Stone Mixture Research Articles

Mix Design and Field Detection of Large-Particle-Size Graded Crushed Stone Mixtures for Pavement Reconstruction

Large-particle-size graded crushed stone mixtures (LPS-GCSMs) can improve the shortcomings of conventional graded crushed stone, such as low strength, high deformation, and a low modulus of resilience. At present, there is no systematic research on the gradation design and field evaluation of the LPS-GCSMs. In this study, compaction and California bearing ratio (CBR) tests and field construction conditions were combined to design six kinds of gradation of LPS-GCSM, and the optimum gradation was revealed. In order to improve the mechanical properties of LPS-GCSM, 2.5% cement was added to the mixture to prepare a low-content cement-modified LPS-GCSM (LCC-LPS-GCSM) based on the suggested gradation. The mechanical properties of the LCC-LPS-GCSM were investigated through unconfined compression strength (UCS) and compression rebound modulus (CRM) tests. Moreover, the compaction and deflection properties of LPS-GCSM and LCC-LPS-GCSM were examined through the test battery. The results showed that the optimum gradation of LPS-GCSM can be achieved with a combination of aggregate sizes of 20–40 mm, 10–20 mm, 5–10 mm, and 0–5 mm at a ratio of 44:20:10:26. The passing rates of 19 mm and 4.75 mm should be approximately at the median value of the gradation in view of field construction uniformity and a coarse aggregate interlocking effect. The UCS and CRM values of LCC-LPS-GCSM increased rapidly from 0 day to 28 days while they slowed after 28 days, which was similar to those of cement-stabilized materials. The field detection suggested that LPS-GCSM exhibited favorable compaction and that the addition of cement improved the stability of the field compaction of the mixture. Adding a subbase course of LPS-GCSM between the old pavement and the LCC-LPS-GCSM base can lead to more uniform stress on the base. The results of this study provide a reference for the gradation design of LPS-GCSM and optimization of the design indicators.

The influence of aeolian sand on the mechanical properties of cement stabilized crushed stone

The utilization of aeolian sand resources for road construction is a specific measure to develop green and low-carbon transportation, and also conforms to the concept of green and sustainable development of roads in China. Based on this, the feasibility of using aeolian sand as a substitute for fine aggregate for cement stabilized graded crushed stone was explored, and the effects of different aeolian sand dosages on the unconfined compressive strength, bending and flexural strength, and splitting strength of cement stabilized crushed stone mixtures were studied. The results indicate that the addition of aeolian sand has a significant deterioration effect on the mechanical properties of cement stabilized graded crushed stone mixtures. The larger the amount of aeolian sand added, the more severe its impact on the mixture. Therefore, controlling the amount of aeolian sand within 6 % can meet the mechanical performance requirements. To ensure the large-scale utilization of aeolian sand resources, future research can comprehensively consider the shrinkage characteristics, durability, and water stability of cement stabilized crushed stone mixtures, and further recommend the maximum dosage of aeolian sand.

Municipal solid waste incineration bottom ash recycling assessment: Carbon emission analysis of bottom ash applied to pavement materials

Inspired by the concept of conserving resources, bottom ash has been increasingly utilized in road construction as a readily available waste material. This study sought to address this gap by quantifying the carbon benefits associated with bottom ash application. Through a comprehensive analysis grounded in life cycle theory, author evaluated the changes in energy consumption and carbon emissions before and after the integration of bottom ash into the road construction process. The analysis employed the raw material production stages of different pavement materials as the system boundary. By determining the optimal amount of bottom ash and calculating the associated values, the study proposed an efficient application scheme for utilizing bottom ash in urban engineering construction projects. The results showed that bottom ash had the least carbon reduction effect in permeable bricks, followed by cement concrete and cement stabilized macadam mixture. The most significant effect was observed in asphalt mixtures. However, energy consumption increased with the addition of bottom ash in asphalt mixtures, whereas it decreased in the other three products. The carbon reduction after applying bottom ash was predicted based on the annual growth rate of urban road construction. Under the premise of maintaining the non-destructive application performance of asphalt mixtures, the optimal carbon reduction benefit for a 20% addition of bottom ash was approximately 17,369.9 tons. In cement-stabilized crushed stone mixtures, the optimal carbon reduction benefit ws achieved with a bottom ash content of 30%, approximately 15,797.7 tons. The practice of utilizing bottom ash in road works was significant in terms of maximising the benefits of carbon reduction.

