Papers by Abbas Mohajerani
World Academy of Science, Engineering and Technology, International Journal of Civil, Environmental, Structural, Construction and Architectural Engineering, Jan 5, 2015
The California Bearing Ratio (CBR) has been acknowledged as an important parameter to characteriz... more The California Bearing Ratio (CBR) has been acknowledged as an important parameter to characterize the bearing capacity of earth structures, such as earth dams, road embankments, airport runways, bridge abutments and pavements. Technically, the CBR test can be carried out in the laboratory or in the field. The CBR test is time-consuming and is infrequently performed due to the equipment needed and the fact that the field moisture content keeps changing over time. Over the years, many correlations have been developed for the prediction of CBR by various researchers, including the dynamic cone penetrometer, undrained shear strength and Clegg impact hammer. This paper reports and discusses some of the results from a study on the prediction of CBR. In the current study, the CBR test was performed in the laboratory on some finegrained subgrade soils collected from various locations in Victoria. Based on the test results, a satisfactory empirical correlation was found between the CBR and the physical properties of the experimental soils.
A typical flexible pavement structure consists of an asphalt wearing course and the underlying ba... more A typical flexible pavement structure consists of an asphalt wearing course and the underlying base and sub-base courses. The subgrade soil is the foundation of the pavement. In recent years,the resilient modulus has been recommended by pavement design guides as an important indicator for characterising the resilient behaviour of these pavement materials under dynamic traffic loading. The resilient modulus can be obtained from the repeated-load triaxial test in the laboratory. This paper reports and discusses some of the results from a study on the evaluation of the resilient modulus for eight Victorian fine-grained soils at different moisture contents and stress levels. The effects of the deviator stress, confining stress, moisture content and plasticity index of soils on the resilient modulus have been investigated, and a relationship has been established and discussed for the soils used in this study.
International Journal of Pavement Engineering, Oct 20, 2015
Abstract Resilient modulus is an important parameter to characterise the resilient behaviour of p... more Abstract Resilient modulus is an important parameter to characterise the resilient behaviour of pavement materials. Resilient modulus can be determined in the laboratory from repeated load triaxial test and is defined as the ratio of deviator stress to recoverable strain. Inherently, it is a challenge to perform repeated load triaxial tests as a routine basic test due to its complicated, time-consuming and expensive procedure; hence, several empirical approaches to estimate the resilient modulus from other soil mechanical properties – California bearing ratio, unconfined compressive strength or physical properties – have been proposed. This study has investigated the application of a dynamic lightweight cone penetrometer for the estimation of the resilient modulus in the laboratory and field conditions for some Victorian fine-grained subgrade soils. The results show the possibility to estimate the resilient modulus of fine-grained soils using the dynamic lightweight penetration index at any moisture content (MC) from optimum MC to soaked conditions.
Materials, Sep 20, 2019
Nanoparticles are defined as ultrafine particles sized between 1 and 100 nanometres in diameter. ... more Nanoparticles are defined as ultrafine particles sized between 1 and 100 nanometres in diameter. In recent decades, there has been wide scientific research on the various uses of nanoparticles in construction, electronics, manufacturing, cosmetics, and medicine. The advantages of using nanoparticles in construction are immense, promising extraordinary physical and chemical properties for modified construction materials. Among the many different types of nanoparticles, titanium dioxide, carbon nanotubes, silica, copper, clay, and aluminium oxide are the most widely used nanoparticles in the construction sector. The promise of nanoparticles as observed in construction is reflected in other adoptive industries, driving the growth in demand and production quantity at an exorbitant rate. The objective of this study was to analyse the use of nanoparticles within the construction industry to exemplify the benefits of nanoparticle applications and to address the short-term and long-term effects of nanoparticles on the environment and human health within the microcosm of industry so that the findings may be generalised. The benefits of nanoparticle utilisation are demonstrated through specific applications in common materials, particularly in normal concrete, asphalt concrete, bricks, timber, and steel. In addition, the paper addresses the potential benefits and safety barriers for using nanomaterials, with consideration given to key areas of knowledge associated with exposure to nanoparticles that may have implications for health and environmental safety. The field of nanotechnology is considered rather young compared to established industries, thus limiting the time for research and risk analysis. Nevertheless, it is pertinent that research and regulation precede the widespread adoption of potentially harmful particles to mitigate undue risk.
