Cement Stabilized Macadam Base Research Articles

Experimental Research on the Anti-Reflection Crack Performance of Basalt Fiber Modified Rubber Asphalt Stress-Absorbing Layer.

Reflection cracks are one of the most common problems in semi-rigid base pavement. Setting a stress absorption layer can effectively delay the occurrence of reflection cracks, but further improvement is still needed in its interlayer bonding performance and anti-reflection crack performance. Considering the excellent crack resistance of basalt fibers and the good elastic recovery ability of rubber asphalt, it is considered worthwhile to incorporate them into traditional stress absorption layers to improve performance. To simulate the actual pavement layer effect, composite specimens consisting of a cement-stabilized macadam base + basalt fiber rubber asphalt stress-absorbing layer + AC-20 asphalt mixture surface layer were prepared to evaluate their performance through interlayer direct shear tests, interlayer tensile tests, three-point bending tests, and overlay tests (OTs). To determine the optimal fiber blending combination, four fiber lengths (3 cm, 6 cm, 9 cm, 12 cm) and four fiber proportions (120 g/m2, 140 g/m2, 160 g/m2, 180 g/m2) were selected respectively. The specific effects of basalt fibers with different lengths and dosages were analyzed. The results show that compared with the absence of fibers, the improvement of interlayer bonding performance of rubber asphalt with basalt fibers is not significant, and it has certain limitations; however, the improvement of anti-reflective crack performance is significant, with an increase of up to 305.5%. This indicates that the network structure formed by basalt fibers and rubber asphalt stress absorption layer can effectively absorb and disperse external loads, causing an excellent crack resistance effect. Meanwhile, the results indicate that the main factor affecting its interlayer bonding strength and anti-reflective crack performance is the fiber content. Based on the comprehensive analysis of the performance and economy of the stress absorption layer of basalt fiber rubber asphalt, the optimal fiber parameter combination recommended is as fiber length 9 cm and fiber content 160 g/m2. These results can provide a reference for the design and performance evaluation of basalt fiber rubber asphalt stress absorption layer, and have certain application value.

Effect of mineral admixtures on the calcium leaching resistance of porous cement stabilized macadam

Porous cement stabilized macadam has a good drainage property, but the loss of strength due to calcium leaching can significantly reduce its road performance. The effect of the dosage of fly ash, silica fume, and slag powder on the calcium leaching resistance of porous cement stabilized macadam base material was investigated using the accelerated leaching method with 4 mol/L ammonium chloride. The results show that calcium leaching occurs simultaneously at multiple contact points between the internal cement paste and the leaching solution, and the leaching depth has exceeded the average thickness of the layered cemented paste within 3d. The dissolution of CH crystals and the decalcification of C-S-H gel increase the porosity of cement and reduce the strength of the base material. Volcanic ash reaction of silica fume and fly ash as well as slag powder by alkali excitation and sulfate excitation will consume CH and generate low alkalinity C-S-H gel with better dissolution resistance, which can reduce calcium leaching and delay the loss of strength. The optimum dosages of fly ash, silica fume, and slag powder are 20%, 15%, and 30%, respectively, and their optimum dosages can be estimated on the assumption that the mineral admixtures completely consume CH.

Investigation of Preparation and Shrinkage Characteristics of Multi-Source Solid Waste-Based Cementitious Materials.

Cement-stabilized macadam (CEM-SM) base layers on highways are prone to early shrinkage cracking in extremely cold and arid regions, mainly caused by the large drying shrinkage of traditional cement-stabilized base materials. A multi-component solid waste cementitious material (SWCM) was designed based on the response surface method. The synergistic reaction mechanism of SWCM was analyzed using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TG). A shrinkage testing system was developed to evaluate the anti-cracking characteristics of stable macadam using multiple solid waste cementitious materials (SWCM-SM), and the strength growth law and frost resistance were analyzed. The results show that the Box-Behnken response surface model was used to obtain the optimal parameter combination for SWCM, including 60% slag, 30% steel slag, and 10% desulfurization gypsum. The compressive strength and flexural strength of SWCM-SM were 24.1% and 26.7% higher than those of CEM-SM after curing 180 days. The frost resistance of SWCM-SM was basically equivalent to that of CEM-SM, and the dry shrinkage strain of SWCM-SM was reduced by 30.7% compared to CEM-SM. It can be concluded that steel slag and desulfurization gypsum stimulate the hydration reaction of slag, thereby improving the bonding strength. Compared to CEM-SM, SWCM-SM exhibits slower hydration reaction and longer hydration duration, exhibiting characteristics of low early strength and high later strength. The early microstrain of the semi-rigid base layer is mainly caused by the occurrence of early water loss shrinkage, and the water loss rate of SWCM-SM is lower than that of CEM-SM. This study concludes that SWCM has good early crack resistance performance for stabilized crushed stones.

