Coarse bauxite residue for roadway construction materials

About 25 million tonnes of bauxite residue (BR) from alumina refining are generated in Australia each year. Managing this residue is costly, and the reuse of coarse BRs is becoming an increasingly attractive and sustainable solution to the problem. Using coarse BR in road construction has the potential for large volume reuse. This study investigated whether coarse BR is a viable road base material in Western Australia. A pozzolanic-stabilised mixture was created to improve the properties ofthe residue to satisfy the minimum requirements for road base. Laboratory tests for resilient modulus and permanent deformation were then carried out. Comparisons were made between the stabilised residue and conventional road base material used in Western Australia. The performance of the stabilised residue was superior to that of the conventional material, which can provide improved performance when used as road base material in Western Australia

Performance, Evaluation, and Enhancement of Hydrated Cement Treated Crushed Rock Base (HCTCRB) as a Road Base Material for Western Australian Roads

Hydrated Cement Treated Crushed Rock Base (HCTCRB) is widely used as a base course material for Western Australian roads. HCTCRB has been designed and used based on an empirical approach and practical experience, respectively, but those are not capable of explaining behavior of HCTCRB. Presently, a mechanistic approach becomes more reliable in pavement design and analysis and behavior of pavements can be more understood. Consequently, characterization of HCTCRB following the mechanistic approach is necessary. This study aimed to analyze the results of laboratory testing so as to assess the mechanical characteristics of HCTCRB. Conventional triaxial tests and repeated load triaxial tests (RLT tests) were performed. Factors, which would affect the performance of HCTCRB such as hydration periods and the amount of water added, were also investigated

Optimal System Design for Instrumented Slope Monitoring in Open Pit Mines

The importance of slope monitoring, and its place in the design and operation of an open-pit mine are presented. Some of the commoner techniques for slope monitoring are reviewed and the limitations and advantages of these compared. Two short case studies are presented; the first illustrates the importance of fully understanding potential failure mechanisms within a slope before designing and installing a monitoring system; the second serves to illustrate a key difference between two types of monitoring system currently in use

CBR test on fibre reinforced silty sand

Geosynthetic fibres are an established family of geomaterials used in a wide variety of civil engineering applications such as pavement systems. In pavement design, CBR ratio count as an important parameter. This study aims to investigate effect of fibre inclusion on CBR ratio. A series of laboratory investigation were carried out to evaluate effects of reinforcing the sub grade soil in pavement system with randomly distributed plastic fibres. In this study, one type of soil (i.e silty sand) and two type of fibre were used. CBR test were conducted on unreinforced samples as well as reinforced ones at different fibre contents (i.e. 0.1%, 0.3%) and different fibre length (i.e. 10mm , 20 mm and 40mm).The results of CBR test showed that the CBR ratio for reinforced silty sand increased even more than two times in some cases as fibre content and fibre length increased. The results proved that application of short randomly distributed fibre is a good method to apply in practical projects

Effective Parameters on Strength of Reinforced Clayey Sand

Soils and their related behavior has always been the subject of many studies. Recent researches show some interests in investigation of inclusion of randomly distributed fiber in soil. This study focuses on effect of fiber inclusion on the strength and other parameters of clayey sand composite material. The first part of this study is related to effective parameters on strength of the clayey sand composite with using natural fiber and plastic fiber with different fiber contents and length. UCS tests were carried out to investigate behavior of the composite under different condition. The fiber percentage varied from 0 % (for unreinforced samples) to 4% and fiber length varied from 8mm to 25mm. The fiber length and fiber content are found to play important roles in the strength of fiber reinforced composite. Furthermore it was observed that ductility of sample increased by fiber inclusion

Initial Soil Springs Stiffness for laterally loaded Piles

Total number of 180 finite element models is created. Soil is modelled by three dimensional elastic isotropic brick elements with cylindrical shaft cavity at the centre. Pile is modelled with ordinary Euler- Bernoulli beam elements. Different connectivity scenarios between the soil and the pile surface are examined. Elastic properties of the soil are changed for each FE model within wide range of possible values. A globally covering database is created for free - head pile stiffness from FE analysis results. Lateral springs stiffness are calculated by equating pile head stiffness from FE models to predicted value from beam on elastic support theory. Spring’s stiffness is correlated to mechanical properties of the soil, shaft diameter, and pile flexibility factor using curve fitting techniques. It is found that spring stiffness is dependent to shaft diameter. It is also found that relative connectivity between the soil and pile’s skin, highly affects the spring’s stiffness. Comparison to work by other researchers is made

