SELF-HEALING BITUMINOUS MATERIALS BY ADAPTIVE ENCAPSULATED REJUVENATORS SYSTEM IS A HOT TOPIC WITHIN ROAD MATERIALS. FOR THE FIRST TIME, THIS WORK EXPLORES THE NATURAL SPORES FOR THE ENCAPSULATION OF REJUVENATORS AS A NOVEL CONTROLLED RELEASE SYSTEM TO PROMOTE THE SELF-HEALING CAPABILITY IN AGED BITUMINOUS MATERIALS. TREATED SPORES WERE OBTAINED FROM NATURAL SPORES BY CHEMICAL PROCESSES. TO SYNTHESIZE SPORE-BASED MICROCAPSULES, FIRSTLY, SPORES WERE DEFATTED, AND THEN THE PROTEIN AND CELLULOSIC MATERIALS WERE REMOVED. SPORES WERE PROCESSED, AND SUNFLOWER OIL AS A REJUVENATOR WAS ENCAPSULATED INSIDE SPORE MICROCAVITIES BY ENCAPSULATING PASSIVE AND VACUUM LOADING TECHNOLOGIES. PHYSICOCHEMICAL AND MICROSTRUCTURAL PROPERTIES OF THE NATURAL SPORE FORMULATIONS WERE EVALUATED. CHANGES IN THE COMPOSITION OF THE SPORES AMONG THE PROCESS WERE STUDIED BY FTIR SPECTROSCOPY. THE MICROSTRUCTURE ANALYSIS SHOWED THAT THE SPORES AFTER TREATMENT WERE EMPTY, SHOWING THE COMPLETE REMOVAL OF ALL CONTENTS INSIDE, KEEPING INTACT MICROSTRUCTURE, AND PROVIDING LARGE CAVITIES FOR MOLECULAR LOADING. FURTHERMORE, SUNFLOWER OIL ENCAPSULATION EFFICIENCY INTO THE SPORE CAVITIES WAS CONSIDERABLY HIGHER WITH VACUUM LOADING THAN BY THE PASSIVE LOADING PROCESS. THE CONTROLLED RELEASE MECHANISM AND THE HEALING EFFICIENCY OF ENCAPSULATED REJUVENATORS IN THE SPORE CAPSULES WERE ALSO QUANTIFIED. IT WAS PROVED THAT THE PROPOSED APPROACH WAS ABLE TO CONTROL THE RELEASE OF THE REJUVENATOR WITH AN ATTRACTIVE BIOMATERIAL POSSESSING A VERY STRONG STRUCTURE. THE MAIN RESULTS PROVIDE THE BASIS FOR FURTHER EXPLORATION INTO THE ENCAPSULATION OF REJUVENATORS IN NATURAL PLANT SPORES AS A PROMISING NOVEL CONTROLLED RELEASE SPORE-BASED SYSTEM FOR THE SELF-HEALING OF BITUMINOUS MATERIALS.

THIS CHAPTER PROVIDES A COMPREHENSIVE SUMMARY OF THE SIGNIFICANT ADVANCES IN SELF-HEALING BITUMINOUS MATERIALS FROM THE ENGINEERING TECHNOLOGIES ASSOCIATED WITH PROMOTING THE AUTONOMOUS HEALING CAPABILITY IN THE ASPHALT PAVEMENTS TO THE LARGE-SCALE APPLICATIONS.

ASPHALT PAVEMENTS AND BITUMINOUS COMPOSITES ARE MAJORLY DAMAGED BY BITUMEN AGING AND FATIGUE CRACKING BY TRAFFIC LOAD. TO ADD, MAINTENANCE AND REPARATION OF ASPHALT PAVEMENTS IS EXPENSIVE AND ALSO RELEASES SIGNIFICANT AMOUNTS OF GREENHOUSE GASES. THESE ISSUES CAN BE MITIGATED BY PROMOTING ASPHALT SELF-HEALING MECHANISMS WITH ENCAPSULATED REJUVENATORS. THE ABILITY OF THE REQUIRED MICROCAPSULES TO BE RESILIENT AGAINST HIGH TEMPERATURES, OXIDATION, AND MECHANICAL STRESS IS ESSENTIAL TO PROMOTE SUCH SELF-HEALING BEHAVIOR WITHOUT COMPROMISING THE FIELD PERFORMANCE OF THE ASPHALT PAVEMENT. THIS WORK PROPOSES, FOR THE FIRST TIME, THE USE OF EXTREMELY RESISTANT BIOBASED SPORES FOR THE ENCAPSULATION OF RECYCLED OIL-BASED REJUVENATORS TO PRODUCE MORE RESILIENT SELF-HEALING PAVEMENTS. SPORE ENCAPSULANTS WERE OBTAINED FROM NATURAL SPORES (LYCOPODIUM CLAVATUM) BY APPLYING DIFFERENT CHEMICAL TREATMENTS, WHICH ENABLED THE SELECTION OF THE BEST MORPHOLOGICALLY INTACT AND CLEAN SPORE ENCAPSULANT. THE PHYSICAL, MORPHOLOGICAL, AND PHYSICOCHEMICAL CHANGES WERE EXAMINED USING FLUORESCENCE IMAGES, ATR-FTIR, SEM, SIZE DISTRIBUTION, XRD, TGA AND DSC ANALYSES. SUNFLOWER OIL WAS USED AS THE ENCAPSULATED REJUVENATOR WITH AN OPTIMAL SOL COLLOIDAL MIXTURE FOR SPOROPOLLENIN?OIL OF 1:5 (GRAM-TO-GRAM). VACUUM, PASSIVE, AND CENTRIFUGAL ENCAPSULATION TECHNIQUES WERE TESTED FOR LOADING THE REJUVENATOR INSIDE THE CLEAN SPORES AND FOR SELECTING THE BEST ENCAPSULATION TECHNOLOGY. THE ENCAPSULATION EFFICIENCY AND THE PROFILES OF THE ACCELERATED RELEASE OF THE REJUVENATOR FROM THE LOADED SPORES OVER TIME WERE STUDIED, AND THESE PROCESSES WERE VISUALIZED WITH OPTICAL AND INVERTED FLUORESCENCE MICROSCOPY. VACUUM ENCAPSULATION WAS IDENTIFIED AS THE BEST LOADING TECHNIQUE WITH AN ENCAPSULATION EFFICIENCY OF 93.02 ± 3.71%. THE REJUVENATOR WAS SUCCESSFULLY ENCAPSULATED INTO THE CLEAN SPORES, AS OBSERVED BY OPTICAL AND SEM MORPHOLOGIES. IN AGREEMENT WITH THE TGA AND DSC, THE MICROCAPSULES WERE STABLE UP TO 204 °

