (bacteria, viruses or parasites) also indicated that biosolids were within the safe acceptable limits. Technical and management suggestions have been provided to minimize the possible environmental risks of using biosolids in road embankment fills.

Recycled-glass blends in pavement base/subbase applications: laboratory and field evaluation

AbstractThis paper presents the findings of a field and laboratory evaluation on the use of recycled glass blends as unbound pavement base/subbase materials. The parent recycled aggregates studied in this research were fine recycled glass (FRG), recycled concrete aggregate (RCA), and waste rock (WR). The geotechnical performance of the recycled aggregate blends of particular interest in this research were FRG blended with RCA (FRG/RCA) and FRG blended with WR (FRG/WR) in pavement base applications. The geotechnical performance of a trial road pavement was assessed by means of initial laboratory tests and subsequently field tests. The initial laboratory experimental program included specialized geotechnical tests including repeated load triaxial and triaxial tests to characterize the recycled materials. The subsequent trial road pavement constructed comprised seven different sections of FRG blends in the pavement base varying from 10 to 30% recycled glass content as well as two control sections with RCA an...

Resilient Moduli Response of Recycled Construction and Demolition Materials in Pavement Subbase Applications

AbstractResults 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 na...

Stabilization of Demolition Materials for Pavement Base/Subbase Applications Using Fly Ash and Slag Geopolymers: Laboratory Investigation

AbstractThe use of recycled construction and demolition (C&D) materials in unbound and cement stabilized pavement base/subbase applications has generated growing interest in recent years. C&D materials consisting of crushed brick (CB), recycled crushed aggregate (RCA), and reclaimed asphalt pavement (RAP) have been investigated in unbound and cement stabilized pavement base/subbase applications. However, the high carbon footprint of using cement for pavement base/subbase stabilization has led to this research to seek alternative low-carbon binders. This study evaluates the behavior of C&D materials when stabilized with geopolymers. Fly ash (FA) and ground granulated blast furnace slag (S) were used as pozzolanic binders and a different alkaline activator solution to pozzolanic binder ratio was tested. A maximum of 4% of dry weight of soil was used for geopolymer stabilization of the C&D materials. The binders used were either 4% FA, 2% FA+ 2% S, or 4% S. The geotechnical engineering and strength propertie...

Suitability of Using Recycled Glass - Crushed Rock Blends for Pavement Subbase Applications

Construction and demolition materials such as recycled crushed rock and recycled glass account for a major proportion of the waste materials present in landfills in Australia. Using recycled glass and crushed rock in road pavement applications would significantly reduce the need for quarry-based virgin materials. Furthermore, recycled materials could be used in parts of the country where aggregate sources are scarce. This paper discusses the suitability and applicability of recycled glass when used in blends with crushed rock for road pavement applications. Performance of the blends was measured using an extensive suite of geotechnical engineering laboratory tests including basic classification tests along with modified compaction, California Bearing Ratio and Los Angeles abrasion tests. Repeated load triaxial tests were also conducted on blends. The test results indicated that the recycled glass could be blended with recycled crushed rock by up to 30% by mass and provide satisfactory engineering performance to be used as a pavement subbase material.

Laboratory Evaluation of the Geotechnical Characteristics of Wastewater Biosolids in Road Embankments

AbstractAn extensive suite of geotechnical laboratory tests were undertaken on wastewater biosolids to evaluate their sustainable usage as a fill material in road embankments. Geotechnical tests undertaken include particle size distribution, specific gravity, Atterberg limits, compaction, consolidation, hydraulic conductivity, California bearing ratio (CBR), field vane shear, direct shear, and triaxial shear. The geotechnical tests indicated that biosolids are equivalent to organic fine-grained soils of medium to high plasticity with high moisture content and liquid limit values. Consolidation tests indicate that biosolids have similar consolidation characteristics to that of organic soils. Shear strength tests on compacted biosolids samples indicated relatively high internal friction angles, comparable to that of inorganic silts. Compacted biosolids samples exhibit a modest cohesion comparable to organic clays. CBR tests results indicate high deformation potential of biosolids. Chemical and environmental...