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High-density polyethylene (HDPE) geomembranes are commonly used as an environmental protection liner due to their good chemical and mechanical resistances and low cost. Ultraviolet (UV) radiation is an essential issue in durability studies for pond applications. This study evaluated a 1.5-mm thick HDPE geomembrane exposed to ultraviolet fluorescent radiation for 8760 h in a laboratory and thermoanalytical and physical analyses were conducted towards the understanding of its performance after exposure. According to the results, although the geomembrane maintained the ductile behavior, it showed a 52.48% final decrease in stress crack resistance (SCR) compared to virgin SCR. Moreover, a considerable antioxidant depletion occurred after 8760 h exposure shown by the Std. OIT (standard oxidative-induction time) results, demonstrating a Std. OIT value decrease of 89.19% compared to the virgin Std. OIT. Such a behavior contributed to the susceptibility of thermal effects in the DSC (differential scanning calorimetry) curves and the losses observed in the SCR values, attesting the geomembrane’s oxidative degradation mechanism occurred and changed the polymer’s structure.

The use of recycled aggregates instead of natural aggregates used in concrete reduces environmental pollution and concrete costs. Recycled Asphalt Pavement (RAP) aggregate used as recycled aggregate has a lower water absorption than natural aggregate due to its bituminous structure, which reduces the water requirement of fresh concrete. In this study, it was aimed to determine the optimum use of RAP particles as aggregate in concrete for read pavements and to determine their durability properties. For this purpose, RAP was used instead of crushed stone aggregate used in concrete road construction. RAP was used by replaced aggregate 0%, 25%, 50% and 100% of the crushed stone aggregate used on the concrete road. The dose of the produced concrete was 350 kg/m3 and the water/cement ratio was kept constant as 0.45. The fresh workability and air content of concretes containing RAP were determined. Compressive strength, splitting tensile strength, electrical resistivity value, accelerated corrosion test of hardened concretes were subjected to corrosion resistance, water absorption and porosity percentage, acid resistance, ultrasonic pulse rate and Scanning Electron Microscope (SEM) and X-ray Diffractometer (XRD) analyzes were determined. In the experimental results, it has been observed that the use of RAP ratio of 25% and 50% remains within the limit values for concrete pavement. It is recommended to be used on reinforced concrete roads that will be exposed to adverse environmental conditions with its high corrosion resistance, thanks to its anti-corrosion feature.

Thermal modification of wood is an environmentally friendly method to improve wood durability, mainly against microorganisms. By employing a process similar to the ThermoWood®, various Gmelina arborea (gamhar) wood specimens were thermally modified at 180 °C, 200 °C, and 220 °C for 3 hours. The effects of the thermal modification process on the resistance to decay by rot-fungi, and attack by subterranean, arboreal, and dry-wood termites were determined. Generally, the thermal modification improved the resistance of Gmelina arborea (gamhar) to decay by Trametes versicolor with increasing process temperature. However, the effect of the process was null on the resistance to biodeterioration by the brown-rot fungus Coniophora puteana and the dry-wood termites Cryptotermes brevis. Even so, the visual damage caused by Cryptotermes brevis was slight. Untreated and thermally modified woods recorded higher resistance to Coniophora puteana than Trametes versicolor. Mass loss caused by Nasutitermes corniger also decreased with increasing thermal modification temperature. According to the visual damage rating values, the attack by Nasutitermes corniger was slight. However, the thermal modification inversely impacted Gmelina arborea (gamhar) attack by Macrotermes sp., as its resistance in the field to the termites decreased with increasing modification temperature. Thus, the thermal modification process contributed to improving the decay resistance of the modified wood to white-rot fungus Trametes versicolor and attack by the arboreal termites Nasutitermes corniger exposed indoors. On the other hand, thermally modified Gmelina arborea (gamhar) wood was very susceptible to Macrotermes sp. in the field. This work would provide a reliable reference document to guide wood industry stakeholders in assessing the performance of untreated and thermally modified Gmelina arborea (gamhar) wood in situations exposed to fungi and termite species adopted.

