Abrasion Loss Research Articles

Two-body wear of occlusal splint materials from subtractive computer-aided manufacturing and three-dimensional printing

ObjectivesTo investigate the two-body wear of occlusal splint materials fabricated from subtractive computer-aided manufacturing (CAM) compared to three-dimensional printing (3DP).Material and methodsForty-eight substrates (n = 12/material) in the design of a mandibular first molar were fabricated using CAM (CAM-TD, Thermeo, pro3dure medical GmbH, Iserlohn, Germany; CAM-CL, CLEARsplint, Astron Dental Corporation, Lake Zurich, USA) and 3DP (3DP-GI, GR22 flex, pro3dure medical GmbH; 3DP-KY, KeySplint soft, Keystone Industries, Gibbstown, USA). The substrates were subjected to mastication simulation (120,000 cycles, 37 °C, 50 N, 1.3 Hz) opposed to enamel antagonists. The two-body wear was measured through matching of the scanned substrates before and after aging using Gaussian best-fit method. The damage patterns were categorized and evaluated based on microscopic examinations. Data was analyzed using Kolmogorov–Smirnov test followed by 1-way analysis of variance (ANOVA). Pearson correlation was calculated between vertical and volumetric material loss. The failure types were analyzed with Chi2-test and Ciba Geigy table.ResultsNo difference in two-body wear results between all materials was found (p = 0.102). Fatigue substrates showed a perforation for CAM and a fracture for 3DP. No abrasion losses on the antagonists were detected.Conclusions3DP substrates showed no differences in two-body wear compared to CAM ones but are more likely to show a fracture. None of the tested materials caused an abrasion on human teeth structure.Clinical relevanceWhile therapies with occlusal splint materials are rising, 3DP offers a promising alternative to CAM in terms of production accuracy and therapeutic success at reduced costs.

Hybrid Fiber Reinforced Concrete Composite for Construction of Rigid Pavements

Reinforcement of cement concrete using a hybrid combination of fibers is one of the recent developments in the concrete composite. This study used a hybrid combination of micro polypropylene graded fiber (up to 6 mm in length) and macro hooked end steel fiber (60 mm in length). The polypropylene fiber was optimized targeting a 20-25% reduction in drying shrinkage and abrasion loss. The steel fiber dosage was optimized for an enhancement of 15-20% in the flexural strength in bending over a conventional pavement concrete. The hardened state properties relevant to pavement concrete such as strengths and durability in terms of abrasion loss and drying shrinkage were investigated. Additionally, flexural behaviour (toughness indices and residual strength factors) and impact resistance were also studied. A minimum improvement of 19% in flexural strength, and 12% in splitting tensile strength, but a reduction in compressive strength (≈ 10%) was noted. A significant reduction in drying shrinkage (53%) and abrasion loss (31%) were noticed for the hybrid fiber reinforced concrete composite (HyFRCC) mix in comparison with the control concrete. Further, a significant improvement up to 14 times in toughness indices, 66-74 units in residual strength factors, and up to 27 times in impact resistance for HyFRCC were encountered. The study finally suggests that a hybrid combination of polypropylene fiber (0.1%) and steel fiber (0.5%) can be used in the construction of a long-lasting, economical, and sustainable concrete pavement including concrete overlays such as bridge deck slabs and white topping pavements.

Performance of Asphalt Mixture Incorporated Encapsulated Cigarette Butts as Bitumen Modifier