Stability Control Method and Field Testing of High Embankment with Red Bed Soft Rock and Soil Stone Mixture Fill Roadbed

Post-construction settlement in embankments is a crucial quality indicator and a significant factor influencing the long-term stability of roadbeds. Especially for the mixed-fill materials, by considering the uncertainty of composition and mechanical properties, it is important to predict and take construction measures to control post-construction settlement. In this paper, taking the construction of high-fill embankments with red bed soft rock mixture as the background, the deformation characteristics of mixed-fill materials were revealed first. Then, a dynamic–static coupling method for roadbed filling was proposed, and corresponding control parameters were provided. Finally, by employing ABAQUS 2016 for long-term settlement numerical simulations and conducting load-bearing preloading tests, the deformation patterns of the high embankment with red bed soft rock mixture fill roadbed were revealed.

Experimental Study of the Freeze–Thaw Damage of Alpine Surface Coal Mine Roads Based on Geopolymer Materials

In the process of mining and transportation, the temporary non-hardened mine-road structure is mainly a mixture of soil and stone, which very easily produces dust hazards via crushing and wind transportation. Geopolymers can be used in the road’s soil and stone mixture so that the road reaches certain strength requirements in line with the short-term use of the mine. However, in alpine open-pit coal mines, which are subject to the influence of weather changes, freezing and thawing phenomena will affect the long-term use of the road and its normal and safe operation. An open-pit coal mine in Xinjiang, China, was chosen as the research object of alpine open-pit coal mines. Using the method of indoor testing, different freeze–thaw freezing temperatures, different numbers of cycles, changes in the mechanical properties of the mine-road materials, and microscopic changes were studied. From the experimental results, it was determined that with a reduction in the freeze–thaw freezing temperature, the specimen strength declines after stabilizing, and with an increase in the number of freeze–thaw cycles, the specimen strength exhibits a linear decline. The specimen’s internal structure gradually changed from dense to loose; the fracture mode changed from toughness fractures to crystal fractures after the removal of the maximum load reduction. The uniaxial compressive strength was reduced to 61%; the tensile strength was reduced to 49%. The fracture zone of the specimen was analyzed using energy spectra, and the main elements changed from O (57.19%), Si (17.07%), and Al (12.19%) without freezing and thawing to O (49.76%), Si (15.70%) and Ca (11.09%) after freezing and thawing.

Activated char from the co-pyrolysis of polystyrene and olive stone mixtures for the adsorption of CO2

Yogurt plastic containers made of polystyrene (PS), olive stone, and mixtures of both have been converted into activated carbon materials transforming them firstly into char via pyrolysis and secondly with activation using either KOH or H2SO4. The pyrolysis of the olive stone gave a higher yield of material than the plastic PS. However, the activation of the PS char with KOH was more effective, reaching surface areas of 508 vs 194 m2 g−1 of the corresponding prepared with olive stone. The prepared materials were tested as CO2 adsorbent in thermobalance and fixed-be column assays. The materials activated with H2SO4 slightly enhanced the adsorption ability of the original char but were far from the performance obtained with KOH activation. The CO2 isotherms showed high synergy of CO2 uptake and selectivity when using activated chars prepared with the char from the mixture of raw materials, specially at a 1:1 mass ratio. The isosteric heat of adsorption values were those expected for a physisorption process. Further experiments in a fixed-bed column were also studied at atmospheric pressure at different inlet CO2 concentrations (10–50%). The CO2 retention increased as the partial CO2 pressure rose. Besides, a very similar performance of the material prepared with plastic and olive stones was obtained at 50%, i.e. 220 and 197 mg g−1 respectively. At low CO2 concentrations, the materials enriched with plastic displayed better performance than those prepared with olive stone. Cycles of adsorption-desorption were carried out in the column to assess the stability of the materials. The curves obtained did not display any substantial change, demonstrating the lack of adsorption retention.

