Search Results (20)

Despite local and national road authorities striving to provide motorists with a durable and safe infrastructure environment, one in six UK roads are currently classed as being in poor condition. In terms of safety, Department for Transport statistics report high numbers of road incidents; 29,711 killed or seriously injured in 2023, representing little change compared to 2022. As such, reported in this paper is research aimed at developing artificial geopolymer cement mortar-based aggregate as a cost/environmentally attractive alternative to calcined bauxite for high friction surfacing applications. Work was undertaken in two distinct phases. In the first, the performance of alkali silicate-based geopolymers comprising a range of industrial wastes as binder materials was assessed using modified versions of standardized polished stone value and micro-Deval tests. In phase two, selected mixes were assessed for resistance to simulated wear by exposing test specimens to 20,000-wheel passes on an accelerated road test machine. Performance was further investigated using a dynamic friction test method developed by the Indiana Department of Transportation. Despite commercially sourced calcined bauxite aggregates exhibiting the highest performance levels, the findings from this preliminary research were generally positive, with acceptable levels of performance noted for manufactured geopolymer-based aggregates. For instance, in accordance with recommended levels of performance prescribed in BBA/HAPPAS standards, this included attainment of polished stone values higher than 65 and, following accelerated road testing, average texture depths greater than 1.1 mm. It is recognized that further research is needed to investigate geopolymer binder systems and blends of aggregate types, as well as artificial aggregate manufacturing procedures. Full article

High Friction Surface Treatments (HFST) are recognized for their effectiveness in enhancing skid resistance and reducing road accidents. While Epoxy-based HFSTs are widely applied, they present limitations such as compatibility issues with existing pavements, high installation and removal costs, and durability concerns tied to substrate quality. As an alternative to traditional Epoxy-based HFSTs, this study investigated the effects of aggregate gradation as designated by agencies on the performance of asphalt-based HFST. Various aggregate types were assessed to evaluate friction performance and the impact of polishing cycles on non-Epoxy HFST. It was found that adjustments in aggregate size and gradation may be necessary when transitioning to asphalt-based HFSTs, given the different nature of asphalt as more temperature susceptible compared to Epoxy. Various asphalt binder grades were considered in this study. A series of tests, including the British Pendulum Test (BPT), Dynamic Friction Tester (DFT), Circular Track Meter (CTM), Micro-Deval (MD), and Aggregate Imaging Measurement System (AIMS), were conducted to measure Coefficient of Friction (COF), Mean Profile Depth (MPD), texture, and angularity before and after polishing cycles. The results showed that the COF in asphalt-based slabs decreased more significantly than in Epoxy-based slabs as polishing cycles increased for HFST and medium gradations. However, in coarse gradation, the COF of slabs using asphalt-based binder matched or even surpassed that of Epoxy after polishing. Notably, the PG88-16 binder for Calcined Bauxite (CB) had the smallest reduction in COF after 140K polishing cycles, with only a 19% decrease compared to a 23% reduction for Epoxy. Full article

This study aims to accurately predict abrasion resistance, measured through the Los Angeles (LA) abrasion test, and modulus of elasticity, assessed using the Micro-Deval Abrasion (MDA) test, to support structural integrity and efficient material use in construction projects. We applied multi-output machine learning models—specifically Linear Regression (LR), Huber, RANSAC, and Support Vector Regression (SVR)—to predict LA and MDA values based on primary input parameters, including Uniaxial Compression Strength (UCS), Point Load Index (PLI), Schmidt Hammer Rebound (Sh_h), and Ultrasonic Pulse Velocity (UPV). The experimental work involved assessing model performance using metrics such as Mean Absolute Error (MAE), R-squared (R²), and Mean Squared Error (MSE). Linear Regression demonstrated superior predictive accuracy, achieving 94% for R² with an MAE of 0.21 and MSE of 0.09 for LA predictions and 92% for R² with an MAE of 0.24 and MSE of 0.11 for MDA predictions. These results underscore the potential of machine learning techniques in accurately predicting critical material properties, offering engineers reliable tools for optimizing material selection and structural design. This research contributes to the advancement of construction practices, promoting the development of durable and efficient infrastructure. Full article

