Particle Size Grading Research Articles

Design and performance evaluation of a new green pavement: 100% recycled asphalt pavement and 100% industrial solid waste

In order to achieve sustainable development of road construction while addressing the occupation of land resources and the environmental impact of recycled asphalt pavement (RAP) and industrial solid waste, as well as the problem of insufficient resistance to permanent deformation and durability of conventional asphalt pavement, this study designed a new type of green pavement, which uses 100% RAP to form a large void matrix skeleton and 100% solid waste to prepare grouting materials. Research has found that green pavement has significantly higher high-temperature stability and durability than conventional asphalt pavement. The green pavement formed with a continuous gradation RAP matrix skeleton can be 100%–1000% higher than the green pavement formed with a single particle size gradation RAP matrix skeleton under the same fatigue stress ratio and load. At the same time, it also has significantly higher low-temperature bending characteristics, strength characteristics, and crack resistance. The above indicates that the green pavement designed in this study has good pavement performance, mechanical properties, and durability, especially the green pavement formed with a continuous gradation RAP matrix skeleton.

Detection of rockfill gradation based on video image recognition

The gradation properties of earth-rock dam-filling materials primarily influence their mechanical properties after compaction. Herein, combined with the characteristics of rockfill gradation detection (RGD) requirements in practical engineering, an intelligent detection method for rockfill gradation based on video image (VI) recognition technology is proposed and applied to engineering applications. By designing a device for VI recording, multi-group RGD tests are conducted. Further, a method for rockfill identification and particle size gradation transformation based on VI is proposed. The accuracy and error of the RGD in traditional screening and VI recognition method are compared and analyzed. The results of the laboratory tests and engineering applications in a construction site reveal that the proposed RGD method is highly efficient, precise, and robust.

Impedance Factor of Hydraulic Conductivity for Frozen Soil Based on Ice Segregation Theory and Its Application

AbstractThe necessity and rationality of using an impedance factor in the calculation of hydraulic conductivity of frozen soil has been an ongoing debate. To address this issue, ice segregation theory was used to analyze the physical meaning of the impedance factor. Based on assumptions sourced from segregation theory, experimental evidence regarding the hydraulic conductivity of frozen soil and the Gibbs‐Thompson effect, a relationship between the impedance factor and soil parameters was deduced. The necessity of the impedance factor was discussed under closed unsaturated and open saturated freezing systems. Finally, the derived impedance factor was compared with the current empirical impedance factor. The results showed the following: (a) The impact of the impedance factor on closed unsaturated freezing systems was small. However, an impedance factor was necessary for water migration in freezing systems with a high degree of ice segregation, such as open saturated freezing systems. (b) The derived impedance factor combined with the VG model had good performance for simulating water migration under different freezing conditions. (c) Compared with the empirical impedance factors, the derived impedance factors considered the effect of segregation acceleration caused by the pore expansion, improving the simulation accuracy of water migration at the freezing front. The parameters used to derive the impedance factor were only the initial porosity and the accumulative curve of the particle size grading, which was easily applied and combined with a VG model as a general method for computing the hydraulic conductivity of frozen soil.

Study on dynamic adsorption characteristics of gangue to heavy metals in goaf and its water purification mechanism under leaching condition

Arid and semi-arid mining areas in Western China are faced with the problems of water shortage, large water inflow of mines and high-salinity of mine water. When the broken gangue is backfilled to the goaf by the solid backfilling mining technology, a large number of voids between the blocks is generated, which can store groundwater and purify water quality. In this study, the real void structure of the gangue backfilling body in the goaf was obtained through CT scanning. By using the COMSOL numerical simulation software, a coupling model of Free and Porous Media Flow and Transport of Diluted Species in Porous Media was established. From the mesoscopic void scale, the effects of particle size distribution, inflow velocity and ion concentration on the flow field characteristics, ion migration and dynamic adsorption characteristics of gangue in the leaching column were explored, and the purification mechanism of broken gangue to heavy metals in mine water was revealed. The results show that: (1) The larger the gangue particle size gradation, the larger the void size, the higher the velocity in the void, and the more significant the average flow velocity difference between the void area and the gangue area. With the increase of inflow velocity, the average velocity in the gangue area and void area also increases, but the average flow velocity in the void area is 5.36 times that in the gangue area; (2) Both the larger particle size gradation of gangue, higher inflow velocity and inlet concentration can improve the velocity of the ion migration in gangue leaching column; (3) The greater the inlet concentration, the faster the flow velocity, the higher the total adsorption rate of gangue in the leaching column; (4) Both decreasing the particle size gradation of the gangue and increasing the inlet concentration can increase the total adsorption capacity of gangue in the leaching column; (5) The removal of heavy metals by gangue is the result of physical adsorption, ion exchange and other reactions. The research results can provide theoretical reference and data support for the treatment of high-salinity mine water in mining areas of Western China.