Use of a novel water separation process for the recovery of the mineral fraction from the stabilized organic fraction found in municipal waste.

Currently, the Stabilized Organic Fraction (SOF) 0-80 mm separated from the municipal waste stream is sent in its entirety to landfill in the mechanical-biological treatment plants operating in Poland. Such action does not align with the adopted EU strategy focused on waste management in the circular economy. This study aimed to assess the technical feasibility of the process of purification of mineral fractions with a grain size of 10-80 mm separated from SOF on a technological installation designed for glass recovery, built at the Marszów Plant. In terms of material, mineral fractions are a mixture of stones, rubble and glass, contaminated with various components, mainly organic. In 2020, the glass recovery installation was expanded with an innovative process of gravity separation to separate mineral fraction from SOF with the use of a jigging machine. A pulse jig used in the mining industry for coal enrichment processes was used for the first time in municipal waste management. The installation allows for the recovery of between 71.1 and 96.6% of mineral fractions contained in the input (84.8 ± 9.5% on average). The proportion of organics, plastics and other impurities in the waste is 4.1 ± 2.1% of the fraction mass. The process consumed water at an average rate of 0.34 ± 0.10 m3 tonnes-1 of treated waste and generated 0.26 ± 0.09 m3 tonnes-1 of wastewater. Electricity consumption averaged 1.20 kWh tonne-1 input.

Promising Ways to Recycle and Use Waste from Gas Purification Facilities of Alumina Production

For the disposal of dust from gas-cleaning facilities of sintering furnaces, in addition to a closed dust circulation scheme, a partial removal of it from electric filters for subsequent use in road construction is proposed. It is shown that dust collected from 4–5 fields of electrofilters containing chlorides and sulfates should be used as additives in a nepheline-crushed stone mixture, which will allow obtaining the required high frost resistance indicators of road mix samples.

Influence of the crushed stone content on the deformation modulus of the soil-crushed stone layer

Introduction. The purpose of the article is to study the dependence of the deformation modulus of the soil-crushed stone layer of the road surface from the content of crushed stone in the soil-crushed stone mixture and the soil moisture in it. The goal was achieved by performing stamp tests of the models of a road clothing and a roadbed.Materials and methods. The research was carried out by performing stamp tests of models of the roadbed and single-layer road clothes with a soil-crushed stone surface. Before the stamp tests, laboratory work were carried out to determine the parameters subject to input control for crushed stone and soil. Models of road clothes are built from crushed stone materials and soil in the tray. Tests of the roadbed and road clothes are carried out using a rigid round stamp included in the standard kit.Results. The modules of deformation of the soil of the roadbed and road surfaces with a soil-crushed stone layer are calculated from the polynomial dependence of settlement on pressure, regulated by ПНСТ 311-2018. According to the test results, the modulus of deformation of the soil of the roadbed, and the general modulus of deformation on the surface of the soil-crushed stone layer, with different content of crushed stone by the volume of the mixture, were determined. The lowest value of the deformation modulus corresponds to the minimum content of crushed stone in the mixture, which is 40 % by volume of the mixture. The highest value of the deformation modulus was obtained at the maximum content of crushed stone in the mixture, which is 60 % by volume of the mixture. Using the general modules of deformation of different road surfaces and the modules of deformation of the soil of the roadbed, the calculation of the deformation modulus of the soil-crushed stone layer with different content of crushed stone in it is performed. To take into account the influence of moisture of the cohesive soil used in the mixture, correction coefficients are given, the values of which are established by laboratory tests. These coefficients allow us to calculate the modulus of deformation of the soil-crushed stone layer depending on the content of crushed stone and the moisture of the soil used in it.Discussion and conclusions. As a result of experimental work, the modules of deformation of soil-crushed stone of different compositions were determined, with the help of which the design of road surfaces was carried out with the subsequent construction of experimental sites in each of the three road building climatic zones of the Omsk region.