Soils and Foundations, Feb 1, 2016
The focus of this review is the design of axially loaded screw piles. Through a comprehensive col... more The focus of this review is the design of axially loaded screw piles. Through a comprehensive collation of all relevant literature regarding the design of screw piles, comparisons are made and relations are drawn which will ultimately be relevant to future efforts associated with the design of screw piles. Contemporary design approaches to screw piling are covered and the consequential relationships among the various geotechnical design parameters are asserted. The review is centred on vertically loaded axial piles in compression and tension in both cohesive and cohesionless soils. Through a rigid analysis of all viable design methods, in relation to the bearing capacity of helical piles, comparisons are made among the different design methods and attention is brought to the need for more research on the settlement of screw piles in order to allow for a more complete design.
Road Materials and Pavement Design, Jul 2, 2019
Quality control of road materials is important in road construction. Various methods have been de... more Quality control of road materials is important in road construction. Various methods have been developed based on the material dry unit weight or density. As a simple alternative method, this research investigates a new technique for the compaction control of sand using a dynamic lightweight cone penetrometer (DLP). This penetrometer has the same design as the widely used standard cone penetrometer but has a lighter hammer mass of 2.25 kg. A large number of tests were carried out in large moulds in the laboratory using two different typical sand samples from Western Australia. Strong correlations were found between the compacted dry density and the dynamic lightweight cone penetrometer index for the two experimental sand samples used in this study with different moisture contents. DLP can provide a rapid, simple and less expensive method for the compaction control of compacted sand fills in the field.
Ocean Engineering, Nov 1, 2016
Liquefaction, which can result in a vessel capsizing, is one of many hazards involved when transp... more Liquefaction, which can result in a vessel capsizing, is one of many hazards involved when transporting bulk cargoes. The objective of this study is to determine the variability of the geotechnical properties of Iron Ore Fines (IOF) under cyclic loading at different moisture contents to determine the liquefaction potential. The geotechnical properties include the void ratio, dry density, degree of saturation and angle of repose. Previous studies have proven that in a partially saturated material, under cyclic loading, these properties directly effect the shear strength and may cause a material to liquefy. Also, by measuring the penetration of a free floating IOF Plunger (IOFP), developed during this study, the loss of shear strength was monitored. The results from this study show that significant variations occur in the geotechnical properties of IOF under cyclic loading at the varying moisture contents tested. Penetration from the IOFP was also observed, which indicated a reduction of effective stress and therefore shear strength within the samples IOF. The samples tested showed signs of liquefaction between the Proctor/Fagerberg and Modified Proctor/Fagerberg transportable moisture limits. It was concluded that the liquefaction potential of IOF is a function of the time of cyclic loading and initial moisture content. 1.2. Transportable moisture limit test methods Currently, in the 2013 IMSBC Code, there are three test methods
Ocean Engineering, Sep 1, 2017
During marine transportation, a combination of cyclic loading, fine particles and moisture within... more During marine transportation, a combination of cyclic loading, fine particles and moisture within a bulk cargo can result in liquefaction causing the bulk carrier to list or capsize. The objective of this study is to investigate incidents where bulk cargoes liquefied during transportation and what resulted from these incidents, including the loss of human life and industry assets. In addition, the effectiveness of determining the Transportable Moisture Limit (TML) using the Modified Proctor/Fagerberg Test (MPFT) for Iron Ore Fines (IOF) is questioned by developing an apparatus used to observe the apparent shear strength of a sample of IOF. Between 1988 and 2016, 23 incidents were reported where liquefaction of a bulk cargo was suspected. These incidents resulted in 138 casualties and the loss of 17 vessels. It was found that incidents are continuing to occur even after the implementation of mandatory testing. Using an apparatus developed for this study, samples of IOF showed a sudden loss of shear strength at moisture contents lower than the TML with indications liquefaction had occurred. Although further testing is required to confirm some assumptions made, the study concluded that the IOF tested was assumed to be liquefiable at the TML determined using the MPFT.
