Compact Test Research Articles

Modelling of crack propagation in miniaturized and normal SENB specimens based on local failure criterion

The use of miniaturized specimen testing methods is a promising way to solve the problem of limited materials in RPV monitoring programs. The use of miniature specimens allows the evaluation of fracture toughness from other specimen materials used. In particular, the small-size compact tensile test specimen (0.16T CT) is promising for the determination of fracture toughness, as it can be produced from the standard size Charpy specimen that has already been tested. However, if we have only 0.16T CT test, we cannot investigate the dimensional response and also have only one restricted deformation state, which may pose problems in verifying geometry independence and determining local parameters for state-of-the-art analyses. It is therefore recommended to prepare at least two tests with two different restricted deformation specimens. Therefore, the testing of mini single edge notched bending (SENB) is also required and can be worked out from the Charpy specimens. The paper presents the determination of fracture toughness for these miniaturized specimens by modifying the virtual crack closure technique (VCCT) simulation method using GTN parameters instead of energy release as the driving force. This allows the calculation of the J-integral to proceed in parallel with the crack propagation.

Development of a high current electron beam facility for compact accelerator neutron source target thermal tests

Target thermal capabilities are one of the major key points for CANS (Compact Accelerator-based Neutron Source) developments. Indeed, high energy (few MeV) and high average current (few tens of mA) proton or deuteron beams are required to produce high thermal neutron flux of 101³ n.cm⁻2.s⁻1 or greater. The targets must therefore absorb and dissipate a high thermal power. In order to make progress on their designs without deuteron or proton beams, we developed a compact electron beamline based on an Electron Cyclotron Resonance (ECR) source that permits testing of targets under relevant thermal conditions at power densities up 3 kW. cm⁻2.

Physical and Mechanical Properties of All-Solid-Waste-Based Binder-Modified Abandoned Marine Soft Soil

Large quantities of abandoned marine soft soil are generated from coastal engineering which cannot be directly utilized for construction without modification. The utilization of traditional binders to modify abandoned marine soft soil yields materials with favorable mechanical properties and cost efficiency. However, the production of traditional binders like cement leads to environmental pollution. This study uses a CGF all-solid-waste binder (abbreviated as CGF) composed of industrial solid waste materials such as calcium carbide residue (CCR), ground granulated blast furnace slag (GGBS), and fly ash (FA), developed by our research team, for the modification of abandoned marine soft soil (referred to as modified soil). It is noteworthy that the marine soft soil utilized in this study was obtained from the coastal area of Jiaozhou Bay, Qingdao, China. Physical property tests, compaction tests, and unconfined compressive strength (UCS) tests were conducted on the modified soil. The investigation analyzed the effects of binder content, compaction delay time, and curing time on the physical, compaction, and mechanical properties of CGF-modified soil and cement-modified soil. Additionally, microscopic experimental results were integrated to elucidate the mechanical improvement mechanisms of CGF on abandoned marine soft soil. The results show that after modification with binders, the water content of abandoned marine soft soil significantly decreases due to both physical mixing and chemical reactions. With an increase in compaction delay time, the impact of chemical reactions on reducing water content gradually surpasses that of physical mixing, and the plasticity of the modified soil notably modifies. The addition of binders results in an increase in the optimum moisture content and a decrease in the maximum dry density of CGF-modified soil, while the optimum moisture content decreases and the maximum dry density increases for cement-modified soil. Moreover, with an increase in binder content, the compaction curve of CGF-modified soil gradually shifts downward and to the right, while for cement-modified soil, it shifts upward and to the left. Additionally, the maximum dry density of both CGF-modified and cement-modified soils shows a declining trend with the increase in compaction delay time, while the optimum moisture content of CGF-modified soil increases and that of cement-modified soil exhibits a slight decrease. The strength of compacted modified soil is determined by the initial moisture ratio, binder content, compaction delay time, and curing time. The process of CGF modification of marine soft soil in Jiaozhou Bay can be delineated into stages of modified soil formation, formation of compacted modified soil, and curing of compacted modified soil. The modification mechanisms primarily involve the alkali excitation reaction of CGF itself, pozzolanic reaction, ion-exchange reaction, and carbonization reaction. Through quantitative calculations, the carbon footprint and unit strength cost of CGF are both significantly lower than those of cement.

