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The objective of this paper is to evaluate differences and similarities of construction programs across various countries in order to encourage international cooperation of construction training and study abroad programs. The information illustrated in this paper was collected through a survey that was administered to construction programs from 11 different countries. The survey was divided into the following four categories: Program Structure, Curriculum, Industry Involvement and General Program. The study identified challenges and opportunities for students in construction programs to study abroad, with specific reference to financial funding at institutions, funding support from industry, lack of understanding around international articulation platforms, wide variation across internship requirements, and the importance of industry recognized certifications. The study demonstrated that 64% of the surveyed programs receive industry support and that all the surveyed programs are engaged and familiar with articulation agreements. In addition, besides programs in Australia and Portugal, internships are a requirement in all other countries surveyed. Also, among all surveyed countries, only Malaysia and South Africa require students to obtain industry certificates during the course of the program.

Background: The ocular surface is separated by a thin layer of tear film from outdoor air pollutants making individuals exposed to outdoor air pollution prone to various ocular surface disorders. The aim of this study was to determine the magnitude of ocular surface disorders symptoms among traffic police officers of Kathmandu, Nepal. Methods: Two hundred traffic police officers working at different traffic police office branches of Kathmandu, Nepal were invited to the police headquarters for eye and vision examination. Among them, 91 individuals (95% males) completed the ocular surface disease index (OSDI) questionnaire and underwent Schirmer’s I tear test. Results: Symptoms of ocular surface disorders were reported by over 80% of the individuals. Approximately two-fifths of the individuals (38%) reported severe symptoms. Only 17% of the individuals’ tear secretion was found to be below normal using the Schirmer’s tear test. No significant association was observed between the OSDI score and Schirmer’s tear test scores (r = 0.008, p = 0.94). A weak but significant relationship was observed between the OSDI score and job duration (r=0.21,p = 0.04). Individual exposed to outdoor air pollution for more than 10 years had higher odds of reporting ocular surface complaints as compared to those who were exposed for less than 10 years (OR = 3.94, p = 0.02). Conclusion: Ocular surface disorder symptoms are common among traffic police officers of Kathmandu, Nepal. The duration of exposure appears to significantly contribute to the increased symptoms in this exposed population.

The purpose of this study was to analyze the cost effectiveness of building new-construction single-family homes through the Leadership in Energy and Environmental Design (LEED) program in six counties of Kentucky. The estimated added LEED construction cost was calculated as well as its respective payback period based on the expected utility savings of LEED certification. A mortgage cost comparison was also performed comparing traditional code built to non-LEED single-family homes. Using descriptive statistical analysis on the simple payback period, mortgage costs were compared internally and by county. This study found that The LEED Certified and Silver level had payback periods less than 30 years, and the total 30 year net difference between non-LEED and LEED certified ranged from $-1,193.20 to $1,667.64.

A three-dimensional finite element model (3D FEM) is built using ABAQUS to analyze the dynamic response of a concrete pavement structure with an asphalt isolating layer under moving loads. The 3D model is prepared and validated in the state of no asphalt isolating layer. Stress and deflection at the critical load position are calculated by changing thickness, modulus of isolating layer and the combination between the isolating layer and concrete slab. Analysis result shows that the stress and deflection of the concrete slab increase with the increase of thickness. The stress and deflection of the concrete slab decrease with the increase of combination between the isolating layer and concrete slab. The influence of changing the isolating layer modulus to the stress and deflection of the concrete slab is not significant. From the results, asphalt isolating layer design is suggested in concrete pavement.