Resumen: Introducción: La reparación de la insuficiencia mitral por prolapso del velo posterior ha evolucionado en los últimos 20 años desde las técnicas clásicas de Carpentier hacia procedimientos menos agresivos con el tejido valvular. Nuestro objetivo es describir la evolución del tratamiento de esta patología en nuestro centro. Métodos: Estudio retrospectivo de pacientes con prolapso de velo posterior operados en nuestro centro desde 2001 a 2021. Recogida de datos intraoperatorios y datos ecocardiográficos y de seguimiento durante 20 años. Resultados: Se incluyeron 260 pacientes operados en dos períodos: hasta 2010, 84 pacientes (grupo A) y desde 2011, 176 pacientes (grupo B). Las técnicas más utilizadas en el grupo A fueron la resección cuadrangular (51 pacientes, 60,7%), la triangular (20 pacientes, 23,8%) y la implantación de neocuerdas (8 pacientes, 9,5%) siendo la tasa de reparabilidad del 98,8%, y en el grupo B fueron la resección triangular (86 pacientes, 48,9%), la implantación de neocuerdas (45 pacientes, 25,6%) y la resección cuadrangular (28 pacientes, 15,9%) con una reparabilidad del 96,6%. La mortalidad hospitalaria fue del 3,6% (n = 3) en el grupo A y del 0,6% (n = 1) en el B. Supervivencia actuarial 50% a los 20 años (A) y 81% a los 10 años (B). Tasa libre de reintervención del 98% (A) y del 97,2% (B). Teniendo en cuenta las técnicas más frecuentemente utilizadas, la recidiva de insuficiencia mitral ≥ II fue mayor en los pacientes con neocuerdas (n = 14, 26,4%) que en los casos de resección cuadrangular (n = 10, 13,2%) o triangular (n = 13, 12,4%). Conclusiones: Nuestro centro ha evolucionado hacia técnicas con menor resección tisular y mayor utilización de neocuerdas, aunque ambas técnicas han mostrado excelentes resultados a largo plazo. Las técnicas resectivas son más reproducibles y duraderas que la implantación de neocuerdas. Abstract: Introduction: Repair of mitral regurgitation due to posterior leaflet prolapse has evolved in the last 20 years from the classic Carpentier techniques towards less aggressive procedures with the valve tissue. The objective of this study is to describe the evolution of our center in the treatment of this pathology. Methods: Retrospective study of 260 patients with posterior leaflet prolapse operated on our center since 2001, including them into two groups: A (until 2010) and B (since 2011). We collected intraoperative data and echocardiographic and follow-up data for 20 years. Results: 260 patients operated on in two periods were included: until 2010, 84 patients (group A) and since 2011, 176 patients (group B). The most commonly used techniques in group A were quadrangular resection (51 patients, 60.7%), triangular resection (20 patients, 23.8%), and neochordal implantation (8 patients, 9.5%), with a reparability rate of 98.8% and in group B, triangular resection (86 patients, 48.9%), neochordal implantation (45 patients, 25.6%) and quadrangular resection (28 patients, 15.9%) with a reparability rate of 96.6%. Hospital mortality was 3.6% (n = 3) in group A and 0.6% (n = 1) in group B. Actuarial survival was 50% at 20 years (A) and 81% at 10 years (B). Reoperation-free rate was 98% (A) and 97.2% (B). Taking into account the most frequently used techniques, the recurrence of mitral regurgitation ≥ II was greater in patients with neochordae (n = 14, 26.4%) than in cases with quadrangular (n = 10, 13.2%) or triangular resection (n = 13, 12.4%). Conclusions: Our center has evolved towards techniques with less tissue resection and greater use of neochordae although both techniques have showed excellent long-term results. Resective techniques are more reproducible and durable than neochordal implantation.