Cigarette butts are non-biodegradable waste, and the difficulties in dealing with cigarette waste is a big concern for communities and environmental groups all over the world. In past years, cigarette butts has been increasingly used on flexible pavement and has become one of the causes that increases pavement strength and reduces environmental challenges. Environmental factors are external influences that affect the performance of flexible pavements. These include snow, chemicals, water, and ageing issues. The aim of this research is to evaluate the mechanical and physical properties of asphalt mixture incorporating encapsulated cigarette butts. Asphalt concrete has a number of problems, including rutting, moisture removal, and binder drain. The use of asphalt is restricted due to high temperatures that cause rutting cracking of the asphalt or coating layer. Therefore, it is necessary to modify asphalt and improve its quality with less affects to environment. In this research, experiments were carried out to compare two types of asphalt which are unmodified asphalt and modified asphalt mixture. For modified asphalt, various percentages of encapsulated cigarette butts were added to the mixtures. The additive used was encapsulated cigarette butts with increment 0%, 0.2%, 1% and 3% for the bitumen and 0%, 5%, 10% and 15% for asphalt mixture. Penetration test, softening point, ductility test, penetration index, los angeles (LA) abrasion test, marshall tests, indirect tensile strength test and dynamic creep test were performed. The findings of the studies performed in this project reveal that varying the percentages of cigarette butts in the asphalt concrete mixture obviously differs in the mechanical and physical characteristics of asphalt mixture. As a result, the addition of CBs to AC resulted in a different abrasion loss value when compared to unmodified AC. At 10% CBs put into the asphalt mixture, the abrasion loss was chosen as the most advantageous level for increasing the performance of AC mixture. Based on the results of the mechanical and physical tests we can infer that 5% of CBs is the best percentage of cigarette butts to add in asphalt mixture. So this study proved that cigarette butts to be an effective material is used as an addition to asphalt binder because it improves performance by increasing paving strength and stiffness.

A novel prediction model for durability properties of concrete modified with steel fiber and Silica Fume by using Hybridized GRELM

The service life performance of conventional and modified concrete subjected to harsh climatic condition environment is directly related to durability properties of concrete like abrasion, freezing and thawing cycles. These properties are critical issues that should be predicted before performing experimental test. On this basis, the basic purpose of this paper is to predict the abrasion loss, freezing and thawing properties of concrete modified with silica fume (SF) and steel fiber (SFb) by using mix design and additional properties. From this point of view, a conducted experimental study was selected as a case study. In the control concrete (CC) mixtures, Portland cement, crushed stone aggregate, and superplasticizer (SP) were used in the selected experimental study. SP in concrete mixtures was used in the amounts of 1.0%, 1.5%, and 2.0% by weight of cement, and so modified concrete was produced with and without SFb according to the target strength of C25. Furthermore, SF and SFb were used in different amounts to modify the concrete. The SF was replaced with cement in the amounts of 7.5%, 10.0%, and 15.0%. In total, 16 different mix designs were prepared with different SP and SF ratios. In addition, SFb was added to all mixtures of designed concrete at a constant amount of 65 kg/m3. Additionally, a 16-mix design was prepared with SFb. Cumulatively, 32 different mix designs were prepared for the experimental study. Tests on the fresh, hardened, and life-cycle performance properties of the concrete were conducted. As for the metaheuristic part of this study, on the basis of the available experimental data, life-cycle performance parameters of the concrete modified with SF and SFb are predicted by using single and hybrid generalized extreme learning machine methods. Eight different data sets were generated with gradually extended input data. Two different outputs were considered: abrasion resistance (AL) and freezing/thawing (FT). Particle Swarm Optimization (PSO) and Grey Wolf Optimization (GWO) algorithms were used to produce binary and ternary hybrid methods. Four different models were proposed as listed: single use of Generalized Extreme Learning Machine (GRELM), binary use of GRELM-PSO, and GRELM-GWO. Finally, PSO and GWO were hybridized and integrated into GRELM. Two quality indicators, namely Root Mean Square Error (RMSE) and correlation of determination (R2), were considered to see the performance of the prediction. The results showed that the proposed ternary prediction model composed of GRELM-PSO-GWO provided more accurate results in all sets from 74% to 91% by extending input parameters, even if complicated parameters are inserted in as an input to the data set.

