Crushed Stone Research Articles

Effect of variations in concrete quality on the crack width in rigid pavement

Cracks pose a significant issue in rigid pavement, leading to substantial damage. The manual mixing and casting of road pavement concrete underscore the importance of concrete quality as a critical parameter. This study investigates crack behavior by varying concrete quality. Loading is performed statically using line loads, shedding light on the impact of concrete quality on crack development. The concrete to be used has a quality fc' of 15 MPa, 25 MPa, and 35 MPa. The fine aggregate used in this study was Lumajang black sand, while the coarse aggregate used was machine crushed stone, and Portland Composite Cement (PCC) was used in all concrete mixes. The reinforcing steel used had a quality fy of 480 MPa, with a reinforcement ratio of ρ=0.010, which was converted to 5-D16 reinforcement. The subgrade density used to support the specimens had a CBR value of 10 %. Specimen dimensions were 2×0.6×0.2 m for length, width, and thickness. Pavement plates, 30 cm thick, were placed on leveled subgrade soil in a steel box set to achieve a 6 % CBR reading. Hydraulic jacks, monitored by a load cell, applied monotonic static loading with 2 kN intervals, reaching a maximum load of 200 kN. Steel tension and plate settlement were measured using a tension sensor and Linear Variable Differential Transformer (LVDT), respectively. A data logger recorded readings, and crack widths were captured by a digital microscope with 0.01 mm accuracy. Experimental results show that low concrete compressive strength values result in larger crack widths, and vice versa. Cracks also occur at earlier loading of concrete quality fc' 15 MPa. In addition, experiments show that the reinforcement stress value has a significant influence on crack width in specimens with low concrete quality

Thermoactivated cement from construction and demolition waste for pavement base stabilization: A case study in Brazil.

Construction and demolition waste (CDW) worldwide generation accounts 10 billion tonnes yearly. The major fraction is landfilled requiring innovative recycling methods to reduce the associated environmental impacts and to increase its circularity. Our study demonstrated the feasibility of using different CDW fines to develop recycled cements and optimized the content of CDW recycled cements with well-graded crushed stone (WGCS) for use as pavement base layer. We scaled up the study obtaining CDW cement and aggregates from a local recycling plant, as well as pilot pavement sections designed, constructed and field deflections measured. As results, the CDW cement pastes exhibited accumulated heat values of up to 111 J g-1 and achieved a compressive strength of approximately 16 MPa. The unconfined compressive strength and resilient modulus (RM) achieved using CDW cement and WGCS were 2-3 and >3000 MPa, respectively. The sections constructed using CDW cement exhibited intermediate behaviour compared to those obtained using reference materials (6% Portland cement-WGCS and a conventional granular base made using WGCS). The deflection decreased over time owing to the pozzolanic reaction.

Performance Study of Black Shale Modified Soil for Road Use Based on Eshelby–Mori–Tanaka Theory

Black shale, as a type of soft rock, exhibits high strength when freshly exposed. However, it easily disintegrates upon contact with water, making it unsuitable for direct use in roadbed construction. Using it as discarded material not only increases construction costs but also pollutes the environment. Therefore, the reuse and modification of black shale have become particularly important. Based on the theory of composite material equivalent inclusions, this study investigates the strength and water stability characteristics of black shale gravel after being mixed with cement and compacted with clay. The results show that the strength of cemented soil increases linearly with the cement content. The water absorption properties of the modified soils with different amounts of black shale added are similar, with an average water absorption rate of about 2.53%. The strength of black shale modified soil is generally positively correlated with the cement content, although the linear correlation is not significant. The modified black shale soil used in the experiment is suitable for the subgrade of medium- and light-grade secondary roads and below. The recommended mass ratio is Mshale:Mclay:Mcement = 70:21:9. The unconfined compressive strength of the material under 7-day curing is 1.36 MPa. The relationship between the strength of modified soil, clay strength, cement content, and gravel addition has been established, clarifying the physical significance of each parameter. The “drying and soaking” cycle can accelerate the strength degradation of modified soil. It is recommended to strengthen the construction of roadbed drainage facilities during construction to maintain a stable and dry environment for the modified soil as a roadbed filling material. The research results not only provide clear technical indicators for the reuse of discarded black shale in engineering but also serve as a basis for proportion of crushed stone discarded material as roadbed fill.