THIS STUDY AIMED TO CHARACTERISE POLYNUCLEAR BIOCAPSULES CONTAINING LOW-COST REJUVENATING AGENTS FOR ASPHALT SELF-HEALING. CAPSULES CONSISTED OF A BIOPOLYMERIC MATRIX OF CALCIUM ALGINATE CONTAINING COOKING OIL AND MINERAL OIL AS REJUVENATING AGENTS, BEING SYNTHESISED USING IONIC GELATION THROUGH THE PUMPING DRIPPING TECHNIQUE. THE PHYSICAL-CHEMICAL PROPERTIES OF THE OIL-IN-BIOPOLYMER EMULSIONS AND THEIR STABILITY OVER TIME WERE STUDIED. THE MORPHOLOGICAL AND THERMOPHYSICAL PROPERTIES OF THE BIOCAPSULES, AS WELL AS THE ENCAPSULATION EFFICIENCY OF THE REJUVENATING AGENTS, WERE QUANTIFIED AND CHARACTERISED BY MICROSCOPIC TECHNIQUES AND LABORATORY TESTS. MAIN RESULTS SHOWED THAT EMULSIONS SHOULD BE USED FOR ENCAPSULATION PURPOSES WITHIN A PERIOD NO LONGER THAN 3H, REDUCING THE EFFECT OF INSTABILITY PHENOMENA. BESIDES, THE BIOPOLYMER-BASED POLYNUCLEAR CAPSULES PRESENTED UNIFORM SIZE, INTERNAL MULTICAVITY MICROSTRUCTURE RESULTING IN HIGH ENCAPSULATION EFFICIENCIES AND THERMAL STABILITY AT HIGH TEMPERATURES, PROVING THAT COOKING OIL AND MINERAL OIL CAN BE POTENTIALLY USED AS LOW-COST REJUVENATING AGENTS AND THERMALLY STABLE ADDITIVES FOR ASPHALT SELF-HEALING PURPOSES.

THIS STUDY EVALUATED THE EFFECT OF TWO ENCAPSULATION METHODS (I.E., DROPPING FUNNEL AND SYRINGE PUMP), TWO CONCENTRATIONS OF THE ALGINATE-BASED ENCAPSULATING MATERIAL (2%, AND 3%), AND THREE OILS AS BITUMEN REJUVENATORS (VIRGIN SUNFLOWER OIL, WASTE COOKING OIL, AND VIRGIN ENGINE OIL) ON THE MORPHOLOGICAL, PHYSICAL, CHEMICAL, THERMAL, AND MECHANICAL PROPERTIES OF ENCAPSULATED REJUVENATORS FOR ASPHALT SELF-HEALING PURPOSES. A GENERAL FACTORIAL DESIGN 2 × 2 × 3 WAS PROPOSED TO DESIGN 12 DIFFERENT CA-ALGINATE CAPSULES. SIGNIFICANT DIFFERENCES ON THE MORPHOLOGICAL, PHYSICAL, AND MECHANICAL PROPERTIES OF THE CAPSULES WERE ANALYSED BY THREE-WAY ANOVA AND TUKEY HSD POST HOC ANALYSES. THE EFFECT OF THE TYPE OF OIL ON THE SELF-HEALING CAPACITY OF CRACKED BITUMEN SAMPLES WAS ALSO EVALUATED. THE MAIN RESULTS SHOWED THAT THE DESIGN PARAMETERS AND THEIR INTERACTIONS SIGNIFICANTLY AFFECTED THE MORPHOLOGICAL, PHYSICAL, AND MECHANICAL PROPERTIES OF THE CAPSULES. CAPSULES SYNTHESISED VIA SYRINGE PUMP METHOD, WITH VIRGIN COOKING OIL AND 2% ALGINATE WAS THE MOST APPROPRIATE FOR ASPHALT SELF-HEALING PURPOSES SINCE ITS UNIFORM MORPHOLOGY, ENCAPSULATION EFFICIENCY UP TO 80%, THERMAL DEGRADATION BELOW 5% WT., AND COMPRESSIVE STRENGTH ABOVE THE REFERENCE ASPHALT COMPACTION LOAD OF 10 N. FINALLY, THE HEALING TESTS SHOWED THAT VIRGIN COOKING OIL CAN BE POTENTIALLY USED AS A REJUVENATOR TO PROMOTE ASPHALT CRACK-HEALING.