Predicting failure in injection-moulded short-fibre subcomponents under varied environmental conditions through fracture mechanics

Injection-moulded short-fibre composites are lightweight materials suitable for high-volume applications; however, current simulation methods (based on failure initiation criteria) to design components using these materials cannot yet accurately predict failure. This work presents a methodology to predict failure of injection-moulded short-glass-fibre reinforced thermoplastic (IM-SFRP) composite subcomponents, based on experimentally measured properties. The material's fracture toughness was characterised by Compact Tension tests for different fibre orientations and environmental conditions. These fracture toughnesses were used as the input for cohesive zone modelling in Finite Element simulations of subcomponents representative of automotive applications, coupled with fibre orientation fields predicted by an injection-moulding process simulation. These coupled simulations presented excellent agreement with the experimental results for subcomponents both in terms of (i) the peak load (highlighting the importance of accounting for the finite fracture toughness of the material to accurately predict the ultimate failure of the subcomponents), and (ii) the pre- and post-peak sequence of failure events (verified using fractographic analyses). This work also verified the applicability of temperature-moisture equivalence, not only for material characterisation using coupons including the material's fracture toughness, but also for the mechanical response of subcomponents until final failure. The methodology demonstrated in this paper contributes to designing safer and more efficient damage-tolerant IM-SFRP components.

Preparation and Mechanism Analysis of Stainless Steel AOD Slag Mixture Base Materials.

To promote resourceful utilization of argon oxygen decarburization (AOD) slag, this research developed a new three-ash stabilized recycled aggregate with AOD slag, cement, fly ash (FA), and recycled aggregate (RA) as raw materials. The AOD slag was adopted as an equal mass replacement for fly ash. The application of this aggregate in a road base layer was investigated in terms of its mechanical properties and mechanistic analysis. First, based on a cement: FA ratio of 1:4, 20 sets of mixed proportion schemes were designed for four kinds of cement dosage and AOD slag replacement rates (R/%). Through compaction tests and the 7-day unconfined compressive strength test, it was found that a 3% cement dosage met the engineering requirements. Then, the unconfined compressive strength test, indirect tensile strength test, compressive rebound modulus test, and expansion rate test were carried out at different age thresholds. The results showed that the mixture's strength, modulus, and expansion rate increased initially and then stabilized with age, while the strength and modulus initially increased and then decreased with increasing R. Secondly, based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) used to analyze the mechanism, it was found that the strength, modulus, and expansion rate of the new material can be promoted by blending AOD slag, due to its ability to fully stimulate the hydration reaction and pozzolanic reaction of the binder. Finally, based on the strength and modulus results, R = 3% was identified as the optimal ratio, which provides a reference point for the effective application of AOD slag and RA in road base materials.

Digital tools used on the teaching-learning process in geotechnical engineering

This article presents the incorporation of information and communication technologies on the teaching-learning process of geotechnical engineering to improve the quality of education and provide practical knowledge to civil engineering students. The content of this paper is divided into three main modules, which are: Treatment of laboratory tests results, Slope stability and Rock mass stability. For this, some software were used, including 2D limit equilibrium stability analysis, stability analysis of rock wedges and a dynamic mathematics, to obtain and analyze soil shear strength parameters, among others. Furthermore, a digital tool was developed to analyze the results gathered in compaction, one-dimensional consolidation, and direct soil shear tests, in order to clarify the relationship between theoretical concepts and practical results of the tests and analyses and to help students on doubts, in addition to increase their interest and motivation to perform the complete interpretation of the collected data. The activities were conducted in classes of geotechnical disciplines of the undergraduate course in Civil Engineering at the Federal University of Viçosa, aiming to promote active learning and improve teaching quality. Based on the results of an applied feedback questionnaire, it was observed that most students were satisfied with the resources used in the classroom, demonstrating that the implemented digital tools work as a didactic instrument that facilitates learning and comprehension of practical problems, in addition to enabling the resolution of several geotechnical engineering problems much more quickly and efficiently.

