Patching Material Research Articles

Analysis of Pore Water Pressure Effect in Asphalt Patch Failure: An Integrated Modelling and Experiment Study

Moisture has been widely accepted as the main cause of asphalt patch failure, while the investigation of pore water pressure (PWP) in asphalt patch is limited. This research investigated the PWP generated in asphalt patch and quantified its impact on mechanical performance considering the inadequate compaction of asphalt patch. A hydro-mechanical model was first developed to analyze the PWP under field conditions, considering the effects of patch geometry, vehicle wandering, traffic loading, and temperature. The moisture-induced stress tester (MIST) was then used to condition patching materials under different PWP levels in a laboratory. After that, indirect tensile (IDT) and interface shear strengths of patching materials were evaluated to quantify the impact of PWP on material degradation. The numerical modeling results show that the maximum PWP can be within or at the interface of the asphalt patch, depending on the wheel path. The magnitude of PWP is related to the patch geometry, traffic load, and temperature. The maximum PWP, whether inside or at the interface of the asphalt patch, can be from 100 kPa to over 300 kPa under common field conditions. The laboratory experimental results suggest that the first 500 cycles of MIST conditioning led to over 30% decrease in both IDT and interface shear strengths of asphalt patch, and the strength ratio was much lower than the recommended level. These findings indicate that asphalt patches with poor compaction quality are very susceptible to moisture-induced damage, and the mechanical performance of patching material should be evaluated after conditioning with PWP effect.

Surgical Outcome After Treatment of Radiation-Induced Scleral Necrosis in Patients With Uveal Melanoma.

Surgical repair might be required in patients with uveal melanoma (UM) that develop advanced forms of radiation-induced scleral necrosis (RISN). In this monocentric long-term observational study, we aimed at analyzing the treatment outcome after RISN surgery. All consecutive cases with UM who underwent surgical intervention for RISN between 1999 and 2020 were included. Achievement of the tectonic stability and evaluation of incidence and the risk factors for a repetitive patch surgery (RPS) were the main endpoints. The final analysis included 57 patients (mean age: 58.7 years; 63.2% female patients), where 55 individuals underwent a patch grafting, and 2 cases were treated with conjunctival reconstructive surgery. The mean follow-up time after grafting was 38.5 months (0.03-221.1 months). Tectonic stability was achieved in 56 (98.3%) patients. Scleral graft (38/55, 69.1%) was the most frequent patching material, followed by Tutopatch (7/55, 12.7%), corneal graft (7/55, 12.7%), dura graft (2/55, 3.6%), and fascia lata (FL) graft (1/55, 1.8%). Eleven patients (20%) underwent RPS after the mean time of 12.9 months (0.3-50.3 months). In the final multivariate Cox regression analysis, the use of Tutopatch (5/7; 71.4%, adjusted hazard ratio = 4.66, P = 0.044) and RISN progression after patch grafting (9/11; 81.8%, adjusted hazard ratio = 9.67, P = 0.008) were independent risk factors for RPS. RISN surgery maintains long-term tectonic stability in most of the cases underwent surgical repair for RISN after brachytherapy for UM. Depending on graft material and, particularly, further RISN progression, an RPS might be necessary in certain cases.

Asphalt pavement pothole repair with recycled material and preheating: Laboratory and field evaluation

Asphalt pavement pothole repair with hot-mix asphalt (HMA) is one of common maintenance activities for transportation agencies, which requires considerable energy use and generates greenhouse gas emission (GHG) for production of HMA. This study investigated mechanical performance and environmental impact of an innovative pothole repair method using recycled asphalt pavement (RAP) and preheating. According to the common failure modes of asphalt patch, comprehensive laboratory tests were conducted on the lab-made and field-cored specimens, including indirect (IDT) strength, interface bonding strength, and abrasion resistance at dry, freeze-thaw, and pore pressure conditions. Based on laboratory testing results of the HMA with 0%–50% RAP contents, HMA with 30% RAP was selected for pothole repair in the field test section because it can lead to satisfactory moisture resistance and comparable interface bonding and abrasion resistance with traditional HMA. After repair, field cores were collected for additional laboratory analysis. The results show that moisture resistance of the patching materials decreased with the increase of RAP content. The freezing thaw (FT) effect was found to cause more degradation in IDT and interface shear strength than dynamic pore water pressure simulated in moisture induced stress tester (MIST), while the pore water pressure caused more abrasion loss of patching material. On the other hand, preheating the pothole before repair was found to be effective in enhancing mechanical performance and durability of asphalt patch under various environmental conditions. With the application of preheating, asphalt patching repaired by HMA with 30% RAP can achieve comparable or better performance than that made with traditional HMA, while reducing energy consumption and carbon emission.