Mechanical Characterization of Industrial Waste Materials as Mineral Fillers in Asphalt Mixes: Integrated Experimental and Machine Learning Analysis

In this study, the effect of seven industrial waste materials as mineral fillers in asphalt mixtures was investigated. Silica fume (SF), limestone dust (LSD), stone dust (SD), rice husk ash (RHA), fly ash (FA), brick dust (BD), and marble dust (MD) were used to prepare the asphalt mixtures. The obtained experimental results were compared with ordinary Portland cement (OPC), which is used as a conventional mineral filler. The physical, chemical, and morphological assessment of the fillers was performed to evaluate the suitability of industrial waste to replace the OPC. The volumetric, strength, and durability of the modified asphalt mixes were examined to evaluate their performance. The experimental data have been processed through artificial neural networks (ANNs), using k-fold cross-validation as a resampling method and two different activation functions to develop predictive models of the main mechanical and volumetric parameters. In the current research, the two most relevant parameters investigated are the filler type and the filler content, given that they both greatly affect the asphalt concrete mechanical performance. The asphalt mixes have been optimized by means of the Marshall stability analysis, and after that, for each different filler, the optimum asphalt mixtures were investigated by carrying out Indirect tensile strength, moisture susceptibility, and abrasion loss tests. The moisture sensitivity of the modified asphalt mixtures is within the acceptable limit according to the Indian standard. Asphalt mixes modified with the finest mineral fillers exhibited superior stiffness and cracking resistance. Experimental results show higher moisture resistance in calcium-dominant mineral filler-modified asphalt mixtures. Except for mixes prepared with RHA and MD (4% filler content), all the asphalt mixtures considered in this study show MS values higher than 10 kN, as prescribed by Indian regulations. All the values of the void ratio for each asphalt mix have been observed to range between 3–5%, and MQ results were observed between 2 kN/mm–6 kN/mm, which falls within the acceptable range of the Indian specification. Partly due to implementing a data-augmentation strategy based on interpolation, the ANN modeling was very successful, showing a coefficient of correlation averaged over all output variables equal to 0.9967.

Artificial Neural Network Modeling of Abrasion Loss and Surface Roughness of Crab Carapace Impregnated Coir Vinyl Ester Composites

Roughness plays an important role in determining how an object would be related with its environment. In tribology, rough surfaces easily obtain wear more quickly and have higher friction coefficients than smooth surfaces. Roughness is often a good analyzer of the performance of a mechanical component. This investigation is aimed to study the abrasion loss and surface roughness behaviors in crab carapace-filled coir fiber reinforced vinyl ester composites. The development of filler-impregnated fiber-polymer composites in recent years necessitated the evaluation and prediction of tribological behaviors in fiber reinforced composites. The composite fabrication was planned by varying the three fabrication parameters with three levels such as fiber length (10 mm, 30 mm, and 50 mm), fiber diameter (0.1 mm, 0.18 mm, and 0.25 mm), and content of crab carapace fillers (0%, 2%, and 4%) as per Design of Experiments (DOEs) in this current investigation. Low velocity integrated wear loss tests on composite samples were carried out, and also the average surface roughness is measured in the fabricated composites. Nonlinear regression equations were developed to study the correlation between tribological behaviors and fabrication parameters. The interaction effect of fabrication parameters was studied using ANOVA two-tail test and validated using response surface plots. In order to forecast abrasion loss and surface roughness behaviors, artificial neural network (ANN) models were constructed, and it was discovered that the produced ANN models effectively predicted the abrasion loss as well as surface roughness behavior within the given ranges.

Insights into structural, thermal, electrical and mechanical properties of copper alumina reinforced chlorinated natural rubber nanocomposites

Current research intended the fabrication of highly durable conducting rubber products of low cost and wide applicability in the field of electronics. Chlorinated natural rubber (Cl-NR) reinforced with copper alumina (Cu-Al2O3) nanocomposites were fabricated by a solvent-free and economically viable industrial compounding technique with special attention to structural, morphological, rheometric curing behaviour, flame retardancy, electrical conductivity, dielectric, thermal and mechanical properties. FT-IR spectra confirmed the presence of Cu-Al2O3 in Cl-NR. The XRD investigation showed the crystalline peaks of Cu-Al2O3 in Cl-NR nanocomposites. The SEM and TEM results indicated that the nanoparticles were uniformly dispersed into the chlorinated rubber in the nano regime. The DSC results indicated that the addition of nanoparticles into the rubber matrix increased the glass transition temperature of the composites. The conductive metal oxide particles in the rubber accelerate the vulcanization process, which could be more beneficial in the industrial sector. The AC conductivity, dielectric properties, tensile strength, modulus, tear strength, heat build-up and hardness of nanocomposites were greatly increased, whereas the elongation at break, abrasion loss and resilience were decreased with the addition of nanoparticles to the chlorinated natural rubber. These increased mechanical properties of rubber nanocomposites with improved processability, controlled morphology and electrical properties are important parameters in the designing of flexible flame retardant electronic devices, electromagnetic induction shielding and conducting adhesive materials.

