Laboratory Specimens Research Articles

Histopathological Profile of Cholecystectomy Specimens at a Tertiary Care Center: A Retrospective Study

Abstract Introduction: Gallbladder is one of the most frequently received specimens in any histopathology laboratory. Its diseases may present with a varied spectrum ranging from congenital anomalies, cholelithiasis, and inflammatory or noninflammatory lesions to noninvasive and invasive neoplasms. Cholelithiasis (gallstones) is the most common lesion and accounts for more than 95% of gallbladder diseases and affects 10%–20% of the adult population. The incidence is 2–4 times higher in females than in males. Aims and Objectives: This study was designed to study the histopathological spectrum of gall bladder diseases in the population, study the most common gall bladder diseases in cholecystectomy specimens, and study the frequency of gall bladder carcinoma. Methodology: This retrospective observational study was done in the Pathology department at a tertiary care hospital and research center, from September 2016 to September 2023. Tissue was fixed in 10% buffered formalin and then processed by the routine paraffin embedding techniques. Sections were cut at 4–5 μ thickness and stained with hematoxylin and eosin stains. Special stains were done if required for confirmation. All the slides were analyzed and reported by a trained histopathologist. Results: Females were affected more as compared to males. The commonest age group affected was 41-50 years. Gallstones were observed in 33.58% of patients. Gallbladder neoplasm was rare and incidental findings. Conclusion: Gallbladder disease demonstrated a diverse spectrum of histopathological changes in the cholecystectomy specimens and showed female preponderance. Gallbladder carcinoma was observed as a rare occurrence and was an incidental finding mainly. Hence, a microscopic (histopathological) examination is required for every cholecystectomy specimen.

Histopathological features of prostatic carcinoma in a Southwest tertiary institution in Nigeria

Background: The diagnosis of prostatic adenocarcinoma is often straightforward, in some cases there may be benign lesions that mimic prostatic cancer histologically. This study aimed to describe the morphological features of prostatic carcinoma from laboratory specimens. Methods: This was a retrospective study using histologically diagnosed cases of prostatic carcinoma from prostatectomy and trucut biopsy specimens. The histological sub-typing of the tumors according to WHO classification scheme of 2003 was done. The tumors were graded and scored using Gleason’s scoring scheme revised and modified at the consensus conference of the international society of urological pathology (ISUP), in 2005. Results: Prostate cancer constituted 18.7% of all malignant tumors and 4.4% of all neoplastic diseases. The majority of cases were small acinar adenocarcinoma 275 (73.7%). Others include pseudo-hyperplastic variant 47 (12.6%), atrophic variant 35 (9.3%), foamy gland carcinoma 16 (4.2%) and signet ring/colloid carcinoma 1(0.2%). More than half were classified as well-differentiated Gleason prognostic group A tumors. There was a statistically significant association between the age of the patient and the Gleason histologic grade and the histologic grade and histologic variant p<0.05. Conclusions: Prostatic carcinoma was thought to be a malignancy associated with elderly men but people of younger age less than fifty years are now diagnosed with the malignancy. Accurate diagnosis with the right grade and scores will go a long way in the management of the malignancy.

A Descriptive Study: Evaluation of Delayed Laboratory Testing in Emergency Room

Precision, accuracy, and short turnaround time (TAT) are important to improve the quality and effectiveness of laboratory services in the Emergency Room (ER). Several studies reported an average of 60% the ratio of anticoagulant to sample is not appropriate, lysis, and clotted samples occurred in the pre-analytical part. This part consisted of the request/registration of laboratory tests, patient preparation, specimen collection, and transportation to the central laboratory. The aim of this research is to evaluate the cause of the long TAT for laboratory research so as to obtain problem solving based on the target. This observational study was conducted in 2021 at the ER laboratory outlet. Observations were made started from the workload carried out by the laboratory technician, sample registration, and data collection from the Laboratory Information System (LIS). The study obtained 14.709 samples from the LIS at the Clinical Pathology Department, Cipto Mangunkusumo Hospital. The highest sample rejection rate was from the ER laboratory outlet due to specimen lysis (2.79%). The average time required for re-collecting specimens was around 2-2.5 hours. This rejection was below the minimum quality standards based on the International Federation of Clinical Chemistry (IFCC). Other problems include the limited number of medical laboratory experts compared to the workload also inefficient Computerized Physician Order Entry (CPOE) registration methods. The main problem of delayed laboratory testing in the emergency department is the pre-analytical part including sample registration and rejection specimens. That rejection mostly comes from lysis specimens, which caused invalid laboratory result.

