Expansive soils pose significant challenges in construction projects due to their high susceptibility to volumetric changes caused by moisture fluctuations. In recent years, various stabilization techniques have been employed to mitigate the adverse effects of expansive soils utilizing lime, cement, or fly ash as the stabilizing agent. This study focuses on the mix optimization of an expansive soil stabilized with lime, cement, and fly ash. In addition, predictive models will be developed to select the optimum stabilizing agent considering the performance and cost to bring down the expansiveness up to the required degree. The utilization of lime, cement, and fly ash as stabilizers for expansive soils shows promising results in terms of improving their geotechnical properties.

Conventional methodologies to derive dam breach parameters do not consider the probabilistic occurrence of natural hazards such as earthquakes. Most of the instances, deterministic complete failure of dams has been considered for providing the flood characteristics in a dam break that are used in disaster mitigation strategies. However, such instantaneous and full dam breaks are not yet recorded in history for Concrete Faced Rockfill Dams (CFRD). Hence this study utilizes the Finite Element models (FEM) for a CFRD dam to derive the probabilistic dam breach parameters. The 2D hydrodynamic model predictions based on the derived dam breach parameters will be useful for efficient disaster risk management without the overestimation of flood risk and exploitation of resources.

The continuous upsurge in concrete consumption made it indispensable to look for alternative solutions. One such is the development of high-strength concrete, incorporating Silica fume and other supplementary material. Consequently, the heat adhered to the process of hydration is relatively elevated, and the process becomes more complex. This could lead to high internal temperature developments, and thereby, to inherent thermal issues in concrete structures. Hence temperature prediction for such structures is vital to identify the potential controlling measures over the construction. Among numerous analytical models, Maekawa's multi-component model is a promising analytical tool for evaluating heat of hydration in normal-strength concrete, but its applicability to high-strength concrete is disputed. In this study, the heat generated during the hydration process of high- strength concrete mixes was measured using a semi-adiabatic experimental method. The experimental results were compared with the multi-component model outcomes, and modifications were found to be necessary for the original model to handle high-strength applications.

The ballast layer, which is responsible for distributing loads from moving trains and preserving track geometry, holds immense significance in overall track performance. However, the gradation of ballast particles has a substantial influence on the shear and degradation behavior of the ballast layer. Moreover, the inclusion of geosynthetics can enhance the stability of the ballast layer by effectively interlocking the granular and highly angular ballast particles, thereby providing additional lateral support. To comprehensively evaluate these effects, a series of large-scale direct shear tests and numerical analyses using the discrete element method were conducted. The results of this study conclusively demonstrated that both the gradation and the insertion of geosynthetics have the potential to significantly enhance the performance of the ballast layer.

While slow drivers believe that driving slowly would ensure safety, fast drivers focus on reducing travel times although they acknowledge the risks associated with speeding. Such versatile speed choice patterns thus increased speed variability and may pose significant safety threats to road users. Hence, this study attempts to evaluate the impact of weather on drivers’ speed choice by conducting a qualitative study in Canada, Australia, and Sri Lanka. The study will be conducted by distributing a questionnaire survey among 450 drivers from each country. The questionnaire is to collect information about respondents’ demographics, travel patterns, and weather-specific speed choice. This study evaluates the impacts of weather on drivers’ speed choice and also attempts to compare the differences of the impacts of weather on drivers’ speed.

Even though detection of corrosion using imaging techniques is well established, determining the severity remains difficult as it requires estimating depth of corrosion from 2-Dimensional image data. A Multi Spectral Imaging setup was fabricated to observe a corroded specimen’s spectral response under various temperatures, following a cooling excitation. It was found that the reflected intensities at certain wavelengths can indicate not only the presence of defects but also a clear path for the quantification of corrosion defects. Furthermore, the MSI setup together with Spectral Unmixing can be used to identify corrosion minerals on the sample, allowing another layer of information on the specimen. The suggested methodology can be extended to UAVs that facilitate the monitoring and assessment of assets enabling proactive maintenance and timely repairs.