Effect of Various Coarse Aggregates on the Compressive Strength of Concrete in Jalalabad City, Afghanistan

One of the most frequently used building materials on the globe is concrete. Concrete is composed of aggregate, water, and cement. This study investigated the influence of different coarse aggregates on the compressive strength of concrete. The coarse aggregates used in the experimental design consisted of crushed granite, crushed river stone, and natural gravel, with river sand as the fine aggregate. Sieve analysis and unite weight was performed on specimens frequently used by citizens. Fresh Portland cement and water-cement ratios of 0.55 and 0.7 were both used. To investigate the influence of various aggregates on concrete compressive strength a specimen for 20 N/mm2 concrete ratio of 1:1.5:3, and 48 concrete cubes measuring 15 cm x 15 cm x 15 cm were casted in the laboratory at Alfalah University. For fresh concrete, the slump test results were 63 mm for crushed granite, 65 mm for crushed river stone, and 50 mm for natural gravel. Crushing the concrete cubes after 7, 14, 21, and 28 days determined the compressive strength. Additionally, the highest compressive strength values achieved for crushed granite were 25.94 N/mm2, crushed river stone was 23.68 N/mm2, and natural aggregate concrete was 17.73 N/mm2. Based on these findings, crushed granite has been recommended for usage in reinforced concrete applications.

Lipid extraction of high‐moisture sour cherry (Prunus cerasus L.) stones by supercritical carbon dioxide

AbstractBACKGROUNDSour cherry (Prunus cerasus L.) stones are the major byproduct of the cherry industry and the efficient management of this biowaste can lead to achieving the food processing sustainability aimed at by the modern food industry. Despite its significant content of lipids, the valorization of cherry stone waste as feedstock for lipid extraction appears to be limited due to the high moisture content. This study explores the primary factors that affect the yield of lipid extraction using Soxhlet, Randall and supercritical carbon dioxide (scCO2) extraction methods, with a particular emphasis on yield optimization for green extraction technologies (scCO2).RESULTSThe investigation revealed an increased lipid extraction yield for scCO2 from 7.4 for dry crushed stones to 20.6 g per 100 g dry weight when the cherry kernels are separated. The high initial moisture content affected all three extraction methods, but mostly impacted the scCO2 extraction, resulting in the co‐extraction of an aqueous phase. Lipid and aqueous yield could be manipulated by time, temperature and pressure. However, no observable influence on the composition of fatty acid methyl esters was detected.CONCLUSIONNumerous approaches are shown to enhance the lipid yield from cherry stone waste, depending on the desired outcome. When dealing with wet samples, Randall extraction proves to be the most effective method. On the other hand, scCO2 extraction presents distinct advantages, such as the extraction of food‐grade lipids and the co‐extraction of a unique aqueous phase, which comes at the expense of a reduced lipid yield. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Potential Use of Reclaimed Asphalt Pavement Aggregate and Waste Plastic Bottles for Sustainable Asphalt Pavement Production

The main objective of this study was to evaluate the potential use of reclaimed asphalt pavement aggregate (RAPA) and waste plastic bottles (WPBs) for sustainable asphalt pavements production in hot weather conditions. To enhance the adhesion between neat bitumen, RAPA, and WPBs-coated aggregates, a rougher surface texture is created for aggregate particles in the modified asphalt mix. This improvement enhances asphalt mix engineering properties, rutting resistance, and stability. However, bituminous mixtures containing 20% RAPA exhibit tendencies toward strip resistance, this mixture is weak in terms of strength and incapable of supporting loads when utilizing the RAPA. Therefore, due to the moisture susceptibility of the RAPA, it is advised to employ several types of aggregates in future studies to determine the optimal aggregate that can resist stripping and, at the same time, handle heavy loads. Finally, for better asphalt mix performance, it is recommended to use a combination of 70% crushed stone aggregate, 20% RAPA, and 10% WPBs in asphalt mix with a 5.0% optimum modifier content. The experimental results for tensile strength ratio, proportional rut depth, and mean rut depth meet the required specifications of the Ethiopian Road Authority for all properties tested. Therefore, this combination is strongly advised for use in hot mix asphalt production.