The Clinical Impact of Urinalysis Screened by Automated Microscopy Compared to Reference Manual Analysis.

Clinical laboratories have replaced conventional manual urine microscopy with automated urinalysis; however, concerns persist regarding its validity in detecting specific elements of urinary sediment crucial for evaluating kidney diseases. This study aimed to assess the accuracy of urinary sediment analysis performed by a large hospital laboratory compared to a standardized microscopic review, focusing on patients both with and without kidney disease. Urine samples were randomly selected from routine laboratory specimens at a university hospital. Laboratory analysis was performed using LabUmat 2 and Urised 3 PRO equipment (Abbott Diagnostics). In the automated analysis, technicians had the option to reclassify urinary sediment elements and, if needed, conduct manual microscopic evaluations to validate findings. The laboratory's analysis was compared with a "reference" analysis, which was double-blinded and conducted by two experienced technicians using bright-field and phase-contrast microscopy. 503 samples were selected, with 52.3% originating from nephrology outpatient clinic patients. Overall agreement between the laboratory results and the reference analysis was 42.1%. The sensitivity (SN) of the laboratory examination for detecting pathological casts, lipiduria, and renal tubular cells was low (<50%), while specificity (SP) was high (>98%). However, for hyaline casts (SN: 50.4%; SP: 80.9%) and dysmorphic red blood cells (SN: 62.3%; SP: 96.2%), accuracy was intermediate. Performance was better for hematuria (SN: 86.1%; SP: 82.3%; ICC: 0.703; R: 0.828) and leukocyturia (SN: 84.9%; SP: 95.1%; ICC: 0.807; R: 0.861). In patients with kidney disease (N=248) and in samples manually reviewed by the laboratory (N=115), accuracy for each urinary element was comparable to the overall sample findings. However, when assessing the ability to identify elements suggestive of nephropathy, only samples manually reviewed by the laboratory showed statistically similar results to those obtained by the reference analysis (p= 0.503, McNemar's test). Employing automated urinalysis seems to be accurate for detecting hematuria and leukocyturia, as well as for screening patients without kidney diseases. However, clinical laboratories attending complex patients should employ personalized strategies to help decide when to perform manual review, thus avoiding misleading urinalysis results.

Ultrasonic Non-Destructive Testing of Accelerated Carbonation Cured-Eco-Bricks

This study aimed to investigate the behavior of accelerated carbonation-cured laboratory specimens using the ultrasonic non-destructive testing (UNDT) method and compare the results with the destructive testing (DT) method. The materials used in the study included a blend of lime kiln dust and ground granulated blast furnace slag (LKD-GBFS) wastes, natural fine aggregate (sand), and alternative fine aggregates from waste tires. The chemical analysis of the LKD and GBFS samples highlighted them as suitable alternatives to OPC, hence their utilization in the study. A 60:40 (LKD-GBFS) blending ratio and a 1:2 mix design (one part LKD-GBFS blend and two part sand) was considered. The natural fine aggregate was partially replaced with fine waste tire rubber crumbs (TRCs) in stepped increments of 0, 5, and 10% by the volume of the sand. The samples produced were cured using three curing regimens: humid curing (HC), accelerated carbonation curing (ACC) with no water curing (NWC) afterwards, and water curing after carbonation (WC). From the results, an exponential model was developed, which showed a direct correlation between the UNDT and DT results. The developed model is a useful tool that can predict the CS of carbonated samples when cast samples are unavailable. Lastly, a total CO2 uptake of 15,912 g (15.9 kg) was recorded, which underscores ACC as a promising curing technique that can be utilized in the construction industry. This technique will bring about savings in terms of the time required to produce masonry units while promoting a change in the basic assumptions of a safer and cleaner environment.