Analysis and Improvement of Oversize Goaf Backfill Engineering Based on Fuzzy Theory

For the mine of large goaf, there are many factors that affect the filling quality. In order to improve the filling quality, it is necessary to identify the factors that have a significant impact. In this paper, the fuzzy mathematical method was used to analyze the five main factors (PC32.5cement sand ratio, slurry concentration, number of slurry lowering, dehydration and drainage, and tailing particle size grading) affecting the filling quality. The priority of each influence factor was calculated, and the priority set was established. It is found that the slurry launching point and particle size grading of the tailings have an obvious effect on filling quality. After increasing the slurry launching point and optimizing the particle size grading, the strength and uniformity of the filling body are improved.

Simulation experimental investigations on particle breakage mechanism and fractal characteristics of mixed size gangue backfill materials

The compression deformation and particle breakage of gangue filling materials are significantly affected by different particle size gradations. To study the mechanical behavior of mixed size gangue backfilling materials in-depth, a physical compression experiment of mixed size gangue was carried out by designing a scheme based on Talbot's theory and fractal theory was used to quantify the breakage degree of mixed size gangue particles. Then, a discrete element numerical simulation was used to study the particle breakage mechanism of mixed size gangue in the compaction process. The results show that under the same vertical load, the settlement decreases monotonically with the increase in the Talbot's exponent (n), and the filling effect is significantly enhanced. The particle size distribution of mixed size gangue sample after compression has extremely good fractal characteristics. The fractal dimension has superior linear function regression relationship with n and crushing ratio. The fractal dimension decreases with increasing n. and the crushing ratio declines with increasing fractal dimension. Large-particle-size gangue is mainly broken at the initial stage of loading, while the crushing ratio of small-particle-size gangue gradually increases after the compaction stage. Large-particle-size gangue is the main bearing structure of the strong force chain, thus forming a strong skeletal structure. In the process of axial loading, cracks are mainly distributed near the “force chain skeleton”, and the contact forces around the skeleton are the first to be broken. This phenomenon causes the breakage of gangue particles, the rearrangement of particle positions and greater subsidence to fill the pores.

Effect of particle size and particle size distribution on critical state loci of granular soils

The critical state soil mechanics captures a wide range of stress–strain behaviour in an understandable context. It provides a conceptual framework for predicting soil behaviour and that is why the critical state is a central part of most advanced constitutive models. This study aims at quantifying the effects of both particle size, and particle size distribution on the critical state loci. Two soils, a natural soil and a tailings, were selected and CSLs were identified for twelve uniform and well graded particle size distributions. Mineralogy and particle shapes were rigorously quantified to ensure other factors are not influencing the results. Particle size has a small influence on the CSL in the sand to gravel range, but silts can have a significantly different CSL. In both natural soil and tailings, particle size distribution appears to have a significant influence on the CSL in e − log p′space and little influence in q − p′ space. Well graded soils have lower CSLs compared to uniform ones, that are generally parallel to the CSLs of their dominant constituent, with the exception of convex distributions where progressively finer particles in larger proportions can form structures noticeably less compressible than any of their constituents.

Assessment of Poorly Compactable Sands by Recycling and Recompaction: Experimental Program and Packing Particle Analysis.

Compaction is a common ground improvement technique based on the densification of soils for an energy level and optimum water content, mainly influenced by the particle size and curve gradation. Poorly compactable sands, characterized as cohesionless, fine and uniformly graded, are a challenge for earthworks since compaction is not effective due to the lack of a larger range of particle sizes to infill the voids and the compaction energy is not relevant either. These characteristics are common to other materials, i.e., desert sand, industrial or mining by-products or quarry fines, which are mostly discarded to landfill and replaced by proper soils, causing serious environmental issues. To enlarge the technical feasibilities of poorly compactable sands, reducing construction waste and raw material consumption, a mechanical stabilization, based on a repetitive series of recycling and recompaction without binder, is experimentally explored. The behavior observed is also analyzed from reported correlations and a packing particle approach, attending to densification stage, saturation degree, recompaction series, coordination number and packing density. The improvement achieved is moderate and dependent on the cycles applied, showing a characteristic repetitive pattern in the compaction curve, and approaching the estimated minimum void ratio and the theoretical maximum packing possibilities without degradation of the material.