An assessment of the immune status of some stone quarry workers in Ondo state, Nigeria.

Stone quarry activities in Nigeria are mostly unregulated such that the workers in these quarries are continuously exposed to the inhalation of silica dust. It has been observed that silica dust particles negatively impact the health of stone quarry workers which usually manifest as respiratory difficulties, asthma-like illnesses and other adventitious events of the lungs. The study was designed to evaluate the probable immunological impact of silica dust inhalation from stone crushing by workers. Blood samples were collected from consenting workers and analyzed for total white blood cells and their subsets. Absolute CD4 cells numbers were also determined. The results indicated that neutrophils and eosinophils numbers increased significantly (P < .05) and CD4 counts declined significantly (P < .001). Alteration in these proportions is a pointer to the injurious impact of silica dust on the immune system of these workers. The findings in this study should spur actions in the education of these workers on the need for the use of proper personal protection equipment and the establishment of a scheme to periodically carry out a health assessment check to identity those at most risk of developing chronic illnesses.

Performance analysis of solar desalination using crushed granite stone as an energy storage material and the integration of solar district heating

ABSTRACT This study explores the feasibility of solar desalination using black powder coated crushed granite stone, evaluating their energetic, exergetic, and economic aspects, wherein the stone bed preheats water for the solar still. In addition, the system integrates with a district heating network to meet desalination needs during off-solar or high-demand hours in which water from the powder-stone grid’s outlet flows through a heat exchanger, powered by district heating’s return flow. Desalination pipe absorbs heat and cools district heating line. The outcomes illustrated that cumulative distilled water for a water depth of 1 cm was 13.1% and 28.2% higher than cumulative distilled water for water depths of 2 cm and 3 cm, respectively. The energy efficiency was improved by 9.5% and 15.7% and the exergy efficiency was enhanced to 13.6% and 27.2% at 1 cm water depth compared to 2 and 3 cm water depths. The integration of the system with the district heating network could lead to a great improvement in the productivity; summer’s low district heating demand allows surplus heat to boost water production and lower outlet water temperature, benefiting both desalination and cooling process. The cumulative productivity will not be sensitive to the water depth anymore, increasing up to 105%, 135%, and 182% for 1, 2, and 3 cm water depths, respectively. This integration has a fascinating effect on the reduction in temperature of the district heating return flow (about 3°C), improving the cooling potential of the flow.

ГІРНИЧО-ГЕОЛОГІЧНІ ПЕРЕДУМОВИ ЕФЕКТИВНОЇ РОЗРОБКИ РОДОВИЩ БУДІВЕЛЬНОГО КАМЕНЮ ТА ЩЕБЕНЕВОЇ СИРОВИНИВ МЕЖАХ ПОШИРЕННЯ ЛЬОДОВИКОВИХ ВІДКЛАДІВ

The study determined the feasibility of multucommodity deposits development of construction and crushed stone, which are localized within the distribution of glacial and fluvioglacial deposits. Overburden is studied as associated minerals, used in the construction industry and landscape design. The objects of the study are deposits of granites and labradorite, which have industrial reserves and are mined, as overburden rocks have enough thickness of fluvioglacial sediments. During the development of crystalline rock, fluvioglacial deposits in many cases are classified as overburden. Traditional mining methods of gravel-sand rocks are usually unsuitable or complicate the development, since the problem of extracting overburden fluvioglacial deposits, as a rule, does not exist at the stage of opening, but already in the mining process. The mining-geological features of fluvioglacial and glacial deposits make it necessary to adjust design solutions when developing crushed stone deposits to ensure the stability of the sides of the quarry and industrial safety requirements. There are the results of studying the geological structure of deposits of building stone and crushed stone within the boundaries of glacial deposits. These are the Sosnivske, Yaroshivske, Koshchiivske, Boguslavske deposits, the "Deshki" area, and the Ostriv deposit, as well as in the "Synii Kamin" block raw material deposit, where overburden rocks are presented by thick glacial and fluvioglacial layers of the flgPIIdn Dnieper climatolite. The following features of the geological structure within these deposits were fixed: 1) a significant change of the physical and mechanical properties of the rocks that make up the fluvioglacial deposits and their granulometric composition; 2) a variety of mining conditions, including the presence of layers of sandy-clay rocks; 3) different degrees of waterlogging of fluvioglacial deposits; 4) a significant change in quality indicators within one deposit. The timeliness and quality of the detection of these features affects the effectiveness of the development of fluvioglacial rocks as co-occurring or by-product mineral. For such reserves, it is recommended to develop and use cut-off parameters for mineral raw materials, which take into account specific mining and geological conditions, during geological and economic assessment.