Seismic Retrofit Case Study of Shear-Critical RC Moment Frame T-Beams Strengthened with Full-Wrap FRP Anchored Strips in a High-Rise Building in Los Angeles

This paper discusses the iteration of a seismic retrofit solution for shear-deficient end regions of 19 reinforced concrete (RC) moment-resisting frame (MRF) T-beams located in a 12-story RC MRF building in downtown Los Angeles, California. Local strengthening with externally bonded (EB) fiber-reinforced polymer (FRP) fabric was chosen as the preferred retrofit strategy due to its cost-effectiveness and proven performance. The FRP-shear-strengthening scheme for the deficient end-hinging regions of the MRF beams was designed and evaluated through large-scale cyclic testing of three replica specimens. The specimens were constructed at 4/5 scale and cantilever T-beam configurations with lengths of 3.40 m or 3.17 m. The cross-sectional geometry was 0.98 × 0.61 m with a top slab of 1.59 m in width and 0.12 m in thickness. Applied to these specimens were three different retrofit configurations, tested sequentially, namely: (a) unanchored continuous U-wrap; (b) anchored continuous U-wrap with conventional FRP-embedded anchors at the ends; and (c) fully closed external FRP hoops made of discrete FRP U-wrap strips and FRP through-anchors that penetrate the top slab and connect both ends of the FRP strips, combined with intermediate crack-control joints. The strengthening concept with FRP hoops precluded the premature debonding and anchor pullout issues of the two more conventional retrofit solutions and, despite a more challenging and labor-intensive installation, was selected for the in-situ implementation. The proposed hooplike EB-FRP shear-strengthening scheme enabled the deficient MRF beams to overcome a 30% shear overstress at the end-yielding region and to develop high-end rotations (e.g., 0.034 rad [3.4% drift] at peak and 0.038 rad [3.8% drift]) at strength loss for a beam that, otherwise, would have prematurely failed in shear. These values are about 30% larger than the ASCE 41 prescriptive value for the Life Safety (LS) performance objective. Energy dissipation achieved with the fully closed scheme was 108% higher than that of the unanchored FRP U-wrap and 45% higher than that of the FRP U-wrap with traditional embedded anchors. The intermediate saw-cut grooves successfully attracted crack formation between the strips and away from the FRP reinforcement, which contributed to not having any discernable debonding of the strips up to 3% drift. This paper presents the experimental evaluation of the three large-scale laboratory specimens that were used as the design basis for the final retrofit solution.

False-Positive Human Immunodeficiency Virus-1 Test Results With Rapid Seroreversion After Third-Trimester Tdap Booster Vaccination.

False-positive and false-negative results in human immunodeficiency virus (HIV) testing are expected at some frequency. False-positive results have been reported in association with various conditions, including pregnancy, autoimmune disease, and infection. We present an atypical case of a pregnant patient receiving false-positive HIV results for both screening and antibody confirmatory tests after a recent routine vaccination. A 34-year-old woman, G4P1021, with a negative first-trimester HIV test result received a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) booster at 35 2/7 weeks of gestation. Test results at 36 2/7 weeks of gestation were positive in both HIV-1/2 antigen-antibody screening and a confirmatory HIV-1 antibody differentiation immunoassay, but follow-up test results at 36 5/7 weeks and later were negative. Repeat testing and erythrocyte typing confirmed that this was not a result of laboratory error or specimen mishandling. HIV antiretroviral therapy was started and was later discontinued. A scheduled primary cesarean delivery performed at 39 1/7 weeks of gestation due to breech presentation was uncomplicated. False-positive results in HIV screen and confirmation testing were associated with receipt of a Tdap vaccine booster 7 days prior. This test result pattern is similar to that seen very rarely in previous cases, and the rapid seroreversion to negative suggests an acute immunologic trigger leading to a falsely reactive antibody. Clinicians should be aware of the potential for false-positive HIV test results in patients who recently received vaccination or with other immune triggers and retest at a short interval if suspected.

A complete experimental study on hard granites: Microstructural characterization, mechanical response, and failure criterion