Enhanced comprehensive properties of stereolithography 3D printed alumina ceramic cores with high porosities by a powder gradation design

• A novel powder gradation design strategy greatly enhances comprehensive properties in ceramic cores by SLA 3D printing. • Particle sizes importantly determine sintering degrees in SLA 3D printed ceramic cores. • The fracture mode of coarse powders varies with changing particle size gradation. • A "non-skeleton" microstructure model is established for SLA 3D printed ceramic cores. • Porosity presents more effect on high-temperature deflection of ceramic cores than particle size. Ceramic cores with complex structures and optimized properties are critical for hollow turbine blades applied in aeroengines. Compared to traditional methods, additive manufacturing (AM) presents great advantages in forming complex ceramic cores, but how to balance the porosity and strength is an enormous challenge. In this work, alumina ceramic cores with high porosity, moderate strength, and low high-temperature deflection were prepared using stereolithography (SLA) 3D printing by a novel powder gradation design strategy. The contradiction between porosity and flexural strength is well adjusted when the mass ratio of the coarse, medium, and fine particles is 2:1:1 and the sintering temperature is 1600 °C. The fracture mode of coarse particles in sintered SLA 3D printing ceramic transforms from intergranular fracture to transgranular fracture with the increase of sintering temperature and the proportion of fine powders in powder system. The sintered porosity has a greater influence on the high-temperature deflection of SLA 3D printed ceramic cores than grain size. On this basis, a "non-skeleton" microstructure model of SLA 3D printed alumina ceramic cores is created to explain the relationship between the sintering process and properties. As a result, high porosity (36.4%), appropriate strength (50.1 MPa), and low high-temperature deflection (2.27 mm) were achieved by optimizing particle size gradation and sintering process, which provides an insight into the important enhancement of the comprehensive properties of SLA 3D printed ceramic cores.

Configuration effect and mechanical behavior of particle reinforced aluminum matrix composites

Strength-toughness matching of particle reinforced metal matrix composites (PRMMCs) has become a key issue to meet their increasing requirements for aerospace, defense and transportation. Composite configuration (i.e., spatial distribution of reinforced particles) can make effects on the mechanical properties of PRMMCs. In this work, structural modeling and properties simulations of silicon carbide particle reinforced aluminum matrix composites were combined with particle swarm optimization to screen the composite configurations with superior mechanical performances. Configuration effect on the strength-toughness matching of PRMMCs were quantitatively indicated by analyzing the particle clustering degree and particle size gradation in the screened composite configurations. A particle clustering parameter was proposed to quantify the particle clustering effect, in which the composite configurations with serious particle clusters yielded much lower toughness. Composite configurations with increasing small particles can produce larger strength and toughness, while the particle size gradation can be presented by the linear and sigmoid functions respectively.

Rheological Impact of Particle Size Gradation on GAP Propellant Slurries.

Over the years, widespread interest has been placed on rheological properties to reflect the processability of propellant slurries. Particle gradation technology plays an essential role in the improvement of the processability of propellant slurries. In this article, rheological properties of glycidyl azide polymer (GAP) propellant slurries were measured by dynamic rheological measurements with a rheometer. Submicron-sized (d 50 = 0.221 μm) and micron-sized (d 50 = 33.02 μm) CL-20 particles and ultrafine (d 50 = 2.40 μm) and micron-sized (d 50 = 341.69 μm) AP particles were utilized to investigate the influence of the addition of CL-20 and particle size gradation on rheological properties. The test results demonstrate that the LVE region remains almost invariable while the yield transition process is delayed when the relative content of submicron-sized CL-20 increases from 10 to 20%. The values of G', G″, and |η*| increase with increasing submicron-sized CL-20. Despite this, the value of |η*| can be effectively reduced to about the same value as the slurries with bimodal AP by the size gradation of CL-20. In addition, particle porosity appears to be a suitable parameter to predict trends concerning the rheological properties of the GAP propellant slurries.