Influence of soil moisture on the deformation properties of soil-crushed stone samples during compression

Introduction. The purpose of the article is to determine the dependence of the influence of soil moisture and the content of crushed stone in a soil-crushed stone sample on the secant modulus of deformation under uniaxial compression. The need for such a mathematical model is necessary in order to introduce correction factors to the values of the stamped deformation moduli of the gravel layer calculated from test data delivered at other soil moisture conditions, e.g. for flume or road tests during a non-calculated period of the year.Materials and methods. Cylindrical samples with a height of 20 cm and a diameter of 10 cm were made to perform tests using a large standard sealing device. The content of crushed stone of a mixture of fractions of 5-10 and 10-20 mm varied in the samples. The methods of saturation of samples with water and their testing by uniaxial compression are given. The rules for processing the experimental results are described, which include: correction of the initial part of the graphical dependence of deformation from pressure and statistical processing of the results. The analysis of methods for calculating the deformation modulus, which are classified into three types, is performed: secant module, tangent module and piecewise linear module. Based on this analysis, a method for calculating the deformation modulus of a soil-crushed stone sample under uniaxial compression is justified.Results. The results of experimental determination of the deformation characteristics of soil-crushed stone samples under uniaxial compression are presented. A mathematical model of the dependence of the deformation modulus of a soil-crushed stone sample from the soil moisture and the content of crushed stone used in the soil-crushed stone mixture is obtained.Discussion and conclusions. Recommendations are given on the application of the research results for the development of an album of standard constructions of road pavement of the lowest type in the districts of the Omsk region.

Matrix Suction Evaluation of Soil-Rock Mixture Based on Electrical Resistivity

The soil-rock mixture is an important construction material in practical engineering. Its physical properties, especially soil-water properties, are particularly important for on-site construction, while both matrix suction and electrical resistivity in unsaturated soils depend on the magnitude of moisture content, and a certain relationship can be established between the two physical quantities. Therefore, in this paper, we designed a matrix suction–electrical resistivity synergistic test device and conducted indoor physical tests on common soil-rock mixtures in the Chongqing area to investigate the correlation between matrix suction and electrical resistivity in soil-rock mixtures. The electrical resistivity comprehensive parameter was used to represent the electrical resistivity characteristics of rock and soil. Based on the experimental results, a matrix suction–electrical resistivity comprehensive parameter model applicable to soil-rock mixtures was established, and the sensitivity analysis of the model parameters was carried out. The results show that the soil-water characteristic curve of the soil-rock mixture has a double-step shape, and the shape of the curve under different compaction degrees is similar. The matrix suction and mass moisture content of the soil-rock mixture were positively correlated with the compaction degree. There was good consistency between the experimentally measured matrix suction and the matrix suction reflected by the electrical resistivity in the model. Moreover, the model curve was able to reflect the drainage process of pores in the soil for soil–stone mixtures with a bimodal pore size distribution, thus providing a new way to measure the matrix suction of unsaturated soil–stone mixtures in practical engineering.