The shear resistance at the sleeper-ballast interface plays a major role in maintaining proper track stability in ballasted railway tracks. The application of under sleeper pads (USPs) at the sleeper-ballast interface of ballasted tracks enhances track stability while reducing track deterioration. Nevertheless, further improving track stability is imperative when ballasted rail corridors are subjected to faster and heavier trains. Hence, this study proposes the novel use of textured under sleeper pads (TUSPs) to enhance track stability by improving shear resistance at the sleeper–ballast interface. The results of large-scale direct shear tests and discrete element method (DEM) simulations reveal that TUSPs improve the sleeper-ballast shear resistance by about 57% and apparent peak friction angle value by about 11% over conventional USPs

The travel time, including the waiting time, is a key parameter for the mode choice of commuters. This study is focused to investigate the average waiting time of a passenger for a bus on selected rural roads. According to the results, it was found that the average waiting time for a single bus route is around ten minutes while it is around five minutes for the road segments where two bus routes are operating. Also, it has been identified that the operational cost of a bus in the selected route is 463.66 LKR/km and the load factor of a bus is 1.52. Furthermore, it has been identified that to avoid the overloading of the buses, the bus fare has to be increased from 21.8% and the headway between the buses has to be reduced from 3 minutes

A well-maintained transportation infrastructure system is an indicator of a well-functioning economy. Road degradation is often considered to be unpredictable and frequent maintenance activities are implemented requiring a huge amount of funding and causing inconveniences for road users. Despite the huge annual investments on this critical infrastructure, practitioners are still unable to adopt the optimum maintenance strategy due to lack of knowledge on cost over socio-economic benefit. This study proposes an optimum pavement maintenance strategy and life-cycle cost prediction by analysing monitoring data collected over 15 years using a probabilistic pavement degradation framework based on roughness (IRI). The outcome of this study could be used in pavement management systems to compare and rank the available intervention options and to select the optimum solution considering both cost and benefit

Using biochar as a partial replacement of Portland cement in cementitious materials is a promising solution to mitigate negative environmental impacts. However, these studies are primarily focused only on the mechanical properties of composites. Therefore, this study aims at evaluating the effectiveness of biochar addition on the heavy metal removability of cement paste coupled with evaluation of the compressive strength. A range of characterization techniques such as Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD) are used to characterize the synthesized cement biochar adsorbents and to identify the main mechanisms of removal of Cu, Pb and Zn using the synthesized adsorbents

Thin-walled steel piers attract most urban construction due to their high strength-to-weight ratio and smaller cross-sections than their counterpart concrete piers. However, its high width-to-thickness ratio makes it vulnerable to local or overall buckling. So, this research aims to determine the lateral performance indices of hollow steel box columns that fail due to local and overall interaction instability when subjected to constant compressive axial force and cyclic lateral loading. First, the effect of each pier's parameters, such as width-to-thickness ratio, slenderness ratio, axial load, stiffener rigidity, and lateral loading patterns on the cyclic inelastic behaviour is explored, and the limit values of various parameters for the required strength and ductility demand are also discussed. Furthermore, the causes of crucial failure types, including buckling and extremely low cycle fatigue failure, are discussed. Finally, empirical equations are proposed for stiffened steel box columns' ultimate strength and ductility capacities

Mine haul roads are a significant part of the mining, and a higher amount is spent on the maintenance of haul roads. Due to the heavy truck loading, haul roads often undergo large rutting which subsequently causes higher operation cost and low production rate. These roads are usually built as unpaved, making them highly susceptible to moisture degradation. However, haul roads are not designed to resist for different climatic conditions in practice. In this study, the stabilisation approach for mine haul road subgrade will be investigated, incorporating saturation effect. Subgrade material will be stabilised using fly ash based additives under different saturation level. Besides, the numerical analysis will be carried out to understand the settlement and stress-strain variation during the stabilisation process under monotonic and cyclic loadings

Landfill leachate is complex in nature, hence, a single conventional treatment unit is insufficient to remove the contaminants, especially the colour from leachate, to achieve discharge standards. Chitosan, has proven to be a prominent adsorbent due to its abundancy, enhanced adsorption capacity and efficient contaminant removal. Hence, an Anoxic-Oxic Membrane Bioreactor coupled with a tertiary adsorption unit composed of glutaraldehyde crosslinked - protonated chitosan was tested for removal of colour from A/O MBR treated landfill leachate permeate. Results manifested a colour removal efficiency of 96±3.8 % obtained at optimum conditions along with an adsorption capacity of 123.8 Pt-Co/g suggesting that modified chitosan can be used as an environmentally friendly biosorbent in a tertiary unit for colour removal in a treatment system used to treat landfill leachate