Mechanical Strength and Microstructure of Soft Soil Stabilized with Cement, Lime, and Metakaolin-Based Geopolymer Stabilizers

Soft soils require particular consideration when designing civil engineering structures due to their high compressibility, low shear strength, and permeability. Using chemical additives and geopolymers to stabilize soft soils is a practical approach to improve their engineering properties. The objective of the study was to explore the use of conventional stabilizers alongside metakaolin-based geopolymers. This study also aimed to investigate the compaction characteristics, mechanical strength, shear behavior, and microstructure of stabilized soft soil. The compaction test was carried out using various amounts of cement (6%, 8%, and 10%) and metakaolin (3%, 5%, and 7%) based on the dry weight of the soil. Cement, lime, and geopolymer were added to the soft soil at 15% of the dry weight of the soil for triaxial shear tests. The compaction test results indicated that the stabilized soil exhibited the highest maximum dry density at 8% cement content. Adding metakaolin (MK) to the cement-modified soil decreased the maximum dry density, smoothed the compaction curve, and increased the optimum moisture content. The unconfined compressive strength (UCS) test revealed that cement-stabilized soil had the highest yield stress, while adding MK to the cement-modified soil reduced the yield stress after 7 days of curing. Compared to untreated soft soil, there was a significant increase in shear strength parameters for cement-, metakaolin-, and lime-stabilized soil. This study demonstrates that adding chemical additives and geopolymers can improve the soft soil’s compaction characteristics, mechanical strength, and shear strength parameters.

Plastic Zone Radius Criteria for Crack Propagation Angle Evaluated with Experimentally Obtained Displacement Fields

The monitoring and maintenance of cracked structures are generally carried out using structural integrity assessments. The plastic zone (PZ) crack path (CP) criteria state that a crack grows in a specific direction when the radius of the plastic zone ahead of the crack tip reaches a minimum value. The PZ can be evaluated using stress intensity factors (SIFs). The SIFs under mixed-mode loading were extracted from the literature from three samples: two single edge notch tension (SENT) samples (E = 2.5 GPa, v = 0.38) made from polycarbonate and one modified compact test (C(T)) sample made from low-carbon steel (E = 200 GPa, v = 0.3). In addition, the CP angle was evaluated for the W and R criteria with experimental data, which included non-linear effects such as fatigue-induced plasticity, crack roughness, and debris. It was found that both can predict the CP for lateral cracks in both tested materials and monotonic and cyclic load when the mode mixity does not change considerably from one crack length to the next or goes beyond 0.2. Moreover, the R criterion exhibited an error as high as 1.7%, whereas the W criterion showed a 6% error on the last crack length for the low-carbon steel sample under cyclic load, which had a 100% increase in mode mixity. Finally, the applicability of LEFM was checked, while the CP was sought by finding the size of the PZ.