Settlement and non-uniform deformation of frozen soil subgrade introduce fatal cracks on semi-rigid base asphalt pavements. This research aims to use reinforced wire mesh to reduce serious cracks on semi-rigid asphalt pavements in frozen regions. Three impact factors, diameter and interval as well as two types of wire mesh have been analysed by loading tests. Results have shown that after setting the reinforced wire mesh: (a) failure load and displacement of the cement-stabilised crushed gravel samples have been improved; (b) diameter and interval of the wire mesh have interactive impacts on reinforced sample load capacity; (c) the reinforced wire mesh can limit cracks by redistributing stress in the specimen; and (d) the multiple linear regression model well reflects the variation of loading properties; the results make sense from the statistics view as well. Results also represent that the strengthened wire mesh can help spread out the applied load, and increase the overall loading capacity of cement-st...

A phase change material (PCM) has a significant capacity to store thermal energy. Because of the complex and tough environment of a highway such as traffic load, drainage, and ultraviolet light, the recent studies on PCM cannot be directly applied to highway construction. The composite shape-stabilized phase change material (CPCM) was prepared by using a membrane layer to encapsulate the PCM to ensure stability. Preparation of the CPCM in highway construction discussed in this research includes: (a) CPCM material properties, (b) proper proportioning for preparing the CPCM by Scanning Electronic Microscope (SEM), Differential Scanning Calorimetric (DSC) and the orthogonal test. CPCM was developed using Teradecane, silica, Ethyl Cellulose (EC) and a dispersant. Performance of the CPCM due to the influence of EC and a dispersant also studied to determine exact proportions used in the CPCM. The optimized ratio of Teradecane, silica, EC and dispersant is 1:1:0.1:0.1. Phase change enthalpy of the PCM was calculated to be 178 J/g and the phase change temperature was determined to be 5.8 °C.

The objective of this paper is to use the discrete element model (DEM) to predict the asphalt mixture dynamic modulus in the hollow cylindrical specimen across a range of test temperatures and load frequencies. The microstructure of the asphalt concrete specimen was captured by X-ray tomography techniques. The hollow circular images were produced from the layer of cylindrical X-ray computed tomography (X-ray CT) images. The asphalt concrete images were divided into three phases according to a density index: aggregate, sand mastic and air void phases. The sand mastic phase was composed of fine aggregates (smaller than 2.36 mm) and asphalt binder. The distribution of air void, sand mastic and aggregate were also investigated along with the depth of the hollow cylindrical specimen. In the DEM simulation, the sand mastic's dynamic modulus using different loading frequencies and test temperatures was used to predict the asphalt mixture's dynamic modulus. The predicted dynamic modulus was at that same loading f...

Many studies have investigated the fatigue resistance of hot-mix asphalt (HMA) mixtures on the basis of the material properties and structural responses. In this study, a four-point bending-beam fatigue apparatus was used to measure the fatigue life of a typical Michigan HMA mixture under various frequencies (1, 5, and 10 Hz) and temperatures (4°C, 13°C, and 21.3°C). The objective of this study was to evaluate laboratory models for predicting fatigue over wide ranges of testing conditions to rank their fatigue performance on the HMA mixtures. In addition, this paper aimed to correlate the flexural stiffness (modulus) with dynamic modulus, because the dynamic moduli of HMA are key input parameters in the Mechanistic–Empirical Pavement Design Guide (MEPDG). The correlation results showed a strong linear correlation between the flexural stiffness and dynamic modulus, with the flexural stiffness being 30% lower than the dynamic modulus. By providing a linkage between dynamic modulus and flexural stiffness, the study helped to substantiate the concept of using dynamic modulus in the MEPDG or to evaluate rutting. In addition, Rowe and Bouldin's stiffness degradation concept was used to compare the ability of different models to predict fatigue life. The results of this study showed that the energy-based fatigue prediction model, which considered rest periods, various testing temperatures, and loading frequencies, correlated well with the laboratory-determined fatigue life.

