Road Construction Practices Research Articles

Life cycle sustainability assessment of road infrastructure: a building information modeling-(BIM) based approach

A significant share of federal and regional infrastructure budgets is spent on constructing, maintaining, repairing, and replacing road infrastructure. Due to its magnitude, sustainable road construction practices can support national sustainable development goals (e.g. The Federal Sustainable Development Strategy of Canada). However, the quest for sustainable road construction practices has been hindered by the lack of expertise, information, and resources. The advent of building information modeling (BIM) provides more extensive access to functional and physical data of construction material. Published literature has overlooked BIM-based methods that facilitate the life cycle sustainability evaluation of road construction techniques. This paper presents a methodological framework for life cycle thinking-based road infrastructure evaluation. This framework compares the life cycle sustainability performance of alternative road pavement construction methods. A BIM-based visual program has been created to automate the proposed framework. The program was demonstrated by comparing three road construction methods for a collector road. Results indicated that geomembrane road is the best solution based on the triple bottom line of sustainability. The proposed Life cycle Sustainability Assessment (LCSA) framework, a BIM-based tool, and the implementation road map will assist infrastructure managers in selecting the most sustainable road construction method that will consequently support United Nations Sustainable Development Goals (SDG).

Impact of Forest Roads on Hydrological Processes

The current review summarizes the knowledge generated by the recently published studies of the last twenty years, in the field of forest road networks, concerning the impact of forest road construction on hydrological processes. The currently applied methodology techniques/practices are discussed, the findings are highlighted and effective mitigation measures to mitigate the impact of forest roads are proposed. Critical for the minimization of the impact of forest roads on overland flow is the significant decrease in road surface runoff and overland flow velocity. The decrease in runoff energy reduces the detachment of soil particles and transportation in streams. The disturbances of forest roads in logging areas should be limited to decrease soil erosion. Additionally, aiming to minimize sediment transportation into the streams, it is very important to reduce the connectivity between the forest roads (or skid trails) and streams. The positive role of vegetation and organic matter on the road prism, naturally/technically established riparian buffers along the streams, and the use of appropriate bioengineering designs for each area significantly decrease the runoff generation and sedimentation. From a construction point of view, the decrease in short and long-term forest road-related impact could be achieved by reducing the depth of excavations and the use of soil compaction limiting technology during forest works. The road network design should be more efficient, avoiding hydrologically active zero-order basins. Techniques that minimize the length and connectivity among skid trails, unpaved roads and streams are highly crucial. Broad-based dips, immediate revegetation and outsloping of the road base are considered good road construction practices. Research should be focused on the hydrologic behavior of forest road networks and on the impact at the watershed scale, the degree of connectivity, utilizing plenty of qualitative field data, especially during intense rainfall events, which has been proven to exacerbate the runoff and sediment generation and transportation into the stream networks.

Assessing compaction of existing railway subgrades using dynamic cone penetration testing

Dynamic cone penetration testing has been extensively used in the past for subgrade performance assessment and quality control in road construction practice. However, the method is not commonly employed on high-speed railways. This is due to lack of field data that prove its feasibility as an alternative method for assessing subgrade quality. To mitigate this gap, a series of in situ tests was performed on existing subgrades built with coarse-grained soils at five different sections along the Tehran–Isfahan high-speed railway in Iran. At each subgrade section tested, four parameters for compaction quality control – blow count, degree of compaction, subgrade reaction modulus and dynamic deformation modulus – were determined at nine different depths from subgrade surface. On the basis of the results obtained, a correlation model was developed to relate the traditional quality control parameters of compacted subgrade fill materials with the blow counts. Finally, a simple method using the correlation models established was proposed for assessment of subgrade compaction quality. The method proposed proved to be an alternative approach for evaluating the state of subgrade compaction and also for assessing the subgrade performance of existing railway subgrades.

Physical mechanical performance of asphaltic emulsions in road oil for flexible pavements

The present study evaluated experimentally, the impact of the application rate, in terms physical and adherence, of four types of emulsions used as road oiling in two asphaltic layers for flexible pavements. Asphaltic layers are composed by an asphaltic base and a hot mix asphalt surface layer. To evaluate the adherence and physical properties, a shearing test was carried out. Four rapid set cationic emulsions were used, by means of three application rates of 0.33 l/m2, 0.50 l/m2, and 0.65 l/m2 (recommended values in Colombian road construction practices). The results demonstrate that an emulsion application rate of 0.50 l/m2 guarantees better adherence in the structural package. Also, that greater resistance against the sliding of the surfaces of the specimens in the shearing test, depends on the residual content of the asphaltic emulsion.