Impact of Rice Husk Ash on the Compaction Characteristics of Soil

Usually, the measurement of maximum dry density (MDD) and optimum moisture content (OMC) is important for assessing the quality control of the compacted fill or earthwork constructions as the compaction parameters. Rice husk ash (RHA), plentifully available in many rice-producing countries, can be used as a building material. This study mainly tries to investigate the effect of RHA on compaction features of sandy soil classified as A-2-4 or SM for soil stabilization. Nominal to a maximal dosage of RHA addition in the soil was considered for the experiments by the standard Proctor compaction tests. The result revealed that by increasing the amount of RHA in the soil, MDD was reduced and OMC increased significantly. It can be concluded that applying a soil-RHA combination is beneficial to soil improvement. Jagannath University Journal of Science, Volume 10, Number II, Dec. 2023, pp. 87-93

Geophysical and Geotechnical Investigations of the Subsurface for Construction Purposes at Federal College of Education Osiele, Abeokuta, Southwestern Nigeria

Knowledge of the surface and subsurface structures are vital for construction procedures. Integrated geophysical and geotechnical methods were applied to image the subsurface for evaluation of the stratigraphy and the competency of each geoelectric layer for construction purposes at the Federal College of Education Osiele, Abeokuta South-western Nigeria. Nine Vertical Electrical Sounding (VES) using Schlumberger electrode configurations were conducted over a current electrode spacing of 200 m. Multi-channel Analysis Surface Wave (MASW) was the seismic technique used for the geotechnical analysis of the study area and laboratory analysis was performed to investigate, Atterberg limit, particle size distribution, compaction test, specific gravity, and California bearing ratio. Results from the geophysical investigation revealed four to five geoelectric layers: topsoil, clayey sand, sandy clay, laterite, and fresh basement. The MASW results have s-wave velocities range of 40–500 m/s and analysis showed four layers. The laboratory analysis revealed that all the ten traverses have specific gravity, which is out of limit except sample 8 which is 2.80, plastic index and Atterberg limits of liquid were within permissible values of 12% and 35% respectively except samples 9 and 10, and California Bearing Ratio within specified limits. Geophysical and geotechnical investigation of the subsurface carried out in the study area for construction purposes revealed that the foundation of a heavy structure should be targeted at around 20 m into the subsurface.

Zero-shot test time adaptation via knowledge distillation for personalized speech denoising and dereverberation.

A personalization framework to adapt compact models to test time environments and improve their speech enhancement (SE) performance in noisy and reverberant conditions is proposed. The use-cases are when the end-user device encounters only one or a few speakers and noise types that tend to reoccur in the specific acoustic environment. Hence, a small personalized model that is sufficient to handle this focused subset of the original universal SE problem is postulated. The study addresses a major data shortage issue: although the goal is to learn from a specific user's speech signals and the test time environment, the target clean speech is unavailable for model training due to privacy-related concerns and technical difficulty of recording noise and reverberation-free voice signals. The proposed zero-shot personalization method uses no clean speech target. Instead, it employs the knowledge distillation framework, where the more advanced denoising results from an overly large teacher work as pseudo targets to train a small student model. Evaluation on various test time conditions suggests that the proposed personalization approach can significantly enhance the compact student model's test time performance. Personalized models outperform larger non-personalized baseline models, demonstrating that personalization achieves model compression with no loss in dereverberation and denoising performance.

Bearing capacity of Percut Sei Tuan clay stabilized with palm shell ash

Improvements to the bearing capacity of the soil have been carried out and developed at this time, one of which is the stabilization of clay soils. There are several alternatives to solve low soil bearing capacity, one of which is using geo-synthetic materials but has a weakness in terms of high cost. Another alternative is to add palm shell ash as a stabilizing agent. The effect of adding palm shell ash has not been thoroughly studied, so further research is needed. The material added is palm shell ash with a variation of 0%, 4%, 8%, 10%, and 12% in each test. The tests carried out in the laboratory were water content (w), specific gravity test (Gs), Atterberg limit test, sieve analysis (sieve analysis), soil compaction test, and CBR (California Bearing Ratio) test. The CBR test was carried out by curing the soil for 1, 3, 5, and 7 days with a mixture of palm shell ash before compaction. The soil in this study belongs to the A-7-5 group. The CBR (California bearing ratio) value increased with the increase in the palm shell ash percentage in the mixture after curing the soil. The highest CBR value was in the variation of 12% palm shell ash with a 7-day curing period of 6.92% with a soil bearing capacity of 5.06.