Deformation failure and acoustic emission characteristics of continuous graded waste rock cemented backfill under uniaxial compression.

In order to study the effect of backfill aggregate particle size on the compressive strength and failure mode of cemented backfill, uniaxial compression tests were carried out on seven kinds of cemented backfills with different particle size gradations. By analyzing the AE characteristics during the failure process of the backfill, the damage evolution mechanism of the cemented backfill with different particle size gradations was discussed. The test results show that with the increase of the Talbot gradation index n, the compressive strength of the backfill specimens first increases and then decreases, and the failure mode gradually changes from shear failure to tensile failure. With the increase of particle size gradation, the particle size of aggregate increases, the interface between aggregate and cement matrix is more likely to be fractured, and the characteristic parameters of acoustic emission are more active. During the failure process of backfill, the AE energy rate increases rapidly in the plastic development stage, and reaches maximum value before and after the peak stress, which can be used as the precursor to judge the failure of waste rock cemented backfill. According to the test results, the damage model and constitutive equations of waste rock cemented backfill with different Talbot particle size gradations are established, which can provide engineering guidance for filling mined-out areas with waste rock to ensure safe production of mines.

Effect of key design parameters on high temperature performance of asphalt mixtures

• Four key design parameters were selected to study their effect on the high temperature performance of asphalt mixtures. • The uniaxial penetration shear test was applied to analyze the variation of high temperature performance of asphalt mixtures. • The multi-way (one way and two-way) ANOVA was adopted to understand the role of factors on the high temperature performance of asphalt mixtures. Rutting is one of the main distresses for asphalt pavements and it has adverse effect on service life. It is associated with the high temperature performance of asphalt mixtures. The paper attempts to investigate the effect of key design parameters on high temperature performance of asphalt mixtures. Initially, the factors consisting of air void ratio, compaction effort, maximum nominal particle size and asphalt binder grade were selected and then the uniaxial penetration shear test was applied to analyze the variation of high temperature performance of asphalt mixtures. Accordingly, the maximum penetration load and the shear strength were used as evaluating indicators. Eventually, the multi-way (one way and two-way) ANOVA was adopted to understand the role of factors on the high temperature performance. The results indicate that the high temperature performance increases an average of 30 % when compaction effort and maximum nominal particle size rise. In contrast, the raise of asphalt grade and air void ratio decrease of 10 %∼30 % of high temperature performance. At the same time, the increase of compaction effort improves the high temperature performance about 20 %∼50 % at two variables condition. In one-way ANOVA, there is no statistically significant difference in the maximum penetration load when changing the air void ratio levels. The compaction effort, maximum nominal particle size, asphalt binder grade significantly influence the change of maximum penetration load. In terms of two-way ANOVA, any combined two factors significantly affect the high temperature results. This provides some guidance for design of asphalt mixtures to elevate high temperature performance.

Influence of particle size distribution on fractal characteristics of waste rock backfill materials under compression

Broken waste rock as backfill materials is filled into the underground goaf and will encounter particle breakage under the overburden pressure. The damage degree of the crushed waste rock materials directly affects the compression properties of the backfill body and the control effect of strata movement and surface subsidence. Fractal theory can be used to quantify the breakage degree of waste rock particles. In this study, compression tests are carried out on the broken waste rock materials with different particle size distributions to investigate the influence of the particle size distribution on the fractal characteristics of waste rock backfill materials under compression. The results show that the waste rock specimens with discontinuous size grading and containing more coarse particles have higher stress when entering the stable deformation stage, larger strain if at the same stress level and larger breakage ratio after compression. The particle size distribution of the crushed waste rock specimens after compressive loading has superior fractal characteristics and the fractal dimension increases with the content of fine particles and decreases significantly under discontinuous size grading. The fractal dimension has significant negative exponential function regression relationship with the strain and the breakage ratio. The strain and the breakage ratio decline with the growing fractal dimension. If the waste rock specimens have continuous particle size gradation and higher content of fine particles, the fractal dimension, the strain and the breakage ratio of the waste rock backfill materials tend to be optimal and stable, proving a desirable initial particle size distribution of the waste rock backfill materials.