Performance and cost evaluations of 100% recycled hot asphalt mixtures for pothole patching applications in flexible pavements

Fixing the potholes using bituminous patching mixtures is a critical and costly pavement maintenance activity. The patching mixture's quality significantly affects patch durability and performance; always using the best material available is advisable. This study investigated the feasibility of using 100% hot recycled asphalt pavements (RAP) as a possible patching material by comparing the performance results with cold patching mixtures (CPM) as well as Superpave hot mix asphalt (SHMA) mixtures. Four different RAP mixtures, two fine-graded and two coarse-graded, from two distinct sources, are obtained. RAP mixtures were handled in a laboratory environment to obtain the hot recycled patching materials. Three different rejuvenators were incorporated into hot-recycled pavement material (HRPM) at manufacturer-recommended dosages to determine the best rejuvenator type. Performances of the mixtures are evaluated in terms of linear viscoelastic characterization, permanent deformation, and low-temperature thermal cracking potentials using dynamic modulus, flow number, and indirect tensile strength tests, respectively. The results show that RAP mixtures with any RAP source, gradation, and rejuvenator type outperformed CPM in performance tests and behaved similarly to SHMA mixtures.

Asphalt Pavement Pothole Repair Using the Pre-Heating Method: An Integrated Experiment and Modeling Study

Pothole repair in asphalt pavements is one of the most common highway maintenance treatments. Improving the longevity of asphalt patch can increase driving comfort, improve road safety, and reduce agency and user costs. This study investigated the effectiveness of pre-heating on pavement pothole repair using laboratory tests, field measurements, and numerical modeling. A test section with artificial potholes and temperature sensors was built for the study. The potholes were repaired using hot-mix asphalt (HMA) after pre-heating using an infrared heater. Laboratory tests were performed on field cores to measure interface shear and tensile strength between patch material and existing pavement and the cohesive tensile strength of patch material. Numerical models were first validated using field temperature measurements and then used to determine the required heating time for reaching the targeted temperatures under different infrared radiation powers and field conditions. The results show that pre-heating increases the temperatures at pothole edges and surfaces and promotes better bonding. With the application of pre-heating, the greater interface shear and tensile strength were found between patching material and the surrounding pavement, in addition to greater indirect tensile strength and lower air voids of HMA patch. To reach the targeted temperature in 3-min heating under different ambient temperatures, certain ranges of power were proposed depending on the infrared radiation power and pothole size. It was found that using high-power heating within the proposed ranges can increase heating efficiency and reduce energy consumption.

%100 Geri Dönüştürülmüş Asfalt Kaplamanın Türkiye'de Soğuk Karışım Bakım Malzemesi Olarak Kullanılabilirliğinin Deneysel Olarak İncelenmesi

In this study, the usability of 100% RAP as a cold patching material (CPM) was experimentally investigated. As part of this study, first, the RAP material has been characterized to determine its binder content and particle size distribution of the extracted aggregate. Then, three sets of RAP specimens (each set has three specimens) were prepared. These specimens were conditioned at 22°C, 40°C and 45°C for three hours. Then, the specimens were compacted with 75 Marshall hammer blows. The compacted specimens were then tested for their Marshall stability, and flow at 22°C. Air contents of the test specimens were also determined . It was observed that as conditioning temperatures of the compacted test specimens increased, their Marshall stability test results increased but their flow and air content test results mostly decreased. Marshall stability test results of all three sets of specimens were well above the specification limits. Moreover, all test specimens except for only one specimen conditioned at 22°C met the flow and air content criteria. It could be concluded that 100% RAP could be used as a CPM especially above 22°C. If it is needed to be used at around 22°C, it must be ensured that it is well compacted so that its air content is below 8% for a durable and comparably long-lasting cold patching application.

