Showing papers by "Arul Arulrajah published in 2014"
TL;DR: In this paper, a comprehensive laboratory evaluation of physical and shear strength characteristics of recycled C&D materials was undertaken using gradation, Los Angeles Abrasion, unconfined compression, California Bearing Ratio (CBR), direct shear and consolidated drained triaxial tests.
212 citations
TL;DR: In this paper, the authors investigated the feasibility of using CCR, a cementitious waste material, as an alkaline activator and fly ash (FA) as a precursor to improve the engineering properties of a problematic silty clay to facilitate its usage as stabilized subgrade material.
171 citations
TL;DR: In this paper, the suitability of recycled construction and demolition materials as alternative pipe backfilling materials for stormwater and sewer pipes was investigated to assess their suitability as a pipe back-filling material.
156 citations
TL;DR: In this paper, the authors evaluated the performance of crushed brick as a supplementary material in cement stabilized recycled concrete aggregates and reported that the results of the flexural beam tests were consistent with past works with cement stabilized quarry produced crushed rock products.
141 citations
TL;DR: In this paper, an extensive suite of geotechnical laboratory tests was undertaken on RAP with contents of 100, 50, 30 and 15% in blends with Recycled Concrete Aggregate (RCA).
Abstract: 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.
133 citations
TL;DR: In this paper, the interface shear strength properties of geogrid-reinforced construction and demolition (C&D) aggregates were determined using a modified large scale direct shear test (DST) apparatus.
Abstract: The interface shear strength properties of geogrid-reinforced construction and demolition (C&D) aggregates were determined using a modified large scale direct shear test (DST) apparatus. Comparisons were made between the results of the various C&D aggregates reinforced with biaxial and triaxial geogrids and with the unreinforced aggregates by means of the modified and conventional DST methods. The modified DST method employed sought to increase interlocking between the C&D aggregates with the geogrids and thus ascertains the true interface shear strength properties of the recycled demolition aggregates. Biaxial and triaxial geogrids were used as the geogrid-reinforcement materials. The C&D aggregates tested with the DST were recycled concrete aggregate (RCA), crushed brick (CB), and reclaimed asphalt pavement (RAP). The modified DST results indicated that the interface shear strength properties of the geogrid-reinforced C&D aggregates were higher than that of the conventional test method and the r...
96 citations
TL;DR: In this paper, the effects of varying deviatoric stress on the resilient modulus of unreinforced and geogrid-reinforced C&D materials were also investigated.
Abstract: 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 mode...
78 citations
TL;DR: In this article, the authors present the findings of a field and laboratory evaluation on the use of recycled glass blends as unbound pavement base/subbase materials, including fine recycled glass (FRG), recycled concrete aggregate and waste rock (WR).
Abstract: This 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...
72 citations
TL;DR: In this article, an extensive suite of engineering and environmental tests were undertaken on spent coffee grounds obtained from several popular cafes in Melbourne, Australia to evaluate their properties and potential use as a non-structural fill material in road embankments.
69 citations
TL;DR: In this article, the feasibility of using Calcium Carbide Residue (CCR) and fly ash (FA) as a cementing agent for the manufacture of non-bearing masonry units without Portland Cement (PC).
61 citations
TL;DR: In this article, an attempt is made to identify the dominant parameter, governing the unit weight, strength, and compressibility characteristics of lightweight cellular cemented clay, which helps control input of water, air foam, and cementing agent to attain unit weight and strength development with curing time.
Abstract: Lightweight cellular cemented clays have wide range of applications in the infrastructure rehabilitation and in the construction of new facilities. Since the inception of this method, the developments in the plant and machinery as well as associated field techniques have surpassed the basic understanding of strength developments in lightweight cellular cemented clay. In this paper, an attempt is made to identify the dominant parameter, governing the unit weight, strength, and compressibility characteristics of lightweight cellular cemented clay, which helps control input of water, air foam, and cementing agent to attain unit weight and strength development with curing time. From this research, it is discovered that water-void/cement ratio, wV/C is the dominant parameter for the above purposes. From the critical analysis of test results, a mix design method to attain the target strength and unit weight is suggested. This method is useful from both engineering and economic perspectives.
TL;DR: In this paper, the Muller resonance compaction (MRC) and vibroflotation (VF) are used to densify the loose granular sand fill in a mega-land reclamation project in the Republic of Singapore.