Development of flexible grouting material for cement-stabilized macadam base using response surface and genetic algorithm optimization methodologies

To repair the voids and cracks in the Cement-stabilized macadam base (CSMB), a grouting material with lower elastic modulus, enhanced fluidity and slight expansion called Flexible Grouting Material (FGM) was developed using superfine cement, fly ash (FA), silica fume (SF), vinyl acetate-ethylene (VAE) copolymer emulsion, and polyvinyl alcohol (PVA) fiber. After that, the study optimized the proportion of FGM using Response Surface Methodology (RSM) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) in Multi-Objective Optimization (MOO). Firstly, to determine the component contents for subsequent experiments, the fluidity, setting time, compressive/flexural strength (1d + 3d), and ratio of compressive strength to flexural strength (C/F, 1d + 3d) were tested. Subsequently, the Response Surface Methodology-Box Behnken Design (RSM-BBD) was employed using VAE content, PVA content, and water-to-cement ratio (W/C) as factors. Additionally, the fluidity, setting time, compressive/flexural strength and C/F (28d), elastic modulus (28d), and drying shrinkage (28d) were considered as responses in RSM-BBD. The VAE content and W/C significantly influenced the response values, while the PVA content had a relatively minor influence. Finally, the NSGA-II was utilized to determine the optimal proportion of FGM. Compared to the control group, the optimal FGM demonstrated 16.53 % increase in fluidity, 37.86 % decrease in elastic modulus (28d), 47.98 % decrease in C/F (28d), 22.22 % reduction in drying shrinkage (28d), and 54.07 % increase in final setting time.

Load response and fatigue life of cement-stabilized macadam base structure considering dynamic and static load differences and tension-compression modulus differences

The conventional semi-rigid base asphalt pavement (SRBAP) construction is designed with the classical theory of linear elastic mechanics. There is a significant discrepancy between the calculation results of the pavement structure load response and the measured results, which leads to inaccurate structural resistance and load response calculations. For this reason, this work depended on the actual structure of the SRBAP, took the linear elasticity theory as a contrast, and considered the difference between dynamic and static loads or the difference between the compressive and tensile modulus of pavement materials. Thus, the pavement structure response to load under three conditions is calculated, and five mechanical indexes are selected for comparative analysis. Furthermore, based on the calculated mechanical response, the structural fatigue life of the cement-stabilized macadam (CSMB) was then calculated, replacing the design index in the fatigue cracking model with the underside tensile stress or equivalent stress. The results demonstrated 20–30% variations between the calculated mechanical responses to dynamic and static stresses. Additionally, there is a substantial discrepancy between the strain computed using the bimodulus theory and the traditional linear elasticity theory, with a maximum divergence of 40%. In the meantime, the fatigue life of the CSMB produced using various design indices is noticeably different, and the fatigue life achieved using equivalent stress as the design index is significantly higher than that obtained using underside course tensile stress. Following is a relationship between the CSMB's fatigue life calculated by underside course tensile stress: viscoelastic theory (dynamic load) > bimodulus theory (tension–compression modulus difference) > classical linear elastic theory; The relationship of fatigue life represented by equivalent stress is as follows: viscoelastic theory > classical linear elastic theory > bimodulus theory.

Research on Water-saving, Moisture-keeping and Curing Technology of Cement Stabilized Base Course of Highway

The cement stabilized macadam base has excellent road performance and economy, and it is widely used. However, cement stabilized macadam also has some shortcomings such as poor anti-scour ability and insufficient frost resistance. To solve this problem, this study uses Scanning Electron Microscope (SEM) to analyze the micro-morphology of the specimen surface under four curing methods, namely moisturizing film, sack, polyethylene film and curing room, explaining the mechanism of curing methods affecting the anti-scour performance of cement stabilized macadam. Through the experimental study of anti-scour performance, it was found that the water-saving and moisturizing film was the closest to the experimental condition of curing in the curing room; the scour rates of the specimens of health-preserving sacks and polyethylene films were both high, and they were respectively 12.1g and 16.7g at 15m; through the experimental study of frost resistance, it was found that these curing methods had little influence on the frost resistance of cement stabilized macadam, and the ratio of compressive strength exceeded 0.6%.