Interfacing Perforated Eardrums with Graphene‐Based Membranes for Broadband Hearing Recovery (Adv. Healthcare Mater. 20/2022)

Eardrum Perforation In article 2201471 by Jiayu Lu, Dan Li, Shankai Yin, and co-workers, multilayered reduced graphene oxide membranes, offering a combination of exceptional mechanical strength, stiffness, lightweight and biocompatibility, are demonstrated to be a unique patching material to enable the closure of perforated eardrums of rats and complete restoration of broadband hearing.

Early-age mechanical properties and hydration degrees of magnesium phosphate cement paste in freezing winter of cold regions

Magnesium phosphate cement (MPC) paste is a good patching material for concrete repair works. This study focused on early-age mechanical properties and hydration degrees of MPC paste in freezing winter of two types of cold regions, which are highland regions and high-latitude regions. MPC pastes with different mix proportions under different curing modes were experienced a series of experiments, including fluidity and setting time, compressive strength, pore structure characterization, thermogravimetric analysis, X-ray diffraction and electron microscopic scanning. Results showed that for winter applications, MPC pastes in simulated highland temperature conditions performed better than those in true high-latitude temperature conditions, illustrated by pore structure analyses and hydration products analyses. The best M/P ratios for highland applications and high-latitude applications were respectively 4 and 5, which respectively delivered 24 h strengths at about 50 MPa and 25 MPa. Even in severe cold winter, the setting of MPC paste depended on the hydration speed instead of the frozen action. Mixing water temperature was good for early-age hydration of MPC paste which cured for six hours in natural cold environment, however, the effect vanished at 24 h. Both the amounts of struvite and unhydrated phosphate, which could be quantitatively assessed by TG-DSC tests or qualitatively assessed by XRD test, were good indicators of the hydration degree of MPC paste in cold weather. These results provided valuable suggestions for winter applications of MPC paste in different types of cold regions.

Laboratory and Field Patching Performance of a Half-Warm Mix Using Waste Cooking Oil–Based Biobinder with Reclaimed Asphalt Pavement

AbstractIn this study, a new half-warm mix patching material was developed using polymerized waste cooking oil (WCO)-based biobinder with 100% reclaimed asphalt pavement (RAP). Laboratory tests wer...

Development and evaluation of a pothole patching material for steel bridge deck pavement

Pothole is one of the most serious distresses of steel bridge deck pavement. Rapid and durable patching material is required for pothole treatment to reduce the maintenance influence on transportation service. In this paper, a cold-mixed patching material was developed on the basis of a fast cured thermosetting binder. The optimal binder formula was determined by optimization and balancing of mechanical property, workability and strength development, through tensile tests, viscosity tests and differential scanning calorimetry tests. After that, the high temperature performance, low temperature performance, moisture susceptibility and fatigue performance of the newly developed material were evaluated through a laboratory experimental program, including wheel track test, 3-point bending beam test, indirect tensile test and fatigue test. On the other hand, a numerical simulation was conducted to assess the structural performance of the material when using on the steel bridge deck. The result showed that the developed binder material had tensile strength over 2MPa and elongation over 100%. The workable time was over 30 min and the favorable compaction time was 36 min after mixing at 25 °C. The patching material had a rapid traffic reopen capability in three hours. In addition, the developed material had rather good mechanical and structural performance when used in pothole patching on steel bridge deck pavement.