Sri Lanka is highly affected by Chronic Kidney Disease unknown etiology (CKDu) especially the North Central Province (NCP). There has been much less studies based on Colloid Facilitated Transport (CFT) of agrochemicals especially on Phosphorus which is highly used as a fertilizer in NCP. From past studies it has been found that P loading in NCP is 10 ppm. Samples have been collected from Madawachya and Horowpathana as High Endemic and Low endemic regional soil samples and have been tested for the basic properties and colloid stability. Column experiments will be done with different ionic strengths with the constant Phosphorus concentration. The colloid stability analysis results showed the stability is high when the pH is high and the ionic strength is low

Often analytical or semi-analytical solutions are not available for the stress integration of complex models. Thus, efficient, and robust numerical integration schemes are required to find the material state during plastic deformations. The motivation of this study was to formulate an implicit numerical integration scheme as an extension of the Cutting Plane Method (CPM) complete with a consistent elasto-plastic tangent operator for second order accuracy at the structure level iterations. The proposed scheme’s features are discussed in relation to the Closest Point Projection Method (CPPM) and CPM. It can be easily implemented in existing finite element analysis frameworks since the required first and second order derivatives are similar to those required in CPPM. Several numerical tests are presented exploring the feasibility of the proposed scheme

This groundwater quality study in Ratnapura district was carried out on two fronts: first, by analysing the data that was already available, and second, by gathering and measuring a fresh set of samples and analysing them separately. The main focus of the analysing of the available data set is to develop Water Quality Index (WQI) for groundwater quality in Ratnapura district with respect to drinking water quality standards. In addition, other analytical methods were utilized, such as multivariate statistical analysis, correlation matrix, etc. The new set of data was mainly analysed for the spatial distribution of hardness due to the prevailing issue of groundwater hardness in parts of the district. The results revealed fascinating aspects of groundwater quality in the area that have never been recorded before

The labour efforts are the lifeblood of construction operations. But, the construction sector of many countries has been facing various challenges due to labour skill shortages. This study attempted to examine the work-related skills of Sri Lankan labour against foreign labour methodically. Using comprehensive qualitative approaches, the skills of Sri Lankan construction labour were systematically compared with foreign labour, particularly Chinese, Indian, Bangladeshi, Nepalese, Saudi Arabian, Malaysian and Korean labour forces were considered in a pair-wise comparison analysis process. Statement categories and codes were developed to perform this qualitative comparison. The overall results display the detailed cross-section of the Sri Lankan labour skills under the cognitive, transferable and self-management skill categories. Kappa statistics resulted in the inter-rater reliability of these findings at a substantial level. The study outcomes lead to a wide range of implications and future scopes on upgrading the industrial and institutional processes in detail

Membrane bioreactors with different configurations were employed to treat some of those leachates. An aerobic MBR (AMBR) system was operated in three Phases. In the first Phase, an AMBR alone, in the second Phase an anaerobic reactor followed by an anoxic reactor and an AMBR and in the third Phase an anoxic reactor followed by an AMBR were operated. The three MBR configurations removed more than 93%, 64.8% and 59% of BOD₅, COD and total nitrogen respectively

Paddy ecosystems constitute a major source of greenhouse gases (GHG), dominated by methane (CH4) and nitrous oxide (N2O). Typical water-logged conditions favor simultaneous production of CH4 and N2O in paddy fields, while their transport and subsequent emission across soil-plant-atmosphere continuum is primarily diffusion-controlled. This study hypotheses the presence of a “critical windows of water and gas diffusivity” in paddy soils. Since the critical windows are regulated by soil and atmospheric controls, it’s essential to understand the controlling factors and develop mechanisms to constrain the windows. This study will propose the best management practices can adopt to avoid the critical windows and minimize GHG emissions and develop predictive models to estimate fluxes from gas diffusivity