THIS STUDY AIMED TO SYNTHESISE ENHANCED BIOCAPSULES CONTAINING OIL AS AN ADDITIVE TO PROMOTE SELF-HEALING IN BITUMINOUS MATERIALS. THE CAPSULES CONSISTED OF A BIOPOLYMERIC MATRIX OF SODIUM ALGINATE AS ENCAPSULATING MATERIAL AND SUNFLOWER COOKING OIL AS A NON-HAZARDOUS REJUVENATING AGENT. OIL WAS INCORPORATED IN FIVE CONCENTRATIONS BY WEIGHT OF ALGINATE, 1:1, 1:3, 1:5, 1:7, AND 1:9, RESPECTIVELY. THUS, FIVE OIL-IN-WATER (O/W) EMULSIONS WERE PREPARED TO SYNTHESISE BIOPOLYMERIC CAPSULES VIA IONIC GELATION USING AN ENCAPSULATOR DEVICE THAT WORKS BY JET VIBRATION TECHNIQUE. THE PHYSICAL PROPERTIES, STABILITY AND DROPLET SIZE DISTRIBUTION WERE MEASURED IN THE O/W EMULSIONS USING MICROSCOPY TECHNIQUES AND LABORATORY TESTS. THE MORPHOLOGICAL AND THE PHYSICAL-MECHANICAL PROPERTIES OF THE BIOCAPSULES WERE ALSO EVALUATED. THE MAIN RESULTS SHOWED THAT THE O/W EMULSIONS INCREASED THEIR VISCOSITY AND PHYSICAL STABILITY WHEN INCREASED THE OIL CONTENT, REDUCING THEIR CREAMING RATE OVER TIME. THE SYNTHESISED BIOCAPSULES PRESENTED SPHERICAL MORPHOLOGY AND HIGH ENCAPSULATION EFFICIENCY. THE SIZE OF THE PRODUCED BIOCAPSULES WAS MAINLY DEPENDENT ON THE SELECTED NOZZLE SIZE, THE FLOW RATE AND VISCOSITY OF THE EXTRUDED O/W EMULSIONS, AND THE VIBRATIONAL FREQUENCY APPLIED AND CONTROLLED ON THE ENCAPSULATOR DEVICE. A REDUCTION IN THE ENCAPSULATED REJUVENATOR CONTENT WAS QUANTIFIED IN THE BIOCAPSULES, RESULTING IN A LOWER VOLUME AND HIGHER DENSITY AND COMPRESSIVE STRENGTH VALUES. FINALLY, THE CAPSULES EFFECTIVELY RESISTED THE LOAD ASSOCIATED TO ON-SITE COMPACTION IN A WAY THAT THEY CAN BE POTENTIALLY

MESENCHYMAL STEM CELLS (MSC) ARE RECOGNIZED FOR THEIR IMMUNOMODULATORY EFFECTS AND REGENERATIVE PROPERTIES, BEING PROMISING THERAPEUTIC AGENTS FOR A WIDE RANGE OF DISEASES. TO ENSURE A LOCALIZED EFFECT OF MSC IN THE ORGANISM BIOBASED HYDROGELS HAVE BEEN TESTED FOR THEIR ABILITY TO ACT AS A MATRIX-EMBEDDED TO IMPROVE MSC TARGETED DELIVERY. IN THIS CONTEXT, NANOCELLULOSE (NC) HAS BEEN USED FOR DRUG DELIVERY, SHOWING BIOCOMPATIBILITY AND DURABILITY IN TIME, BUT UNTIL NOW NC HAS NOT BEEN TESTED FOR MSC GROWTH EXPLOITING THE SIZE AND ALDEHYDE CONTENT OF NC. IN THIS STUDY, CELLULOSE NANOCRYSTALS (CNC), CELLULOSE NANOFIBERS (CNF) AND MICROFIBRILLATED CELLULOSE (MFC) WERE STUDIED AFTER ONE-POT OXIDATION AND FURTHER CROSSLINKING WITH CHITOSAN (MASS RATIO 1:5). SIZE AND ALDEHYDE CONTENT OF OXIDIZED NC SAMPLES WERE EVALUATED TO ANALYZE THEIR INFLUENCE ON THE HYDROGEL'S PROPERTIES. THE CROSSLINKED HYDROGELS WERE ANALYZED BY FESEM, SWELLING ABILITY, FTIR, COMPRESSION TESTS, THERMAL STABILITY, AND STABILITY IN CULTURE CELL CONDITIONS. OXIDIZED-MFC HYDROGEL IMPROVED THE MECHANICAL STABILITY AND SWELLING BEHAVIOR, BUT IT LACKS STABILITY AT CELL CONDITIONS POSSIBLY DUE TO ITS LOW ALDEHYDE CONTENT (0.54 MMOL/G). CONVERSELY, OXIDIZED CNF AND OXIDIZED CNC FORMED SUITABLE CROSSLINKED HYDROGELS FOR CELL ADHESION, AND FOR GROWING AND PROLIFERATING OF MSC 3D SPHEROIDS AFTER 120 H. HOWEVER, ONLY HYDROGEL WITH PO-CNF/CHITOSAN SHOWS ANTIBACTERIAL ACTIVITY AS WELL AS MSC PROLIFERATION.