Influence of Cow Bone Powder on Selected Engineering Properties of Lime-Stabilized Soil

This study investigates the influence of cow bone powder (CBP) on consistency and compaction characteristics of lime-stabilized soil. Twelve soil samples were collected from four routes connecting Ado-Ekiti. Index and compaction tests were performed on the natural and stabilized samples. The soil samples were classified according to AASHTO groups and eventually restructured into four (4) groups: A-6, A-7-6, A-4, and A-7-5. They were named samples A, B, C, and D respectively. The oxide compositions of the samples were determined. Lime was blended with soils at proportions of 0, 2, 4, 6, 8,10 %, and the optimal lime content (LimeOpt) was obtained. The LimeOpt + soil mixture was mixed with 2, 4, 6, 8,10 % of CBP. The Soil + LimeOpt + CBP mixtures were subjected to consistency limits and compaction tests. Plasticity index (PI) of soils A, B, C, and D was 14.19, 21.06, 11.64, and 14.19 % respectively, while the MDD was 1640, 1730, 1630, and 1631 kg/m3. Soil A, B, C, and D + LimeOpt all had reduced PIs of 7.68, 16.40, 5.04, and 12.05%, respectively. For the MDD of soil + LimeOpt mixtures, 1789, 1920, 1906, and 1898 kg/m3 were also found for Samples A, B, C, and D. Soil + LimeOpt + CBP showed that both the PI (from 0.6 to 81.7%) and MDD (from 0.1 to 14.6%) improved. On the other hand, the addition of lime to soils A, B, C, and D showed that 8% lime content offered the optimal CBR performance. Further addition of CBP to the soil + LimeOpt mixtures equally improved both the soaked and unsoaked CBR of soils A, B, C, and D predominantly with 6% CBP addition offering the peak performance. This suggests that CBP is viable and can save cost, mitigate environmental hazards, and complement lime. Strength and durability evaluation of the ternary mixture is however recommended.

Stabilization of Clay Soil Using Lime and Polypropylene Fibre

Abstract: Soil is the basic foundation for any civil engineering structures. It is required to bear the loads without failure. In some places, soil may be weak which cannot resist the oncoming loads. In such cases, soil stabilization is needed. Numerous methods are available in literature for soil stabilization. But sometimes, some of the methods like chemical stabilization etc. adversely affect the chemical composition of the soil. The following material were used for preparing the samples; Clay soil Lime Polypropylene fibre (12mm length) Clay soil used for these experiments was brought from site, near EB Office, Kadayanallur. The physical properties of soil were determined as per IS specifications. This project aims to conduct a study to check the improvements in properties of clayey soil by adding lime (constant 3% weight of the clay soil) and various percentage of Polypropylene fibre (0%,0.25%, 0.50%, 0.75%, and 1.0% weight of the clay soil). These mixtures were investigated by conducting standard proctor compaction test, unconfined compression test and CBR test. The test were performed as per Indian standard specifications. Finally the maximum strength is obtained at 0.50% PPF and by maintaining 3% lime.

Fractal Analysis on the Crushing Characteristics of Soil-Soft Rock Mixtures under Compaction