Evaluation of reclaimed asphalt pavement as base/subbase material in Egypt

The application of reclaimed asphalt pavement (RAP) has become a common practice in road construction as a substitute to natural aggregate. The significance of RAP amount on the resilient modulus behavior, shear strength and hydraulic conductivity characteristics of unbound granular base materials were investigated in this research. RAP was blended with crushed aggregate by different percentages ranging from 0% to 100% by the blend weight. The laboratory testing program includes modified compaction, California Bearing Ratio (CBR), permeability, and repeated and static triaxial tests. A descriptive statistical analysis was conducted on all testing results. Furthermore, the X-ray computed tomography (CT) scanning technique was applied to investigate the internal (micro) structure of specimens. It was noted that with the addition of more RAP to the blend the resilient modulus increased and the coefficient of permeability decreased. The apparent cohesion of the RAP blends increased almost linearly and the friction angle decreased as the RAP replacement level increased. The CT scanning results indicated that the virgin crushed aggregate has a higher void ratio than the RAP blends, which interpreted the lower permeability and higher resilient modulus of RAP blends. In conclusion, blending RAP with virgin aggregate produces superior quality material for road bases.

Resistance to Moisture-Induced Damage of Half-Warm-Mix Asphalt Concrete with Foamed Bitumen.

Hot-mix asphalt (HMA) remains the predominant material for pavement surfacing. Mixing is performed at about 180 °C, depending on the bitumen used. Environmental concerns in terms of emissions and energy demand are fostering new sustainable technologies in road construction. Warm-mix asphalt (WMA) and half-warm-mix asphalt (HWMA) mixtures meet current expectations in that they are produced at lower temperatures, 100–130 °C, ensured by foaming the bitumen with water. The extent of temperature reduction requires that the mixture has adequate moisture and frost resistance, which is particularly important in countries that have a low-temperature climate. Asphalt concrete AC 8 S with 50/70-grade foamed bitumen modified with 0.6 wt.% surface-active agent (SAA) was used in the tests. To provide the AC mixture with the required resistance to climatic factors (water, temperature below 0), hydrated lime was added at 0, 15, 30, and 45 wt.% as limestone filler replacement. The influence of the hydrated lime addition on the air void content and resistance to moisture and frost damage was investigated according to the WT-2 2014 methodology based on EN 12697-12: 2008 and to the modified AASHTO T283 method. The optimum content of hydrated lime for filler replacement was determined through statistical analysis of the test results. With the optimum hydrated lime replacement of 30%, the required level of moisture and frost resistance of HWMA concrete with foamed bitumen is achieved. The results of this study confirmed the suitability of HWMA concrete with foamed bitumen for application in road construction practice.

Use of Recycled Material in WMA- Future of Greener Road Construction

Sustainable road construction practice requires an asphalt mix technology that is environmental friendly, energy-efficient, economical and protective for humanity and health. India and many other countries are using Hot Mix Asphalt (HMA) technology for asphalt road construction. HMA has several disadvantages like high production temperature (155˚C to 165˚C), which increases Green House Gas (GHG) emissions. These emissions increase Global Warming and severely affect the respiratory system of paving crew workers. Warm Mix Asphalt (WMA) technology can reduce the mixing and compaction temperature by around 30˚C in comparison to HMA. WMA has many advantages over HMA like fuel-saving, reduced emissions, improved visibility at the site, more incorporation of Reclaimed Asphalt Pavement (RAP). RAP is the old aged flexible pavement material that can be recycled back to construct a new pavement. Researchers found two major issues with the use of RAP in asphalt mixes such as high emission during mixing of RAP with virgin aggregate and premature cracking due to aged (stiff) binder. WMA may resolve these two issues, first by reducing binder’s viscosity at lower production temperature (reducing high emissions during production of asphalt mix) and second, reducing secondary aging of RAP aged binder. Some WMA additives also works as rejuvenators and provide good coating. This paper discusses the WMA technology, it’s classification, mix design guidelines for WMA, era of recycling, use of RAP and Reclaimed Asphalt Shingles (RAS) into WMA and role of rejuvenators in WMA.