K-M reservoirs were initially proposed in 1968 under Mahaweli Master Plan as major storage reservoirs in Mahaweli Scheme. This reservoir project was started in 2007, and these reservoirs were constructed in Amban Ganga catchment, the largest sub-catchment of the Mahaweli Basin. These reservoirs and connecting tunnel would increase the water availability in Mahaweli Basin by retaining unutilized catchment inflows in Amban Ganga and Kalu Ganga rivers to provide agricultural, drinking water supply and hydropower benefits. An efficient reservoir operation will be essential to maximise the benefits while minimizing the spillages and ensuring dam safety. Hydrological modelling tools such as SWAT and reservoir simulation models such as HECResSim are convenient for identifying inflows and evaluating reservoir operation patterns that are mandatory for developing effective and efficient reservoir operation plans

The Lateral Distortional Buckling (LDB), another mode of instability in steel-concrete composite (SCC) beams, is not fully understood by the structural engineering research and design community, and therefore further investigations are needed for better understanding. This research focuses on a numerical investigation to study different influential parameters on the LDB behavior of SCC beams. In standard codes of practice, the LDB phenomenon in SCC beams is commonly classified as a type of Lateral Torsional Buckling (LTB), leading to conservative designs. Hence, the current standard code-based estimations of ultimate resistance to LDB need to be compared with numerical findings. Finally, it is expected to suggest possible improvements to the design practice that lead to safe and economical designs

Geopolymer concrete (GPC) presents a potentially viable solution for sustainable construction. GPC manufacturing and testing procedures, on the other hand, are time-consuming and expensive, which may hinder the growth of mix design and GPC implementation. Machine Leering might be a helpful tool for studying and anticipating GPC features to save time and money. In this study, a database will be created by conducting a thorough review of peer-reviewed papers. Following that, machine learning techniques will be utilized to determine the best input parameters for predicting the mechanical properties of GPC. Then the model will be optimized by refining parameters that result in the best predictions for the test data. Finally, the accuracy of the model will be tested using statistical measures

Recycled glass has been used in the construction industry for several decades as sustainable construction material. In this research, claddings are proposed in buildings as one of the applications with recycled glass. Due to the increased claddings demand using conventional materials, researchers pay more attention on identifying alternative cladding products since recently. Also, external claddings have been identified as critical component in buildings than before due to catastrophic fire incidents. Present day engineers seek building claddings with improved fire and mechanical performance. This study provides a knowledge capture on fire and mechanical assessment for claddings which should satisfy detailed product compliance before reaching to the market and benefits industries and scientific community to understand the compliance requirement of claddings in facilitation of introducing new products to the market

Structural defects in critical bridge members can be detrimental to the longevity of civil structures and could spell severe repercussions to human life and cause extensive financial loss. Trained professionals risk their lives every day to inspect areas with low accessibility, detect defects at an early enough stage and monitor them over time. With remarkable advancements in mobile robotics, edge computing hardware, and imaging sensor technology, computer vision is revolutionizing structural health monitoring. The work conducted focusses on studying the feasibility of different imaging systems including visible light spectra and multi spectral spectra to detect and quantify defects. We suggest how laboratory experimentation conducted currently using stationary cameras can be extended to mobile UAV platforms for effective structural health monitoring of inaccessible structures

Geopolymers are a sustainable expansive soil stabilizer compared to Portland cement with respect to greenhouse gas emissions and energy intensive production processes. This research focuses on developing a novel geopolymer binder using readily available industrial waste products; fly ash and rice husk ash to improve expansive road subgrades, and on exploring their short and long term strength gain and durability aspects. The research comprises of experimental work under which an optimized mix design will be generated, followed by an in depth analysis of the mechanical, durability and microstructural characteristics of the stabilized soil mixtures. Next, a full-scale numerical simulation of a stabilized road section will be carried out using ABAQUS software, which will be used to simulate the stabilized subgrade response for dynamic traffic loads

Prefabricated modular construction is an upcoming alternative construction technology, which can minimize construction time and wastages while improving the quality of construction in contrast to the traditional construction techniques. However, one main construction barrier is the difficulty in transporting and launching of the modules. Similarly, the use of Portland cement in construction raises has considerable sustainability concerns. In this light, the focus of this study is to promote the use of aerated mortar produced from waste and by-products in prefabricated modular walls. Moreover, the project seeks to test the mechanical, fire, thermal and acoustic performances of the developed aerated wall panel both experimentally and numerically