Research on the road performance of self-adhesive basalt fiber geotextiles based on the background of long-life pavements

Achieving sustained asphalt pavements can minimize the structural damage brought on by minor pavement cracks, which will reduce the high repair and maintenance costs resulting from pavement distress. This study introduces a new composite geomaterial, self-adhesive basalt fiber geotextiles (SBFG) prepared by hot-melt lamination of basalt fiber cloth and modified asphalt, intended for the deterrence and control of reflection cracks in asphalt pavements. In this study, the self-adhesive geotextile was placed between the cement-stabilized macadam base and AC-20 surface layer to prepare composite samples, and the road performance was evaluated by a three-point bending test, Overlay Tester, dynamic shear rheology test, and the crack expansion time under different parameters of SBFG was simulated by ABAQUS finite element to predict the whole life cycle of the pavement structure. The results indicate that the fracture energy of the SBFG sample is the largest among all samples, and the structural design of fiber reinforcement disperses the concentrated stress at the crack tip, increases the stress area, and prolongs the time of crack expansion from the subgrade to the surface layer; Smooth and stable load loss curve of the sample in the reflection crack test, with slow crack expansion. This new geomaterial has an excellent rutting factor and maintains good resistance to permanent deformation at high temperatures; In the finite element prediction of fatigue cracking life of asphalt pavement, the structural life of the pavement with the addition of SBFG was improved by 78.3% compared to the control group. The application of basalt fibers in geosynthetics provides a new idea for achieving prolonged asphalt pavements.

Laboratory investigation on performance of waste-oil cutback asphalt as prime coat on cement stabilized macadam base

The commonly used prime coat materials have shortages such as insufficient interlayer bonding performance, high cost, and serious environmental pollution. To solve the above problems, this study attempts to take waste-oil as the diluent and blend it with asphalt to prepare a new prime coat material: waste-oil cutback asphalt. And the feasibility of this prime coat material is studied on semi-rigid base. Through penetration test, direct shear test, and pull-out test, the optimum blending proportions and construction conditions of the waste-oil cutback asphalt are determined, and the feasibility of the waste-oil cutback asphalt was evaluated by comparing it with kerosene cutback asphalt and PC-2 emulsified asphalt. The results illustrate that the mass ratio of waste-oil to asphalt is 1:1, and the content of penetrant is 10 % of the asphalt mass (47.6 % waste-oil, 47.6 % asphalt, 4.8 % penetrant in the percentage of 100 %) can be used as the optimum blending proportion of waste-oil cutback asphalt. The average penetration depth of waste-oil cutback asphalt is 5.4 mm, which meet the standard requirements. The direct shear strength is 0.292 MPa, which is 23.7 % and 86.0 % higher than that of PC-2 emulsified asphalt and kerosene cutback asphalt. And the pull-out strength is 0.235Mpa, which is 11.4 % and 92.6 % higher than that of theirs. The optimum construction condition is 1.1 L/m2, and the best construction time is 1 day after the construction of the base course. It indicated the interlayer bonding performance of waste-oil cutback asphalt is significantly improved than traditional prime coat materials. Thus, the waste-oil cutback asphalt can be used as a new type of environmentally friendly and high-performance prime coat material on cement stabilized macadam base.