This study, performed during the ORCHYD European project, devoted to drilling deep geothermal boreholes, has many potential applications to mechanical studies. It gathers geological descriptions of three outcropping granites from Scandinavia (Kuru Grey and Red Bohus) and from the South of France (Sidobre). Microstructural investigations include optical microscopy and X-ray tomography. The three granites chosen contain grain sizes that cover all the common ranges for granites: fine, medium and coarse. As the mineral phase volume fractions are similar in each, the grain defects and grain boundaries are carefully studied in an attempt to understand the physical and mechanical properties of the three granite rock samples measured at laboratory specimen scale. The rocks are tested for UCS, BTS and triaxial compressive strength with confining pressures up to 225 MPa or/and high strain-rates up to 103/s. The micro-structural parameters influencing the mechanical behaviour are highlighted. Test results show that the effect of confining pressure and strain-rate on compressive strength are uncoupled. These effects are then estimated independently, and a fracture criterion in compression accounting for both variables is proposed for the family of very hard granites. This criterion takes as a single reference strength measure for each rock the deviatoric stress at failure under 20 MPa confining stress in the quasi-static regime. It is then compared with existing datasets for which both quasi-static and dynamic regime data are available. This complete data set on these three very hard granites (UCS ∼ 200 MPa), together with a synthesis for failure prediction, has the potential to inform numerous rock engineering projects and be of value to the scientific community.

Prediction of resilient modulus and critical dynamic stress of recycled aggregates: Experimental study and machine learning methods

This paper aimed to investigate the feasibility of partially or completely replacing natural aggregates with recycled aggregates from construction and demolition wastes for low-carbon-emission use as coarse-grained embankment fill materials. The laboratory specimens were prepared by blending natural and recycled aggregates at varying proportions, and a series of laboratory repeated load triaxial compression tests were carried out to study the effects of material index properties and dynamic stress states on the resilient modulus and permanent strain characteristics. Based on the experimental results and by considering the main influencing parameters of the resilient modulus and permanent deformation, an artificial neural network (ANN) prediction model with optimal architecture was developed and optimized by the particle swarm optimization (PSO) algorithm, and its performance and accuracy were verified by supplementary analyses. A shakedown state classification method was proposed based on the unsupervised clustering algorithm, and a prediction model of critical dynamic stress was established based on the machine learning (ML) method and the shakedown state classification results. The research results indicate that the stress state has a greater influence on the resilient modulus and permanent deformation characteristics than other factors, and the shear stress ratio has a significant effect on the shakedown state. The resilient modulus and critical dynamic stress of such specimens vary linearly with confining pressure. The improved PSO-ANN prediction model exhibits high prediction accuracy and robustness, superior to several other commonly used ML regression prediction algorithms. The resilient modulus and critical dynamic stress prediction methods based on ML algorithms can provide technical guidance and theoretical basis for the design and in-service maintenance of similar unbound granular materials.

Exploring Damage Patterns in CFRP Reinforcements: Insights from Simulation and Experimentation.

Carbon Fiber Reinforced Polymers (CFRP) have become increasingly significant in real-world applications due to their superior strength-to-weight ratio, corrosion resistance, and high stiffness. These properties make CFRP an ideal material for reinforcing concrete structures, particularly in scenarios where weight reduction is crucial, such as in bridges and high-rise buildings. The transformative potential of CFRP lies in its ability to enhance the durability and load-bearing capacity of concrete structures while minimizing maintenance costs and extending the lifespan of the infrastructure. This research explores the impact of reinforcing structural elements with advanced composite materials on the strength and durability of concrete and reinforced concrete structures. By integrating Carbon Fiber Reinforced Polymer (CFRP) reinforcements, we subjected both rectangular and T-section concrete beams to comprehensive three-point bending tests, revealing a substantial increase in flexural strength by 45% and crack resistance due to CFRP reinforcement. The study revealed that CFRP reinforcement increased the flexural strength of concrete beams by 45% and improved crack resistance significantly. Additionally, the load-bearing capacity of the beams was enhanced by 40% compared to unreinforced specimens. These improvements were validated through finite element simulations, which showed a close alignment with the experimental data. Furthermore, an innovative simulation study was conducted using a finely tuned finite element numerical model within the Abaqus calculation code. This model accurately replicated the laboratory specimens in terms of shape, dimensions, and loading conditions. The simulation results not only validated the experimental observations but also provided deeper insights into the stress distribution and failure mechanisms of the reinforced beams. Novel aspects of this study include the identification of specific failure patterns unique to CFRP-reinforced beams and the introduction of an enhanced interaction model that more accurately reflects the composite behavior under load. In CFRP-reinforced beams, specific failure patterns were identified, including flexural cracks in the tension zone and debonding of the CFRP sheets. These patterns indicate the points of maximum stress concentration and potential weaknesses in the reinforcement strategy. The study revealed that while CFRP significantly improves the overall strength and stiffness, careful attention must be given to the bonding process and the quality of the adhesive used to ensure optimal performance. These findings contribute significantly to the understanding of material interactions and structural performance, offering new pathways for the design and optimization of composite-reinforced concrete structures. This research underscores the transformative potential of composite materials in elevating the structural integrity and longevity of concrete infrastructures.