ENCAPSULATED REJUVENATORS BASED ON SUNFLOWER OIL AND ALGINATE BIOPOLYMER HAVE RECENTLY GAINED ATTENTION TO PROMOTE SELF-HEALING IN ASPHALT MIXTURES. HOWEVER, THE COMPLEX INTERACTION BETWEEN THESE MILLIMETRE-SIZE CAPSULES AND THE ASPHALT MORTAR AND THE POTENTIAL EARLY RELEASE OF THE REJUVENATOR FROM THE CAPSULES COULD COMPROMISE THE MECHANICAL PERFORMANCE OF THE ASPHALT COMPOSITE. THIS STUDY EVALUATES THE EFFECT OF AN OPTIMISED ALGINATE CAPSULE DESIGN WITH SUNFLOWER OIL ON THE RHEOLOGICAL PROPERTIES OF SHORT-TERM AGED (STA) AND LONGTERM AGED (LTA) ASPHALT MORTARS. A TOTAL OF 15 CAPSULE DESIGNS WERE SYNTHESISED BY THE VIBRATING JET TECHNIQUE AND BASED ON FIVE OIL-IN-WATER (O/W) EMULSIONS VARYING THEIR BIOPOLYMER:OIL (B:O) MASS RATIO (1:1, 1:3, 1:5, 1:7, AND 1:9) AND THREE CACL2 2 SOLUTIONS (2%WT., 5%WT., AND 8%WT. OF DEIONISED WATER). MORPHOLOGICAL, PHYSICAL, THERMAL, AND MECHANICAL PROPERTIES OF EACH CAPSULE WERE STATISTICALLY EVALUATED TO SELECT THE OPTIMAL DESIGN. THE SELECTED CAPSULE WAS INCORPORATED TO STA AND LTA CYLINDRICAL ASPHALT MORTARS TO EVALUATE THEIR RHEOLOGICAL PROPERTIES, THROUGH THE DYNAMIC SHEAR MODULUS, USING THE DYNAMIC MECHANICAL ANALYSIS (DMA) TEST AND THEIR SUSCEPTIBILITY TO PERMANENT DEFORMATION USING A MODIFIED MULTI-STRESS CREEP RECOVERY (MSCR) TEST. THE MAIN RESULTS SHOWED THAT THE CAPSULES HAD SIZES BETWEEN 1.12 AND 1.64 MM WITH REGULAR SPHERICAL MORPHOLOGY. THE OPTIMUM CAPSULE DESIGN WAS THAT WITH A B:O RATIO OF 1:7 AND 5%WT. OF CACL2, 2 , WHICH PRESENTED A SIZE OF 1.54 MM, HIGH ENCAPSULATION EFFICIENCY AND THERMAL/MECHANICAL STABILITY. THE ADDITION OF THE OPTIMISED CAPSULE DESIGN TO STA AND LTA MORTARS RESULTED IN I) A SOFTENING EFFECT, SIGNIFICATIVELY REDUCING THE DYNAMIC SHEAR MODULUS AT LOWER TEMPERATURES, AND II) NO SIGNIFICANT IMPACT ON THE SUSCEPTIBILITY TO PERMANENT DEFORMATIONS.