Laboratory testing and model calibration of a crushed stone backfill in a geosynthetic reinforced soil wall

The objective of this study was to understand the effect of the choice of backfill constitutive models on the numerical simulation of a geosynthetic reinforced soil-integrated bridge system (GRS-IBS). The #89 material, a crushed angular granite stone, characterized by maximum particle sizes of 9 mm, was used for the reinforced backfill for the retaining wall. Consolidated drained triaxial tests were conducted at confining stresses of 48 kPa, 83 kPa, and 117 kPa. The average friction angle was 42 degrees. Two soil models (the linear-elastic perfectly-plastic and the Hardening Soil) were calibrated using the laboratory test results. The calibrated soil models were then used to model the reinforced backfill material in finite element simulations of the abutment. Results of the calculated vertical stresses at the instrument position showed reasonable agreement with the field measurement. The non-linear model predicted about twice the deformation (lateral displacement and bridge seat settlement) compared to the linear-elastic perfectly plastic model. Settlement results showed maximum values corresponding to 0.22% and 0.45% of the abutment height for linear-elastic perfectly-plastic model and Hardening-Soil model, respectively, which are less than 0.5% limit recommended by US FHWA, while the lateral displacements were 0.22% and 0.44% of the abutment height for linear-elastic perfectly-plastic model and Hardening Soil model, respectively, both less than the 1% limit recommended by the US FHWA.

Preventive geochemical barriers during transport construction

The article discusses the possibility of using chlorite crushed stone as part of geochemical barriers in transport construction. It has been shown that during the construction of railways and during their operation, the main pollutants are petroleum products and heavy metal ions. To substantiate and study the neutralizing properties of chlorite crushed stone, infrared spectroscopy, ionomer, atomic absorption spectrometry and the gravimetric method for determining petroleum products were used. Research has shown that chlorite crushed stone is a quartz-albite-chlorite shale with a small inclusion of carbon; its physical and mechanical characteristics are not inferior to granite crushed stone. The oil capacity of chlorite crushed stone depends on the concentration of petroleum products in the model solution and ranges from 0.03 to 0.5 g/g. Chlorite crushed stone has a capacity towards nickel, iron and cadmium ions, while their simultaneous presence in the model solution does not have selectivity towards these ions. It has been proven that when the capacity of chlorite crushed stone is fully realized in relation to one of the heavy metal ions, it is not washed out and replaced by another metal ion (for example, nickel and iron ions). It has been proven that the presence of organic contaminants in the model solution does not significantly affect the capacity of chlorite crushed stone for heavy metal ions. It has been shown that chlorite crushed stone, due to its physical, physical-mechanical and chemical properties, can be used in geochemical barriers to protect the environment from pollution.

Granite Crushing Screenings as a Component Factor in the Concrete Structure Formation. Part II: Experimental Studies of Structure-forming Potential