Decreasing Blood Transfusions in Premature Infants Through Quality Improvement.

Packed red blood cell transfusions (pRBCT) in preterm infants have been associated with significant morbidity. Although infants <26 weeks' gestational age typically require several pRBCT, preterm infants born between 26 and 34 weeks' gestational age may also require pRBCT during their hospitalization that are potentially preventable. We aimed to reduce pRBCT in this population by 20%. This quality improvement project was conducted in the Duke University Hospital NICU between July 2018 and February 2023. Interventions included the implementation of evidence-based transfusion thresholds, supporting bone marrow erythropoiesis, and reducing laboratory specimen volumes by increasing capillary test panels. The rates per 1000 patient days for pRBCT (outcome measure), number of new patients initiated on erythropoietin (process measure), number of basic metabolic panels (process measure), and total capillary panels (process measure) were monitored during the project period. Statistical process control charts were used to observe trends over time. Among infants born between 26 0/7 and 34 6/7 weeks' gestational age, the rate of pRBCT decreased from an average of 23.8 to 12.7 transfusions per 1000 patient days, which is a 46.6% decrease. Increases in the use of erythropoietin and capillary panels were observed, along with a decrease in the use of basic metabolic panels. There was no change in mortality or the rate of necrotizing enterocolitis. Improvement was sustained for 24 months after implementation. pRBCT can be decreased in preterm infants born between 26 and 34 completed weeks' gestation through a combination of strategies utilizing quality improvement methodology.

Performance and Accelerated Ageing of an Industrial Hydraulic Lime Mortar Applied on Different Substrates

Mortar that is typically employed for interior or exterior coatings can be characterised using laboratory-prepared specimens according to specific test standards; however, its performance undergoes changes following application on substrates. When selecting mortar, it is vital to anticipate its in-service behaviour after its application on substrates to make the most informed choice. Most of the research work carried out to date analyses the characteristics of mortar in laboratory specimens. Some studies analyse these characteristics after its application to support, but very few exist that compare both behaviours. With this objective in mind, this research determined the properties of mortar when cured within laboratory moulds and assessed the behaviour of the same mortar after application on diverse substrate types. This study specifically evaluated the behaviour of a pre-dosed hydraulic lime mortar when applied on concrete blocks, lightweight concrete blocks, concrete slabs, hollow ceramic bricks, and solid ceramic bricks. Later, this behaviour was compared to the same type of mortar hardened in laboratory moulds and the same type of mortar applied on substrates and subjected to accelerated ageing. Moreover, data from previous experimental work were used to compare the behaviour of the pre-dosed hydraulic lime mortar with that of pre-dosed cement mortar when applied on similar substrates. The research drew upon a comprehensive characterisation of the physical and mechanical parameters of mortar, revealing that the performance of these types of mortar undergoes significant changes after application on substrates under in-service conditions, mainly when applied on more porous substrates. It was concluded that the application of mortar to substrates increased bulk density, decreased open porosity, enhanced compressive strength, and resulted in faster capillary absorption. For mortars subjected to accelerated ageing, a notable reduction in water vapour permeability was observed, which was attributed to changes in the pore profile.

Differentiation of Cutaneous Metastatic Breast Cancer from Cutaneous Adnexal Tumors Using Wnt9b Polyclonal Antibody Stain

Objective: The histologic diagnosis of cutaneous metastatic breast cancer can be challenging as the differentials can include primary cutaneous glandular neoplasms and metastases from other glandular neoplasms which present very similar on H&amp;E. Many immunohistological markers including GATA3 and CK7 have been employed to screen for primary or metastatic breast cancer cells and because of this, we wanted to develop a stain capable of differentiating these diagnoses quickly and accurately. Methods: We utilized 61 archived dermatopathology laboratory specimens of various benign and malignant cutaneous adnexal and breast tissues for analysis with a polyclonal Wnt9b antibody stain. Results: The average staining in benign categories (cutaneous adnexal and benign breast tissue) as well as metastases from non-breast carcinomas was negative. Among the malignant cutaneous adnexal and metastatic breast tissues, a significant difference was observed in staining as adnexal carcinomas were weakly positive (0.53+) and primarily seen in the outer layer of glandular structures, while metastatic breast tissues were strongly positive (3.63+) (P&lt;0.01). The specificity in both adnexal and metastatic breast tissues was 100% while the sensitivity for adnexal carcinomas was 37% and metastatic breast was 94%. A larger sample size could greatly improve these values. Conclusion: These results demonstrate that Wnt9b has specific staining for cutaneous metastatic breast cell nuclei and could be utilized as a diagnostic to differentiate from cutaneous adnexal tumors in routine dermatopathological applications. Keywords: Metastatic Breast Carcinomas; Cutaneous Adnexal Tumor; Staining; Polyclonal Antibody; Histological Markers