Trip distribution modelling using neural network

Trip distribution is the second important stage in the 4-step travel demand forecasting. The purpose of the trip distribution forecasting is to estimates the trip linkages or interactions between traffic zones for trip makers. The problem of trip distribution is of non-linear nature and Neural Networks (NN) are well suited for addressing the non-linear problems. This fact supports the use of artificial neural networks for trip distribution problem. In this study a new approach based on the Generalised Regression Neural Network (GRNN) has been researched to estimate the distribution of the journey to work trips. The advantage of GRNN models among other feedforward or feedback neural network techniques is the simplicity and practicality of these models. As a case study the model was applied to the journey to work trips in City of Mandurah in WA. Keeping in view the gravity model, the GRNN model structure has been developed. The inputs for the GRNN model are kept same as that of the gravity model. Accordingly the inputs to the GRNN model is in the form of a vector consist of land use data for the origin and destination zones and the corresponding distance between the zones. The previous studies generally used trip generations and attractions as the inputs to the NN model while this study tried to estimate the trip distribution based on the land uses. For the purpose of comparison, gravity model was used as the traditional method of trip distribution. The modelling analysis indicated that the GRNN modelling could provide slightly better results than the Gravity model with higher correlation coefficient and less root mean square error and could be improved if the size of the training data set is increased

Evaluation of Pile Lateral Capacity in Clay Applying Evolutionary Approach

This paper presents the development of a new model to predict the lateral capacity of piles inserted into clayey soils and subjected to lateral loads. Gene Expression Programming (GEP) has been utilized for this purpose. The data used for development of the GEP model is collected from the literature and comprise 38 data points. The data are divided into two subsets: Training set for model calibration and independent validation set for model verification. Predictions from the GEP model are compared with the results of experimental data. The model has achieved a coefficient of correlation, r, of 0.95 for training and validation sets and average prediction ratio (APR) of 0.97 and 1.04 for training and validation sets respectively. The results indicate that the GEP model performs very well and able to predict the pile lateral capacity accurately

Before and after studies to reduce the gap between road users and authorities

The paramount importance of safety for busy urban roads always comes from the responsibility towards protecting the vulnerable road users, who seem to be the victims in most road crashes. Thus, authorities tend to focus on reducing the travelling speed of the vehicles, whereas some road users may consider the move to interfere with mobility. In this paper, a case study in Perth’s two roads was conducted to compare two engineering treatments of speed reductions on these two busy shopping strips. The study aim is to illustrate the effect of using the electronic flashing signs rather than the standard signs in terms of speeding reduction and harm minimisation. Crash data were analysed and supported the safety benefits of the electronic flashing signs. In terms of speeding, a Chi-Square analysis showed that there is an association between the engineering treatment type and the three detected speeding levels. Authorities have measures the reduction of the travelling speeds of vehicles and found it to be encouraging. The study found that despite the reduced crashes of after the treatments, but the public seem to show different attitudes to the above safety issue. The study has shown that certain engineering measures can reduce the travelling speed of the vehicles without disturbing mobility. Road users are is concerned with delay and other behavioural issue as the results of the questionnaires reveal. There are clear, positive safety benefits from the case study

Durability of Fly Ash Geopolymer Concrete in a Seawater Environment

This paper presents the results of a study on the durability of fly ash geopolymer concrete in a seawater environment. In this research, three different geopolymer mixes and a control mix were examined to determine the effective porosity, chloride ion penetration, and corrosion of steel reinforcement bars under open circuit potential and accelerated corrosion tests. High chloride ingress was observed on the geopolymer paste. A depassivation of the passive film of the steel reinforcement bar in fly ash geopolymer was faster than for the OPC concrete. Small corrosion activities were conversely evident in the geopolymer concrete under the accelerated corrosion test at an applied voltage of 30 V. Decreased corrosion rates were observed for the geopolymer concrete. The results obtained from these tests indicate that the nature of the geopolymer paste certainly influences its durability in the seawater environment