Albedo Change Mechanism of Asphalt Concrete Surfaces

Albedo, or average solar reflectance, is an important property affecting the development of temperature profiles within asphalt concrete (AC) pavements. It influences material durability and has an urban heat island effect. The albedo of new AC pavements ranges from 0.05 to 0.10 but rises rapidly to a stable value ranging from 0.15 to 0.25 within the first year of service. The mechanism of this rapid increase has typically been associated with oxidation of the asphalt binder, loosely referred to as “aging,” but has never been verified in the laboratory. To test this hypothesis, AC mixtures, prepared using PG 64-22 unmodified asphalt binder and aggregates, were subjected to accelerated aging using various techniques. The albedo of the AC mixtures was found to have statistically the same value of about 0.05 regardless of the extent and method of aging. An alternate hypothesis introduced is that the albedo increases as a result of abrasion loss of the surface binder, which has been tested in the laboratory. When this new abrasion procedure was applied to four field cores, the albedo increased in the same way observed in the field. This laboratory study confirmed that abrasion and loss of surface binder is the primary mechanism for the rapid increase in albedo of AC pavements.

Evaluation of High Los Angeles Abrasion Loss Aggregate in Stone Matrix Asphalt

Stone matrix asphalt (SMA) was developed in Germany over 40 years ago to resist rutting from studded tire wear. In recent years, there has been increased interest in SMA in the U.S.A. The foundation of SMA mixes is a coarse aggregate stone skeleton that forms a load-bearing matrix. Typical requirements of aggregate are between 30% and 40% loss measured by Los Angeles abrasion test. South Carolina’s granitic aggregate sources are mostly between 45% and 60% loss. In this study, sources with 44%, 53%, and 56% loss were evaluated for pavement rutting, moisture susceptibility, draindown, and cracking potential. The original plan started with designs using 12.5 mm nominal maximum aggregate size (NMAS) to increase macrotexture, from a safety standpoint, but eventually changed to 9.5 mm NMAS to be more consistent with typical coarse aggregate stockpile gradations in South Carolina. The designs were tested with and without fiber. The fiber designs met draindown requirements while the fiberless ones failed at elevated temperatures. The designs met the rut susceptibility criteria and the data indicated that moisture damage did not compromise the designs. The cracking test index (CTindex), a measure of cracking potential, showed good resistance for all of the designs with the exception of the 9.5 mm NMAS with fiber, which had poor results even when compared with high RAP (reclaimed asphalt pavement) dense-graded mixtures. The macrotexture for the 12.5 mm NMAS designs was comparable with other South Carolina open-graded friction course mixtures. Overall, the sources with 44% and 53% loss by Los Angeles abrasion test performed equivocally, with the 9.5 mm fiber design having lower cracking resistance.

Use of Ultra-High-Performance Concrete to Produce Standard Coarse Aggregates

Abstract The present study proposes to develop and use an ultra-high-performance concrete (UHPC) to produce standardized coarse aggregates. To that end, production protocols were established to control particle size distribution, shape, porosity, and compressive strength aimed at railway ballast as an application example. The artificial aggregate was produced to mimic the characteristics of a natural aggregate of gneiss used as ballast in Brazil. The characterization results showed that the artificial aggregate exhibited similar characteristics to those of gneiss, especially density, compressive strength, micro-deval abrasion loss, and resilient modulus, which are important for the application adopted. Moreover, the UHPC aggregate behaved better than gneiss after wetting-drying cycles in weather-resistance tests.