The paper considers the results of experimental studies of the individual and joint influence of macro-, meso- and micro-nanofractions of granite crushing screenings on the processes of structure formation and properties of cement concrete. It has been established that in the processes of formation of the structure of fine-grained concrete and the potential for resistance to its destruction, all fractions of stone crushing screenings perform their specific functions as a component factor. Macro-sized (crushed stone) grains of screening of the 5–10 mm fraction form a macro-scale frame of the addition system, which perceives force load with the accumulation of loading energy and braking of main cracks. Sand mesoparticles of fraction 0.16–5 mm fill the intergranular space of the system for adding macroparticles with dissipation of external loading energy in the matrix material. The microfraction of granite crushing screenings (the fraction is &lt;0.16 mm), along with the effect of replacing the volume of cement stone, exhibits physical and chemical activity in the phase formation of hydrate compounds. It is shown that in the initial screening of granite crushing, the structure-forming role of its particles is not manifested effectively enough, the main reason for which is the “excess” of sand fractions, which push apart the grains of macrofractions and increase the water demand of the concrete mixture. Traditional methods of enriching screenings do not solve this problem. The principle of conditioning screenings by saturating them with macro- and micro-sized fractions is discussed. Based on this principle, a technology for mechanical processing of screenings has been developed to produce a “line” of products for targeted use in the building materials and products industry. The introduction of such technology will significantly increase the efficiency of construction and technological recycling of stone crushing screenings through maximum use of the structure-forming potential of their polydisperse composition.

Inovadora brita graduada tratada com cimento de alto desempenho como concreto compactado com rolo

Abstract The main causes of poor performance of cement-treated crushed stones (CTCS) pavement layers are material-related heterogeneity, porosity, and brittle cementitious matrix, leading to fast fatigue degradation. Seeking to improve CTCS mechanical properties and structural response it was studied different grading curves such as DER-SP, EN 14227-1 CBGM 2 and RCC-ACI were studied. The aim of the laboratory study was to rank and select among the classical particle size distribution models like Talbot &amp; Richart, and analytical models as compressible packing model – CPM, the best grading curve which was capable of producing mixtures with the best aggregate interlocking and improved mechanical resistances. The effect of cement content (4% and 5%) as well as the potential of using silica fume in suspension (percentages of 5, 7 and 10% of cement mass) to improve the interfacial transition zone were evaluated. It was found that CPM is a powerful tool for aggregates ranking aggregates and designing well-graded mixtures like CTCS; the CBGM 2 EN 14227-1 mean curve achieved the best packing density. The effect of increasing the cement content from 4 to 5% in terms of mechanical strength has the same result as the addition of 7% of silica fume in mixtures with 4% cement. Eventually, mixtures with 5% cement and 10% silica fume showed modulus of elasticity similar to traditional CTCS; nonetheless, the HP-CTCS (high performance CTCS) split tensile strength was significantly higher (about 28%), leading to a lower Et,sp/fct,sp relationship, which is a highly positive outcome to improve mechanical durability of this innovative dry compacted concrete.

Automation of primary crushing control

The article deals with issues related to the synthesis of an automatic control system for a jaw crusher, for which the main control and disturbance channels were identified and its mathematical model was obtained. Implementation of mechanization and automation systems at crushing and screening plants is necessary for the production of granite crushed stone, which is massively used in the construction of agricultural facilities. Based on the analysis of the mathematical model, a decision was made to choose the law of regulation and its parametric identification was carried out. Analysis of the quality indicators of the regulation of the synthesized system revealed their significant dependence on the disturbing effect, which required the synthesis of a disturbance compensator, the inclusion of which in the structure of the system made it possible to realize the requirements imposed on it.

Economical Measures against Soft Ground at High Embankment on Peaty Ground

Peat, which is considered a special soil, is widely distributed over approximately 2,000 km2 in Hokkaido, Japan. In terms of engineering properties, peat is extremely high in water content, ignition loss, and void ratio and extremely in low shear strength. Ground improvement methods using cement are effective for the rapid construction of embankments on peaty ground. However, to avoid differential settlement and lateral flow, most of such construction is carried out with an improvement ratio of ap=50%. In this case, the improvement can certainly be expected to be effective. However, it is less economical than other soft ground improvement methods. The challenge is to reduce the cost of improving the ground. Our institution (the Civil Engineering Research Institute for Cold Region, PWRI) has developed an economical measure against soft ground that uses cement with a reduced improvement ratio in combination with a crushed-stone mat (gravel foundation reinforcement), and we conducted the test construction of a 16-meter-high embankment to verify effectiveness of the method. The crushed-stone mat consists of a 50-cm layer of crushed stone covered with a geo-synthetic material. The test construction achieved the following results. (1) Settlement of the embankment was significantly reduced. (2) Slip failure did not occur. (3) Displacement to the surrounding ground did not occur. (4) The geotextile in the crushed-stone mat exhibited less strain than that which would cause the geo-synthetic to exceed its design strength. These results show that this economical measure against soft ground was effective at stabilizing the high embankment constructed on peaty ground.