THIS PAPER AIMS TO EVALUATE THE EFFECT OF METALLIC WASTE ADDITION ON THE ELECTRICAL, THERMOPHYSICAL AND MICROWAVE CRACK-HEALING PROPERTIES OF ASPHALT MIXTURES. WITH THIS PURPOSE, ASPHALT MIXTURES WITH TWO DIFFERENT TYPES OF METALLIC WASTE, STEEL WOOL FIBRES AND STEEL SHAVINGS, ADDED IN FOUR DIFFERENT CONTENTS, WERE TESTED. ELECTRICAL AND THERMOPHYSICAL PROPERTIES OF ASPHALT MIXTURE SPECIMENS WITH, AND WITHOUT, METALLIC WASTE WERE MEASURED. THE SPATIAL DISTRIBUTION OF THE METALLIC WASTE INSIDE THE ASPHALT MIXTURE SAMPLES WAS EVALUATED BY USING X-RAY COMPUTED TOMOGRAPHY. IN ADDITION, CRACK-HEALING PROPERTIES OF ASPHALT SAMPLES USING MICROWAVE RADIATION HEATING WERE ASSESSED AT TWO DIFFERENT HEALING TIMES, 30 S AND 40 S. TO QUANTIFY THE EFFICIENCY OF THE HEALING PROCESS, FIVE HEALING CYCLES WERE CARRIED OUT FOR EACH ASPHALT SAMPLE. THE MAIN RESULTS SHOWED THAT ASPHALT MIXTURES WITH SHAVINGS PRESENTED LOWER AIR VOID CONTENTS THAN MIXTURES WITH FIBRES. MOREOVER, FIBRES PRODUCED AN INCREASE IN THE ELECTRICAL CONDUCTIVITY OF THE MIXTURES BECAUSE LONG FIBRES IN THE MIXTURES FORM ELECTRICALLY CONDUCTIVE CHANNELS. IN CONTRAST, SHAVINGS DID NOT HAVE SIGNIFICANT EFFECT ON THE ELECTRICAL PROPERTIES OF THE MIXTURES. LIKEWISE, IT WAS PROVEN THAT METALLIC WASTE REDUCED THE THERMAL CONDUCTIVITY AND THE SPECIFIC HEAT CAPACITY OF ASPHALT MIXTURES. CONVERSELY, SHAVINGS DECREASED THE THERMAL DIFFUSIVITY OF ASPHALT MIXTURES REGARDLESS OF THEIR CONTENT. OVERALL, IT WAS FOUND THAT THE HEALING LEVEL REACHED BY THE ASPHALT MIXTURES TESTED BY MICROWAVE RADIATION DEPENDS ON THE HEALING TIME AND THE TYPE AND CONTENT OF METALLIC WASTE USED. CT-SCANS RESULTS PROVED THAT THE SPATIAL DISTRIBUTION OF METALLIC WASTE INSIDE THE ASPHALT MIXTURE SAMPLES WAS NOT UNIFORM AND PLAYED AN IMPORTANT ROLE IN THE ASPHALT SELF-HEALING PROPERTIES USING MICROWAVE RADIATION HEATING. (C) 2018 ELSEVIER LTD. ALL RIGHTS RESERVED.

ENCAPSULATED REJUVENATING AGENTS FOR SELF-HEALING OF BITUMINOUS MATERIALS HAVE GAINED SIGNIFICANT INTEREST WITHIN THE ROAD SCIENTIFIC COMMUNITY, TURNING THESE ENHANCED MATERIALS INTO A HOT TOPIC. IN THIS STUDY, VIRGIN COOKING OIL, WASTE COOKING OIL, AND VIRGIN ENGINE OIL WERE USED AS ENCAPSULATED REJUVENATORS TO RESTORE PROPERTIES OF AGED BITUMEN AND THEIR CAPACITY FOR ASPHALT SELF-HEALING. THE ALGINATE-BASED CAPSULES AND THEIR COMPONENTS WERE CHARACTERISED BY CHEMICAL, PHYSICAL, MORPHOLOGICAL, THERMAL STABILITY, AND MECHANICAL TESTS. SELF-HEALING RECOVERY TESTS OF CRACKED LONG-TERM AGED BITUMEN BY THE EFFECT OF OIL RELEASE WERE ALSO PERFORMED. MAIN RESULTS SHOWED THAT ALL REJUVENATING OILS PRESENTED FUNCTIONAL GROUPS CONTRIBUTING TO THE CHEMICAL RESTORATION OF AGED BITUMEN. ENCAPSULATION OF STABLE O/W EMULSIONS WAS ACHIEVED. CAPSULES PRESENTED UNIFORM SIZE, MULTICAVITY MICROSTRUCTURE, HIGH ENCAPSULATION EFFICIENCY, THERMAL AND MECHANICAL STABILITY. FINALLY, ALL REJUVENATING OILS WERE SUCCESSFULLY DIFFUSED INTO AN AGED BITUMEN, ALTHOUGH VIRGIN COOKING OIL PRESENTED THE HIGHEST HEALING CAPACITY.

DUE TO THEIR SUSTAINABILITY AS WELL AS PHYSICAL AND MECHANICAL PERFORMANCE, DIFFERENT NATURAL FIBERS, BOTH VEGETAL AND ANIMAL FIBERS, HAVE BEEN SUCCESSFULLY USED IN ADOBE MIXTURES (AMS) TO ENHANCE PROPERTIES SUCH AS CRACKING CONTROL, FLEXURAL TOUGHNESS AND WATER EROSION RESISTANCE, AMONG OTHERS. HOWEVER, THE USE OF JUTE FIBERS (JFS), ONE OF THE MOST LARGELY PRODUCED VEGETAL FIBER WORLDWIDE, HAS NOT BEEN EXTENSIVELY STUDIED ON AMS. CONSEQUENTLY, THIS STUDY EVALUATES THE EFFECTS OF THE INCORPORATION OF VARYING DOSAGES (0.5 AND 2.0 WT%) AND LENGTHS (7, 15, AND 30 MM) OF JFS ON THE PHYSICAL/THERMAL/MECHANICAL/FRACTURE AND DURABILITY PERFORMANCE OF AMS, A SPECIFIC TYPE OF EARTH-BASED CONSTRUCTION MATERIAL WIDELY USED GLOBALLY. EXPERIMENTAL RESULTS SHOWED THAT THE INCORPORATION OF 2.0 WT% DOSAGES OF JFS INCREASED THE CAPILLARY WATER ABSORPTION OF AMS, WHICH MIGHT AFFECT AM DURABILITY. THE LATTER RESULT COULD BE EXPLAINED BY THE ADDITIONAL POROSITY GENERATED BY THE SPACES LEFT BETWEEN THE JFS AND THE MATRIX OF ADOBE, AS WELL AS THE INHERENT WATER ABSORPTION OF THE JFS. THE INCORPORATION OF JFS SIGNIFICANTLY IMPROVED THE BEHAVIOR OF AMS IN TERMS OF THERMAL CONDUCTIVITY, DRYING SHRINKAGE CRACKING CONTROL, FLEXURAL TOUGHNESS AND WATER EROSION PERFORMANCE, WITHOUT AFFECTING THEIR COMPRESSIVE AND FLEXURAL STRENGTH. FOR EXAMPLE, FLEXURAL TOUGHNESS INDICES WERE INCREASED BY 297% AND CRACK DENSITY RATIO AS WELL AS WATER EROSION DEPTH VALUES WERE REDUCED BY 93% AND 62%, RESPECTIVELY, WHEN 2.0 WT%-15 MM LENGTH JFS WERE INCORPORATED INTO AM. SINCE THE LATTER COMBINATION OF JF DOSAGE AND LENGTH PROVIDED THE OVERALL BEST RESULTS AMONG AMS, IT IS RECOMMENDED BY THIS STUDY AS JF-REINFORCEMENT SCHEME FOR AMS FOR CONSTRUCTION APPLICATIONS SUCH AS ADOBE MASONRY AND EARTH PLASTERS.