Prediction the micro-Deval abrasion loss of rock aggregates from mainly the ultrasonic pulse velocity and some strength parameters

Prediction the micro-Deval abrasion loss of rock aggregates from mainly the ultrasonic pulse velocity and some strength parameters

Preparation of Artificial Pavement Coarse Aggregate Using 3D Printing Technology

Coarse aggregate is the main component of asphalt mixtures, and differences in its morphology directly impact road performance. The utilization of standard aggregates can benefit the standard design and performance improvement. In this study, 3D printing technology was adopted to prepare artificial aggregates with specific shapes for the purpose of making the properties of artificial aggregates to be similar to the properties of natural aggregates. Through a series of material experiments, the optimal cement-based material ratio for the preparation of high-strength artificial aggregates and corresponding manufacturing procedures have been determined. The performance of the artificial aggregates has been verified by comparing the physical and mechanical properties with those of natural aggregates. Results indicate that using 3D printing technology to generate the standard coarse aggregate is feasible, but its high cost in implementation cannot be ignored. The 3D shape of the artificial aggregate prepared by the grouting molding process has a good consistency with the natural aggregate, and the relative deviation of the overall macro-scale volume index of the artificial aggregate is within 4%. The average Los Angeles abrasion loss of artificial cement-based aggregate is 15.2%, which is higher than that of diabase aggregate, but significantly lower than that of granite aggregate and limestone aggregate. In a nutshell, 3D printed aggregates prepared using the optimized cement-based material ratio and corresponding manufacturing procedures have superior physical and mechanical performance, which provides technical support for the test standardization and engineering application of asphalt pavements.

WEAR PROPERTIES AND MICROSTRUCTURE OF WC–10Co–4Cr POWDER COATING APPLIED TO CULTIVATOR BLADES VIA HVOF

Abrasion of cultivator equipment parts working in the soil causes serious losses if necessary precautions are not taken. The cultivator blades used to plow the soil in agricultural production wear out over time. In order to reduce this wear, the hardness and wear resistance of the material should be increased first. In this study, some of the 30MnB5 cultivator blades were heat-treated and some were coated with HVOF technique. The samples were obtained by plowing the soil at 15-cm working depth and 5.4-km[Formula: see text]h[Formula: see text] forward speed in two fields with different soil moisture contents. As a result of the experiments, abrasion losses and surface deformation of the blade material were observed and the effect of soil moisture on wear was also determined. After the treatment of 49.5[Formula: see text]daa (decare) with soil at 9% moisture content, the heat-treated 30MnB5 sample was worn 5.6 g, and the sample coated with WC–10Co–4Cr was worn 3.2[Formula: see text]g. Abrasions at 14% soil moisture were 6.3 g and 3.6[Formula: see text]g, respectively. It was observed that the coated material was less corroded than the heat-treated material. While the results obtained will contribute to the prevention of economic losses, the release of metals into the soil will also be prevented.

Effects of RH-WMA Additive on the Design Binder Content (DBC) of Warm Porous Asphalt (WPA)

Warm mix asphalt (WMA) in a pavement construction is a technology that is beneficial and contributes towards reduction of the global warming issues. In this research, WMA was used to design porous asphalt pavement with addition of organic additive which is known as RH-WMA. A Dutch modified gradation to suit Malaysian quarry practice was used to prepare the WMA. The RH-WMA additive ranges between 2 to 5 percent was added to base binder of penetration 60/70 to determine the design binder content (DBC) of the RH-WMA mix. The DBC was then determined based on the binder drainage and Cantabrian tests. The binder drainage test was used to set an upper limit while the Cantabrian test for abrasion loss was adopted to determine the lower limit of the DBC. The results for Cantabrian test indicate significant contribution of incorporating RH-WMA additive into WMA to minimize abrasion loss as compared to unmodified mixes. The binder drainage test results showed that the mixes incorporating RH-WMA additive exhibited higher drainage in varying degrees depending on the quantity of RH-WMA. The discussion was made based on target binder content, critical binder content, maximum binder content and the maximum retained binder content of the of the resulted mixes obtained from the binder drainage test.