Investigation of flexible pavement maintenance patching factors using a finite element model

Patching of flexible pavements is one of the most important functions of pavement maintenance. Although finite element modeling has become commonplace in the world of pavement engineering, modeling has not yet been significantly leveraged for maintenance applications which improve safety, ride quality, and pavement service life. The objective of this study was to model viscoelastic properties of pavement and patching materials to determine the effect of various repair factors on pavement performance using the finite element method. Specifically, surface permanent deformation, local shear stress concentration, and horizontal strain distribution were investigated. Two types of models were simulated; the first model applied static loading to a surface layer fixed on a plate and the second model applied cyclic traffic loading to a two-layered flexible pavement system. The results demonstrate the importance of patching using a semi-permanent method. The results also demonstrated the accumulated effect of repeated loading using a time-dependent material response. Results also indicated that a larger patching area resulted in less influence of the shape of the area, while a circular area proved superior to a conventional rectangular patch for sizes near the tire footprint and smaller than it. Different responses were observed depending on the type of patching material modeled, demonstrating the effect of material choice in maintenance applications. Finally, mesh optimization was performed to ensure appropriate mesh sizes are used in future studies to accurately represent the pavement layers and patches.

Bond characteristics between conventional concrete and six high-performance patching materials

Repair of damaged concrete structures with patching materials is required for a wide variety of bridge and building applications. Despite the capabilities of conventional patching materials in replacing the spalled concrete, they are often unable to restore the original structural capacity. This has motivated research investigations to develop high-performance patching materials that can help damaged concrete structures regain their strength and durability characteristics. Such characteristics, however, are not properly achieved without a satisfactory bond between the concrete substrate and the patching material applied. To investigate this critical aspect, six high-performance patching materials, i.e., proprietary and nonproprietary ultra-high performance concrete, polypropylene and alkali-resistant glass fiber-reinforced concrete, high-early strength concrete, and shrinkage-compensating cement concrete, were systematically investigated and compared in the current study. The conducted experiments included a holistic set of splitting tensile and slant shear tests performed on the samples prepared with various surface roughnesses. The experimental test results provided firsthand information about the bond characteristics between normal-strength concrete and six high-performance patching materials. With the determination of corresponding adhesion and friction coefficient factors, the outcome of this study facilitates the selection and use of high-performance patching materials, depending on the availability of materials and repair needs.

Experimental study on bond behavior of corroded rebars coated by anti-corrosive materials in polymer cement mortar

This study investigates the bond behavior of anti-corrosive coated corroded rebars in a polymer cement mortar (PCM) as a common patching material to repair corrosion-induced damaged reinforced concrete structures. Cementitious and epoxy types of anti-corrosive coating materials are utilized. The corroded rebars are prepared by accelerated corrosion test in laboratory with a 5–10% target corrosion degree. The single effect of the coating materials on the bond behavior is investigated using coated round and deformed rebars. The combined effects of the corrosion and the coating materials are investigated using coated corroded deformed rebars. To thoroughly understand the bond behavior and mechanism, the effects of the corrosion and the coating materials on the change in the geometrical properties and surface roughness of the rebars are quantitatively analyzed by laser scanning tests. Finally, a two-end pull-out test is conducted to measure and investigate the bond-slip relationship, ultimate bond strength, bond toughness, and bond ductility.Similar to the findings on cementitious coated deformed rebar confined in concrete in a previous study by the authors, the results of the current study revealed that in the PCM, the cementitious coated rebar presents promising good bond performance regardless of the corrosion degree compared to the epoxy coated rebar. This is because when the ribs of the deformed rebars would deteriorate owing to corrosion, the rough surface of a cementitious coated rebar can sustain well its bond performance compared with the smooth and glassy surface of an epoxy coated rebar. Moreover, the direct effect of the surface roughness characteristics of these coating materials is clarified using coated round rebars. Consequently, the cementitious coated rebar achieves a considerably higher bond strength with a brittle behavior than the epoxy coated rebar, which presents a ductile behavior.