Parametric Modeling and Numerical Simulation of a Three-Dimensional Random Aggregate Model of Lime–Sand Piles Based on Python–Abaqus

A lime–sand pile is a three-phase particle composite material composed of a lime matrix, sand, and a loess aggregate at the meso level. Establishing a random aggregate model that can reflect the actual aggregate gradation, content, and morphology is the premise of numerical simulations of the meso-mechanics of lime–sand piles. In this paper, the secondary development of Abaqus 2022 is realized by writing Python 3.12 scripts, and a parameterized three-phase mixed lime–sand pile random meso-spherical aggregate model is obtained. A meso-modeling idea of lime–sand piles is creatively proposed, the integrated-generation algorithm of a spherical aggregate of different materials is written, and the material’s properties and mesh generation are given by the algorithm. Finally, a numerical simulation of temperature–expansion statics is carried out using an established mesoscopic model. Under different mixing ratios, the expansion force increases with an increase in the lime proportion. The increase in the expansion force is approximately 45% of that without an increased lime proportion. The simulated expansion forces are 8.81 kN, 12.61 kN, and 18.89 kN, respectively, which are similar to the experimental results for laboratory specimens, and the relative error is less than 3%. In the case of different height ratios, with increases in height, the change in the expansion force is very small, and the relative error between the simulated value and the experimental value is less than 2%, which further verifies the reliability of the mesoscopic random model of lime–sand piles. The model can be used to guide the practical application of engineering.

EPH95 Leveraging Data Aggregators to Annotate Deidentified Genomic Data Derived from Commercial Laboratory Specimens to Study COVID-19 Severity

EPH95 Leveraging Data Aggregators to Annotate Deidentified Genomic Data Derived from Commercial Laboratory Specimens to Study COVID-19 Severity

Carbonation and corrosion of steel in fly ash concrete, concluding investigation of five-year-old laboratory specimens and preliminary field data

Carbonation development and reinforcement corrosion were investigated on concretes exposed for a five-year period at 90% RH, 20 ℃, and 5% CO2, and for a six-year period at natural carbonation. Portland cement-based binders with 0%, 18%, and 30% fly ash were investigated. The fly ash blends showed lower carbonation resistance compared to PC both at laboratory and field exposure, a large difference in carbonation performance was observed between the laboratory exposed specimens. The carbonation rate was fastest on the laboratory specimens and showed square-root time dependency the first 2.5 years, but reduced rate at later age. Deeper carbonation depths were in general observed in the vicinity of the reinforcement compared to the unreinforced laboratory exposed specimens. Not all specimens were fully carbonated at the steel-concrete interface. The correlation between degree of carbonation of the steel-mortar interface, the open circuit potential, and the observed corrosion of the steel bars varied between binders and bar position (top or bottom). The measured corrosion rate in the laboratory exposed (90% RH, 20 ℃, and 5% CO2) carbonated concrete was on average 0.2 μA/cm2, with an upper value of 0.6 μA/cm2. The highest corrosion rate was measured in the fly ash concrete. No corrosion rate data are yet available for the field exposed concretes.