This study proposes an optimum Decision Support System (DSS) that can inform reliable maintenance planning for railway infrastructure considering major hazards in their operation life. Inaccurate and incomplete asset information impacts the resilience of railway infrastructure through sub-optimal decisions. Markov Chain rule is used to develop transition matrices to predict the performance of their operation life. To identify the vulnerable components in railways, the distributions of probability of failure or any damage state of interest of an asset are analysed with respect to damage measures. The rapid recovery feature of resilience is advanced by developing restoration curves concerning time and cost. The improvement in maintenance and restoration measures will save money and time and provide extended social and economic impacts

Many researchers presumed that the CKDu has a strong coexistence with the presence of agrochemicals and heavy metals in groundwater, which is the prime drinking source of the agricultural community of the North Central province. These chemicals can potentially migrate to groundwater via soil colloids by a process called colloid-facilitated transport (CFT). In this study, soil characterization in CKDu-affected areas were done and colloid-facilitated heavy metal transport is investigated using a series of batch and column experiments. Observed data will be numerically simulated and parameterized using numerical models to predict transportability of colloid-mediated agrochemicals to groundwater. Results would provide implications to unravel the role of colloidal domain and numerical models will forecast the extent and time for CFT of heavy metals

Thin-walled steel piers are becoming more popular in urban areas due to their high strength-to-mass ratio, high torsional rigidity and shorter construction time. Several studies have been conducted to improve the strength and ductility of steel piers. However, many techniques still exhibit issues related to recovering seismic resistance after a large earthquake load. This study suggests an axial-moment hybrid column arrangement with low yield strength steel to address these challenges. Where the inner column resists the axial load and the replaceable outer column resists the lateral load. So that following a major earthquake, the damaged outer column can be quickly replaced, while the inner column can support the axial load. As a result, the seismic capacity of the steel box pier could be quickly rebuilt without interfering with the bridge's operation following the earthquake

Landfill leachate contains toxic contaminants which adversely affect the ecosystem if not properly treated prior to discharge. Effluent obtained using A/O MBR exceeded the specified discharge standards for organics and colour. Hence, this work investigates the efficiency of low cost adsorbents, with a focus on removal of organics and color from the permeate of an A/O MBR system. Biochar derived from sawdust and rice husk are used as base materials and further modifications are carried out to investigate the increase in the adsorption capacities. Different analytical techniques are used to characterize the adsorbent materials. Regeneration studies for the spent adsorbents along with adsorption kinetic and isotherm studies are carried out in identifying adsorption processes considering all variants of the adsorbents

Rockfill dams which are commonly found worldwide bear large water bodies and to assess the stability, numerical methods have been used by previous researchers However, it is commonly observed in literature that the initial configuration of the Finite Element model has not been defined properly In this research a two dimensional model of the Kotmale dam is analyzed under two cases considering the construction sequence and without considering the construction sequence The deformations obtained are compared with the actual deformations obtained from the site A significant variation can be observed without construction stage analysis whereas when the construction stages are considered the deformation values agree with the observed readings Furthermore, it is evident that without construction stage analysis the deformed shape is completely different, and it is incorrect

Topography of a model will highly influence the uncertainty of hydraulic model predictions, thus making it a critical factor in urban flood modeling studies Currently, there are numerous methods to represent the actual terrain with topographic data other than traditional geographic surveys Such derived topographic maps are Digital Elevation Model ( from LiDAR and SRTM based on remote sensing methods However, these models and DEM from other sources have their own advantages and limitations Thus, main concern lies in improving the detailed representation of terrain incorporating all these models while balancing requirements and demands The research is focused on the development of an accurate terrain using different models which possess different characteristics which would ultimately fuel optimal meshing in modeling software

Due to numerous reasons, commuters tend to shift from public transport modes to private modes causing an increased demand to road network which eventually resulted in numerous issues like congestion, environmental pollution and accidents While investigating the reasons behind the mode shift, this study investigates the service intensity in the existing bus transport system in Kandy district by developing an index which covers capacity, frequency and route coverage As the second stage, the travel behaviour of passengers is assessed using a choice model based on the utility maximization theory Adjusted likelihood ratio index, t statistics and respective sign of parameters are used to show the model accuracy The outcome shows that travel time and cost are the significant factors affecting the mode choice behaviour of commuters

Timber utility poles are extensively used in Australia for power distribution and telecommunication networks. There are an estimated 5.3 million timber utility poles in Australia with an estimated value of more than $12 billion. Due to various deterioration processes, strength of poles degrades with time, which potentially reduces the life time of the poles. Failure of poles can have serious safety concerns and economic implications. Thus, it is crucial to optimise the life of existing timber poles. This can be done through application of effective asset management programs (i.e., inspection, assessment and decision making programs) that can bring about significant savings to the utilities. This study aims to improve in-service inspection of timber poles through the use of non-destructive stress wave propagation (SWP) methodology.