The transition to a circular economy requires new materials and products with new production designs, technologies, and processes. In order to create new materials with physico-chemical qualities suitable for application in the building materials engineering sector, stone dust and polymer waste—two environmentally hazardous industrial wastes—were combined in this study. The materials obtained were evaluated based on an analysis performed using the Micro-Deval test. The results obtained showed a Micro-Deval coefficient value of 7.7%, indicating that these artificial aggregates can replace the natural aggregates used in road construction. Additionally, it was shown that the stone dust used could be applied as a sorbent for dyes without later leaching this dye from the final synthetic stones. Another category of materials that meets the principles of the circular economy and was developed in this study is bituminous mastic, which is currently used for the hot sealing of joints in road infrastructure. For this purpose, a composite material was developed using stone dust and cooking oil to replace the filler, a non-regenerable source used for obtaining bituminous mixtures. Specific standard methods were used to assess the degree to which the new materials approach the behavior of commercially available products. Full article

Skid resistance is a critical aspect for traffic safety since it significantly influences vehicle control and minimizes the distance required for emergency braking. The surface characteristics of pavements play a pivotal role in determining skid resistance. To achieve the optimal skid resistance performance, the pavement must sustain a specific level of friction. Thus, it is advantageous to apply surface treatments in areas that require enhanced friction. This study investigate the impact of factors such as the aggregate source, size, morphological properties, and abrasion levels on the skid resistance and frictional characteristics of a high-friction surface treatment (HFST). A complete investigation was conducted on HFST samples by analyzing the aggregate morphology using the Aggregate Image Measurement System and performing Micro-Deval abrasion testing. The skid resistance was evaluated with the British Pendulum Tester (BPT). The findings revealed that different aggregates and sizes exhibited varying behaviors post-polishing. Notably, fine-sized aggregates demonstrated higher British pendulum number (BPN) values, which indicate superior frictional performance. Models that predicted skid numbers based on the average texture and angularity indices initially demonstrated the balanced influences of both morphological properties before polishing. However, after polishing, the surface texture emerged as the primary determinant of the skid resistance, which overshadowed the angularity’s impact. Full article

Phosphate waste rock (PWR) is gaining attention as a potential alternative aggregate for concrete. Its valorization could reduce the environmental impacts of quarrying natural resources and stockpiling phosphate mining waste. This study comprehensively investigated the properties of fine and coarse aggregates produced from three rock types selected from PWR in Morocco: Flint, Phosflint, and Dolomite. A range of techniques was used to study their characteristics, including microstructural observations up to the microscale and X-ray computed tomography (X-CT), mineralogical and chemical compositions, physical and geotechnical properties such as Los Angeles (LA), micro-Deval (M_DE), flexural strength, real dry density, and total porosity. The results showed that the coarse fractions of Flint, Phosflint, and Dolomite are code A or B of NF P 18-545 and exhibit good shape, density, and water absorption properties. Flint aggregates had the highest wear and fragmentation resistance with the lowest and finest porosity. They contained mainly quartz but also small proportions of Dolomite and fluorapatite. Phosflint aggregates had high resistance, shown by code A in LA and M_DE values, and flexural strength equal to 17.1 MPa. They contained phosphate microfacies with a Ca/P atomic ratio equal to 1.8, cemented by cryptocrystalline silica. Dolomite aggregates’ mineralogical make-up consisted mainly of dolomite with the presence of quartz particles in addition to impurities. They also displayed significant total porosity (10–12%), as confirmed by X-CT. These findings were discussed to develop insights for the use of three types of PWR as alternative aggregates for concrete production. This investigation contributes to unveiling the properties of PWR as concrete aggregates and encourages circularity between the mining and construction sectors. Full article

Glass is considered a sustainable material with achievable recovery rates within the EU. However, there are limited data available for construction glass waste management. Furthermore, glass is a heavy material, and considering the geographical limitations of Cyprus, the transportation trading cost within the EU is extremely high. Therefore, another method for utilizing this by-product should be developed. The aim of this research is to investigate the production of a low-cost, lightweight and fireproof material able to retain its structural integrity, using the geopolymerization method with the incorporation of randomly collected construction glass waste. The glass waste was initially processed in a Los Angeles abrasion machine and then through a Micro-Deval apparatus in order to be converted to a fine powder. Mechanical (compressive and flexural strength), physical (setting time and water absorption) and thermal properties (thermal conductivity) were investigated. The fire-resistant materials presented densities averaging 450 kg/m³ with a range of compressive strengths of 0.5 to 3 MPa. Additionally, a techno-economic analysis was conducted to evaluate the viability of the adopted material. Based on the results, the final geopolymer product has the potential to be utilized as a fire resistance material, preventing yielding or spalling. Full article

