Aggregates In Road Construction Research Articles

Valorization of Mining Waste as Aggregates for Road Construction: Circular Economy in the Andean Region of Peru

Valorization of Mining Waste as Aggregates for Road Construction: Circular Economy in the Andean Region of Peru

Utilisation of Reused Steel and Slag: Analysing the Circular Economy Benefits through Three Case Studies

This research explores sustainable construction practices focusing on material reuse, specifically reclaimed structural steel and slag. In general, the building stock is not designed for deconstruction, and material recovery for reuse at the end of life of buildings is complex and challenging. The study evaluates the benefits of content reuse through a thorough analysis of three case studies—BedZED eco-friendly housing, Angus Technopôle building, and the use of steel slag aggregate in road construction. It highlights the value of reclaimed structural steel and by-products like steel slag in waste reduction, energy conservation, and resource preservation. The BedZED case study showcases recycled steel’s cost-effectiveness and economic viability in construction, while the Angus Technopôle building exemplifies the adaptive reuse of an old steel frame building. Additionally, the third case study showcases the benefits of using Electric Arc Furnace C slag in asphalt-wearing courses, highlighting the reduction in greenhouse gas emissions and environmental impact. The versatility of reclaimed structural steel and slag is evident in integrating material reuse in building construction and road infrastructure. These case studies illustrate the potential for reusing steel and its by-products in various construction contexts, from eco-friendly housing to road development. Therefore, the study aims to demonstrate the feasibility and benefits of sustainable practices within the construction industry by showcasing the successful incorporation of reclaimed steel and slag in these projects. Considering the significant contributions of building construction to global greenhouse gas emissions, raw material extraction, and waste production, the study advocates for adopting circular economy (CE) principles within the construction industry. Finally, the analysis of case studies underscores the advantages of reclaimed structural steel and the valorisation of steel slag through the lens of CE and their contribution to sustainable development.

Life cycle assessment and pavement performance of recycled aggregates in road construction

Integrating environmental goals in the construction of infrastructure has attracted great attention over the past two decades. The use of construction and demolished waste materials (C&D) as a base layer for pavement structures gained popularity as a sustainable alternative to virgin aggregates (VA). An experimental testing program was designed to investigate several recycled materials as a potential replacement to VA in flexible pavements base layer. The testing program included routine tests, matric suction, static, and repeated load triaxial tests to measure the general engineering properties and evaluate the material performance under static and cyclic loading. The results of the laboratory testing program were employed to predict the pavement performance utilizing different combinations of C&D waste as a base layer for flexible pavement structures using the AASHTOWare Pavement ME Design at different climate conditions. The sustainability of using C&D material as a partial or full replacement of VA base material in pavement construction was evaluated by using the life cycle assessment (LCA) approach. The results showed that all the C&D materials yielded a much thinner base layer compared to the natural VA achieving the same pavement performance. Moreover, the reduction in the thickness is more significant in cold and wet climatic conditions rather than the hot and dry climatic conditions. LCA results revealed that the VA base layer had the highest environmental impact on all tested categories. VA materials, used as a base layer, show 65% higher global warming potential compared to C&D materials as a base layer in all climatic conditions.

Environmental feasibility and implications in using recycled construction and demolition waste aggregates in road construction based on leaching and life cycle assessment – A state-of-the-art review

Due to rapid population growth and urbanization, construction activities have increased worldwide resulting in generation of enormous volume of construction and demolition (C&D) waste. On one hand, C&D waste is generated during the construction, destruction, and rehabilitation of existing structures. While on the other, the transportation sector consumes large volumes of aggregates for pavement construction and maintenance. The extraction of finite natural aggregates causes potential damage to the environment. Recycled C&D waste, once converted into recycled aggregates, has the potential to be utilized in pavement layers due to its sound quality and composition; also resulting in lowering the landfill loads. This review article critically summarizes the environmental risks regarding chemical composition and leaching behavior of C&D wastes in pavements. Additionally, this review evaluates the environmental impacts of C&D waste aggregate production and application in pavements using life cycle assessment (LCA). Overall, the aim of this study is to investigate the environmental impacts and benefits of C&D waste to enable highway administrations to adopt and promote the use of C&D waste in development of sustainable road infrastructure. In this way, the review articleattemptsto promotea new era of sustainable road construction and achieve net zero waste goal.