Risk perception among residents living near industries in Godawari Municipality of Lalitpur, Nepal.

The industrial sector stands out as a significant contributor to environmental pollution. Those who reside in close proximity to industrial areas commonly harbor concerns about potential health and environmental hazards. This study aimed to find out the perception of risk and self-reported health impacts among individuals living near industries in Godawari Municipality, Lalitpur, Nepal. Conducted as a community-based cross-sectional study, it involved 270 households. Face-to-face interviews were employed, utilizing a pretested structured questionnaire. The study zone encompassed the communities of Godawari Municipality within a 3-kilometer radius of industrial sites. Specifically, stone mines, stone crushers, and brick kilns were purposefully selected, while study participants were randomly sampled using a random table. Data analysis was performed using IBM SPSS, incorporating both univariate and bivariate techniques. Among those residing near industrial zones, a mere 9.6 % reported experiencing wheezing or whistling in the past 12 months. A substantial 36.3% consistently felt stressed due to industrial activities in their vicinity. Approximately half (51.9 %) of the participants indicated that the contaminated air in the area had adverse effects on human health. Furthermore, a palpable perception of elevated risk was associated with the proximity of industries (p<0.001). Over half of the participants perceived a notable risk stemming from the presence of industries near their homes, largely due to pollutants. These individuals also disclosed various health repercussions and expressed significant apprehension regarding their future well-being in the area. The implications of these findings are substantial, particularly for local-level planning and the development of industrial sites. Addressing the concerns surrounding people's heightened perception of risk from nearby industries is pivotal in fostering harmonious coexistence and informed decision-making.

Study of the characteristics of pavement elements made of reinforced soil with the use of secondary resources

The importance of using secondary resources on the basis of industrial waste is understood by both governments of developed countries and business (production of Portland cement using ground metallurgical slag as a mineral additive at Novotroitsk, Magnitogorsk, Sterlitamak, KatavIvanovsk and other plants in the South Urals). The use of secondary raw materials requires the creation of technological infrastructure for processing of secondary raw materials, the costs of which can be quickly recouped due to the cheapness and availability of industrial secondary raw materials and freeing the territory from environmental pollution. In order to recoup the costs of the infrastructure, it is necessary to guarantee full compliance of the quality of pavement elements with the requirements of GOST R 59120-2021. Secondary raw materials have a great variety and laboratory analysis of the quality of pavement elements is required in order to design compositions with the best quality, satisfying all regulatory requirements. In our work the authors present the results of laboratory research and evaluation of the possibility of using clinker-free lime-slag binder based on the mineral product of soda production and metallurgical slags to strengthen and stabilize soils for their use in pavement structures in the construction of roads for various purposes and climatic zones. It is experimentally shown that the addition of lime-slag binder in the amount of 8-10% of the dry weight of both cohesive (loamy soil, loamy sand) and non-cohesive (fine sand) soil allows to obtain reinforced soil with improved strength and elastic-deformative characteristics, which can be used instead of scarce natural crushed stone and gravel in the construction of underlying layers of pavements in the construction and reconstruction of highways. This technology can be used not only in the Russian Federation, but also in a number of other countries, including those with hot dry climates (e.g., the Republic of Egypt).

Determining the energy of impact of a railroad rolling stock wheelset when derailing over reinforced concrete sleepers using impact trace parameters