A micromechanical model of elastic-damage properties of innovative pothole patching materials featuring high-toughness, low-viscosity nanomolecular resin

Innovative pothole patching materials reinforced with a high-toughness, low-viscosity nanomolecular resin, dicyclopentadiene (DCPD, C10H12), have been experimentally proven to be effective in repairing cracked asphalt pavements and can significantly enhance their durability and service life. In this paper, a three-dimensional micromechanical framework is proposed based on the micromechanics and continuum damage mechanics to predict the effective elastic-damage behaviors of this innovative pothole patching material under the splitting tension test (ASTM D6931). In this micromechanical model, irregular coarse aggregates are approximated and simulated by randomly allocated multi-layer-coated spherical particles in certain representative sizes. Fine aggregates, asphalt binder (PG64-10), cured DCPD (p-DCPD), and air voids are formulated into an isotropic elastic asphalt mastic matrix based on the multilevel homogenization approach. The theoretical micromechanical elastic-damage predictions are then systemically compared with properly designed laboratory experiments as well as three-dimensional finite elements numerical simulations for the innovative pothole patching materials.

Finite element modeling of mechanical responses of concrete pavement with partial depth repair

Partial depth repair (PDR) is usually used to repair surface distresses of concrete pavement. The mechanical property of patch material was mainly considered when selection the patch material. However, the stress state in the patch material or surrounding concrete varies depending on patch location and depth. This study aims to evaluate mechanical responses of PDR patch in concrete pavement under moving traffic loading using finite element modeling. The FE model was first validated using field test results reported in the literature. Totally seven different patching materials, three different patching locations, and two different patching depths were considered in the analysis. The critical tensile stresses in the patch and the surrounding concrete under moving tire loading were analyzed for each case. The analysis results show that for PDR patch in the middle of concrete slab, the maximum tensile stress in the thicker PDR patches is greater than that in the thinner ones. For PDR patch in the corner of concrete slab, the tensile stress can be found not only at the bottom of slab and patches, but also at the surface of slab and patches. When low modulus patch material is used, the tensile stress at the bottom of slab with the thinner PDR patch is smaller. On the other hand, the tensile stress at the bottom of slab with thicker PDR patch is smaller when high modulus patch material is used. Based on analysis results, recommendations for selection of patching material were made for repairing concrete pavement at different locations. The study findings can help select appropriate material for PDR of concrete pavement for different patch locations and depths.

Tricontrollable pixelated metasurface for absorbing terahertz radiation.

The incorporation of materials with controllable electromagnetic constitutive parameters allows the conceptualization and realization of controllable metasurfaces. With the aim of formulating and investigating a tricontrollable metasurface for efficiently absorbing terahertz radiation, we adopted a pixel-based approach in which the meta-atoms are biperiodic assemblies of discrete pixels. We patched some pixels with indium antimonide (InSb) and some with graphene, leaving the others unpatched. The bottom of each meta-atom was taken to comprise a metal-backed substrate of silicon nitride. The InSb-patched pixels facilitate the thermal and magnetic control modalities, whereas the graphene-patched pixels facilitate the electrical control modality. With proper configuration of patched and unpatched pixels, and with proper selection of the patching material for each patched pixel, the absorptance spectra of the pixelated metasurface were found to contain peak-shaped features with maximum absorptance exceeding 0.95, full-width-at-half-maximum bandwidth of less than 0.7 THz, and maximum-absorptance frequency lying between 2 THz and 4 THz. The location of the maximum-absorptance frequency can be thermally, magnetically, and electrically controllable. The lack of rotational invariance of the optimal meta-atom adds mechanical rotation as the fourth control modality.

Spray injection patching for pothole repair using 100 percent reclaimed asphalt pavement

Pothole repair of asphalt pavements is one of the most commonly performed roadway maintenance operations, and it is costly. Reclaimed asphalt pavement (RAP) has become an increasingly attractive material for pothole repair due to its economic and environmental advantages. This study investigated the performance of spray injection patching materials for pothole repair that utilize 100 percent RAP and compared the results to the performance of patching materials made with virgin aggregate. This study was designed to investigate how well different patching products resist critical types of distresses that are observed in the field and typically require patching. The primary characteristics examined in the study include stability, adhesion, moisture susceptibility, and durability of the patching material. The performance of various combinations of materials was observed in laboratory tests to determine the most cost-effective and best-performing patch material. The results show that the material’s performance depended on the type of aggregate and emulsion used in the mixtures. The results also indicate that the mixtures that contained RAP had good stability and adhesion properties compared to the mixtures made with virgin aggregate. This research proved the feasibility and advantages of using RAP for spray injection pothole repair.