Effect of Mechanical Properties on Performance of Cold Mix Asphalt with Recycled Aggregates Incorporating Filler Additives

The utilization of recycled asphalt pavement in the construction and maintenance of flexible pavement with asphalt emulsion is advantageous and environmentally friendly. It saves energy due to zero heat loss during the mixing and laying of pavement compared to hot mix asphalt. Recycled asphalt pavement (RAP) is a sustainable material in place of virgin aggregates in road construction. The focus of this study is (i) virgin aggregate production, (ii) the utilization of waste material (additive), (iii) reducing the production temperature, and (iv) recycled RAP material in the pavement. This paper attempts to create a venue for using RAP greater than 50% during pavement construction. Cold mix asphalt (CMA) containing 0%, 50%, and 100% RAP materials with different dosages of cement, fly ash, and Stabil-road at 1%, 2%, and 3% of dry aggregate weight were used for ascertaining the mechanical and volumetric properties of mixtures. The mechanical properties for CMA samples, such as stability, tensile strength, moisture susceptibility, stiffness modulus, and the abrasion loss of CMA samples, were evaluated with and without RAP incorporation. Present laboratory studies revealed that a cold mix containing 50% RAP materials produced a higher stability value than the control mix, irrespective of the types of additives in its contents. All the additives can potentially resist moisture damage in the mix. Also, a significant improvement in the resilient modulus was considered for RAP-incorporated mixtures with the additives.

Geotechnical Suitability of Soils in Road Construction for Sustainable Development in Tropical Africa: Case of Lateritic Graveled Soils of Bandjoun (West, Cameroon)

The environmental impact of the exploitation of geomaterials and their relatively high cost, coupled with the increasingly low financial capital in developing countries, are pushing road actors to turn to inexpensive local ecological materials. The present study is conducted on lateritic graveled soils of Bandjoun (LGSB) in the West Cameroon Region. The aim is to determine whether lateritic gravel soils, particularly those in Bandjoun, can be an ecological and economical alternative to rock aggregates in road construction, considering their geotechnical parameters and environmental impact. These soils were described in the field and were also subjected to complete geotechnical identification in the laboratory. The LGSB presents Californian bearing ratio indices ranging from 26% to 83.3%, a plasticity index of 10.11%, a fines content of 12.05%, an average methylene blue value of 4.25, a water content at the Proctor optimum of 27.6% and a dry density of 1.75 g/cm3. They are silty or clayey gravels and sands of subgroup A-2-7 according to the Highway Research Board classification; sandy and gravelly soils with fines of class B according to the classification of the Road Construction Guide; and silty gravels according to the classification of the Central Laboratory of Bridges and Highways. These soils can be used naturally in pavement layers, in particular in subgrade for all traffic classes and in subbase for low traffic. The tonnage of these soils has been estimated at 18,389 t. The global warming index shows that the use of these soils (18,389 t) in road construction can reduce 31,629–62,706 kg of carbon emissions. The use of lateritic soils in road construction is a very interesting alternative to reduce the environmental impacts associated with the manufacture of rock aggregates. So, lateritic soils should be used instead of rock aggregates for cleaner, more environmentally friendly road construction. The present work presented a specific evaluation of the geotechnical properties and ecological impact of lateritic graveled soils for road construction, as well as their potential for ecological and economic utilization.

Image-based methods for automatic identification of elongated and flat aggregate particles

The content of elongated and flat aggregates is a critical detection index in road engineering. In this study, using image sequences of falling aggregates, two multi-view morphological methods were proposed for aggregate shape classification. The multi-view features of the aggregates were constructed by combining multiple single-view features from different views. Furthermore, a joint-view normalization method was proposed to improve the three-dimensional shape characterization capability of the multi-view features. Based on the multi-view features, a support vector machine was adopted to achieve aggregate shape classification. In addition, multiple two-dimensional aggregate morphologies from different views were directionally guided and fused to construct a multi-view image, which could reflect the three-dimensional shape of the aggregates. The multi-view images were then fed into ResNet18 for aggregate-shape classification. Notably, compared with single-view morphological methods based on the aggregate morphology in the vertical and random views, the two multi-view morphological methods developed herein significantly improved the classification accuracy. Moreover, it was found experimentally that increasing the height of the field of view improved the classification accuracy of the multi-view morphological methods. The proposed multi-view morphological methods demonstrate significant potential for application in the automatic identification of elongated and flat aggregates in road construction.