Analysis of the structural behavior of reinforced concrete components with acoustic emission analysis

The use of non-destructive testing methods can provide insights into processes within the interiors of structures. Acoustic emission testing is one of the non-destructive testing methods that allows the detection of material damage during its occurrence. When structures, such as concrete components, fail under load, elastic waves are generated, propagating within the component. These signals can be detected by acoustic emission sensors placed on the surface of the component, enabling the tracking of the material's condition and the location of failure. This paper summarizes recent applications of acoustic emission measurements on large-scale laboratory specimens made of reinforced concrete. The first example describes measurements during a tensile fatigue test on a large- scale reinforced concrete specimen to investigate the fatigue behaviour of an embedded concrete dowel. The second example involves measurements during a dynamic three-point bending test to examine the fatigue behaviour of a prestressed concrete railway sleeper. The third example describes a full-scale test conducted on a flat slab concrete test specimen with dimensions of 2.8 m × 2.8 m. The objective of these investigations is the development and optimization of new components to enhance punching shear resistance and provide an economical solution. To detect microcracking during loading acoustic emission measurement has been carried out using broadband sensors with a measurement frequency of up to 200 kHz which were especially developed for the detection of microcracks in concrete. For the three-dimensional location of the acoustic emission events, 16 of these acoustic emission sensors were attached to the surface of the specimens. Most of the events were in the centre of the sample in the punching area. These events form a circular structure with a diameter of approximately 1m. A visual inspection of the sample after the experiment shows that macroscopic cracks have formed in this area, which extend up to the surface of the sample.

Investigating the Field Performance of High- Recycled Asphalt Pavement Mixtures with Bio-oil Recycling Agent

The use of recycling agents (RAs), along with recycled asphalt pavement (RAP) modifiers, has been increasing over recent years. However, the field performance of asphalt mixtures containing high-RAP materials modified with RAs has raised some concerns with the long-term performance of RAs. This study evaluated the laboratory and field performance of high-RAP mixtures with and without bio-oil RA. Five sets of plant-produced specimens were collected: 1) plant-produced laboratory-compacted; 2) field-compacted, cored after paving; 3) field-compacted, cored after one year; 4) field-compacted, cored after two years; and 5) field-compacted, cored after three years. The Hamburg wheel tracking test was used to evaluate the specimens’ resistance to rutting and moisture damage, while the semi-circular bending test was performed to examine the cracking resistance of specimens. The laboratory test results showed that using the bio-oil RA increased cracking resistance and decreased rutting and moisture damage resistance of the RAP-blended mixtures. However, after one and two years of exposure to environmental conditions and traffic loads, the specimens modified by RA showed better moisture damage and rutting resistance. The cracking resistance of laboratory and field-aged specimens, estimated by flexibility index, implied that the bio-oil RA used in this study could not provide long-term improvement for the RAP-blended mixtures. Field observations suggest that using bio-oil RA may have resulted in inferior pavement performance compared with the control section. However, drawing conclusions based on just two years of data might yield inconclusive results. Longer field performance monitoring is, therefore, warranted for a more comprehensive analysis.

Mechanical Behavior of Intact and Increasingly Jointed Marble Laboratory Specimens

Mechanical Behavior of Intact and Increasingly Jointed Marble Laboratory Specimens

Development of Macrotexture Test Method for Dense-Graded Asphalt Mixtures

The design and construction of pavements necessitate careful consideration of longevity, cost-effectiveness, sustainability, and safety, with a focus on enhancing the durability and lifespan of dense-graded asphalt (DGA) surface mixtures. This paper discusses a research project the Federal Highway Administration (FHWA) initiated to assess the macrotexture characteristics of DGA mixture pavement—particularly concerning safety at higher speeds. The project aims to develop an efficient testing procedure for measuring macrotexture during mixture design and field-testing processes, striking a balance between longevity, cost-effectiveness, sustainability, and safety in pavement design and construction. The study began with a comprehensive review of existing practices, leading to the selection and testing of a unique laser texture scanner capable of noncontact macrotexture measurement. The subsequent phase involved validating the suggested macrotexture measurement system through data collected from State-sponsored projects under the FHWA Mobile Asphalt Technology Center program. Macrotexture measurements were collected from field cores and laboratory-compacted specimens from various State departments of transportation projects and analyzed. Preliminary analysis of the limited dataset to date revealed a positive correlation between average macrotexture measurements from gyratory specimens’ top surface and field core macrotexture measurements. The FHWA developed a draft test method for measuring macrotexture on laboratory specimens and field cores, thereby aiming to reduce procedural variability. Interlaboratory macrotexture test results demonstrated good reproducibility, with an average coefficient of variation of approximately 20%. Overall, this research project seeks to advance the understanding and measurement of macrotexture in DGA mixture pavements and thereby contribute to the development of safe pavements.