Effect of Cement and Fly Ash Dosages on the Characteristics and Performance of Microsurfacing Mix

In this study, the role of mineral fillers on the microsurfacing mix characteristics and performance was assessed for 10 different combinations of mineral filler type (cement and fly ash) and dosages (0%–3%). The mixes were initially characterized in terms of compatibility, cohesion, and adhesion using Schulze-Breuer and Ruck test, cohesion test, and boiling water test, respectively. Subsequently, the performance of microsurfacing mixes, that is, raveling and rutting resistance, was determined using wet track abrasion test and loaded wheel test, respectively. Results indicated that the filler–emulsion system’s compatibility improved significantly with the addition of cement at the proper dosage. In contrast, mixes with only fly ash as mineral filler had inferior filler–emulsion compatibility. Also, the rate of strength development and adhesion was higher with cement than fly ash. The performance, that is, raveling and rutting resistance, positively correlates with the 60-min cohesion, adhesion, and compatibility (abrasion loss). Interestingly, the combination with 2% cement and 1% fly ash as mineral filler had the best mix characteristic and performance, indicating that the careful selection of the type and the dosage of mineral filler could maximize the durability of the microsurfacing mix.

Enhancement of the thermal and physicochemical properties of styrene butadiene rubber composite foam using nanoparticle fillers and electron beam radiation

Abstract This study investigates the physicochemical and thermal properties of styrene–butadiene rubber (SBR) nanocomposite foam. Nano-calcium carbonate (CaCO3) was prepared from eggshells (ESs) waste. Sponge rubber nanocomposites were prepared and were irradiated by electron beam (EB) radiation at 25, 75, and 150 kGy. Their physicochemical properties, including foam density, compression set (CS), hardness, abrasion loss, and expansion ratio, and their thermal stability were investigated. The physicochemical properties were enhanced by adding 2.5 phr of a foaming agent. Among the composites examined, the foam composites containing nano-CaCO3 had the lowest CS, abrasion loss, and expansion ratio and the highest hardness and foam density. The results confirmed that the thermal stability was improved by incorporating nano-CaCO3 into the SBR foam and as the radiation dose increased. The sponge containing nanoclay demonstrated an intermediate behavior, whereas that with CaCO3 nanoparticles showed low average cell diameter and size and high cell wall thickness. The radiation process enhanced the foam density, CS, abrasion loss, hardness, and thermal property of the developed nanocomposites by inducing the formation of intermolecular crosslinks within the composite matrix. The results showed that physicochemical properties improved by increasing the radiation dose at 25 kGy.

Improving the mechanical performance of poroelastic road surface with low polyurethane content through surface activation

The poroelastic road surface (PERS) mixture with low polyurethane content (PERS-LPC) can reduce the construction cost of PERS pavement, which exhibits promising noise reduction capacity, whereas its mechanical performance needs to be further enhanced for real practice. This study aims to investigate the effectiveness of surface activations of crumb rubber and aggregate to improve the mechanical performance of PERS-LPC. Molecular dynamics (MD) simulations and indoor experiments have been conducted, including the indirect tension (IDT) test implemented on the dry-cured and freeze–thaw PERS-LPC specimens and Cantabro test performed on water-bathed specimens. The results showed that, the oxygen-containing groups, introduced by UV irradiation and KMnO4 soaking, enhanced surface polarity of crumb rubber and rubber-polyurethane bonding strength. The surface activity of basalt aggregate was increased by the inclusion of Portland cement but not by hydrated lime. The IDT strength of the dry-cured PERS-LPC mixture was improved by 10.3–17.5% with activated rubbers and by 35.6% with activated aggregates. The tension strength ratio (TSR) of the freeze–thaw mixture was increased only by 2% with activated rubber but up to 20.8% by the inclusion of 0.5 wt% cement. The Cantabro abrasion loss (CAL) of PERS-LPC specimens was reduced significantly from 20.1% to 11.6% with the soaked rubber and dropped dramatically to 7.9% after inclusion of 0.5 wt% cement. It was recommended to activate crumb rubber with UV irradiation for 24 h and mineral aggregate with 0.5 wt% cement in PERS-LPC mixture in terms of performance enhancement and operation convenience. The findings of this research were expected to support the mix design of an inexpensive and durable PERS-LPC mixture for noise reduction.