More than 90% of the Sri Lankan land transportation is facilitated by roads. Their condition has been deteriorated mainly by ongoing traffic loads and environmental loading and the deterioration is further accelerated due to inefficient road monitoring and management. The cost related with the maintenance of road infrastructure without considering the cross-asset interdependency has made an extra burden on the country's economy. Therefore, the main aim of this project is to develop a prioritization framework to support fund allocation decision of asset managers considering an integrated approach of cross assets (road pavements, bridges and water pipes) using monitoring data and integrated degradation modelling tool. The research for the first time, will integrate multiple assets related to the road network to a strategic prioritization platform for fund allocation for rehabilitation of roads.

Despite showing a great success of applications in many commercial fields, machine learning (ML) and data science models in general, show a limited success in scientific fields, including hydrology. The approach is often criticised for its lack of interpretability and physical consistency. This has led to the emergence of new paradigms, such as Theory Guided Data Science and physics informed machine learning. The motivation behind such approaches is to improve ML models' physical meaningfulness by blending existing scientific knowledge with learning algorithms. Following the same principles, in this contribution, existing hydrological knowledge is incorporated to guide the learning algorithms to automatically build readily interpretable rainfall-runoff models with good prediction accuracies. Here, Genetic Programming is used as the ML technique.

Ballasted rail tracks are the most popular and conventional rail track foundation system. The ballast layer is the prominent load-bearing layer that distributes loads from the superstructure (wheel, rail, and sleeper) to the underlying layers (sub-ballast and subgrade) at a minimal level through a wider area. Ballast particles breakage with time due to high cyclic and impact loads is the main crisis that affects the shear capacity and service life of tracks, which leads to increased maintenance cost. One of the popular methods to maintain required shear resistance and decrease ballast degradation is the adaption of geosynthetics into the substructure. Thus, this study aims to analyze the improvement in the degradation and deformation behavior of railway ballast by the introduction of geosynthetics.

Predicting the shear behaviour accounting for the axial-flexure-shear (N-M-V) interaction is vital in structural analysis. Existing numerical approaches to predict such responses include sectional analysis, displacement based finite element analysis (using line elements, area elements and solid elements) and force-based finite element analysis (using line elements). In line element formulations the axial strain and the shear strain distribution along sections are commonly assumed to be linear and parabolic, respectively. This study aims to investigate the impact of such kinematic constraints at the section level towards the response of RC elements with respect to the initial stiffness, post-cracking stiffness, load carrying capacity and post-peak ductility. For this purpose, a selected series of beams was analyzed. The analysis results suggest that in the nonlinear region, the section kinematic assumptions in line element formulations and sectional models results in an underestimation of the shear strain distribution along the sections and an overestimation of the axial strains of the tensile zone near the loading point.

Nanofiltration (NF) is a pressure-driven membrane technology, generally applicable for the purification of hard groundwater. Membrane technology is an appropriate option for small-scale water treatment applications compared to conventional treatments for immediate implementation in remote areas. Such systems have been established in the chronic kidney disease of unknown etiology (CKDu) prevalence areas of the North Central Province (NCP), Sri Lanka for groundwater treatment. The NCP groundwater quality investigations have revealed that, low molecular weight dissolved organic carbon (DOC) moieties, ranging from 100-3000 Daltons, are present in the water and hinder the performances of the membranes in water treatment plants. The existence of DOC together with hardness will predominantly affect the membrane performance via exaggeration of fouling due to the formation of DOC-ion ternary complexes. Investigation on membrane fouling mechanism by DOC and hardness will therefore help to identify fouling mitigation measures and facilitate the design of an effective NF treatment system.