Sedimentary phosphate extraction in open-pit operations generates large volumes of waste rock (WR), which are mainly overburdens and interburdens. Traditionally, the WR is mixed and stored on the surface in waste rock piles (WRPs). This paper presents a case study of the Benguerir mine site in Morocco. It investigates the potential valorization of each WR lithology based on the geological and geomechanical properties to reduce their environmental footprint and create added value to “waste.” The WR samples (soils and rocks) were collected from drill cores and mining trenches in the Benguerir mine. The geological characterization results using petrographic descriptions indicate the presence of nine phosphate layers and, in addition to the overburdens, eight interburdens. Four types of WR are identified: carbonate, siliceous, marly clay, and phosphate. The geomechanical characterization of soil-like samples showed an average plasticity index (PI) of 50% according to the methylene blue value (MBV) of 7.1, classifying them in the A3–A4 categories as plastic and clayey marl soils. The hard rock samples have excellent mechanical properties in terms of their uniaxial compressive strength (UCS), Los Angeles abrasion value (LA), and micro-Deval value (MD). The average compressive strength is 104 MPa for the flint, 35 MPa for the phosphate flint, 32 MPa for the silexite, 26 MPa for the limestone, 11 MPa for the indurated phosphate, and 8 MPa for the marly limestone. Based on the obtained results, these WRs can be considered as an excellent alternative secondary raw material for use in civil engineering applications, ceramics, and cement industries. Full article

This paper aimed to analyze the reduction in the ballast layer permeability simulated in a laboratory in saturated conditions by the presence of rock dust as a contaminant of three types of rocks explored in different deposits in the northern region of the state of Rio de Janeiro, Brazil, through laboratory testing relating the physical properties of rock particles before and after sodium sulfate attack. Sodium sulfate attack is justified by the proximity of some sections of the planned EF-118 Vitória-Rio railway line to the coast and of the sulfated water table to the ballast bed, which could degrade the material used and compromise the railway track. Granulometry and permeability tests were performed to compare ballast samples with fouling rates of 0, 10, 20, and 40% rock dust by volume. A constant head permeameter was used to analyze hydraulic conductivity and establish correlations between the petrography and mercury intrusion porosimetry of the rocks, namely two types of metagranite (Mg1 and Mg3) and a gneisse (Gn2). Rocks, such as Mg1 and Mg3, with a larger composition of minerals susceptible to weathering according to petrography analyses, tend to be more sensitive to weathering tests. This, in conjunction with the climate in the region studied, with average annual temperature and rainfall of 27 °C and 1200 mm, could compromise track safety and user comfort. Additionally, the Mg1 and Mg3 samples showed greater percentage variation in wear after the Micro-Deval test, which could damage the ballast due to the considerable changeability of the material. The mass loss caused by abrasion due to the passage of rail vehicles was assessed by the Micro-Deval test, with Mg3 (intact rock) declining from 8.50 ± 1.5 to 11.04 ± 0.5% after chemical attack. However, Gn2, which exhibited the greatest mass loss among the samples, showed no significant variation in average wear, and its mineralogical characteristics remained almost unchanged after 60 sodium sulfate cycles. These aspects, combined with its satisfactory hydraulic conductivity rate, indicate that Gn2 is suitable for use as railway ballast in the EF-118 railway line. Full article

During the routing of coarse particles in sedimentary environments, the particles are subjected to abrasion, leading to mass loss and changes in the particles’ morphology. The particles become more spherical, rounded, and smooth. Here, particles’ (quarried dolomite) morphological evolution of three shape aspects (form, roundness, and texture) and the mass decreases obtained in two sets of experiments in two different setups are presented. Abrasion experiments were carried out in cycles. Between cycles, morphological parameters and mass losses were tracked. Abrasion was investigated with consideration of the energy and power the apparatuses used that the material was subjected to, in contrast to the often-used estimated travel distances or duration of the abrasion. The goal was to examine if the two setups can be comparable and inter-transferrable, also to other similar abrasion setups. The experimental equipment, a micro-Deval apparatus and a Los Angeles machine, are standardised and widely used. The applied tests were modified. Morphological/shape parameters were determined using dynamic image analysis. The results of the tests show the influence of machine power (energy introduction rate) on mass loss and morphological change. Los Angeles (high-energy) abrasion resulted in higher mass loss values than micro-Deval (low-energy) abrasion. The mass loss results can be brought to comparable values by a newly introduced mass- and power-dependent coefficient. Low-energy abrasion resulted in faster rounding than high-energy abrasion, whereas form stayed nearly the same. In contrast, form changed rapidly during high-energy abrasion. Full article