Simulation Analysis of Cement-Stabilized Macadam Compaction Processing Based on the Discrete Element Method

The mechanical properties of cement-stabilized macadam (CSM) base mixture are closely related to its forming process. Although the present study investigates the macroscopic effects of molding on cement-stabilized macadam, mesoscopic research analyses of the internal composition’s structural characteristics and change trends after molding lack sufficient intuitiveness. In this study, we built three-dimensional models of cement-stabilized macadam for heavy compaction molding and vibration molding tests based on the discrete element theory. The effects of different molding methods on cement-stabilized macadam’s internal structure were revealed from the mesoscopic perspective by tracking changes in porosity, coordination number, force chain development and internal particle position during the simulation molding process. The simulation results show that (1) the first 10 compactions had a significant influence on the molding effect, and specimens’ height and porosity decreased the fastest; (2) after the simulation experiments, the average coordination number of particles in the vibration molding specimen was 2.3% higher than that of the heavy compaction molding specimen; (3) after the simulation experiments, the vibration molding specimen’s porosity was 2.5% lower than that of the heavy compaction molding specimen; and (4) the vibration molding specimen’s particle distribution was more uniform, whereas the heavy compaction molding specimen’s particle distribution was dense at the top and sparse at the bottom. Overall, the effect of vibration molding is superior to that of heavy compaction molding.

Study on the Characteristics of Sandstone and Feasibility to Replace Limestone in Cement Stabilized Macadam Base

Study on the Characteristics of Sandstone and Feasibility to Replace Limestone in Cement Stabilized Macadam Base

Study on Properties of Cement Stabilized Macadam with Recycled Aggregate of Different Replacement Rates under Vibrating Mixing

It has the goal of green construction to use recycled aggregate of waste cement concrete in cement stabilized macadam base to replace recycled aggregate of base. In this paper, the properties of cement stabilized macadam with natural aggregate and recycled aggregate under different replacement ratios are compared. The test results show that the physical properties (apparent density, mud content, crushing value, water absorption, etc.) of recycled aggregate are lower than those of natural aggregate, but meet the requirements of the specification. With the increase of the proportion of recycled aggregate in cement stabilized macadam, the optimal moisture content required for the maximum dry density of fully recycled aggregate mixture increased by 20.6% compared with that of natural aggregate mixture; the unconfined compressive strength of cement stabilized macadam with recycled aggregate at 7d and 28d showed a downward trend, and the strength of cement stabilized macadam with fully replaced recycled aggregate at 7d and 28d decreased by 10% and 1% respectively 0%. In addition, the strength of full substitution 28 increased by 11.1%. The research shows that the recycled aggregate base can meet the construction requirements, and the vibration mixing has better advantages, which provides a reference for engineering application.

Characteristics of High-speed deflection basin and structural parameter Back-calculation of asphalt pavement with different structural states

In this paper, the three-dimensional viscoelastic-elastic finite element (FE) models of semi-rigid base asphalt pavement were built and optimized. Multiple parameter combinations including deflectometer speeds, relaxation moduli and phase angles of asphalt surface, moduli of cement stabilized macadam base, subgrade moduli, and friction coefficients between the surface and base layers were set. Four geometric indicators of high-speed deflection basin including peak deflection (PD), deflection basin area (DBA), normalized lag area ratio (NLAR) and symmetry difference (SD) were proposed. The variations of the above four indicators under different pavement structural parameter combinations were simulated. Artificial neural networks (ANNs) were trained applying the PD, DBA, NLAR, SD indicators or the six-point deflection values/ deformation velocity values as the input data to back-calculate the pavement structural parameters. The accuracy, sensitivity and stability of the ANNs were further studied. The results show that the high-speed deflectometer speed has a significant impact on the PD, DBA, NLAR and SD indicators. The PD and DBA indicators are positively correlated with the deterioration state of asphalt surface, cement stabilized base, subgrade and surface-base interlayer bonding states. The deterioration state of different layers and the interlayer bonding state have different correlations on NLAR and SD indicators. The interlayer bonding state should not be ignored during pavement structural parameter back-calculation. It is recommended to directly apply the six-point pavement deformation velocities to train the back-calculation ANN. The results provide reference for the characteristic analysis of high-speed deflection basin and the back-calculation of pavement structural parameters.

Mechanical properties of emulsified recycled cement-stabilized macadam based on step-by-step filling gradation design.