An Analysis of Reclaimed Asphalt Pavement from a Single Source—Case Study: A Secondary Road in Romania

The paper presents a comprehensive analysis on reclaimed asphalt pavement (RAP) milling material collected from a single source, namely from a secondary road in Romania, county road DJ109. The following characteristics are investigated: particle size, binder content, material variability and uniformity, and the clustering phenomena. Variability is demonstrated using the results of particle size gradation and binder content. The coefficient of uniformity and the coefficient of curvature demonstrate that the RAP used in this research is a well-graded material. However, the visual analyses conducted on RAP highlight the presence of RAP particle agglomeration and the need for further testing. The study presents three different experimental phases: (i) RAP-milling old asphalt pavement, RAP; (ii) RAP milling after binder extraction, RAPabe; and (iii) RAP after Los Angeles crushing, RAPac. After processing, the coarse part (C) had a great influence on the fine part (F), and F/C ratio increased, respectively, from 0.4 to 1.5 and 1.61. Material variability on the extended site, the difference between the design values and particle size, as well as the existing clustering process indicated that RAP material collected from secondary roads must be pre-processed prior to its storage and reuse in the recycling process. Considering that secondary roads represent 71% of the overall network of asphalt course roads in Romania, and around 24,000 km of roads are in need of at least extensive maintenance (wearing asphalt courses) or rehabilitation, RAP is a highly recyclable material. Therefore, this study provides advice and guidance for re-using RAP in new pavement mixtures.

Stability analysis of varying height waste dump in open-pit mine under particle size gradation and reconstruction effect of waste materials

ABSTRACT This study determines the safety-stability factors of the waste dump benches at different heights and analyses the deformation law, stress variation, and crack propagation characteristics of typical slope models. The meso-mechanical parameters obtained by discrete element numerical simulation are modified through slope radar monitoring data. The results show that the critical height of the dumping benches of the studied open-pit mine is 60 ~ 70 m, and the amount of bench settlement is positively correlated with the height of the benches. After the critical height is exceeded, the bench forms a three-wedge failure due to uneven settlement.

Research on the working performance of fouled ballast bed under the multi-scale effect

In order to explore the influence of different particle size gradations of dirty materials on the service performance of the ballast bed, the clean track bed, the completely fouled ballast bed polluted by coarse coal and fine coal, respectively, were studied based on the discrete element method. In order to explore the influence of the multi-scale particle size gradation of the dirty material on the service performance of the ballast bed, the clean ballast bed, the completely dirty ballast bed polluted by coarse-particle coal, and the completely dirty ballast bed polluted by coarse-particle coal were simulated, respectively, based on the discrete element method, which are used to analyze the dynamic response of track bed under different working conditions under cyclic load. The model is verified by the lateral resistance and vertical stiffness of the ballast bed to prove the accuracy of the discrete element model. On this basis, the dynamic cyclic load is considered to analyze and study the mechanical response and change law of the ballast bed with different degrees of contamination. Studies have shown that after the ballast bed is contaminated, its lateral resistance and vertical support stiffness are reduced, the amount of settlement increases, the coordination number between ballasts is declined, and the fine-grained dirty material has a worse effect on the ballast bed; The displacement value of the ballast particles decreases with the increase of the depth of the ballast bed; The displacement value of the ballast particles under the rail is the largest, and the ballast particles on the ballast shoulder appear dilatancy; The displacement of the ballast particles at the laterally symmetrical position of the track structure is close to but not completely same; Dirty materials aggravate the frequency of ballast particles, and the impact of fine-particle coal powder is particularly significant.

Axial compressive behavior of square steel tube confined rubberized concrete stub columns

An innovative square steel tube confined rubberized concrete column is proposed in this study to alleviate the pollution from waste rubber and improve the mechanical properties of conventional concrete. The axial compressive behavior of square steel tube confined rubberized concrete (Ru-STCC) stub column is experimentally studied. A total of thirty-two specimens, including four square steel tube confined concrete (STCC) stub columns and twenty-eight Ru-STCC stub columns, were fabricated and tested. The variables included rubber particle volume replacement ratio, steel tube thickness, rubber particle size and concrete strength grade. The failure mode, axial ultimate compressive strength, rigidity, ductility, strain characteristics, and confinement effects were analyzed. The results show that the failure modes of Ru-STCC specimens were the core concrete shear failure and steel tube buckling. Ultimate axial compressive strength and rigidity were found inversely proportional to the volume replacement ratio, When the volume replacement ratio reached 20%, the ultimate axial compressive strength and rigidity reduced by more than 20%. With the increase of steel tube thickness, the ultimate axial compressive strength increased by more than 10%. Concrete strength grade and rubber particle size have significant effects on rigidity and ductility, respectively. In addition, the differences between square concrete-filled in steel tube (CFST), rubberized concrete-filled in steel tube (Ru-CFST), STCC, and Ru-STCC stub columns were discussed by compressive strength and deformation capacity. The axial ultimate compressive strength of square Ru-STCC specimens was evaluated using various calculation models. The simplified formulae for the prediction of axial ultimate compressive strength were also presented.