Экотоксикологическая оценка влияния материала дорожных одежд на загрязнение почвы придорожной полосы

The ecological safety of the use of nepheline sludge in the construction of the lower foundations of pavements is shown. Using electron microscopy and chemical analysis, the area of influence of nepheline sludge used in the construction of road pavements on the roadside soil, which is limited by a distance of 10 m, was determined. Studies have been carried out on ecotoxicity using monocotyledonous and dicotyledonous plants and soil infusories of the genus Colpoda steinii. results, which confirmed the possibility of using nepheline sludge as a component of pavement in the form of nepheline-crushed stone mixture. Keywords: NEPHELINE SLAM, PAVEMENT MATERIAL, ECOLOGY, TOXICITY, ENVIRONMENTAL SAFETY

Effect of fiber on mechanical properties of cement stabilized macadam mixture

In order to improve the crack resistance of semi-rigid base materials, polyester fiber (PET), polypropylene fiber (PP), polyacrylonitrile fiber (PAN) and polyvinyl alcohol fiber (PVA) were selected to prepare cement-stabilized crushed stone mixture. The mechanical properties of fiber-cement stabilized crushed stone mixture were studied by unconfined compressive strength, splitting strength and compressive rebound modulus tests. The results show that the fiber can effectively improve the compressive strength and splitting strength of cement-stabilized crushed stone mixture when the fiber content is 0.05%-0.11%, and both the compressive strength and splitting strength of the mixture increase with the increase of fiber content. The compressive strength and splitting strength of the mixture with the same fiber and dosage showed a trend of slow growth first, then rapid growth, and then gentle growth during the curing period of 90d. Adding PET, PP and PAN reduced the compressive resilience modulus of cement-stabilized macadam mixture, while adding PVA increased the compressive resilience modulus of cement-stabilized macadam mixture.

Development of PMC Numerical Model for Soil and Stone Mixture

Soil and stone mixture is widely distributed in China, and its physical and mechanical properties are complex, which has a significant impact on geotechnical engineering. Usually soil and stone mixture shows anisotropic features along or perpendicular to the direction of settled layers, and the strength will be significantly affected by intermediate principal stress. True triaxial tests were carried on, Paul–Mohr–Coulomb (PMC) failure criterion was used for the strength analysis in soil-stone mixture, and related parameters of PMC model were obtained. A user-defined PMC numerical constitutive model was developed for FLAC3D. Composite failure criteria of shear failure and tension cut-off were applied for numerical analysis, and nonassociated flow rule was proposed based on the Mohr–Coulomb model. Verification modelling was applied as well, and deviation between analytical and numerical solutions in strains of X direction, Y direction, and Z direction was 1.0013, 1.0003, and 1.002, respectively.

Texture Depth and Cost Analysis of Slurry Seal Cationic Rapid Setting Cold Asphalt Mixture

Slurry seal is a mixture of asphalt emulsion, fine aggregate, mineral filler, water, and other added ingredients are mixed evenly without heating and is spread over the surface of the pavement with a maximum thickness of 10 mm. This study was conducted to determine the relationship of the depth texture and skid resistance resulting from the modification of the aggregate and filler slurry seal based texture depth test of sand patches. Slurry seal is made using basalt stone aggregate filler Ordinary Protland Cement (OPC), limestone filler aggregate OPC and aggregate rock with filler standard OPC composition: High Calcium Fly Ash 50%: 50%. Increasing the texture depth will add road surface roughness. Slurry seal with basalt stone aggregate having the largest texture depth is 1.837 mm so as to provide the greatest improvement of skid resistance. Texture depth slurry seal with limestone aggregate is 1,767 mm that mean increasing skid resistance. Slurry seal standard aggregate has a depth of 1,673 mm texture which represents an increase skid resistance smallest slurry seal between basalt stone aggregate and limestone. Slurry seal with cheapest price is limestone slurry seal aggregate Rp. 44,817.00 / m2 compared basalt aggregate Rp. 45,085.00 / m2 and a standard stone mixture of cement and fly ash filler Rp. 44,914.00 / m2.

On the Application of Diopside Rock of the Aldan Deposit in the Production of Concretes

The study on the possibility of heavy-weight concrete production using diopside aggregates from Aldanslyuda ore mining and processing plant has been conducted. It is established that diopside crushed stone, namely, the crushed stone mixture of fractions from 5 to 20 mm is suitable for concretes of strength class up to 60 MPa production. It is recommended to carry out further validating research on the application of diopside rocks in high-strength concrete production. To do that it is necessary to use river sand, the water demand of which is less than of the sand from sifting of crushing solid stone, as a fine aggregate or to replace part of the latter. The physical and mechanical properties of the concretes developed on the basis of diopside aggregates have been investigated.