International Journal of Pavement Engineering, Jul 18, 2014
ABSTRACT
Canadian Geotechnical Journal, Feb 1, 2018
A commodity, such as iron ore fines, shifting in the hold of a bulk carrier can lead to the vesse... more A commodity, such as iron ore fines, shifting in the hold of a bulk carrier can lead to the vessel listing or capsizing. The objective of this study is to investigate the factors of safety pertaining to slope failure for both untrimmed and trimmed cargoes of iron ore fines during marine transportation. In order to determine the shear strength parameters needed to perform this analysis, triaxial testing was performed on samples of iron ore fines under varying densities and moisture contents. Using the shear strength parameters of the material, the Morgenstern-Price method of slices and infinite slope analysis, referred to as rotational and translational slope stability analyses, were used to determine the factors of safety against slope failure. The study concludes that, considering a factor of safety of 1.5, an untrimmed cargo of iron ore fines is unstable at angles of heel that bulk carriers are expected to experience during a typical voyage. If the cargo is trimmed it is shown to be significantly more stable. The results support the recommendation that it becomes mandatory for cargoes of iron ore fines to undergo trimming in order to reduce the chance of slope failure occurring, which may result in the loss of human life and industry assets. Keywords-Iron ore fines; cargo shift; factor of safety against slope failure; triaxial testing; marine transportation via bulk carrier
Transportation geotechnics, Jun 1, 2016
The resilient modulus has been recognised as an important property that governs the performance o... more The resilient modulus has been recognised as an important property that governs the performance of pavement materials under the dynamic wheel loads. The resilient modulus can be obtained from a repeated load triaxial test with a series of a combination of deviator and confining stresses. It is traditionally reported as a function of the deviator and confining stresses, which can be a practical challenge in selecting the appropriate resilient modulus value for a pavement design. In this study, eight different Victorian fine-grained soils with different moisture contents were used for the determination of the resilient modulus and the evaluation of a proposed simplified method. The resilient modulus from the simplified method is reported as a single value, which is taken as the average value from the simplified testing method. It has been found that the resilient modulus obtained from the proposed simplified and the standard testing method are almost identical.
International Journal of Pavement Research and Technology
Littered cigarette butts (CBs) are a form of poorly biodegradable waste. Attempts have been made ... more Littered cigarette butts (CBs) are a form of poorly biodegradable waste. Attempts have been made to prevent the pollution caused by the waste through the recycling of CBs in construction materials. A novel method involving the encapsulation of CBs with paraffin wax and bitumen was developed, which investigated its use in hot-dense asphalt concrete with promising results. The objective of this study was to carry out a comprehensive leachate analysis to examine the effectiveness and efficiency of the encapsulation method for the prevention of heavy metal leachates from CBs and to investigate the physical properties of wax and bitumen encapsulated CBs. The leachate analysis was conducted using the Australian Bottle Leaching Procedure (ABLP) for pH values 2.9, 5.0, and 9.2. The leaching behavior of encapsulated CBs was insignificant compared to fresh CBs due to the immobilization of metals after being encapsulated in bitumen and wax. The findings suggest that the variance in pH influences the behavior of the metal concentration leached. Generally, pH 2.9 resulted in the highest metal contamination for all sample types, followed by pH 5.0 and pH 9.2. The water absorption decreased significantly from 383% for fresh CBs to 4% and 5% for bitumen and wax encapsulated CBs. Micro-X-ray CT imaging was used to study and analyze the porosity and pore structure of CBs, and a substantial decrease in porosity from 66% to 0.5% was determined when CBs were encapsulated with bitumen.