Structural Performance of Cement-treated Base Layer by Incorporating Reclaimed Asphalt Material and Plastic Waste

The reuse of reclaimed asphalt material (RAM) and polyethylene terephthalate (PET) plastic waste is a reliable approach to limit the use of virgin aggregates for road construction and mitigate environmental challenges. This study highlights the structural performance of the cementitious base or cement-treated base (CTB) layer by incorporating reclaimed asphalt and plastic waste material. Structural compatibility of CTB layer with different proportions of RAM (20%, 45%, 70% and 95%), virgin aggregates and plastic waste (5%) is recognized by the moisture-density relationship, unconfined compressive, indirect tensile strength, flexural strength and California bearing ratio tests. In the current study, a ranking methodology is used to analyze the overall suitability of the cementitious base mix proportions using different laboratory test parameters. Furthermore, a finite element analysis using the ANSYS software is performed to investigate the effect of CTB layer on the pavement structural responses. Also, using the central public works department guidelines, a cost comparative study is provided. Experimental results showed that all the cementitious base mixes met the requirements for the unconfined compressive strength, except for the 95% and 70% RAM mixes. Therefore, 20%-45% of RAM can partially be used in the CTB layer to replace virgin aggregates partially. The finite element analysis results showed that CTB reduced fatigue strain by 57% and surface deformation by 47%. Moreover, it has been concluded that by utilizing a cementitious base with RAM, there is a 30% cost reduction. KEYWORDS: Reclaimed asphalt material, Cement-treated base, Polyethylene terephthalate, Finite element analysis, Unconfined compressive strength.

Comparative Study on Physical Characterization of Reclaimed Asphalt Pavement and Natural Aggregate in Flexible Pavement

Reclaimed Asphalt Pavement (RAP) has gained significant attention in recent years as a sustainable alternative to natural aggregate in road construction. This study presents a comparison of the physical attributes of RAP and natural aggregate, with a focus on their potential use as base and subbase materials in flexible pavements. The physical attributes of RAP and natural aggregate were evaluated using standard laboratory tests, including particle size distribution, specific gravity, water absorption, impact value test, Los Angles Abrasion test, flakiness and elongation test. The research concluded that RAP is comparable to natural aggregate in terms of particle size distribution and bulk density but has lower water absorption, impact, and abrasion values. The results shows that RAP is almost 53% more tougher that natural aggregate when tested for Aggregated Impact test and 30% more harder than natural aggregate when compared by Los Angeles abrasion test. Also, heatmap was used to analyse the relationship between physical attributes of natural aggregate and reclaimed asphalt pavement which depicted 93% similarity The findings suggest that RAP has the potential to replace natural aggregate in flexible pavements, further study is required to determine its long-term performance and durability.

Mechanical Properties of Unbound Perlis Limestone and Granite Aggregate Mixture for Road Application

The most important component of road construction is aggregate. As 70–80 percent of aggregates are used in road construction, the majority of aggregates used in Malaysia’s road construction are granite aggregates. Due to the lack of substitutes for aggregates and the rise in demand, this may hinder the development of the road construction process. This research seeks to identify high-quality alternatives to granite aggregate that can be utilised to their full potential. Since there is no granite in Perlis, Malaysia, the mechanical properties of the Perlis limestone aggregates were evaluated to ensure that they can be used alone or in combination with granite aggregates in road construction. The AIV, ACV, and LAA tests were conducted on both individual samples of Perlis limestone and granite aggregate, as well as combinations containing various percentages of each. In all tested parameters, the results indicated that Perlis limestone aggregates were superior to granite aggregates. In addition, when Perlis limestone and granite were combined in an unbound state with the presence of limestone, the strength and resistance to abrasion and impact increased linearly. It is believed that incorporating Perlis limestone into unbound layers of road construction, such as roadbase and subbase, will enhance their performance.