The objective of this study is to predict the dynamic modulus of asphalt mixture using both two-dimensional (2D) and three-dimensional (3D) Distinct Element Method (DEM) generated from the X-ray computed tomography (X-ray CT) images. The 3D internal microstructure of the asphalt mixtures (i.e., spatial distribution of aggregate, sand mastic and air voids) was obtained using the X-ray CT. The X-ray CT images provided exact locations of aggregate, sand mastic and air voids to develop 2D and 3D models. An experimental program was developed with a uniaxial compression test to measure the dynamic modulus of sand mastic and asphalt mixtures at different temperatures and loading frequencies. In the DEM simulation, the mastic dynamic modulus and aggregate elastic modulus were used as input parameters to predict the asphalt mixture dynamic modulus. Three replicates of a 3D DEM and six replicates of a 2D DEM were used in the simulation. The strain response of the asphalt concrete under a compressive load was monitored, and the dynamic modulus was computed. The moduli of the 3D DEM and 2D DEM were then compared with both the experimental measurements results. It was revealed that the 3D discrete element models successfully predicted the asphalt mixture dynamic modulus over a range of temperatures and loading frequencies. It was found that 2D discrete element models under predicted the asphalt mixture dynamic modulus.

The hollow cylindrical asphalt mixture specimens were modeled with discrete element method. The dynamic moduli of the samples were predicted. The microstructure of asphalt concrete specimen was captured from an X-ray tomography images. The asphalt concrete hollow cylindrical images were divided into aggregate, mastic and air voids domain. The particle size of the mastic was less than 2.36mm in this paper. Aggregate, mastic and air voids domain were identified from the density index of the X-ray computed tomography images. The coordinates of aggregate, mastic and air voids domain was defined by density index to develop two dimensional (2D) and three dimensional (3D) discrete element models (DEM). The dynamic modulus of the asphalt mixture was calculated from stress divided strain in each temperature and frequencies. The comparison of predicted and laboratory measurement dynamic modulus has been investigated in this paper. When compared with the dynamic modulus of 2D DEM and 3D DEM against the laboratory measurement, the average difference was 6.25% for 3D DEM; the average difference was 17.72% for 2D DEM; and the average difference of dynamic modulus was 22.19% when compared with 3D DEM and 2D DEM. It was found that 3D DEM had better predicted dynamic modulus comparing 2D DEM.

In the USA, many highway agencies have successfully implemented the Superpave volumetric mixture design procedure. Yet, a number of studies have shown that the Superpave volumetric mixture design method alone is insufficient to ensure reliable mixture performance over a wide range of traffic and climatic conditions. As highway agencies begin the implementation of the AASHTO Mechanistic-Empirical Design Guide (MEPDG), they will be tasked with the development of local calibration factors specific to the materials, construction practices, loading regimes and environment of their region. The local calibration factors specific to the materials include the test of the dynamic modulus of asphalt mixtures. In fact, the dynamic modulus of asphalt mixtures is an important input parameter for pavement thickness design. Therefore, the objectives of this paper are to: 1) review the current status of Superpave simple performance tests for asphalt mixes; 2) measure the dynamic modulus of Superpave asphalt mixes, and; 3) compare with the predictive equations for the dynamic modulus to establish a correlation. The dynamic modulus data will be used in the MEPDG design procedure for asphalt pavements.

The objective of this study is to predict the asphalt mixture dynamic modulus using both two-dimensional (2D) and three-dimensional (3D) discrete element models (DEM) generated using the X-ray computed tomography images. An experimental program was developed with a uniaxial compression test to measure the dynamic modulus of asphalt mastic and asphalt mixtures at different temperatures and loading frequencies. In the DEM simulation, the mastic properties and aggregate elastic modulus were used as input parameters. The strain response of the asphalt mastic and mixture models under a compressive load was monitored, and the dynamic modulus was computed. The mixture properties were obtained using images of aggregate, mastic, and air voids from the X-ray CT. The experimental measurements of dynamic modulus were employed to compare with the 2D and 3D predictions. It was found that the 3D discrete element models were able to predict the mixture modulus across a range of temperatures and loading frequencies. The 3D DEM models prediction is much better than that of the 2D DEM models.