ABSTRACT Low-temperature storage is one of the most effective techniques to maintain the quality and durability of cut flowers. Both quality maintenance and durability are dependent on plant metabolism factors such as antioxidant system. The objective was to evaluate the effect of low-temperature on precooling and storage after harvest, on the metabolism of calla lily [Zantedeschia aethiopica (L.) K. Spreng] concerning the antioxidant system, levels of hydrogen peroxide (H2O2), and malondialdehyde (MDA). Therefore, different storage temperatures (4 ºC and 21 ºC) were tested as well as the effect of precooling in different periods (0 to 24 hours). It was observed that the activity of catalase (CAT) and superoxide dismutase (SOD) was increased at 4 °C, as well as inflorescence durability in the commercial standard (around 12 days). At 21 °C, the content of H2O2 and MDA was higher and the visual quality reduction in the inflorescence was accelerated. Low-temperature leads to a higher activity of the enzymes of the antioxidant system (CAT and SOD) and increases postharvest longevity for calla lily. Precooling did not influence the visual quality and longevity of calla lily. Long-term exposure periods at low temperatures, with 12 and 24 hours of precooling caused stress, evidenced higher MDA levels and higher CAT activity. SOD activity was related to low temperature and shorter precooling periods resulted in better antioxidant system activity and lower MDA levels.

This paper examines the effect on mechanical properties such as compressive strength, flexural strength, and dynamic modulus of elasticity (DYE) of different proportions of wollastonite (β-CaSiO3) and colloidal nano-silica (n-SiO2) partially replacing cement. Durability indicators (water absorption, sorptivity and sulphate treatment test) were also examined to ascertain the quality of hardened paste mixes with respect to the control mix. The regression models were found for mechanical properties using different parameters from the results obtained, and statistical relations were established and validated. Regression analysis shows the significance of every parameter considered and model for the prediction of mechanical strengths. Finally, the results were substantiated by the microstructural characterization by FESEM. β-CaSiO3 and colloidal n-SiO2 replaced cement by 15%, and 1.5%-6% with an offset of 1.5%, respectively at low (0.25), medium (0.40) and high (0.55) water/binder (w/b) ratio. FESEM micrographs showed dense Calcium-silicate-hydrate (CSH) gel and stratlingite (CASH) was formed by blended cement paste mixes containing β-CaSiO3 and n-SiO2. n-SiO2 at 3% and CaSiO3 at 15% replacements of cement (NS3 mix) was the optimum replacement level for the cement paste mix. Analysed regression model suggests that the models and parameters were found significant and can also be used for prediction (based on R2 values and p-value).

Sandstones have been widely used in construction for their abundance, aesthetics, and ease of extraction. To determine sandstones’ quality, it is essential to analyse their petrographic and petrophysical properties and sensitivity (durability and conservation) to environmental agents. This paper evaluates the physical-mechanical changes undergone by Sierra de la Demanda (Burgos, Spain) sandstone under combined and induced water and salt aggression and assesses ESTEL 1100’s effectiveness and suitability as a treatment. This sandstone is porous, permeable, dense and quartz-rich with high hardness and strength. The treatment improved its petrophysical properties by modifying its pore geometry and connectivity, reducing absorbency, permeability and anisotropy, and further increasing its hardness and resistance. Salts did not substantially modify its properties as its porosity type absorbed the crystallisation pressure. Ultimately, its pore system and predominantly quartz composition make it a high-quality, weather-resistant material compatible with the treatment applied.