Soil-rock mixtures (SRM) are extensively utilized as filling materials in engineering slopes and roadbeds. A comprehensive understanding of the crushing characteristics of SRM during compaction is essential for precisely controlling its mechanical properties, particularly when dealing with SRM comprising soft rock blocks. This study conducted heavy compaction and screening tests to investigate the crushing and compaction behaviors of soil-soft rock mixture (SSRM) with varying coarse particle content (P5 content), the primary focus was primarily on analyzing the double fractal characteristics of coarse and fine particles. The research findings are as follows: with the increase of P5 content, the maximum dry density of SSRM initially rises and then declines, reaching its peak when P5 content is 70%. Soft rock blocks in SSRM exhibit extreme fragility during compaction, the crushing index of coarse particles exhibits a linear increase with the rise in P5 content, whereas the crushing index of fine particles displays a “double peak” characteristic. After compaction, a linear positive correlation is observed between the fractal dimension and the crushing index of coarse and fine particles. With the increase in P5 content, the slope of the relationship curve between the fractal dimension and the crushing index of coarse particles remains relatively constant, while the intercept gradually decreases. Moreover, the fractal dimension of fine particles effectively reflects the compaction characteristics of SSRM, and the relationship between the fractal dimension of fine particles and dry density aligns with the compaction curve of SSRM.

Hot In-Place Recycled Asphalt Mixtures: RAP Analysis, Compaction Characteristics and Field Evaluation

The substantial accumulation of reclaimed asphalt pavement (RAP) poses a pressing issue in road construction. The hot in-place recycling (HIR) technique has garnered widespread attention due to its high recycling rates of RAP and minimal environmental hazards. This study focuses on the RAP analysis, compaction characteristics, and field evaluation of hot in-place recycled asphalt pavements (HIRAP). Firstly, a novel test method of RAP analysis was proposed to evaluate the suitability of RAP. Subsequently, compaction tests reveal the compaction characteristics of hot in-place recycled asphalt mixture (HIRAM). Finally, the field performance of HIRAP was assessed. The research findings indicate that the RAP analysis method can accurately characterize the status of RAP. Increasing the RAP temperature improves the compaction characteristics of HIRAM. The field tests show that using HIR technology improves the performance of the pavement, in particular with a compaction of 99.7%. This study will establish a theoretical foundation for further promoting the HIR technique.

The Unconfined Compressive Strength of Hy-drated Lime Stabilized Clayey Soil at Different Water Contents and Different Curing Times

This research was done to find out how adding hydrated lime and extra water content to clayey soil samples affecting their unconfined compressive strength (UCS). The clayey soil is a locally available soil from the clayey soil area in Cyrene, northeastern of Libya. In the soil samples, hydrated lime (HL) was added at a rate of 5% of the dry weight of the soil. The standard compaction test was conducted on the untreated natural soil sample “NS” so that the optimum water content at the maximum dry density can be determined wop1. Because of the addition of hydrated lime to the soil will affect the dry density-water content relationship, the standard compaction test was conducted again on the treated soil sample “NS+5%HL” to determine another optimum water content wop2. These optimum water values {wop1 =17.8 & wop2=19.5} will be used to prepare unconfined compressive strength specimens. In the experimental work two soil mixtures will be used beside the natural soil mixture. The first mixture "NS+5%HL+wop1" and the second mixture "NS+5%HL+wop2" were prepared in addition to the natural soil mixture "NS+wop1". All unconfined compressive strength specimens for the first and second mixtures were extracted and tested at 7 and 14 days of curing, then comparison were made. The first mixture, "NS+5%HL+wop1" will be compared with the natural soil mixture, "NS+ wop1" in order to understand the impact of HL addition. The effect of the water content changing can be seen when the second mixture, "NS+5%HL+wop2" is compared with the first mixture, NS+5%HL+wop1. According to the findings, Although the first mixture’s specimens have the least dry density value, the UCS values increased by 218.5 and 386.5% at 7 and 14 days of curing, respectively, when compared to the natural soil mixture. This illustrates the result of the added hydrated lime. At curing times of 7 and 14 days, respectively, the UCS values for the second mixture fell by 8.61 and 14.11% when compared to the first mixture. And this illustrates the impact of variations in water content.