Thermal segregation of asphalt material in road repair

Abstract This paper presents results from a field study of asphaltic pavement patching operations performed by three different contractors working in a total of ten sites. It forms part of an ongoing research programme towards improving the performance of pothole repairs. Thermal imaging technology was used to record temperatures of the patching material throughout the entire exercise, from the stage of material collection, through transportation to repair site, patch forming, and compaction. Practical complications occurring during patch repairs were also identified. It was found that depending on the weather conditions, duration of the travel and poor insulation of the transported hot asphalt mix, its temperature can drop as high as 116.6 °C over the period that the reinstatement team travel to the site and prepare the patch. This impacting is on the durability and performance of the executed repairs. Cold spots on the asphalt mat and temperature differentials between the new hot-fill asphalt mix and existing pavement were also identified as poorly compacted areas that were prone to premature failure. For example, over the five-minute period, the temperature at one point reduced by 33% whereas the temperatures of nearby areas decreased by 65% and 71%. A return visit to the repair sites, three months later, revealed that locations where thermal segregation was noted, during the patching operation, had failed prematurely.

Experimental Study on Performance of MgO-based Patching Materials for Rapid Repair of Concrete Pavement

PURPOSES : This study aims to develop a repair material that can enhance pavement performance, inducing rapid traffic opening through early strength development and fast setting time by utilizing MgO-based patching materials for repairing road pavements. METHODS : To consider the applicability of MgO-based patching materials for repairing domestic road pavements, first, strength development and setting time of the materials were evaluated, based on MgO to ratio, water to binder ratio, and addition ratio of retarder (Borax), by which the optimal mixture ratio of the developed material was obtained. To validate the performance of the developed material as a repair material, the strength(compressive strength and bonding strength) and durability (freezing, thawing, and chloride ion penetration resistance) was checked through testing, and its applicability was evaluated. RESULTS : The results showed that when an MgO-based patching material was used, the condensation time was reduced by 80%, and the compressive strength was enhanced by approximately 300%, as compared to existing cement-based repair materials. In addition, it was observed that the strength (compressive strength and bonding strength) and durability (freezing and thawing, and chloride ion penetration resistance) showed an excellent performance that satisfied the regulations. CONCLUSIONS : The results imply that an emergent repair/restoration could be covered by a rapid-hardening cement to meet the traffic limitation (i.e. the traffic restriction is only several hours for repair treatment). Furthermore, MgO-based patching materials can improve bonding strength and durability compared to existing repair materials.

Clinical analysis of sphenoid sinusitis after transsphenoidal sellar surgery

To analyze the possible influence factors of sphenoid sinusitis after endoscopic transsphenoidal sellar surgery. A retrospective analysis of 177 patients who underwent transsphenoidal sellar surgery, from January 2009 to January 2014 in Tianjin Huanhu Hospital was performed. All patients were followed up with nasal endoscope. The risk factors of sphenoid sinusitis after surgery were analyzed statistically, such as sex, age, categories of disease, surgical produres, tumor size, using artificial or self material repair, with or without EC glue intraoperatively, etc. SPSS 17.0 software was used to analyze the data. After surgery, there were 34 (19.2%) patients developed postoperative sinusitis. EC glue was the sole risk factor for postoperative sinusitis (34.57% vs 6.25%, χ(2)=22.701, P<0.01), but the sex, age, categories of disease, surgical produres, tumor size and patching material had no significant difference (all P>0.05). In patients with endoscopic transsphenoidal sellar surgery, regular postoperative nasal endoscopic follow-up found that the use of EC glue was the risk factor for the development of postoperative sphenoid sinusitis.