A novel binder system for cement-based composites depending upon the strength and durability characteristics is introduced in this study. The possibility of calcined red mud cement pastes with and without colloidal nano-silica (CNS) over Ordinary Portland Cement paste (OPC) at three W/B ratios (0.3, 0.4, 0.5) is evaluated. The optimum percentage of cement replacement by red mud (15%) was selected from compressive strength values of different cement replacements (5%, 10%, 15%, and 20%). Colloidal nano-silica (CNS) was added at 0.5%, 1%, 1.5%, and 2 % to the selected red mud cement paste. Water absorption, sorptivity, resistance to sulfate attack, and resistance to acid attack tests were conducted for optimum red mud cement paste with and without CNS. The experimental results are explained based on tortuosity with empirical formulas and mathematical models of pore network distribution. The tortuosity is directly proportional to the inter-connectivity of the pores. The mixes with 15% calcined red mud and 1.5% CNS replacement performed better strength and durability at all W/B ratios. The mix (R15NS1.5) with minimum tortuosity value results in the higher overall performance of the paste. The mixes with a 0.3 W/B ratio give high-performance cement paste compared to higher W/B ratios.

The main objective of this work is to test several nanoconsolidant treatments (pure Nano Estel, 1:1 diluted Nano Estel and Tecnadis ZR-110), with the aim of improving the intergranular cohesion of the Novelda Stone. The treatments were applied in laboratory by capillary suction and their effectiveness and depth of penetration have been evaluated on the basis of the petrophysical characteristics of the stone (petrography, elemental physical properties, hydric properties and ultrasound propagation), before and after consolidation. Subsequently, in order to estimate the durability of the treatments, accelerated ageing tests (salt crystallisation, freeze-thaw and wet-dry) were carried out. According to the results, we can conclude that none of the treatments is suitable for the treatment of Novelda stone. However, we consider that with further in-depth study Tecnadis ZR-110 could offer good results.

Fatigue life has to be considered in the design of many concrete structures at various stress levels and stress ratios. Many flexural fatigue test results of plain normal-weight concrete are available in the literature and almost every set of test results provides different fatigue equations. It is necessary, though, to have a common fatigue equation to predict the design fatigue life of concrete structures under flexural load with reasonable accuracy. Therefore, a database of flexural fatigue test results was created for concrete with strengths ranging from 25 to 65 MPa; this database was used to derive new fatigue equations (Wöhler fatigue equation and S-N power relationship) for predicting the flexural fatigue life of normal-weight concrete. The concept of equivalent fatigue life was introduced to obtain a fatigue equation using the same stress ratio. A probabilistic analysis was also carried out to develop flexural fatigue equations that incorporate failure probabilities.

The investigation dealt with the stabilization of expansive soil with combinations of lime, steel slag and reinforced with two types of fibres, copper filaments and polypropylene fibres. The investigation began with the characterization of the soil for its geotechnical properties. The initial consumption of lime required for the modification of the soil properties was determined from the Eades and Grim pH test. Cylindrical specimens of soil with dimensions 38 mm x 76 mm were cast using this lime content as a stabilizer along with varying quantities of steel slag for determination of optimum steel slag content. The pure lime stabilized soil as well as lime-steel slag modified soil specimens were reinforced with different proportions of copper filaments for determination of optimum fibre content. One dosage of polypropylene fibres was also adopted as reinforcement in specimen preparation. The optimal combinations identified were then subjected to a maximum of three cycles of wetting and drying followed by determination of unconfined compression strength (UCS). The expansive soil required a minimum of 3% lime for its modification. The optimum dosage of steel slag was identified as 5% and optimum copper filament content as 1%. Polypropylene content of 0.3% was also adopted as one combination. The results of the investigation revealed that lime stabilized fibre-reinforced soil with copper filaments was the most durable combination followed by polypropylene fibres. The introduction of steel slag in the mix could not generate enough beneficial durability to the soil after three cycles of wetting and drying.

The presence of clay soil causes problems at the base of the structure: it swells when wet and shrinks when dry, which provides a reduction in the resistance to cutting of the soil. Plastic waste in the form of polyamide powder (PA-12) from the 3D printing industry can be used to improve the mechanical properties of the soil. This experimental study is an attempt to combine these two objectives of stabilizing the soil by using waste PA-12. The mechanical and shear resistant properties gave us confidence in choosing PA-12 as a stabilizer in clay soils, making them composite soils.