The widespread use of natural aggregates is one of the main causes of the depletion of natural resources, as aggregates are constituents of several construction materials. Alternatively, it is, today, proven to be feasible to use mining tailings, either natural or recycled materials, to produce artificial aggregates through specific processes. A possible way to produce artificial aggregate is through the alkali activation of the powdered material in a process called geopolymerization. This study proposes to use a basalt powder and two different metakaolins as precursors for the production of an alkali-activated artificial aggregate, with a specific shape and size achieved by using 3D-printed molds. The experimental aggregates were evaluated using traditional tests for natural aggregates, such as resistance to compression, specific density and resistance to abrasion and fragmentation. Furthermore, the material was chemically analyzed in order to evaluate the geopolymerization process promoted by the two adopted metakaolins. The physical tests showed that artificial aggregates do not perform well in terms of resistance to wear and fragmentation, which can be improved. However, they revealed promising results in terms of skid, polishing and micro-texture. Full article

The present study focused on the petrography and geotechnics of aggregates of two sites around the city of Mongo for their use in construction. The study area is located in central Chad, in the Guéra province, at the eastern and north-western entrance to the city of Mongo. The area corresponds to a crystalline basement, and granitic massifs are abundant. Two deposits were studied: the Mongo massif, closest to the town of the same name, and the Oyo massif at the eastern exit of Mongo. The petrographic analysis showed that the studied materials are granites, light grey in color, composed of 30% quartz, 15% biotite, 20% feldspar, 30% plagioclase and 5% other minerals. From the geotechnical point of view, the materials of the Mongo site are more resistant to wear compared to those of Oyo which are less resistant. According to the results of micro-Deval and Los Angeles tests, the use of aggregates obtained from the Mongo site granites are usable in base courses for T1–T3 traffic admitting an axle of 8 to 10 tons and in surface dressings, contrary to those of Oyo, which are not favorable in road construction. Full article

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. Full article

The aim of this article is to present the current knowledge and experiences related to wear and fragmentation resistance tests and to indicate those of their aspects that require further research. For this purpose, a review of the literature was performed. Results show that tests of resistance to wear (the M_DE/DS test) and fragmentation (the LA test) are performed worldwide according to different standards (and thus following different test methods), which prevents a comparison of the obtained results. Comparative research into the M_DE/DS and LA tests indicates that the M_DE/DS test is more effective. The disadvantage of both tests lies in the dimension range of the aggregate. In addition, the use of steel balls in the LA test may not reflect the actual influence that the internal properties of the material have on the fragmentation process. A final review of the available knowledge allowed the formulation of proposals regarding further research directions, such as proposed changes of test methods, extensive analysis, and selection of optimal dimensions for tested aggregates, analysis of short-term and long-term tests, as well as extensive research into and an analysis of the impact of crushing on the physical, mechanical, and geometric properties of aggregates. Full article

Article concerns problem of jig beneficiation of mineral aggregates and focuses especially on problem of separation of hard-enrichable materials. Investigative programme covered tests in laboratory and semi-plant scale and material with different content of regular and irregular particles, along with various particle size fractions, was under analysis. Two patented solutions were utilized as methodological approach and densities and absorbabilities of individual products were determined and major novelty of approach consist in separate beneficiation of regular and irregular particles. Results of laboratory investigations showed that more favorable separation effectiveness was observed for the narrow particle size fractions of feed material. In terms of absorbability difference between separation products from I and IV layer was 0.4–0.5% higher for regular particles, and up to 0.5% higher for irregular grains. Differences in densities of respective products were 0.1% higher for regular particles. Results of semi-plant tests confirmed the outcomes achieved in laboratory scale. The qualitative characteristics of separation products in terms of micro-Deval and LA comminution resistance indices were one category higher for regular particles, and two categories higher for irregular grains, comparing to the raw material. Full article