THIS RESEARCH AIMED TO EVALUATE THE EFFECT OF THE ADDITION OF BIOBASED ENCAPSULATED REJUVENATORS ON THE SELFHEALING PROPERTIES OF ASPHALT MIXTURES. WITH THIS OBJECTIVE, POLYNUCLEAR CAPSULES WERE SYNTHESISED USING ALGINATE BIOPOLYMER AS ENCAPSULATING MATERIAL AND SUNFLOWER OIL AS REJUVENATOR. THE CAPSULES WERE PHYSICALLY AND MECHANICALLY CHARACTERISED BY OPTIC AND SCANNING ELECTRON MICROSCOPY TECHNIQUES AS WELL COMPRESSIVE TESTS. FOUR TYPES OF SEMI-DENSE ASPHALT MIXTURES WERE MANUFACTURED, VARYING IN CAPSULE CONTENT: 0.0%, 0.125%, 0.25%, AND 0.5%WT. THE SELF-HEALING PROPERTIES OF EACH MIXTURE WERE EVALUATED BASED ON MECHANICAL CRACKING, CAPSULE ACTIVATION, AND HEALING LEVEL QUANTIFICATION PROCESSES. A NEW CONFINED UNIAXIAL COMPRESSION TEST WAS DEVELOPED FOR CAPSULE ACTIVATION. THE SELF-HEALING CAPACITY OF THE ASPHALT MIXTURES WAS DETERMINED UNDER FORCE AND FRACTURE ENERGY CRITERIA. STATISTICALLY SIGNIFICANT DIFFERENCES IN THE HEALING VARIABLES WERE ANALYSED THROUGH ONE-WAY ANOVA AND TUKEY POST-HOC TESTS. THE MAIN RESULTS SHOWED THAT THE CAPSULES PRESENTED REGULAR SPHERICAL MORPHOLOGY AND HIGH MECHANICAL STABILITY TO RESIST THE MIXING PROCESS AT HIGH TEMPERATURE. THE NEW ACTIVATION APPROACH EFFECTIVELY ACTIVATED THE ALGINATE-BASED CAPSULES INSIDE THE ASPHALT MIXTURES PROMOTING THEIR SELFHEALING. FORCE AND ENERGY CRACK-HEALING CRITERIA IMPROVED WITH THE ADDITION OF CAPSULES IN THE ASPHALT MATRIX, WITH HEALING VALUES BEING HIGHER FOR THE FORCE CRITERION THAN THOSE FOR THE ENERGY ONE. FINALLY, THE ADDITION OF CAPSULES IN A CONTENT EQUAL OR GREATER THAN 0.25%WT. SIGNIFICANTLY IMPROVED THE SELF-HEALING PROPERTIES OF THE ASPHALT MIXTURES.