The polymer demand for geotechnical applications has been growing. The geomembrane is a geosynthetic, manufactured, polymeric product and is often specified in environmental projects. Geomembranes started to be used in the 1930s but became more widespread in the 1940s. In the 1970s, geomembranes began to be specified for landfills. Over the past forty years, millions of square meters of HDPE geomembrane have been used in different applications. One of the most important issues for HDPE geomembranes is durability, involving very long-term property requirements. A rupture in the liner that has a geomembrane may provide losses in terms of human lives, environmental impacts, and financial costs. This paper summarizes the mechanisms and concepts involved in the HDPE geomembrane aging and describes the important contributions of laboratory and field studies over the years around the world. Different conditions and exposures drive the HDPE geomembrane behavior, including field temperature conditions and contact with different chemical substances. Accelerated laboratory testing with HDPE geomembrane simulating field boundary conditions is critical to ensure proper use of this geosynthetic in the future.

Durante mucho tiempo, los residuos han alimentado varias cadenas de valor. Ante esta problemática, se han buscado cadenas de valor en ingeniería civil. Esta operación de recuperación reúne una ventaja económica y una cuestión medioambiental. El proceso de valorización en el ámbito de la construcción permite dar respuesta a múltiples problemas, tales como: la preservación de las reservas naturales de áridos mediante la valoración de los materiales de sustitución de las obras de ingeniería civil, y la reducción del transporte y de las emisiones de CO2. La gestión de los desechos sólidos es una de las principales preocupaciones ambientales del mundo. Con la reducción de los espacios para vertederos y debido a su elevado coste, el uso de residuos se ha convertido en una alternativa atractiva disponible para diversas aplicaciones. Por otro lado, la sostenibilidad es un objetivo de calidad para el ingeniero. La durabilidad del material de hormigón en su entorno se considera una preocupación importante en el sector de la construcción. El mecanismo de degradación química de este material es su descalcificación gradual en el tiempo en contacto con un entorno agresivo. Esta degradación provoca cambios en las propiedades fisicoquímicas y mecánicas del hormigón. Para evaluar experimentalmente la durabilidad del hormigón, hay que estudiar su comportamiento en relación con una serie de mecanismos que podrían degradarlo. El problema se puede tratar como la durabilidad del hormigón en ambientes agresivos. En este estudio se investigó el efecto de la adición de residuos industriales (fibras metálicas) sobre la durabilidad de hormigones y morteros que contienen un 10% de fibras en sustitución del cemento. Los resultados presentados se refieren a los obtenidos con las siguientes pruebas: Prueba de humectación-secado, prueba de lixiviación monolítica, ataque químico y evaluación de resistencia a la compresión mediante prueba de oscultación sónica. Abstract For a long time, waste has fuelled several value chains. Faced with this problematic, value chains in civil engineering have been sought. This recovery operation brings together an economic advantage and an environmental issue. The process of valorization in the field of building and construction makes it possible to answer to multiple problems, such as: the preservation of the natural reserves of aggregates by the valuation of the materials of substitution for the works of civil engineering, and the reduction of the transport and CO2 emissions. Solid waste management is one of the main environmental concerns in the world. With the shrinking of spaces for landfilling and because of its high cost, the use of waste has become an attractive alternative made available for various applications. On the other hand, sustainability is a quality goal for the engineer. The durability of the concrete material in its environment is considered a major concern in the building sector. The mechanism of chemical degradation of this material is its gradual decalcification over time in contact with an aggressive environment. This degradation causes changes in the physicochemical and mechanical properties of the concrete. To experimentally evaluate the durability of concrete, one must study its behaviour in relation to a number of mechanisms that could degrade it. The issue can be treated as the durability of concrete in aggressive environments. In this study, we investigated the effect of the addition of industrial waste (metallic fibers) on the durability of concretes and mortars containing 10% of fibers in substitution of cement. The results presented concern those obtained with the following tests: Wetting-Drying Test, Monolith Leaching Test, Chemical Attack and Evaluation of Compression Resistance by Sonic Auscultation Test.