Recycling of Bangka tin slag used as fine aggregate in hot mix asphalt concrete

Bangka Tin Slag is a by-product of tin production on Bangka Island. Meanwhile, tin slag is a waste product from the tin smelting process. Every year, the tin smelting process in Bangka Island produces a large number of slags, while its utilization is still relatively small. On the other hand, the demand for aggregate in road construction has increased from time to time. Recycling tin slag used as fine aggregate in hot mix asphalt can maximize the utilization of tin slag and fill the aggregate demand in the construction. This research aims to substitute the fine aggregate with the tin slag in Asphalt Concrete - Binder Course mixture. In this study, the use of Bangka Tin Slag aggregate in asphalt mixture is 0%, 25%, 50%, 75%, and 100%. Based on the examination in this work, Bangka Tin Slag has a great potential to be used in hot mix asphalt concrete, especially in Asphalt Concrete - Binder Course mixture. The result shows the optimum asphalt contents in this mixture are between 6.25% and 6.5%.

The application of coal mining waste to the production of construction ceramics: radiological and mechanical aspects

The article presents the results of research on the physical and radiological properties of building ceramics made of mining waste. One method of using mining waste is to use it as aggregate in road construction. However, this alone is not enough to dispose of the entire amount of waste generated. Another promising method of using mining waste is the production of building ceramics (bricks). However, some properties (e.g. the content of natural radionuclides) of the waste may limit the possibility of such use. In the scope of this work, the properties of bricks made from mining waste - shale collected from dumps, were examined. It has been shown that the properties of bricks prepared in this way meet the criteria set out in various standards and legal acts and can be used in construction.

Influence of Steel Slag Addition on Strength Characteristics of Clayey Soil

Abstract: The disposal of industrial waste or by-products has become more difficult and expensive as a result of the increasing environmental regulations and shortages of suitable disposal sites. When molten steel is separated from impurities in steel making furnaces, steel slag is produced as a by-product of the process. In the construction industry, steel slag has long been used in various applications in the construction industry such as aggregates in road construction, railway ballast and hydraulic protection structures. Using steel slag for soil stabilization is a modern application of steel slag. In this study the main approach is to investigate the effect of steel slag on the strength characteristics of clayey soil. Steel slag is blended with clayey soil in amounts of 10%, 15%, 20%, 25%, and 30% of dry weight. In our study, the optimum content of steel slag was determined by considering the maximum unconfined compressive strength. A series of further laboratory tests have been performed on this optimum mix to evaluate its suitability as a stabilizer material. The test was also conducted with conventional stabilizing material such as l0% fly ash and 5%cement with clayey soil and the obtained optimum mix was determined. Then the results are compared accordingly. In the above study, it has been observed that the addition of steel slag results in significant improvement in strength parameter as compared to fly ash but less strength in case of cement. Also from the cost comparison, it has been observed that cost of optimum mix of steel slag is less as compared to cement. It is therefore used to stabilize clayey soil.

Integrated and comparative Structural-LCA analysis of unbound and cement-stabilized construction and demolition waste aggregate for subbase road pavement layers formation

A more extensive use of recycled aggregate in road construction is key to meeting the ambitious targets of the EU circular economy action plan. However, scepticism among designers, contractors and road agencies remains a bottleneck. This integrated structural-environmental study demonstrates the advantages of using recycled construction and demolition waste aggregate (CDW-RA) in substitution of primary natural aggregate (NA) for the formation of subbase layers in both flexible and semi-rigid road pavements. The structural responses of different pavements with a 0.30 m subbase layer made up of four materials, i.e., two unbound and two cement-stabilized obtained including NA and CDW-RA, were compared. The environmental-related impacts were also assessed by means of a life cycle assessment (LCA).Laboratory tests and structural design led to pavement structures with the same thickness for the upper hot-mix asphalt layers, i.e., 0.26 and 0.28 m for the two unbound and the two cement-stabilized subbase materials respectively. The pavement with unbound CDW-RA subbase showed the best LCA outcomes because of the more favourable environmental performance of CDW-RA compared to NA. Although the stabilization of NA and CDW-RA reduces the thickness of the top hot-mix asphalt layers by 0.02 m, the environmental benefits are outweighed by the impact associated with the usage of cement. This study encourages the use of CDW-RA in road subbase layers with similar characteristics to those investigated here. The LCA results also support the use of alternative and more environmentally friendly binders that can enhance the environmental sustainability of stabilized materials in road construction.

