Search Results (32)

This study presents the geotechnical evaluation of phosphogypsum, a byproduct of phosphate fertilizer production. The objective is to assess the suitability of phosphogypsum or its mixtures with natural materials as a technically viable and environmentally responsible backfill material for the restoration of closed and abandoned quarries. This study adds to the scarce existing literature on the use of phosphogypsum for quarry reclamation and further investigates the behavior of phosphogypsum mixtures incorporating clay and marble dust. A comprehensive experimental program was conducted to evaluate typical geotechnical properties, i.e., grain size distribution, Atterberg limits, compaction characteristics, permeability, compressibility, and shear strength. The results indicate that phosphogypsum is fine grained, low in plasticity, and exhibits relatively high permeability and compressibility, which limits its application as a deep fill material. The addition of clay increased the liquid and plastic limits but had a limited positive effect on strength and compressibility. In contrast, mixtures with marble dust improved particle gradation, reduced permeability, and enhanced compaction behavior without significantly increasing plasticity or settlements. Notably, the most promising mixture of phosphogypsum with a modest proportion of marble dust demonstrates improved shear strength and reduced hydraulic conductivity, making it suitable for use in the upper layers of quarry fills. Full article

Chert gravel, a byproduct of sand quarrying, remains an underutilized material in construction due to its low microwave (MW) absorption and high mechanical strength. The present study deals with the potential of MW irradiation as a novel, energy-efficient method for processing chert gravel into high-quality aggregates, reducing reliance on virgin materials. The research systematically examines MW exposure duration (1–2.5 min), rock size (150–800 g), moisture conditions, and cooling methods (air vs. water quenching) to optimize fragmentation. Experimental results indicate that larger rock sizes (600–800 g) yield coarser, less uniform aggregates, while prolonged MW exposure (>2 min) induces extensive micro-fracturing, producing finer, well-graded particles. Water quenching significantly intensifies fragmentation, generating irregular but highly fragmented aggregates, whereas pre-wetted samples exhibit finer and more uniform breakage than dry samples. The findings introduce a novel approach for optimizing chert gravel fragmentation, a material previously considered unsuitable for MW treatment. The study proposed a customizable methodology for tailoring aggregate properties through precise control of MW parameters, offering a sustainable alternative to conventional crushing. The results contribute to resource conservation, reduced energy consumption, and climate change mitigation, paving the way for more sustainable construction practices. Full article

The disposal and recycling of industrial by-products such as marble and limestone powders pose pressing environmental challenges due to the substantial amounts of waste generated annually by marble processing plants and limestone quarries. The integration of these by-products into concrete production is justified by their widespread availability and the potential to alleviate the environmental burden. This study used a statistical mixture design approach to systematically assess the effects of limestone and marble powders, with varying fineness levels, as partial cement replacements (up to 17%) on the rheological and mechanical properties of self-compacting concrete (SCC). The experimental findings revealed that the density of the SCC mixtures ranged from 2475 to 2487 kg/m³. Mixtures incorporating limestone powder exhibited superior flowability, achieving a slump flow of up to 69 cm, an 8% improvement compared to those containing marble powder. However, marble powder with a specific surface area of 330 m²/kg demonstrated significant improvements in compressive and tensile strengths, with increases of 18%. Statistical analysis using analysis of variance (ANOVA) validated the reliability of the predictive models developed, which demonstrated coefficients of determination (R²) that exceeded 0.94 and p-values below 0.05. These models enable precise predictions of critical performance metrics, including density, slump flow, box flow, compressive strength, and tensile strength, thus reducing the need for extensive experimental procedures. Full article

The excessive use of materials that are generally difficult to discard, such as stone materials, has caused growing ecological concern. Among these, marble is extracted from quarries, but when the raw material is exhausted, these places are deserted. For this reason, several measures have been adopted in recent years to requalify these areas. In addition, recent technological developments involve the creation of innovative green materials that privilege the circular economy and waste recycling. This research presents the development of innovative, sustainable filaments for the fused filament fabrication (FFF) printing technique from recycled marble waste (MW) and biocompostable and biodegradable polylactic acid (PLA) matrix. MW was added to the polymer in concentrations of 10 wt.%, 20 wt.%, and 30 wt.%, and the blends were extruded to develop innovative green filaments. The chemical/structural properties of the raw materials and the thermal and mechanical features of the new composites were investigated. Composites containing 10 and 20 wt.% of MW showed good printability. In contrast, extrusion and printing difficulties were observed with 30 wt.% of MW. Finally, this paper proposes a project to renaturalize and requalify a disused marble quarry located in Trani (Apulia, Italy) with 3D printing devices using the newly produced eco-filaments, which have better features. The main purpose of this article is to propose a concrete, economic, and sustainable application of 3D printing involving processes such as waste and by-product recycling and renaturalization of disused quarries, with both economic and environmental benefits. Full article