THIS STUDY AIMED TO DETERMINE AN OPTIMAL DOSAGE OF SUNFLOWER OIL (I.E., VIRGIN COOKING OIL, VCO) AS A REJUVENATOR FOR ASPHALT SELF-HEALING PURPOSES, EVALUATING ITS EFFECT ON THE CHEMICAL (CARBONYL, AND SULFOXIDE FUNCTIONAL GROUPS), PHYSICAL (PENETRATION, SOFTENING POINT, AND VISCOSITY), AND RHEOLOGICAL (DYNAMIC SHEAR MODULUS, AND PHASE ANGLE) PROPERTIES OF LONG-TERM AGED (LTA) BITUMEN. FIVE CONCENTRATIONS OF SUNFLOWER OIL (VCO) WERE USED: 1%, 2%, 3%, 4%, AND 5% VOL. OF LTA BITUMEN. VCO WAS ENCAPSULATED IN ALGINATE BIOPOLYMER UNDER VIBRATING JET TECHNOLOGY USING THREE BIOPOLYMER:OIL (B:O) MASS RATIOS: 1:1, 1:5, AND 1:9. THE PHYSICAL, THERMAL, AND MECHANICAL PROPERTIES OF THE CAPSULES WERE STUDIED, AS WELL AS THEIR EFFECT ON THE PHYSICAL PROPERTIES OF DENSE ASPHALT MIXTURES. THE MAIN RESULTS SHOWED THAT AN OPTIMAL VCO CONTENT OF 4% VOL. RESTORED THE CHEMICAL, PHYSICAL, AND RHEOLOGICAL PROPERTIES OF LTA BITUMEN TO A SHORT-TERM AGEING (STA) LEVEL. VCO CAPSULES WITH B:O RATIOS OF 1:5 PRESENTED GOOD THERMAL AND MECHANICAL STABILITY, WITH HIGH ENCAPSULATION EFFICIENCY. DEPENDING ON THE B:O RATIO, THE VCO CAPSULE DOSAGE TO REJUVENATE LTA BITUMEN AND ASPHALT MIXTURES VARIED BETWEEN 5.03?15.3% WT. AND 0.24?0.74% WT., RESPECTIVELY. FINALLY, THE CAPSULE MORPHOLOGY SIGNIFICANTLY INFLUENCED THE BULK DENSITY OF THE ASPHALT MIXTURES.

EXTRINSIC SELF-HEALING OF BITUMINOUS MATERIALS USING ENCAPSULATED REJUVENATORS IS A HOT TOPIC WITHIN ROAD MATERIALS. BASED ON A CIRCULAR ECONOMY VISION FOR MORE SUSTAINABLE AND RESILIENT ASPHALT PAVEMENTS, THIS STUDY EXPLORES FOR THE FIRST TIME THE USE OF PYROLYTIC OIL FROM WASTE TYRES AS A PROMISING ENCAPSULATED REJUVENATOR TO PROMOTE THE EXTRINSIC SELF-HEALING IN BITUMINOUS MATERIALS. PYROLYTIC OIL-IN-WATER EMULSIONS, AND CAPSULES AND THEIR COMPONENTS WERE PRODUCED AND CHARACTERISED THROUGH GAS CHROMATOGRAPHY-MASS SPECTROMETRY (GC/MS) AND SARA FRACTIONS ANALYSIS, FLUORESCENCE MICROSCOPY METHODS, CREAMING INDEX, THERMOGRAVIMETRIC ANALYSIS (TGA-DGT), OPTICAL AND SCANNING ELECTRON MICROSCOPY (SEM), ENCAPSULATION EFFICIENCY AND MECHANICAL PROPERTIES. MAIN RESULTS SHOWED THAT THE PYROLYTIC OIL CAPSULES PRESENTED AN ADEQUATE MORPHOLOGY FOR THE SELF-HEALING ASPHALT, WITH A GOOD THERMAL STABILITY, PHYSICAL?CHEMICAL AND MECHANICAL PROPERTIES. OVERALL, IT WAS ALSO PROVEN THAT THE PYROLYTIC OIL IS A REJUVENATOR THAT CAN DIFFUSE IN THE AGED BITUMEN REDUCING ITS VISCOSITY TO PROMOTE THE SELF-HEALING OF THE MICROCRACKS.

CRACKING OF ASPHALT MIXTURES IS A MAIN DISTRESS IN FLEXIBLE PAVEMENTS. THE ADDITION OF ENCAPSULATED REJUVENATORS DURING THE FABRICATION OF THESE MIXTURES IS A NOVEL SELF-HEALING TECHNIQUE THAT COULD EXTEND THE SERVICE LIFE OF THE MATERIAL. THIS SELF-HEALING MECHANISM CONSISTS IN THE AUTONOMOUS SEALING OF CRACKS DUE TO THE RELEASE OF HEALING AGENTS CONTAINED IN BIOPOLYMER CAPSULES. HOWEVER, THE RELIABLE USE OF THESE MIXTURES REQUIRES THE UNDERSTANDING OF THE IMPACT OF THE ADDED CAPSULES ON THE MECHANICAL PROPERTIES OF THE MATERIAL, ESPECIALLY DURING THE INITIAL PHASE OF THE SERVICE LIFE OF THE STRUCTURE. THIS PAPER PRESENTS THE CHARACTERIZATION OF THE LINEAR VISCOELASTIC PROPERTIES OF SHORT-TERM AGED ASPHALT MORTARS WITH AND WITHOUT POLYNUCLEAR CAPSULES CONTAINING SUNFLOWER OIL USING THE DYNAMIC MECHANICAL ANALYSIS (DMA) TECHNIQUE. THE RESULTS SHOW THAT AT MOST TEMPERATURES AND LOADING FREQUENCIES THERE ARE NO STATISTICALLY SIGNIFICANT DIFFERENCES IN THE VISCOELASTIC PROPERTIES OF THE MORTARS WITH AND WITHOUT CAPSULES, SUGGESTING THAT THE VISCOELASTIC MECHANICAL PROPERTIES DURING THE INITIAL PHASE OF THE SERVICE LIFE OF THESE SELF-HEALING MIXTURES ARE NOT COMPROMISED.