Experimental Study of the Usability of Recycling Marble Waste as Aggregate for Road Construction

The road construction industry consume a considerable amount of natural aggregates in the world. As a consequence, the increase in the natural aggregates demand increases the construction cost. On the other hand, marble spoil waste, generated from marble cutting and polishing process, is an environmental nuisance in the world. Indeed, an economical solution to this problem is the reuse of these wastes as an aggregates for road construction. The main objective of this study is to evaluate the usability of aggregate, obtained by crushing marble waste, as a conventional aggregate for road construction using an experimental investigation. To achieve this objective, these experimental tests were carried out on fine and coarse marble aggregate samples: sieve analysis, Atomic Absorption Spectrometry, calcium carbonate content, scanning electron microscope (SEM), X-Ray- diffraction (XRD), densities, water absorption, equivalent of sand, Los Angeles, Micro Deval, flakiness index, and shape index. Finally, experimental test results show that the chemical composition and the physical and mechanical properties of marble aggregate recommend it to be used as a conventional aggregate for road construction.

Feasibility Studies of Engineering Properties of Coarse Aggregates from Demolition Waste and Natural Aggregates for Road Construction

Construction and Demolition (C&D) waste constitutes a major portion of total solid waste origination in the world and most of it is used in landfills. The disposal of this construction and demolition waste is becoming a major concern as it is disposed unscientifically in India. The C&D waste is usually dumped on the sides of canals, minor roads and at the entrance of the cities and towns. This causes environmental problems and affects the quality of life of people. This paper discusses the possibility of replacing natural coarse aggregate with recycled concrete from demolition waste aggregate for road construction. Aggregate strength, gradation, absorption, specific gravity, shape and texture are some of the engineering properties that are desirable for road construction. Therefore, the experimental program was focused on the evaluation of engineering properties of the recycled aggregate over a period of 6 months. The findings from the study showed that the recycled concrete aggregate can be used for construction of transportation infrastructure. However, further research is needed particularly on the long term field performance of the recycled aggregate concrete before it can be used with confidence.

Assessing the Applicability of Fine Copper Slag in Road and Structural Fill Application

Mineral wealth is declining over the globe, but waste generation from many industries is increasing. As a consequence, the researchers started exploring alternative minerals that might be used instead of sand. Researchers revealed that silica-containing materials such as stone dust, copper slag, coal fly ash, carbonate sand, and others might be used to replace sand. The feasibility of employing copper slag as a fine aggregate alternative was investigated in this article. Copper slag is a by-product of the flotation and filtration processes used to extract copper from ore with high concentrations of copper. With an annual production of roughly 2.5 million tonnes, the total quantity of fine copper slag produced is currently above three million metric tonnes (MT). Copper slag (CS) is a sulfur-free waste product from copper roasting. It was found that the use of CS as a fine aggregate (60 percent) to replace fine aggregates in road construction was investigated. The use of fine copper slag in the building of embankment/subgrade fill would surely add value by minimizing waste accumulation on fertile land on the one hand and resource mining on the other. The current study focuses on specific gravity, an important property of any construction material, and a need for the design process. The material's Grain Size Distribution is also investigated to determine the particle size distribution. The quantity of Copper Slag that should be used to replace the fine aggregates is established via a trial and error procedure. Finally, the viability of the material proposed to be used in the subgrade layer, i.e., Copper Slag, is checked by analysis pertaining to the cost aspect of the roadway.

Steel slag quality control for road construction aggregates and its environmental impact: case study of Vietnamese steel industry-leaching of heavy metals from steel-making slag.