Basalt rock dust (RD) is a rock quarry byproduct that may improve soil health in organic farming systems. RD was applied at two contrasting organic farms (the no-till VT-Farm in Thetford, Vermont, and the tilled MA-Farm in Barre, Massachusetts) and in soil batch reactors to investigate the impacts of basalt RD applications (6.7 tons ha⁻¹) on physical and chemical soil health properties. Triplicate soil pits at two fields (RD and no RD) at each farm were sampled down between 80 to 110 cm depths in 2020. Median coarse (>2 mm) and very coarse aggregates (>50 mm) increased by 15% to 25%, and soil organic carbon concentrations increased by 69% to 135% for RD added, compared to no RD, in the top 20 cm of the soil profile at both farms. Plant-available Ca, Mg, and K increased between 62% and 252% in the top 30 cm for both farms. Plant-available micronutrients (B, Mn, Cu, and Zn) showed limited increases from the RD addition at the two farms. The laboratory batch reactor results confirm the increased Ca and Mg release rates tested across soils, but K, P, and the micronutrient batch reactor results did not increase from the RD addition. One contrary finding was (−41% at the VT-Farm) the lower plant-available P and soluble P (−5 to −29%) under the RD addition, suggesting that further studies on the interactions with Fe and pH from the RD addition are warranted. Full article

The sourcing of raw materials is becoming an increasingly concerning issue for the European Union, which is adopting a series of strategies aimed at mitigating the dependence on third countries for procurement. The supply of feldspars, for instance, which is significant within the ceramic industry, raises concerns due to heavy reliance on third countries. Therefore, it is imperative to identify potential alternative sources for procurement, including the recycling of waste from the extraction of ornamental granite rocks enriched in such minerals. The Sardinia region in Italy, once a global leader in granite extraction, has now witnessed a significant reduction in production due to intense competition worldwide, resulting in severe economic repercussions. Additionally, traces of this period remain in the territory in the form of enormous quantities of extraction waste, defacing the landscape and posing potential environmental issues. This study is part of a broader research initiative aimed at identifying a physical process to concentrate rare earth element (REE) minerals from granite waste in a quarry located in Buddusò, Sardinia. The specific objective of this study is to analyze the whole rock composition, crushing powder, and the diamagnetic by-products generated by gravity and magnetic separations to identify potential applications for their use. Full article

This paper presents a study on the combined use of two by-products, namely quarry dust (QD) and ferronickel slag (FNS), as a full substitute for natural sand to improve the greenness of concrete production. Quarry dust was used in increments of 25% to a maximum of 75% substitution, where nickel slag was used as the remaining proportion of fine aggregate. All the combinations of quarry dust and nickel slag were found to be compliant with AS 2758.1 and they showed notably better grading than 100% sand. In this research, standard concrete tests, such as the slump test for fresh concrete, and compression, tensile and shrinkage tests for hardened concrete, were conducted. Scanning electron microscopy and X-ray diffraction analysis were also conducted for microstructural investigation. The results concluded that the combinations of quarry dust and nickel slag in concrete as a whole substitution of sand provide similar results for these properties. Specifically, 25% quarry dust with 75% nickel slag proved to be the most promising alternative to sand, with compressive and splitting tensile strengths of 62 and 4.29 MPa, respectively, which were 16% and 20% higher than those of the control mix. Also, lower drying shrinkage was observed for this combination compared to the control mix. The higher strength is attributed to the rough texture and angular shape of both quarry dust and nickel slag providing a better mechanical interlocking. The validity of this result has also been confirmed through image analysis of micrographs from various specimens. In microstructural investigations, specimens with QD and FNS exhibited fewer voids and a more compact surface compared to the control specimen. This shows the potential for further research into the use of quarry dust and nickel slag in the production of green concrete. Full article