The California Bearing Ratio (CBR) has been<br> acknowledged as an important parameter to c... more The California Bearing Ratio (CBR) has been<br> acknowledged as an important parameter to characterize the bearing<br> capacity of earth structures, such as earth dams, road embankments,<br> airport runways, bridge abutments and pavements. Technically, the<br> CBR test can be carried out in the laboratory or in the field. The CBR<br> test is time-consuming and is infrequently performed due to the<br> equipment needed and the fact that the field moisture content keeps<br> changing over time. Over the years, many correlations have been<br> developed for the prediction of CBR by various researchers,<br> including the dynamic cone penetrometer, undrained shear strength<br> and Clegg impact hammer. This paper reports and discusses some of<br> the results from a study on the prediction of CBR. In the current<br> study, the CBR test was performed in the laboratory on some finegrained<br> subgrade soils collected ...
Several trillion cigarettes produced worldwide annually lead to many thousands of kilograms of to... more Several trillion cigarettes produced worldwide annually lead to many thousands of kilograms of toxic waste. Cigarette butts (CBs) accumulate in the environment due to the poor biodegradability of the cellulose acetate filters. This paper presents some of the results from a continuing study on recycling CBs into fired clay bricks. Physico-mechanical properties of fired clay bricks manufactured with different percentages of CBs are reported and discussed. The results show that the density of fired bricks was reduced by up to 30 %, depending on the percentage of CBs incorporated into the raw materials. Similarly, the compressive strength of bricks tested decreased according to the percentage of CBs included in the mix. The thermal conductivity performance of bricks was improved by 51 and 58 % for 5 and 10 % CBs content respectively. Leaching tests were carried out to investigate the levels of possible leachates of heavy metals from the manufactured clay-CB bricks. The results revealed ...
A typical flexible pavement structure consists of the surface, base, sub-base and subgrade soil. ... more A typical flexible pavement structure consists of the surface, base, sub-base and subgrade soil. The loading traffic is transferred from the top layer with higher stiffness to the layer below with less stiffness. Under normal traffic loading, the behaviour of flexible pavement is very complex and can be predicted by using the repeated load triaxial test equipment in the laboratory. However, the nature of the repeated load triaxial testing procedure is considered time-consuming, complicated and expensive, and it is a challenge to carry out as a routine test in the laboratory. Therefore, the current paper proposes a numerical approach to simulate the repeated load triaxial test by employing the discrete element method. A sample with particle size ranging from 2.36mm to 19.0mm was constructed. Material properties, which included normal stiffness, shear stiffness, coefficient of friction, maximum dry density and particle density, were used as the input for the simulation. The sample was...
Materials, 2021
Cigarette butts (CBs) are the most common littered waste in the world and may contain polycyclic ... more Cigarette butts (CBs) are the most common littered waste in the world and may contain polycyclic aromatic hydrocarbons (PAHs) from the incomplete combustion of tobacco during burning. Therefore, to investigate the potential PAH residual remaining in fired clay bricks (FCBs) incorporating CBs and examine the environmental impact of utilizing toxic waste in the production of FCBs, a comprehensive PAH extraction analysis was conducted. The Soxhlet extraction method was utilized to conduct a qualitative and quantitative analysis of sixteen toxic Environmental Protection Authority (EPA) Polycyclic Aromatic Hydrocarbons (PAHs) in FCB samples incorporating CBs using gas chromatography–mass spectrometry (GC–MS). The concentrations of the mean total (Σ)PAHs for FCBs incorporating 0%, 0.5%, 1%, 1.5%, and 2% CBs by weight (wt) were found to be 0.183, 0.180, 0.242, 0.234, and 0.463 µg/mL. As expected, PAHs with higher water solubility and volatility, naphthalene, fluorene, anthracene, pyrene, f...