Steel slag is an industrial by product of steel manufacturing processes and has been widely utilized within civil and construction materials for road materials and environmental remediation in countries like Japan, USA, and European Union nations. However, the current utilization of steel slag in Vietnam is very low mainly because of lack of quality control of slag treatment and chances for reuse of treated steel slag. This paper presents the up to date steel slag production status in Vietnam through the extensive survey and sampling at seven large steel factories. The paper also highlights the environmental and quality control issues of these steel slags to use as road construction aggregates by assessing the heavy metals concentration in the leachate. The basic oxygen furnace (BOF) and electric arc furnace (EAF) slag samples were collected to evaluate leaching properties of metals leached from the slags. The two standardized batch leaching tests of steel slag roadbed material in Japan (JIS K 0058-1) and toxicity characteristics leaching procedure (TCLP-EPA method 1311) were performed to the evaluated the hazardous metals. The results of the leaching test show that almost all of the concentration of the metals in the leached solution does not exceed the National Standard for Industrial Wastewater Discharge (QCVN 40-2011). The pH and parameters such as total chromium, nickel, copper, lead, arsenic, and manganese differ from the two test methods. The acidic conditions employed in the EPA 1311 were not representative of condition excepted during slag reuse in road constructions because in the operation condition of the road, acidic liquid is absent. The leaching test results confirmed that JIS test which uses deionized water with gentle mixing prevents the slag sample from size degradation is suitable for the environmental assessment of steel slag use for roadbed material. This research suggests that the adjustment of pH value prior to disposal or reuse as base materials and official guideline should be promulgate by the authorities to ensure the leachate meet the surface water quality standard.

GHG Emission Reduction Opportunities for Road Projects in the Emirate of Abu Dhabi: A Scenario Approach

The transportation sector is considered one of the driving forces behind the increased release of greenhouse gases (GHGs), with road transport being this sector’s main emissions contributor. In turn, efforts should be devoted to reducing emitted GHGs from this sector, and many such opportunities lie in the road transport life cycle. This paper investigated fourteen emission reduction scenarios based on the green initiatives issued by the Abu Dhabi Government. The explored measures are either related to road works and road municipal services or to traffic movement. The proposed measures were evaluated with reference to a baseline study previously reported by the authors for three different road projects in Abu Dhabi city. Findings reveal that normalized GHG emission reduction could be significantly reduced by (i) replacing 30% of internal combustion engine passenger cars with battery electric vehicles where the power demand is covered almost equally from nuclear and liquified natural gas (LNG) sources, (ii) reducing the number of passenger cars by 10%, and (iii) having one-fifth of passenger cars powered by LNG. A lesser significant reduction could be achieved by replacing conventional lamps with light-emitting diode (LED) lamps or by having one-fourth of lighting powered by solar energy. Even lesser reduction could be achieved by (i) replacing a portion of Portland cement with ground granulated blast furnace slag in concrete structures, (ii) fully utilizing treated sewage effluent for roadside-plant irrigation, (iii) reducing desalinated water used for roadside-plant irrigation by 20%, and (iv) increasing the number of higher efficiency passenger cars by 10%. Replacing hot-mix asphalt with warm-mix asphalt and using asphalt with a high stiffness modulus in the base layer results in low emission reduction. The use of 15% recycled asphalt or the use of 50% recycled aggregate in road construction has the least impact on emission reduction. When all explored scenarios were combined, an overall normalized GHG emissions reduction of 9–17% during the road project life cycle could be achieved.

Financial and economic evaluation of construction and demolition waste recycling in Hanoi, Vietnam.

Increasing waste generation and the absence of a formal recycling industry are exacerbating the inadequacy of Construction and Demolition Waste (CDW) management in Hanoi, Vietnam. This study assesses potential CDW recycling in Hanoi by estimating the prospective supply of and demand for CDW recycling plants and evaluating their likely costs and benefits. Supply of concrete waste was calculated based on the weight-per-construction-area method whilst demand for recycled concrete aggregates (RCA) was determined by estimating the amount of aggregates for road construction in Hanoi from 2013 to 2017. Two potential models of CDW recycling plants were considered: a stationary plant and a mobile plant, with capacities of 1,000 and 360 tons/day, respectively. Our findings reveal that demand for RCA exceeds waste concrete supply, suggesting a promising market for RCA. Positive Net Present Value and Internal Rate of Return values of the stationary plant indicate its feasibility as an investment option. Meanwhile, the introduction of mobile recycling plants might require governmental intervention to internalize recycling positive externalities. Supporting policies might include a combination of a virgin material tax, green public procurement, and quality standard development.