Since the recycling of waste original cement-stabilized macadam (OCSM) base has important environmental and economic significance, the addition of emulsified asphalt to OCSM to form emulsified recycled OCSM (ER-OCSM) can improve the flexibility of recycled mixtures. However, the influence of emulsified asphalt on the mechanical performance of such mixtures remains to be investigated. This study presents a gradation design and ER-OCSM established using the step-by-step filling method and investigated the mechanical properties of the ER-OCSM mixture. The apparent characteristics, crushing value and needle-like particle content of the OCSM milling material were tested. Based on step-by-step filling theory, the appropriate test method to achieve a uniform and dense state according to the characteristics of different aggregates was selected, and the dense skeleton gradation design method for recycled cement macadam was obtained. The mechanical properties of the ER-OCSM were analyzed by performing indoor physical laboratory tests. The natural gradation of the OCSM milling material exceeded the gradation range recommended in the Technical Guide for the Promotion of Science and Technology of the Construction Project of the Main Highway in Jiangsu Province (Trial), but the designed gradations were basically within the range. At the same age and temperature, the flexural strength and dynamic elastic modulus of the ER-OCSM decreased gradually with an increase in the emulsified asphalt content. Because ER-OCSM had temperature-sensitive characteristics, the adhesiveness of the asphalt between particles in the mixture decreased with increasing temperature, which was manifested as the unconfined compressive strength, flexural tensile strength and dynamic elastic modulus decreasing with an increase in temperature (the decrease was slight within 5–25°C but noticeable within 25–60°C). Furthermore, a higher emulsified asphalt content caused a more noticeable decrease. The flexural strength of the tested ER-OCSM showed noticeable correlations with the splitting strength, unconfined compressive strength and dynamic elastic modulus. The proper addition of emulsified asphalt can reduce the rigidity of ER-OCSM. However, the emulsified asphalt content should be strictly controlled; otherwise, the mechanical properties of the material will decrease greatly, adversely impacting the comprehensive road use performance.

A GPR-Based Test Study on the Influencing Factors of the Dielectric Constant of Cement-Stabilized Macadam Bases

Dielectric constant is an important parameter for the nondestructive test of cement stabilized macadam base (CSMB) on road by ground-penetrating radar (GPR). However, few studies have been reported on the quantitative relationship between the dielectric constant and the compaction degree, strength indicators, and influencing factors of CSMB. To address the problem, groups of CSMB specimens, which were different in gradation of aggregate (fine or coarse), compaction degree, and curing time, were made and tested for dielectric constant and influencing factors with the help of the Swedish MALA GPR. The relationship between the dielectric constant of CSMB and the influencing factors such as the compaction degree, moisture content, percent residues of aggregate on the sieve of maximum particle size and curing age, and the relationship between the dielectric constant and the unconfined compressive strength were investigated based on several test data and theoretical analysis. The major findings are as follows. There is a good logarithmic correlation between the dielectric constant and the compaction degree of CSMB, and quantitative functions have been established. There is a good linear relationship between the dielectric constant and the unconfined compressive strength of CSMB, and quantitative functions have been established. A comprehensive equation between the dielectric constant of CSMB and the influencing factors such as the compaction degree, moisture content, percent residues of aggregate on the sieve of maximum particle size, and curing age has been established and validated with high significance and small error. The findings are a theoretical basis for the application of GPR to the test and quality assessment of CSMB on roads.

Effect of early strength anti-cracking materials on drying shrinkage of recycled cement stabilized macadam

ABSTRACT The increasing road maintenance projects lead to a large amount of construction waste and long-term closed traffic, enabling a rigid demand for early strength recycled cement-stabilized macadam (ERCSM), which can achieve rapid cold recycling. Given that ERCSM is prone to early drying shrinkage cracking, this study aimed to reduce the occurrence of early drying shrinkage cracking by adding early strength anti-cracking materials (EAMs). Therefore, a drying shrinkage test of cement mortar was carried out to determine the types, contents of anti-cracking materials, and their mixing proportions with early strength composite materials. The effect of EAM on the drying shrinkage of ERCSM was also studied. The results show that the anti-cracking material E1 has better crack resistance. Two types of EAMs (M1 and M2) composed of E1 and different early strength composite materials, were determined. EAM could reduce the drying shrinkage of the recycled cement-stabilized macadam base, and M2 had a better resistance to early shrinkage. After adding M2, the total drying shrinkage coefficient at 2 and 3 d decreased by 91.7% and 74.7% compared with the control group, respectively. Microscopic test show M2 can accelerate the hydration process of cement and promote the formation of expansion products at early ages.