Urban runoff (UR) is a major nonpoint source pollutant degrading the water quality of the receiving waters and heavy metals are identified as a most critical pollutant group in UR. The limited availability of land poses tight constrains to common methods adopted for managing UR like detention and retention basins such as swales, bio retention basins, settlement ponds and wetlands to improve water quality. Although evidence of use of pervious concrete in the urban environment is present, little effort is made towards enhancing its pollutant removal capability. Therefore, this study will focus on enhancing the heavy metal removal ability of pervious concrete using a low-cost adsorbent material, bio char.

Fly ash and Rice Husk Ash (RHA) are abundantly available waste products, principally located in Asian countries. Currently, a significant proportion of these materials are disposed of in landfills, lagoons and rivers but offer potential to utilize in AAC. This study quantifies the environmental and economic factors by assessing the Greenhouse gas (GHG) emission, environmental impacts and benefits, and cost analysis of utilizing fly ash and RHA in AAC compared to Portland Cement (PC) concrete. Alkaline activator is a key component responsible for the highest GHG emission, cost and environmental impact amounts obtained for fly ash geopolymer and blended alkali-activated concrete compared with PC concrete. Utilization of waste fly ash and RHA is responsible for providing significant benefits in terms of fresh and marine water ecotoxicity by avoiding waste disposal at the dumpsites, rivers, and storage lagoons.

Assessment of Critical Factors Influencing the Performance of Labour in Sri Lankan Construction Industry

This study intended to extensively investigate on the factors influencing labour performance in the Sri Lankan construction industry. A qualitative study conducted from a literature review and a series of interviews revealed 117 factors under 6 categories. Subsequently, a questionnaire survey was carried out among the construction firms in Sri Lanka and the responses were received from 217 contractors. Overall, 73 factors were identified as critical based on their Relative Importance Index values. Lack of training facilities, delay in salary payments, lack of labour motivation, low salary for labourers and poor performance evaluation of labour skills were found as the top five ranking factors. This study also highlights the need for training programmes that contain the direct scope of productivity improvement, and identified the expected programme outcomes for the effective design of new training programmes to improve the practices on labour operations.

Landfill leachate management is one of the major concerns when it comes to solid waste management through landfilling or open dumping. This liquid consists of dissolved organic matter, inorganic macro compounds, heavy metals and xenobiotic organic compounds. In recent studies, leachate has been identified to be a main secondary source of emerging contaminants. In order to eliminate the environmental impacts and to satisfy regulatory requirements of leachate discharge, leachate should be managed properly. Treatment of landfill leachate is the mostly used method of leachate management. Different treatment technologies have been utilized to treat leachate and membrane bioreactor has proven to perform well in leachate treatment.

Railway transportation is becoming popular with the growing demand and the numerous advantages of the presence of high-speed trains in many countries. In spite of its advantages, acceleration of track deterioration due to heavier loads and higher speeds is one of the major challenges in its development. Under repetitive train loads, the degradation of the key load-bearing ballast layer is vital and leading to a decrease in shear strength, excessive track settlements and hinder track drainage. To overcome these drawbacks, adoption of resilient rubber pads such as rail pads (RP), under sleeper pads (USP) and under ballast mats (UBM) has become the most popular method in many countries. However, only limited studies have been conducted on the geotechnical behaviour of ballast when these rubber pads are adopted. Therefore, this study focuses on evaluating the stress-strain and degradation behaviour of ballast with and without the inclusion of rubber elements to track.

Development of a low fidelity model to replace railway substructure foundation

Railway network is one of the main transportation modes which is economical and widely used all over the world. A typical railway track of ballast consists of the superstructure and the substructure. The superstructure consists of the rails, the fastening systems, and the sleepers, whereas the substructure consists of the ballast, the sub-ballast and the subgrade. The behaviour of the superstructure and substructure below is always interdependent. Although software with advanced soil models is often used to represent the complex soil characteristics, merging such a model with the superstructure modelled in detail will demand unrealistic large computational cost. Adopting a law fidelity model which can represent the railway substructure with a sufficient accuracy can reduce the computational cost significantly. This study focuses on coupling simplified substructure models with high fidelity finite element superstructure model with acceptable accuracy and recommending the best simplified model to be used in a particular case.