Predicting the abrasion loss of open-graded friction course mixes with EAF steel slag aggregates using machine learning algorithms

This study presents a comparative assessment of machine learning techniques for modeling the abrasion loss (AL) of open-graded friction course (OGFC) mixes. The proposed approach is Orthogonal Matching Pursuit (OMP), Huber Regressor (HR), Lasso Lars CV (LLCV), Lars CV (LCV), and Ridge Regressor (RR). To construct and validate the proposed models, a sum of 228 experiments of OGFC mixes with different proportions of natural aggregates and electric arc furnace (EAF) steel slag were performed. Based on the analyses with 4 different combinations of input parameters, the proposed OMP model exhibits the most accurate prediction of AL of OGFC mix in both training and validation phases. Comparison of results of the developed models indicated that the OMP model has the potential to be a new alternative to assist engineers/practitioners in estimating the AL of OGFC mixes. In addition, the effect of % replacement of natural aggregates with electric arc furnace steel slag can also be studied.

Evaluation of the use of a HiMA binder to extend the durability of porous friction courses (PFC)

ABSTRACT Porous friction courses (PFC) are thin layers of asphalt mixtures with open gradations and high air void contents, which are placed over conventional flexible pavements. Although they improve various safety and environmental issues, their main difficulty is their short service life. A common practice to enhance PFC durability is the use of modified asphalt binders (e.g. regular polymer-modified asphalt (PMA) or asphalt rubber). However, this approach has not been enough to achieve life-spans close or equal to those of dense-graded hot mix asphalt. The use of highly polymer-modified asphalts (HiMA), which are binders modified at polymer doses near 7–8% by total weight of the binder, constitutes an alternative to overcome this challenge. This work evaluates the mechanical performance of four PFC mixtures fabricated with a regular polymer modified (PMA) and a HiMA binder, and two aggregate sources. The experimental plan included the semicircular bending (SCB), IDEAL-CT, Cantabro abrasion loss and Tensile Strength Ratio (TSR) tests at intermediate temperatures and various ageing conditions. Results indicate an enhanced cracking and degradation resistance for PFC mixtures containing HiMA and suggest that the use of this type of asphalt binder could increase the service life of these mixtures.

Bioinspired Imbricated Microthorn Scale Surfaces and their Abrasive Wear Performance

HighlightsImproving the wear resistance of soil-engaging components is an urgent need for the agricultural machinery industry.Sandfish (Scincus scincus) epidermis with exceptional wear resistance was selected as a bionic prototype.By adopting a bionic engineering approach, a novel bioinspired microthorn scale surface was designed and prepared.Numerical simulations were performed with EDEM to investigate the wear resistance mechanism.Abstract. To solve the problem of abrasive wear failure of the soil-engaging components of agricultural machinery, the imbricated microthorn scale structure of the sandfish (Scincus scincus) epidermis surface was selected as a bionic prototype. By adopting a bionic engineering approach, nine bionic microthorn scale surface specimens with different geometric structure parameters were designed and prepared. Wear resistance tests were performed in a rotating abrasive wear testing system. The results of the wear tests showed that the imbricated microthorn scale structured surfaces had substantially less abrasion loss than a conventional smooth surface. The influence of the geometric structure parameters on the wear performance was also identified. Numerical simulations were performed to explore the wear resistance mechanism of the imbricated microthorn scale structured surfaces. The abrasion of the bionic surfaces mainly occurred at the edge of the microthorn that faced the abrasive particle flow. The trajectory of subsequent abrasive particle flow was modified by the large dispersion of particle flow; hence, the number of particles that impacted the surface decreased. Therefore, the wear resistance performance of the bionic surfaces was enhanced. This bioinspired surface can provide a technical reference to mitigate the abrasive wear failure of the soil-engaging components of agricultural machinery. Keywords: Abrasive wear, Archard wear, Bionic design, Discrete element method, Scale surface.