Chert, a by-product rock of sand quarrying, has historically posed economic challenges for aggregate production, resulting in significant “waste” accumulation in quarries. Our study investigates the effect of microwave irradiation on the mechanical properties of chert gravel, a mineralogically homogenous material composed of fine quartz grains. The results, which demonstrate that increased irradiation time leads to a substantial decrease in chert gravel strength (by a factor of 4–6 for 2.5 min of irradiation), underscore the potential impact of this research on comminution processes. With quenching altering the fractional content of the samples after the crushing test, reducing the Gravel-to-Sand ratio, this study is driven by the promising potential of crushed chert gravel as a pivotal aggregate within the concrete and asphalt industries, offering a practical solution to their material needs. The urgent need to rehabilitate previously utilized quarry areas, offering an environmentally beneficial solution for which we all should be responsible, motivated the present study. Full article

Owing to the ongoing accumulation of industrial by-products, the management and disposal of waste have emerged as a significant issue. Employing these industrial wastes as an alternative to replace cement holds potential as a promising solution for conserving energy and reducing CO₂ emissions. In this study, pig and beef bone powder were used as cement replacements in concrete, and the mechanical properties were studied. Bone powders were prepared from random bones collected from local slaughterhouses, butchers, and restaurants. The pig bone powder (PBP) and beef bone powder (BBP) were prepared by direct fire contact, oven-calcined for 4 h at 300 °C, crushed, and sieved to size 0.4 to 2 mm. A concrete mix design was formulated for a target compressive strength of 21 MPa at 28 days of curing. This design included three different levels of cement replacement with each type of bone powder (10%, 15%, and 20% by mass). These mixes were then evaluated and compared to a control mix without any bone powder replacement (PB-0). This study evaluated the mechanical properties via compressive strength and flexural testing. The results showed that the workability of the mixtures decreased with the increase in bone powder content. Bone powder functions as a pozzolanic substance, engaging in a chemical reaction with the calcium hydroxide in concrete to produce compounds that exhibit cement-like properties; however, an increase in bone powder content worsened the mechanical properties. The most promising results were obtained for a 10% replacement percentage of BBP and PBP, obtaining strengths of 21.15 MPa and 22.78 MPa, respectively. These are both above the design strength, with PBP concrete even exceeding the strength of PB-0 (21.75 MPa). These results showed a good agreement with the standard values and allow to use these wastes as a replacement for cement, becoming a sustainable solution to the exploitation of quarry materials and, in turn, to the problem of contamination by biological waste from the meat industry. Full article

The use of quarry by-products can enable the commercialization of a clay building material (reconstituted earth) thanks to minimal valorized and perennial stocks of materials. This study shows that quarry by-products can be used to mix design a clay-based building material for the manufacture of CEB. These soils are composed of quarry tailing and clayey muds. Proctor and dry compressive strength tests have shown that the proportion of mud that achieves the highest possible compressive strength is a balance between increasing density through the aggregate arrangement, increasing clay activity, and decreasing density through the increase in water content. These tests resulted in the formulation of materials with compressive strengths of 5.8 MPa and 8.4 MPa at densities of 2135 kg/m³ and 2178 kg/m³. The influence of mud incorporation on the material granulometry and on its characteristics was also studied. Moreover, a model allowing us to link the compressive strength, the clay activity, and the dry density is proposed for the materials composed of quarry by-products. This model enables us to facilitate the mix design and the standardization of the earth material. Full article

Emulsion aggregate mixtures (EAMs) are aggregate blends stabilized with an asphalt emulsion for pavement base layer applications. These are typically prepared using crushed aggregates and designed primarily using a tensile strength-based criteria. Advances in granular material testing technologies have led to the development of advanced resilient response characterization devices such as the University of Illinois FastCell (UI-FastCell). Simultaneously, fractionated reclaimed asphalt pavement (FRAP) and Quarry by-product (QB) materials are becoming increasingly common in pavement construction. This paper evaluates the inclusion of QB and FRAP in EAMs. First, the design of selected EAMs was performed using a combined Asphalt Academy TG2 and Anderson and Thompson mixture design approach. The selected mixtures were first assessed for Indirect Tensile Strength (ITS) and Tensile Strength Ratio (TSR) to track changes in both strength and moisture damage resistance with the inclusion of FRAP and QB. In addition, advanced anisotropic resilient characterization was performed using the UI-FastCell to assess the changes in resilient modulus and permanent deformation characteristics. Our results show significant enhancements in tensile strength, increased moisture damage resistance, and reduced permanent deformation with the inclusion of FRAP and QB materials in EAMs. The combined inclusion of 30% FRAP and 70% QB negatively affected the resilient response of the EAM; however, the inclusion of FRAP content to 50% with no QB materials improved its suitability for pavement base layer application. Full article