Materials, 2020
Our cities, parks, beaches, and oceans have been contaminated for many years with millions of ton... more Our cities, parks, beaches, and oceans have been contaminated for many years with millions of tonnes of unsightly and toxic cigarette butts (CBs). This study presents and discusses some of the results of an ongoing study on recycling in fired-clay bricks. Energy savings: the energy value of CBs with remnant tobacco was found to be 16.5 MJ/kg. If just 2.5% of all bricks produced annually worldwide included 1% CB content, all of the CBs currently produced could be recycled in bricks, and it is estimated that global firing energy consumption could be reduced by approximately 20 billion MJ (megajoules). This approximately equates to the power used by one million homes in Victoria, Australia, every year. Bacteriological study: CBs were investigated for the presence of ten common bacteria in two pilot studies. Staphylococcus spp. and Pseudomonas aeruginosa were detected in fresh used CB samples, and Listeria spp. were detected in old used CB samples. All of the CB samples except the dried...
Materials, 2020
Cigarette butts (CBs) are the most commonly littered waste material in the world. It is estimated... more Cigarette butts (CBs) are the most commonly littered waste material in the world. It is estimated that over 5.7 trillion cigarettes are consumed worldwide each year. Consequently, millions of tonnes of highly toxic waste are contaminating the environment. CBs are composed of cellulose acetate filters—a polymer with poor biodegradability—and which, depending upon the environmental conditions, can take many years to decompose. In this study, fired clay bricks were manufactured with 0.5%, 1%, 1.5%, and 2% CBs by mass and tested against control bricks with 0% CBs. The results revealed a decrease in compressive strength from 48.6 MPa for 0% CB content bricks to 30.8 MPa for 1% CB content bricks, and a decrease in dry density with the increase in CB content, from 2114 kg/m3 for the control bricks to 1983 kg/m3 and 1969 kg/m3 for 1% and 2% CB content bricks. The highest value of water absorption appeared for 2% CB content bricks, which reached an absorption rate of 13.1% compared to 9% for...
Resources, Conservation and Recycling, 2020
Waste tyres and their accumulation is a global environmental concern; they are not biodegradable,... more Waste tyres and their accumulation is a global environmental concern; they are not biodegradable, and, globally, an estimated 1.5 billion are generated annually. Waste tyres in landfill and stockpiles are renowned for leaching toxic chemicals into the surrounding environment, acting as breeding grounds for mosquitoes, and fuelling inextinguishable fires. The properties of waste tyre rubber and engineering applications have been previously reported in a range of publications with respect to the environmental, economic, and technical factors. This study compiles and reviews this research with a focus on geotechnical engineering applications, such as earthworks and infrastructure construction. The applications of waste rubber in construction materials includes cementitious concrete, asphalt concrete, and granular materials for earth structures. Crumb rubber, when used as a sand replacement in flowable concrete fill, improved ductility and strength-to-weight ratio. A 40 MPa concrete mix with 0.6% rubber crumb content exhibited optimal strength and air entrainment capabilities, displaying minimal damage after 56 freeze/thaw cycles. Rubber, as a partial replacement for aggregate in road base and sub-base layers, adversely affected the California Bearing Ratio (CBR) of the graded aggregate base course. Rubber-soil mixtures as the interface of foundation and structure yielded a 60-70 % reduction in vertical and horizontal ground accelerations when subjected to earthquake simulation modelling. There is concern regarding the toxicity of waste rubber incorporated products due to leachates of heavy metals and other chemicals common in tyres. Further comprehensive studies in this area are needed. Leachate studies should be conducted under different pH and liquid to solid ratios.
Materials, 2019
Fibres have been used in construction materials for a very long time. Through previous research a... more Fibres have been used in construction materials for a very long time. Through previous research and investigations, the use of natural and synthetic fibres have shown promising results, as their presence has demonstrated significant benefits in terms of the overall physical and mechanical properties of the composite material. When comparing fibre reinforcement to traditional reinforcement, the ratio of fibre required is significantly less, making fibre reinforcement both energy and economically efficient. More recently, waste fibres have been studied for their potential as reinforcement in construction materials. The build-up of waste materials all around the world is a known issue, as landfill space is limited, and the incineration process requires considerable energy and produces unwanted emissions. The utilisation of waste fibres in construction materials can alleviate these issues and promote environmentally friendly and sustainable solutions that work in the industry. This stud...
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Papers by Abbas Mohajerani