The Potential u se of Crumb R ubber in H ot A sphalt M ixes in E gypt u sing Dry P rocess

Since 1960 Using crumb rubber modifier (CRM) in hot asphalt mixtures has become a frequent practice in road construction. Using the CRM by the dry process method is not commonly used, although it has great advantages such as it is less fuel consuming and it does not require storage container like the wet process method. This research evaluates the mechanical properties of dense graded asphalt rubber mixtures manufactured using the dry process. The results obtained from this mixture compared with similar asphalt mixture without CRM. The mechanical properties of all mixtures evaluated using a set of tests such Marshall Stability and flow test, moisture susceptibility test, indirect tensile strength test, dynamic modulus and flow number test. The research results showed that using CRM with 0.75% of aggregate’s weight increased the mixture’s stability, flow and enhanced its cracking and permanent deformation resistance.

Towards high-performance materials for road construction

Due to constant increase of traffic, modern road construction is in need of high-performance pavement materials. The operational performance of such materials can be characterized by many properties. Nevertheless, the most important ones are resistance to rutting and resistance to dynamical loads. It was proposed earlier to use sulfur extended asphalt concrete in road construction practice. To reduce the emission of sulfur dioxide and hydrogen sulfide during the concrete mix preparation and pavement production stages, it is beneficial to make such a concrete on the base of complex sulfur modifier. In the present work the influence of the complex modifier to mechanical properties of sulfur extended asphalt concrete was examined. It was shown that sulfur extended asphalt concrete is of high mechanical properties. It was also revealed that there as an anomalous negative correlations between strain capacity, fatigue life and fracture toughness.

Application of Functional Resonance Analysis Method to Sustain Human-Centered Design Practice in Road Construction

The Functional Resonance Analysis Method (FRAM) involves mapping out interrelated functions to gain an understanding of how to monitor and optimize system performance. A FRAM model was applied to study the application of predictive, human-centered design review of an asphalt job truck for road construction. The model provided for a constructive means to communicate, reflect upon, and strategize methods to support ongoing human-centered design practice in the business. Practical recommendations were made with regard to resource allocation and management activity. This paper will describe the development of the model, the application, and the findings.

The limits of partial life cycle assessment studies in road construction practices: A case study on the use of hydrated lime in Hot Mix Asphalt

Extensive published literature shows that hydrated lime improves Hot Mix Asphalt (HMA) durability. Its impact on the environmental impact of HMA has not been investigated. This paper presents a comparative Life Cycle Assessment (LCA) for the use of HMA without hydrated lime (classical HMA) and with hydrated lime (modified HMA) for the lifetime of a highway. System boundaries cover the life cycle from cradle-to-grave, meaning extraction of raw materials to end of life of the road. The main assumptions were: 1. Lifetime of the road 50years; 2. Classical HMA with a life span of 10years, maintenance operations every 10years; 3. Modified HMA with an increase in the life span by 25%, maintenance operations every 12.5years. For the lifetime of the road, modified HMA has the lowest environmental footprint compared to classical HMA with the following benefits: 43% less primary total energy consumption resulting in 23% lower emissions of greenhouse gases. Partial LCAs focusing only on the construction and/or maintenance phase should be used with caution since they could lead to wrong decisions if the durability and the maintenance scenarios differ. Sustainable construction technologies should not only consider environmental impact as quantified by LCA, but also economic and social impacts as well. Avoiding maintenance steps means less road works, fewer traffic jams and hence less CO2 emissions.

PROBLEMS AND PROSPECTS OF PETROLEUM BITUMEN PRODUCTION

Abstract. The world production petroleum bitumen for road construction is considered. The problems and prospects of the bitumen production in the world and Russia are shown. At present leading positions on Russian bitumen market occupy the companies Gazprom Oil, Rosneft and Lukoyl. They cover nearly 80% of total volume of bitumen production in the RF. In world road construction practice the residual road oil bitumen is basically used, from which more than 80% of motor roads are built in the west. The significant quality growth of oil bitumen was the result of the appearance of modified and polymeric-bitumen bindings(PBB). Amongst block polymer of the styrene (SBC - styrene block copolymer), used in road construction, the main modifier for production of polymer-modified bitumen in the world is butadiene styrene thermoelastolayer SBS (SBS - styrene butadiene styrene). In 2014 at Moscow NPZ the installation on production PMB of new generation G-Way Styrelf is launched. The installation was built by the joint-venture Gazprom Oil and French concern Total and is considered to produce 60 thousand tons of PMB and 7 thousand tons of bitumen emulsion per annum. The production is realized in accordance with technology Styrelf, designed by concern Total and adapted to Russian climatic conditions. The Russian bitumen is in demand on foreign market as well.