THIS PAPER PRESENTS THE SYNTHESIS AND CHARACTERISATION OF BIOPOLYMERIC CAPSULES FOR ASPHALT SELF-HEALING. A SODIUM ALGINATE BIOPOLYMER EXTRACTED FROM THE CELL WALL OF BROWN ALGAE WAS USED AS THE ENCAPSULATING MATERIAL TO CONTAIN WASTE COOKING OIL (WCO) AS A POTENTIAL ENCAPSULATED REJUVENATING AGENT FOR AGED BITUMEN. POLYNUCLEAR CAPSULES WERE SYNTHESISED BY IONIC GELATION. THE SIZE, SURFACE ASPECT AND INTERNAL STRUCTURE OF THE WCO CAPSULES WERE EVALUATED USING OPTICAL AND SCANNING ELECTRON MICROSCOPY. THE PHYSICAL-CHEMICAL PROPERTIES AND THERMAL STABILITY OF THE WCO CAPSULES AND THEIR COMPONENTS WERE ALSO EVALUATED. MOREOVER, THE DIFFUSION PROCESS AND SELF-HEALING CAPABILITY OF THE RELEASED WCO ON CRACKED BITUMEN TEST SAMPLES WERE DETERMINED BY IMAGE ANALYSIS THROUGH FLUORESCENCE MICROSCOPY. THE MAIN RESULTS OF THIS STUDY SHOWED THAT THE WCO CAPSULES PRESENTED A SUITABLE MORPHOLOGY TO BE MIXED IN ASPHALT MIXTURES. WCO CAPSULES AND THEIR COMPONENTS PRESENTED MECHANICAL AND THERMAL STABILITY AND PHYSICAL-CHEMICAL PROPERTIES WHICH SUGGEST THEIR FEASIBILITY FOR SELF-HEALING APPLICATIONS. IT WAS PROVEN THAT THE ENCAPSULATED WCO CAN DIFFUSE IN THE AGED BITUMEN, REDUCING ITS VISCOSITY AND PROMOTING THE SELF-HEALING OF MICROCRACKS.

THIS PAPER PRESENTS THE FIRST ANALYSIS ON THE EVALUATION OF THE THERMOPHYSICAL AND HEATING PERFORMANCE OF SELF-HEALING ASPHALT MIXTURES WITH DIFFERENT CONTENTS OF STEEL WOOL FIBRES FOR THEIR POTENTIAL USE AS A SOLAR RADIATION ABSORBING MATERIAL IN AN ASPHALT SOLAR COLLECTOR PROTOTYPE. WITH THIS AIM, FOUR DIFFERENT DENSE-GRADED ASPHALT MIXTURES WERE PREPARED USING THE SAME AGGREGATE GRADATION AND BITUMEN CONTENT, BUT WITH DIFFERENT CONTENT OF STEEL WOOL FIBRES: 0%, 2%, 4%, AND 6% BY TOTAL VOLUME OF BITUMEN. PHYSICAL AND THERMAL PROPERTIES, SUCH AS BULK DENSITY, AIR VOID CONTENT, THERMAL CONDUCTIVITY, SPECIFIC HEAT CAPACITY, AND THERMAL DIFFUSIVITY WERE EVALUATED ON THE ASPHALT TEST SPECIMENS. STEEL WOOL FIBRE DISTRIBUTION INSIDE THE ASPHALT MIXTURE SAMPLES WAS ALSO EVALUATED BY X-RAY COMPUTED MICROTOMOGRAPHY. MOREOVER, THE THERMAL BEHAVIOUR OF A SOLAR COLLECTOR PROTOTYPE, USING AN ASPHALT MIXTURE WITH 4% OF STEEL WOOL FIBRES AS A SOLAR RADIATION ABSORBING MATERIAL WAS EXPOSED TO SOLAR RADIATION CONDITIONS SIMULATED IN LABORATORY USING A NOVEL DIRECT NORMAL IRRADIANCE EXPERIMENTAL MODEL. THIS MODEL WAS DEVELOPED BY THE AUTHORS TO EXPERIMENTALLY SIMULATE THE MAXIMUM AND MINIMUM IRRADIANCE CONDITIONS FOR THE CITY OF CONCEPCION IN CHILE. THE MAIN RESULTS SHOWED THAT SELF-HEALING ASPHALT MIXTURES WITH STEEL WOOL FIBRE ADDITION REDUCED THEIR THERMOPHYSICAL PROPERTIES, EXPLAINED BY AN INCREMENT IN THEIR TOTAL VOLUME AND DUE TO THE FIBRE DISTRIBUTION INSIDE THE SAMPLES. ADDITIONALLY, THIS STUDY PROVES THAT ASPHALT MIXTURES WITH 4% OF STEEL WOOL FIBRES CAN BE POTENTIALLY USED AS A RADIATION ABSORBING MATERIAL, TRANSMITTING THE INFRARED RADIATION FROM THE ASPHALT PAVEMENT SURFACE TO THE WATER STORED INSIDE IT. IN SHORT, THIS STUDY PROVIDES THE FIRST ASSESSMENT ON THE FUNDAMENTAL THERMOPHYSICAL VARIABLES OF SELF-HEALING ASPHALT MIXTURES WITH METALLIC FIBRES, WITH THE PURPOSE OF EXPLORING THEIR FUTURE USE FOR ENERGY HARVESTING APPLICATIONS.