The need for proactive maintenance of reinforced concrete structures with non-destructive testing (NDT) is less disputable today than ever. One of the most promising strategies in this regard is the in-situ measurement of the reinforcement corrosion rate. This study explored the reliability of modulated current confinement method (hereafter MCC) based on a review of in-situ measurements made with that technique in real-life structures over a 13-year period. The most prominent problems detected included defective confinement of the polarization current in low-resistivity environments and over-polarization of passive reinforcement. The findings, which showed enhancement of MCC reliability to depend on improving the electrochemical current regulation and control methodologies presently in place, are being applied to improve the design of the next generation of corrosion meters.

Wood decay have the greatest impact on in-service wood structural elements. In most cases, decay is associated with excessive accumulation of moisture in the wood. The structural design conditions have an effect on the wood moisture content and this affects the service life of the material. In this study, which involved an experimental trial specifically designed to embrace different structural design conditions, the moisture content evolution in different places affected by different design conditions was evaluated over a period of three years in Madrid (Spain). The effect of protection by eaves, separation from the ground and the vertical or horizontal arrangement of the wood elements on the monthly evolution of the moisture content and decay risk are assessed.

Self-healing of concrete is the process in which the material regenerates itself repairing inner cracks. This process can be produced by autogenous or autonomous healing. Autogenous healing is a natural process, produced by carbonation and/or continuing hydration. Autonomous healing is based on the use of specific agents to produce self-healing, which can be added directly to the concrete matrix, embedded in capsules or introduced through vascular networks. Some examples are superabsorbent polymers, crystalline admixtures, microencapsulated sodium silicate, and bacteria. This review is structured into two parts. The first part is an overview of self-healing concrete that summarises the basic concepts and the main advances produced in the last years. The second part is a critical discussion on the feasibility of self-healing concrete, its possibilities, current weaknesses, and challenges that need to be addressed in the coming years.

The objective of this study is to evaluate the effect of the species on the biological resistance of wood against decay and to propose corrective values of the critical dose. To evaluate the species effect, the evolution of the number of days per year with moisture content exceeding 18% was assessed in flat sawn 20x100x750 mm3 test samples of Laricio, Scots and Radiata pines and also of Norway spruce, Eucalypt (globulus) and sweet chestnut during the years 2016, 2017 and 2018, exposed at seven locations in Spain with the most representative Spanish climates. A value of 1.0 is proposed for the four conifers, 2.51 for the Eucalypt and 1.84 for the Sweet chestnut. As regards the species effect it was not possible to separate that corresponding to the different wetting/releasing ability of each species and that of their crack susceptibility, both aspects having to be evaluated together as “species factor”.

The objective of this study was to investigate relation of diameter of pilot hole and screw, and machining accuracy on withdrawal strengths of the screws and durability of the dining tables. For this purpose, fasteners and material types on the failure loads of dining table corner joints have been analyzed experimentally and statistically. Double ended thread bolts with different drilling regimes have been used as fastener types. Parallel investigation of rigidity and durability of tables, according to the current EN norms, and withdrawal capacities in accordance with the procedures described in ISO 9087 was performed. According to the results, it is concluded that the diameter of the drilled hole significantly influences the value of the withdrawal strengths of the screws. By analyzing the effect of drilling diameter on rigidity of tables, a statistically significant difference was determined. As the drilling diameter increases, the rigidity of the examined dining tables decreases.