The object of research is reinforced concrete sleepers that are subjected to the impact of a wheel in a railroad rolling stock. A procedure is given to theoretically estimate the energy at the impact of a wheel into a reinforced concrete sleeper when a rolling stock wheelset derails. Experimental studies of the geometric parameters of impact traces that occur on reinforced concrete sleepers, depending on the height of the center of mass of the striker above the impact site, were conducted. Based on the results of the experiments, the average geometric parameters of the impact traces were obtained. It was established that the dependence of impact traces on the height of the center of mass of the striker above the place of impact into the reinforced concrete sleeper has a non-linear distribution. Experimental studies of the effect of the location of the reinforced concrete sleeper base on the geometric parameters of impact traces were conducted. It was established that the location of the reinforced concrete sleeper on a solid base and on crushed stone ballast does not exert a significant effect on change in the geometric parameters of impact traces. The obtained experimental values are within the limits of 3σ determined for the rigid abutment of the sleeper. It was established that when testing a reinforced concrete sleeper in a crushed stone box, the amount of energy depends on the height of the striker. At a height of 0.95 m, the amount of energy absorbed by the sleeper together with the ballast was 475 J, and at a height of 1.42 m – 710 J. Analytical dependences were obtained between the length of the face of the impact trace and the amount of absorbed energy, as well as the depth along the direction of the force and the amount of absorbed energy. It was established that the length of the impact trace has an extremum, which does not allow recommending this parameter for estimating the amount of absorbed energy for energy values E&lt;200 J. To determine the amount of energy absorbed by the sleeper, it is recommended to use the parameter of the depth of the impact trace

Analisis Biomekanika dan Beban Kerja pada Pekerja Pemecah Batu Tradisional di Grindulu, Tegalombo, Pacitan

In industries that still use human power to move materials, even though some relatively modern industries have used machines as a tool for moving materials, manual material handling (MMH) is still very necessary because it has advantages compared to using tools, namely. Manual material handling usually occurs in confined spaces and where workers rely heavily on the human body to lift items, but if manual material handling (MMH) is not carried out ergonomically, accidents can occur. Damage to body tissue due to removal. The method used in this research is a questionnaire based on the NBM (Nordic Body Map). Regarding the worker's position, RWL (Recommended Weight Limit) is a method used to explain some movement errors in traditional stone body presses. From the results of the analysis of the Grindulu River for two Tegalombo stone crushers, Pacitan, the results were good or there was no potential for injury because the results were less than 1, namely the value for worker 1 was 0.162 (Good) and worker 2 was 0.384 (Good). obtained from distributing questionnaires from 2 respondents on the banks of the Grindulu river, Tegalombo, Pacitan, conclusions can be drawn. 1. Using Biomechanical forces on organisms and investigating the interaction effects of body forces, including forces arising from inside and outside the body, workers do not experience potential injury and produce a score below 1 (Good).&#x0D; &#x0D; Keywords: Biomechanics, Material Handling Manual, Nordic Body Map, Recommended Weight Limit

Mechanics and road performance of mudstone modified stabilized gravel subgrade in arid desert areas

This study investigates the feasibility of using mudstone to enhance poorly graded gravel in certain arid regions of the S21 Altay-Urumqi Highway project in Xinjiang. Despite mudstone typically being considered a poor-quality rock, its combination with higher-performance materials like cement, lime, and fly ash can stabilize expansive soils for use as roadbed fill. In the experiments, 30% and 40% mudstone were added to the gravel mixture. The experiments were compared with unmodified K80 and 35% crushed rock mixes. The findings reveal that adding 30% mudstone substantially increased the California Bearing Ratio (CBR) of the gravel mix by over 20%. However, excessive mudstone inclusion could weaken load-bearing capacity. Moreover, mudstone-modified specimens exhibited superior unconfined compressive strength (UCS), splitting strength, compressive resilience modulus (CRM), drying shrinkage resistance, and temperature shrinkage resistance. Under optimum cement dosage, the UCS of mudstone-modified specimens outperformed unmodified specimens, consistently surpassing fly ash-altered groups. Although mixed fly ash initially exhibited lower strength, it gradually approached cement-stabilized strength with an extended curing time. Incorporating crushed stone into the grading curve significantly increased splitting strength due to its high strength and hardness. In contrast, adding mudstone introduced a notable proportion of fine aggregates, resulting in a looser grading skeleton prone to early cracking. This research demonstrates that mudstone enhancement significantly improves roadbed performance, including increased CBR, splitting strength, and crack resistance. The use of mudstone in arid desert areas enhances overall performance while reducing shrinkage coefficients. The suggested approach for semi-rigid pavements in arid deserts recommends specific mineral proportions, various aggregate sizes, an appropriate amount of cement, and 30% mudstone to create dense structures with a higher quantity of coarse aggregate.