Abstract: Loose granular sand deposits formed during the land reclamation process are vulnerable to liquefaction upon imparting seismic forces. These loose granular sand fills could encounter bearing failures or compress beyond tolerable limits under static and dynamic loads. To eliminate such failures, loose granular soils require densification to enhance their engineering properties. Deep compaction is the only means to improve these thick deposits of loose sand fill in many foreshore land reclamation projects. Muller resonance compaction (MRC) and vibroflotation are deep vibratory compaction techniques, which are suitable to densify thick layers of loose granular fills. This paper describes the applications of deep compaction vibratory techniques in a mega-land reclamation project in the Republic of Singapore where the efficacy of densification was verified by cone penetration tests (CPT) undertaken in a pilot test area. In the MRC technique, high vibrating energies are used, which results in the whole m...
TL;DR: In-situ tests with a BAT permeameter as part of a hydrogeological study to determine the horizontal hydraulic conductivity of Singapore marine clay at Changi were conducted in this article.
01 Jan 2014
TL;DR: In this article, the physical and geotechnical characteristics of recycled crushed brick (CB) to reuse in different civil engineering applications were described and the results were also found to meet the peak and residual shear strength and local road authority requirements.
Abstract: Construction and demolition (C&D) materials are defined as the materials obtained from demolition activities such as crushed concrete, crushed brick and reclaimed asphalt. The disposal of these materials in landfills is a major problem to the environment. The urgency and significance of recycling C&D materials has been raised because of scarcity of natural aggregates, difficulties in finding landfill and other environmental concerns. Hence, the present paper describes the physical and geotechnical characteristics of recycled crushed brick (CB) to reuse in different civil engineering applications. The laboratory experiments involved modified compaction test, particle size distribution, specific gravity, water absorption and Los Angeles abrasion. Furthermore, the interface shear strength properties of the CB material with geogrids and their performance as a pavement subbase material was ascertained by using a large direct shear testing (DST) apparatus. The higher tensile strength triaxial geogrid was found to attain higher interface shear strength properties than that of the lower tensile strength biaxial geogrid. The DST results however indicated that the interface shear strength properties of the geogrid-reinforced CB material were less than that of the respective material without reinforcement. The results were also found to meet the peak and residual shear strength and local road authority requirements for typical construction materials in civil engineering applications.
01 Jan 2014
TL;DR: In this article, the authors investigated the contact erosion mechanism at the interface of granular working platform and the overlying dispersive soil layer under vertical ground water fluctuation and found that significant amount of settlement occurs due to contact erosion failure at the pavement embankment foundation.
Abstract: Generally pavement embankments constructed on soft subgrades requires an overlying working platform. The working platforms provided with granular materials of higher constriction sizes are highly susceptible to the formation of preferential flow path for the overlying embankment materials. Hence, the risk of contact erosion failure is higher at the interface of granular working platform material and the road embankment material below the pavement layers. This kind of contact erosion failure is often under estimated and requires a thorough investigation. Moreover, in the road embankment constructed with dispersive soil the contact erosion failure may be much more severe. In such case the finer particles of the embankment materials may get transported with a slow vertical ground water movement. Hence, this may lead to reduction in embankment stability and deformation on pavement structure. This kind of failures occurs in long term process and difficult to identify in early stage. Therefore, in order to study the long term deformation failure below the pavement layers, this paper investigates the contact erosion mechanism at the interface of granular working platform and the overlying dispersive soil layer under vertical ground water fluctuation. Here a new erosion test apparatus is developed with care to study the contact erosion mechanism below the pavement layers and experiments were conducted in a laboratory prototype-scale. The test results revealed that significant amount of settlement take place due to contact erosion failure at the pavement embankment foundation.
TL;DR: In this article, the chemical and organic properties of sludge from a major sewage treatment plant in south-eastern Australia were investigated and the results showed that the concentrations of all OCPs and majority of PAHs were below or close to laboratory detection limits.
Abstract: With the aim of reusing municipal sewage sludge, this paper presents the chemical and organic properties of sludge from a major sewage treatment plant in south–eastern Australia. The results show that the concentrations of all OCPs and majority of PAHs were below or close to laboratory detection limits. Concentrations of heavy metals in sludge samples were compared with typical sludge testing results from the USA and UK. Concentrations of heavy metals from the south–eastern Australian sludge samples were noted to be much lower than concentrations of same metals reported in the UK but slightly higher than in the USA. Concentrations of lead in south–eastern Australian sludge samples were however found to be lower than the US sludge samples. Results on the leachate testing on aerated and nitrogen purged samples revealed minor differences in the results. Potential reuse options for the sewage sludge in agricultural applications are also discussed.