A study on the rheological properties of recycled rubber-modified asphalt mixtures.

Using waste rubber in asphalt mixes has become a common practice in road construction. This paper presents the results of a study on the rheological characteristics of rubber-modified asphalt (RMA) concrete under static and dynamic loading conditions. A number of static and dynamic creep tests were conducted on RMA mix specimens with different rubber sizes and contents, and a series of resonant column tests were conducted to evaluate the shear modulus and damping values. To simulate the stress-strain response of traffic-induced loading, the measurements were taken for different confining pressures and strain levels. The results of the study indicated that rubber modification increases stiffness and damping ratio, making it a very attractive material for use in road construction. However the grain size of the rubber is very important. Although RMA may cost up to 100% more than regular asphalt, the advantages it brings, such as an increased service life of the road and proper waste utilization contributing to a more sustainable infrastructure, may justify the added cost.

Optimum lime content identification for lime-stabilised rammed earth

The rising price of energy and a recognition of the human impact on climate change has resulted in growing interest in environmentally–friendly construction techniques such as rammed earth. Modern rammed earth is generally stabilised with small quantities of Portland cement in order to improve its strength and durability, however an alternative is to use lime to stabilise the raw soil. This is common practice in road construction, for example, but is less common in RE. This paper presents experimental results illustrating the existence of an optimum lime content that maximises the unconfined compressive strength and stiffness of an engineered lime-stabilised rammed earth and the experimental procedures employed to determine it. The effect of curing regime (oven as opposed to natural drying) on the final unconfined compressive strength of the material was also investigated. An optimum lime content for the tested soil has been identified and several methods to determine its rough value presented which have the potential to reduce testing times and so associated costs.

Road Wildlife Ecology Research in China

This paper comprehensively summarizes the research advancing the impact of highways on wildlife and the countermeasures used in China. By the end of 2011, the total length of highways and expressways in China was 4.1 million and 85,000 kilometers, respectively, and both are listed as the second longest road systems in the world. Wildlife biodiversity in China is listed as the eighth highest in the world, and thus the conflict between wildlife biodiversity and road systems has increased in recent years. In China, road mortality levels, wildlife road effect zones, wildlife migration and behavior differed between pre- and post-road construction activity. Road networks resulted in the fragmentation of wildlife habitat in multiple different regions in China. In response to this, countermeasures have consisted of route re-selection, locating suitable areas for wildlife crossing construction, and erecting wildlife warning signs along the roadside to alert drivers. However, such basic research efforts and recommendations have only recently begun in China, compared to western developed countries. As a result, the recommended countermeasures were often absent during road construction practices that were monitored in this study. We provide three major recommendations from our research findings in road wildlife ecology in China: 1.) develop and initiate basic studies in road wildlife research in China; 2.) develop multidisciplinary collaborations and co-operations during highway construction; and 3.) establish and strengthen international exchange and collaborations with western developed countries to advance the issue of road-wildlife ecology in China.

Development of Guidelines for Low Volume Concrete Road Construction in Sri Lanka

The purpose of the study was to develop guidelines for construction of low volume concrete roads in Sri Lanka. A survey was carried out to study current concrete road construction practices and knowledge of the contractors involved in concrete road construction. Survey results show that good practices have not been adopted in low volume road construction in Sri Lanka. The authors have introduced best practices which can be easily adopted by the local road construction industry. Incorrect joints construction was observed in concrete roads during the site visit and the Authors have introduced a new device for contraction joint construction. A modification to the available method was proposed to measure surface undulation on local concrete pavements and allowable undulation was determined through field investigation. A comparison of various kinds of concrete producing and curing methods and their performance were studied. The authors have evaluated the effectiveness of rebound hammer method which has been used for quality control by some consultants. Rebound hammer reading was compared with compressive strength which was found out from core cutter samples. Double beam vibrator with inbuilt camber was introduced to consolidate and form the camber of the surface layer. Check lists for subgrade /subbase, shoulder, formwork and concrete placing and finishing have been introduced to address weakness and enhance the quality of the pavement construction. Quality and Cost control techniques in the field of low volume concrete road construction in Sri Lanka are also described. Further, the proposed guideline describes the most appropriate methods for preparation of subgrade, subbase and shoulder, and mixing, placing and finishing of concrete.