Effect of Physical Properties and Chemical Substitution of Excipient on Compaction and Disintegration Behavior of Tablet: A Case Study of Low-Substituted Hydroxypropyl Cellulose (L-HPC)

As final attributes of dosage form largely depend on the properties of excipients used, understanding the effect of physicochemical properties of excipients is important. In the present study, six grades of L-HPC with varying degrees of particle size and hydroxypropyl content and the influence of the grade on compaction as well as disintegration behavior were studied. All grades of L-HPC were compressed at different compression loads to achieve different tablet porosity. Compressibility and compactibility of L-HPC grades were evaluated using a modified Heckel equation and percolation model. Further effects of particle size and hydroxypropyl content of L-HPC on tablet porosity and disintegration time were evaluated using a 32 full-factorial design. From compaction studies, it was found that compressibility of L-HPC largely depends upon the particle size with lower particle size grade showing lower compressibility. Whereas consolidation/bonding behavior of L-HPC is independent of particle size and % hydroxypropyl content. By factorial design, it was found that particle size and % hydroxypropyl content have a significant effect on the disintegration behavior of L-HPC. It was found that smaller particle sizes and higher hydroxypropyl content of L-HPC show longer disintegration time. Thus, careful consideration of excipients selection should be made to achieve desired quality attribute of the product.

Physical and mechanical characterization of pyroclastic materials in Baleng area (Bafoussam, West-Cameroon): implication for use in civil engineering

Bafoussam, like other regions along the Cameroon Volcanic Line has huge pyroclastic resources. These materials are widely used in civil engineering works and result from different volcanic activities and therefore display locally different geotechnical properties. Thus, pyroclastic rocks in the Takouche quarry (Baleng-Bafoussam) were subjected to physical and mechanical analysis in order to determine their suitability and to optimize their use in civil engineering. Results indicate that the Takouche pyroclastic rocks are organized in five strata according to their color, structure and grain size. Except the stratum 2 with a water content of 14.4%, the others and the mixture of all strata displayed a low water content (> 7%) and therefore a low percentage of fine particles and are suitable for the production of concretes and realization of pavement bases. Based on absolute density (2.53–2.75 t/m3), pyroclastic materials of Takouche are common aggregates of the ungraded sand type and can be used for road construction and concrete works. The sand equivalent (69.0–92.8%) and the absorption coefficient (0.01–0.14%) reveal that these materials are very clean sands and contain poorly accessible pores. However, materials of stratum 2 with a sand equivalent of 69.0% and absorption coefficient of 0.14% allow the formation of concretes, exclusively with the use of Portland cement. The optimal dry density (1.83–2.07 t/m3) and optimal water content (8.0–12.5%) which are Optimum Proctor Modified parameters evidenced that materials from stratum 2 require treatment/correction before their use in road embankments. Meanwhile, materials from the remaining strata and the mixture of strata can be directly used and need to be improved only as base layer for heavy traffics T4 and T5. Referring to the 95% CBR values which range from 25 to 98, materials of stratum 1 and the mixed strata can be used as base layers for T3 traffic. In the mean-time, materials from stratum 3 and stratum 4 can be used as base layers for roads with a low volume of traffic. Nevertheless, materials from stratum 2 with a 95% CBR value of 25 need to be improved before their use as base layer. Moreover, the particle size distribution curves of materials extracted from stratum 1 to stratum 4, and the mixture of all strata do not belong to any particle size grading of sand for concrete. This study suggests proposals with the aim to improve the quality of the studied materials for their better use as concrete sand and backfill material. The correction involves the addition of fine volcanic ash to the pyroclastic rocks collected near the Takouche quarry. The resulting gains in compressive strength of concrete are quite considerable and vary from 52.87% to 97.23%, compared to the strength of concrete usually formulated by local users. The CBR coefficient after correction increases significantly with the maximum value of 115. Finally, the corrected aggregates provide good characteristics for their better use in road construction and concrete formulation.