Efficient Screening and Enhanced Exopolysaccharide Production by Functional Lactic Acid Bacteria (LAB) in Lactose Supplemented Media

Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) can be considered as natural biological thickeners that have attracted considerable attention in the food industry. This study aimed to evaluate and select potentially EPS-producing strains LAB and to assess the influence of carbon source and aeration on EPS production. Nine LAB strains were assessed as potential EPS producers, and Rahnella aquatilis ATCC 55046 was employed as the positive control strain for EPS. The compaction test and the observation of viscous colonies in a solid medium did not yield sufficient evidence for the presence of EPS. The assessment of capsules through staining provided evidence of EPS presence only for Rahnella aquatilis ATCC 55046. The EPS yield was subsequently assessed in De-Man Rogosa and Sharpe (MRS) broth medium supplemented with 2% (w/w) fructose (MRS-f) or lactose (MRS-l), as well as in whey (Whey) and whey supplemented with 2% (w/w) lactose (Whey-l). The EPS production in the various culture media under study ranged from 194 to 1,187 mg of EPS/g of polymer dry mass (PDM). These results suggest that the culture medium and carbon sources had an impact on the EPS production of the different strains. Bifidobacterium animalisBb12 achieved the highest EPS production in MRS-f. In the case of MRS-l, the control strain recorded the highest EPS value, along with Lactobacillus acidophilus LAC-1. Regarding Whey, Lentilactobacillus Kefir NCFB 2753 exhibited the highest EPS production, while in Whey-l, Lacticaseibacillus paracasei LCS-1 emerged as the top performer in terms of EPS production. This suggests that certain strains exhibit potential for use in the production of novel fermented EPS products, whether dairy or non-dairy.

Sustainable utilization of landfill mined soil like fraction in subbase layer for asphalt road applications

The scarcity of natural resources, and energy demand/carbon footprints related to their processing and transportation, has led to the quest for alternate materials for road/pavement construction and other infrastructure development. On the other side, landfill mined soil like fraction (LMSF) forms significant proportion of mined legacy landfill waste that exists at different locations around the world; however, it has found limited applications. The present study explores the utilization of LMSF in development of novel asphalt road subbase layers for resilient road infrastructure. 30–60% of LMSF replacement has been studied, and findings based on gradation analysis, compaction tests and California bearing ratio (CBR) tests are quite encouraging. Most combinations of subbase layers studied exceed the design requirements for low volume roads in Indian scenario (rural and outer urban roads); while 30% LMSF in wet mix macadam satisfies the requirements of Indian and other international codes. The cost-benefit analysis shows significant saving in material cost due to utilization of LMSF in road subbase layer. The potential utilization of low cost and sustainable LMSF in asphalt road subbase layer would allow design of superior roads with CBR exceeding design values, resulting in better life cycle performance of road infrastructure with high resilience to fatigue effects, water inundation and overloading conditions.

Interfacial characteristics of fiber asphalt mastic and aggregates: Impact on mixture crack resistance performance

The interfacial characteristics between fiber-modified asphalt mastics and aggregates play a crucial role in the performance of asphalt mixtures. To explore these interfacial interaction characteristics, three types of fibers (basalt, glass, and polyester), five levels of fiber content (ranging from 0.1% to 0.5% by mixture mass), and two types of aggregates (limestone and basalt) were selected, and an optimal mixture design was established. Contact angle tests, binder bond strength tests, and disk-shaped compact tension tests were conducted to investigate the impact of fiber type, fiber content, and aggregate type on interface characteristics. The results indicate that the addition of fibers can enhance the interfacial strength, with basalt fibers exhibiting superior reinforcement effects. As fiber content increases, the influence of aggregate type on interfacial strength decreases. Under ambient conditions, a composite failure mode was observed, while at low temperatures, cohesive failures dominated. The incorporation of fibers led to an increase in interfacial cohesion strength. The interfacial interaction strength between fiber asphalt mastic and aggregates exhibits a favorable linear correlation with the fracture energy and peak crack mouth opening displacement of the asphalt mixture. Overall, this study elucidates the microscopic mechanisms involved in fiber asphalt mixtures, laying the foundation for further in-depth research.