Mechanical Properties of Gangue Cement Stabilized Road Foundation Mixture

In this study, coal gangue was used to replace the four single-graded natural gravels of 0~5 mm, 5~10 mm, 10~20 mm, and 20~26.5 mm to design the mix ratio and to study the influence in particle size changes of coal gangue on the mechanical properties of the mixture. The research results show that: The maximum dry density of the mixture with coal gangue is lower than the density of the natural crushed stone water-stable mixture, and the optimal moisture content is higher than that of natural crushed stone water-stable mixture; coal gangue aggregate is mixed with cement stabilized in the crushed stone mixture, and the 7d and 28d unconfined compressive strength, splitting strength, and compression rebound modulus values of the mixture are all reduced, which has a degrading effect on the mechanical properties of the mixture; however, both can attain high speed, which is the basic strength requirements for expressways, including first-class highways.

Ecologically safe device technologies of road covering with the using technogenic materials

The influence of nepheline sludge on the soil of a roadside strip when used in the device of road coverings is studied. Chemical analysis of soil samples taken from the roadside strip of a highway constructed using a base made of nepheline sludge was performed. It is shown that the change in the content of calcium-the main element of the sludge at a distance from 5 to 100 m from the road did not exceed its value in the background sample, and the content of exchangeable aluminum in the soil of the analyzed areas was at a very low level-less than 0.5 mg/kg and practically did not affect its content in the soil at all sampling points from 0 to 150 m from the road. Based on the conducted ecotoxicity studies using single-and dicotyledonous plants, the possibility of using nepheline sludge as a component of road covering in the form of a nepheline-crushed stone mixture has been established and the absence of toxicity in the analyzed soil samples at various distances from the roadside strip has been proved.

Calculation of Residual Deformations of Granulated Materials from Exposure to Repeated Loads

The analysis of the models for calculating residual deformations accumulated by granular materials under the influence of repeated loads is performed. Determined the hereditary nature of the accumulation of deformation of granular materials. This allowed the use of integral calculus for the analytical solution of the problem of the dependence of residual deformation on the number of repeated loads, the value of the main stresses. The solution is obtained in the form of logarithmic and power-law functions that associate the accumulated deformation with the deformation arising from the first load application with the number of applied loads. The deformation from the first load application is represented by the sum of the two components, instantaneous irreversible and viscoplastic. The viscoplastic component of the deformation is a consequence of stress relaxation in a relatively short period of time equal to the duration of the impact of the load. The analysis of experimental data on the triaxial compression of various granular materials is carried out and the parameters obtained for the power and logarithmic functions are determined. The materials studied include: granite, gneissic, granodiorite and diorite crushed stone, sand and gravel and crushed stone and gravel mixtures with a mineral part from various rocks, fortified sands. The possibility of application of the obtained solutions for the calculation displacement of the surface of the pavement layers of granular materials is shown. The tasks of further research are formulated.

Study and Application of Gneiss in Preparation of Graded Gravel Base Material

Because a lot of abandoned tunnel slag is produced in road engineering construction and the using rate is low, based on the Shijiazhuang section of the Xifu section of the Taihang mountain highway, the lithology of abandoned tunnel slag is analyzed. Its physical and mechanical properties are evaluated by laboratory tests, and its feasibility as an aggregate of graded gravel base is demonstrated. The gradation of the crushed stone mixture is composed of fine aggregate limestone mixed with abandoned tunnel gneiss, and the related characteristics are studied. The results show that the strength of the mixture could be significantly improved by replacing the fine aggregate with limestone, and the California load ratio (CBR) value of the crushed stone mixture with 0~3 mm and 3~5 mm limestone could reach 377.2%, and the unconfined compressive strength could reach 1.2 MPa.