Development of a recycled polymer modified binder for use in stone mastic asphalt

The number of commercial vehicles using Irish roads has increased considerably in recent years, leading to higher demands being placed on pavement materials and increased use of polymer modified bitumens. This has also coincided with significant changes in Governmental policy which has produced large increases in Irish recycling rates. Improved recycling levels are set to provide Ireland with a new challenge: to find potential uses for the large quantities of recycled polymer that are becoming available. Towards this end, the potential of developing a recycled polymer modified binder was investigated. The polymers most commonly recycled in Ireland were identified and sourced from industry. Fundamental bitumen tests were conducted to assess the effect of the recycled polymer and a mixing methodology developed. It was found that the addition of 4% recycled HDPE into a pen grade binder produced the most promising results, and the mixing process was then optimised with respect to mixing parameters and binder additives. A developmental recycled binder was produced and compared in performance tests to binders currently used in road construction practice. Results obtained from wheel track and fatigue tests show that although the binder does not deliver equivalent performance levels to a proprietary polymer modified binder, it does out-perform traditional binders used in stone mastic asphalt. Recommendations are offered on the further development of the recycled polymer modified binder to achieve the standards currently required.

Evaluation of Life-Cycle Cost Analysis Practices Used by the Michigan Department of Transportation

Life-cycle cost analysis (LCCA) has become a common practice in road construction at the state level during the past decade in the United States. It enables pavement engineers to conduct a comprehensive assessment of long-term costs, and ideally agency highway funding can be allocated more optimally. Michigan Department of Transportation (MDOT) has adopted LCCA in the pavement selection process since the mid-1980s, yet its application in actual projects has not been reviewed. Using case studies, this paper seeks to analyze MDOT's accuracy in projecting the actual costs over the pavement service life and choosing the lowest-cost pavement alternative. Ten highway sections in Michigan were chosen and grouped into four case studies. Their estimated and actual accumulated costs and maintenance schedules were compared. While results indicate that MDOT LCCA procedure correctly predicts the pavement type with lower initial construction cost, actual costs are usually lower than estimated in the LCCA. This outcome may be partly because the cost estimation module in MDOT's model is not site specific enough. Refinements to its pavement construction and maintenance cost estimating procedures would assist MDOT in realizing the full potential of LCCA in identifying the lowest cost pavement alternatives for the pavements studied.

Impact of July 2004 high-intensity rain on Hilepani-Jayaramghat-Diktel Environment-Friendly Road in East Nepal

The high-intensity rain of 5-13 July 2004 activated numerous landslides, gullies, and debris flows in the watershed of the Dudh Koshi River in east Nepal. As a result, the Hilepani- Jayaramghat- Diktel Environment-Friendly Road was devastated. Apart from the rainfall, geological, geomorphic, land use, and road construction practices were other important factors leading to the disaster. Most of the damage was concentrated on concave slopes, whereas the ridges and convex slopes were relatively safe. The entire alignment was devoid of any breast or retaining walls necessary to protect the high, steep, and bare soil cut slopes, and it resulted in extensive cut slope failures. Similarly, side and cross drains were almost nonexistent. As a result, severe damage was seen at almost every gully crossing. There were very few gully protection structures (viz. check dams) and, like the retaining walls constructed below the road, they also suffered from poor construction quality and failed due to weak foundation and inadequate keying practices. Some of the most awkward structures were the loops founded on unstable slopes with high (up to 15 m) and robust gabion walls at the bends, and deep box cuts above them. In these circumstances, the concentrated runoff and subsequent debris flow from the box cut devastated the entire hairpin bend.

The South African Harvesting Code of Practice

SYNOPSIS The South African Harvesting Code of Practice is a set of guidelines developed by harvesting specialists to assist the Forest Industry to select correct harvesting and road construction practices that are consistent with appropriate environmental management principles. The focus is not only on “green issues” but on the effects of harvesting on ergonomics (worker's environment), economics, the natural environment and productivity. Environmental auditing is a management tool designed to protect and improve the environment by assisting management in the control of practices which may have an impact on the environment and to assess compliance with company environmental practices. The Harvesting Code of Practice will have an important role to play in setting environmental standards to be documented in company policies. The development of the Harvesting Code of Practice involved the evaluation of several other international codes, the assessment of local equipment and processes used and an investigation in their possible impacts on the working environment.