In the present work, rock dust was evaluated as an adsorbent and heterogeneous photocatalyst in the discoloration of Basazol Yellow 46 L dye, which is widely used in the dyeing of molded pulp packages. Although rock dust is produced in large quantities in quarries as a byproduct of rock exploration, little is known about its application as a photocatalyst. Rock dust was characterized by XRD, SEM/EDS, photoacoustic spectroscopy, and N₂ physisorption and had its photocatalytic activity assessed through phenol and salicylic acid degradation tests. The characterization results showed that the rock dust is mainly composed of silica and alumina in a triclinic structure, has a bandgap energy of 2.36 eV, and has a specific area of 1.5 m²/g. Rock dust was proven to be photocatalytically active in phenol and salicylic acid degradation tests and also presented the adsorptive and photocatalytic capacity for the discoloration of effluent containing Basazol Yellow 46 L dye. Full article

Quarry by-products (QB) pose a major environmental challenge for quarries as they accumulate in large quantities, and their beneficial uses are continually sought out. Research at the Illinois Center for Transportation introduced seven applications to utilize QB in chemically stabilized base/subbase pavement layers. These applications were evaluated for field performance through accelerated pavement testing. This paper presents results for the environmental benefits and trade-offs of including QB or blends of QB with recycled materials in pavements. The seven QB applications and a control section were evaluated in terms of environmental impacts using life cycle assessment (LCA). The LCA was conducted in accordance with the International Standard Organization ISO 14044:2006 guidelines. The life cycle impacts were calculated in terms of energy consumption and global warming potential. Three scenarios for (1) as-constructed thicknesses, (2) as-designed thicknesses, and (3) thinner sections for local roads were considered. LCA analysis results were interpreted in terms of the normalized impacts and the response benefits based on falling weight deflectometer resilient deflections to reflect on the impacts due to relative service life expectancy. It was shown that cement-stabilized QB pavement layers, particularly those having QB blended with recycled pavement materials, can have lower environmental impacts when normalized over pavement life and anticipated traffic (i.e., when pavement life expectancy is considered). Full article

Geopolymer-based sustainable red mud bricks (SRMBs) were cast using industrial by-products under ambient curing. The ingredients used were red mud, fly ash, ground granulated blast furnace slag and alccofine, along with quarry dust and alkali activators as binders. This paper briefly presents the characterization, strength and durability studies conducted on SRMBs. The optimization techniques were used to fix the right mix proportions. The optimized mix proportion was identified as R45F40G10A05: 45% red mud, 40% fly ash, 10% ground granulated blast furnace slag and 5% alccofine. The compressive, flexural and split tensile strength of the ambient-cured specimens after 28 days were observed as 35.38 MPa, 6.4 MPa and 1.67 MPa, respectively. The results were analysed and validated by the finite element method using Analysis of Systems (ANSYS) software. The percentage of water absorption in the SRMBs was less than 6%, and it was an entirely efflorescence-free product with a pleasing appearance and colour. Fifty percent of the targeted compressive strength was acquired after three days of ambient curing. SRMBs are a green product casted by encapsulating industrial by-products into a functional building element. Thus, SRMBs are a suitable and alternative product to conventional clay burnt bricks. Full article

The infrastructure demands for mega cities, urbanization and environmental concerns are pushing for smart and sustainable solutions. Structural lightweight concrete is gaining popularity in the concrete industry because of its intrinsic properties of resisting the load and being lighter in weight. Therefore, in this study, a green structural lightweight concrete was targeted by fabricating a plastic-based aggregate incorporating different industrial by-products to reduce the carbon tracks along with an alternate lightweight structural material. Thus, the compatibility of the different industrially by-products (dune dust, fly ash, and quarry dust) with plastic to produce a sustainable structural lightweight aggregate was evaluated in this study. The major physical characteristics of manufactured aggregates along with fresh, hardened, and durability properties of concretes were studied. Results revealed that altering the filler type had altered the texture and size of the developed aggregate. The aggregates developed with dune dust showed the largest particle size, bulk specific gravity, and strength while the ones with fly ash had the smallest size and water absorption. The decrease in the strength was found to be 24.7, 43.6, and 29% for dune dust, fly ash, and quarry dust respectively, once the filler percentage was increased from 50 to 70%. Additionally, all the concretes incorporating developed aggregates have evidently demonstrated their likely usage in structural lightweight applications by complying with ASTM C330/C330M-14 for compressive, flexural, and splitting tensile strength values, in addition to the improved durability behavior. Full article