Property Evaluation of Cement-Stabilized Macadam Modified via Phosphorus Slag Materials

Phosphorus slag, known as the waste product of the phosphate ore industry, is causing critical environmental issues due to its direct exposure to natural spaces. In this article, a partial replacement of the natural fine aggregate ordinarily used in cement-stabilized macadam (CSM) base by phosphorus slag was explored to be an effective solution for phosphorus slag waste. CSM specimens were fabricated by adding various dosages of phosphorus slag particle and fine powder, whereas the optimum moisture content and maximum dry density were analyzed through compaction tests. Compressive strength, bending tensile strength, fatigue life span, dry shrinkage, and temperature shrinkage performance at different curing durations were investigated to evaluate the properties of modified macadam. Results show that phosphorus slag reduced the early compressive strength of CSM to a small extent, but the compressive strength finally increased at 90 days’ curing. The modified slag particles and slag fine powder exhibited different behaviors to repeated loading, moisture loss, and temperature difference. Finally, according to the strength change, fatigue performance comparison, and shrinkage strain caused by the incorporation of phosphorous slag materials into the CSM, it was verified that 25% of the particles to 40% of the fine powder is the best replacement ratio.

Experimental Study on Performance and Base Compaction of Cement Stabilized Macadam with Vibration Mixing

In order to improve the engineering application prospect of vibration mixing cement stabilized macadam, the performance of vibration mixing cement stabilized macadam and the compaction performance of base course are studied in this paper. The proportioning scheme of cement crushed stone stabilized soil is designed, and the proportioning of cement stabilized crushed stone is established by compaction method and testing compressive strength. Through the indoor test, the 7-day and 28-day unconfined compressive strength of ordinary mixing and vibration mixing are compared. The results show that the 7-day strength is increased by 38.6% and the 28-day strength is increased by 32.5%. The compaction test of ordinary mixing and vibration mixing cement stabilized macadam base is carried out. The research results show that the compactness of vibration mixing cement stabilized macadam after rolling for one time and final rolling is increased by 1.5% and 3.1% respectively. The research shows that the improvement of compaction technology of cement stabilized soil pavement under vibration mixing can improve the performance index of pavement and can be popularized.

Research on Application of Cement Stabilized Macadam Base Construction Technology in Municipal Road Construction

Research on Application of Cement Stabilized Macadam Base Construction Technology in Municipal Road Construction

Effect of Fly Ash on Leaching Characteristics of Cement-Stabilized Macadam Base.

To study the leaching characteristics of a cement-stabilized macadam base with fly ash, a calcium leaching test, using varying cement and fly ash dosages in an ammonium chloride solution, was designed to obtain the rate of calcium ion leaching, porosity, and permeability coefficient of cement-stabilized macadam with leaching time. The results showed that the number of leached calcium ions increased with the cement dosage in the leaching of cement-stabilized macadam. With an increase in the cement dosage, the leaching rate of calcium ions decreased, and the leaching process of the material was delayed. The incorporation of fly ash could effectively slow down the degree of calcium ion leaching. The permeability coefficient increased gradually with the extension of leaching time, and the increase in fly ash content had a more significant effect on the improvement of the permeability coefficient than the increase in cement dosage did.

Influence of initial defects on the fatigue behaviour of cement-stabilized macadam base through DEM

ABSTRACT Fatigue failure of cement-stabilized macadam (CSM) base has always been a concern in highway construction. The microscopic initial defect is an important factor affecting its fatigue performance. The objective of this paper is to investigate the fatigue cracking of CSM materials under cyclic loading through numerical simulation and to analyze the influence of microscopic initial defects. The mesoscale random particle model was established using the discrete element method (DEM). The discrete fracture network (DFN) was used to characterize the microscopic initial defects in cement mortar. A parallel bond evolution method was also developed to simulate the time-dependent fatigue damage under cyclic loading. Then virtual semicircular bending (SCB) fatigue tests were carried out to reproduce the mesoscopic fatigue cracking. The results show that the established mesoscale model can accurately simulate the evolution of microcracks. The fatigue damage presents nonlinear accumulation, and the interface is a weak area of fatigue failure. Through optimizing the cracking propagation path, initial defects induce the penetration crack and reduce the fatigue life. The large-size defects should be more concerned. Fractures with a radius greater than 0.15mm should be controlled within the density range of 20 m/m2, which is beneficial to improve the anti-fatigue performance of CSM.