Objective: In the context of the advancement of antiretroviral therapy and, as the characteristics of people living with HIV progress toward an aging population, understanding the causes of treatment interruption becomes crucial. The aim of the study was to determine the change in reasons for antiretroviral treatment discontinuation for 12 years. Secondarily, compare annual antiretroviral regimen discontinuation rate and factors associated., Methods: We conducted an analysis using data from people living with HIV who were receiving antiretroviral therapy and discontinued it for any reason. The study included people with HIV infection who visited an outpatient hospital pharmacy clinic from January 2010 to December 2021. Two periods were differentiated for the analysis: 2010-2015 and 2016-2021. The reasons for antiretroviral treatment discontinuation followed classification described by Swiss cohort. In the context of this study, it is pertinent to note that the term 'interruption' will be consistently used in this article to refer to the act of switching or stopping antiretroviral treatment. To examine factors associated with antiretroviral therapy discontinuation, we utilized Kaplan-Meier methods and Cox proportional models., Results: We included 789 people living with HIV, predominantly male (81,5%). The main reason for discontinuation was clinical decision (50.2%) followed by adverse effects (37.9%). Focusing on clinical decision, we observed a trend change that went from antiretroviral treatment simplification regimen (56.1%) in the first part of the period analyzed to the therapeutic optimization (53.6%) in the second half. Furthermore, factors that were statistically significantly associated with antiretroviral treatment discontinuation were people with HIV ≥50 years (HR 1.60; 95%CI 1.25-2.04), post-discontinuation single-tablet regimen (HR 1.49; 95%CI 1.06-2.11) and antiretroviral drug classes., Conclusions: Over the 12 years there has been a change in the main cause of antiretroviral treatment discontinuation, currently therapeutic optimization being the main reason. Integrase inhibitors-based regimens and singletablet regimen strategies were less likely to be discontinued than others antiretroviral drug classes, allowing for better clinical management due to the efficacy profile, especially in people living with HIV ≥50 years with comorbidities., (Copyright © 2024 Sociedad Española de Farmacia Hospitalaria (S.E.F.H). Publicado por Elsevier España, S.L.U. All rights reserved.)

This study presents a new approach to the utilization of industrial by-products in construction materials by using fly ash (FA) in the production of glass fiber-reinforced polyester (GRP) pipe. The FA was substituted by 10% and 20% (by weight of sand) in the mixtures to produce GRP pipes of 350 mm in diameter and 6 m in length for testing. Stiffness modulus (SM), axial tensile strength (ATS), and hoop tensile strength (HTS) tests were conducted on the produced GRP pipes and their elasticity modulus (EM) values were also calculated. To observe the microstructure of the GRP pipes and the interfacial transition zone of the layers, SEM and microscopic analyses were performed. Furthermore, a strain-corrosion test was conducted to obtain information about long term-performance of samples. The results showed that the FA-filled GRP pipes were found to meet the requirements of the related standards, and that the use of FA in the GRP pipe industry may be an important alternative approach to the utilization of industrial wastes via effective recycling mechanisms.

In this paper, the influence of additions of nanosilica (nSi) and microsilica (mSi) on the behav­iour of binary and ternary mixtures in chloride environments is studied. The main objective is to obtain high-performance self-compacting concrete (HPSCC) with a high durability which can meet specific demands in such aggressive environments. Ten blends were manufactured using Portland cement (CEM I 52.5 R) and additions of nSi and mSi in binary and ternary mixtures. The results of three tests frequently used to evaluate resistance to chloride penetration– electrical resistivity, migration and chloride diffusion –were studied and compared. Both binary and ternary mixtures presented significant improvements in chloride resistance, generally in proportion to the total content of the addition. In all the ternary mixtures, high resistivity is obtained, which indicates that such mixtures have a notably low chloride penetrability. Furthermore, these mixtures provided extremely low chloride diffusion coefficients even at small addition ratios.

The existence of a possible anisotropy, determined by the orientation of any mineral or by micro­crack network in granite rock, isn´t easily detected by the naked eye. Five granitic rocks from Galicia (Spain), namely Albero, Gris Alba, Gris Mondariz, Rosa Porriño and Traspielas, were characterized petrographically by means of textural and mineralogical studies, using optical polarizing microscopy, and fractographic studies were carried out under scanning electron microscopy. Longitudinal wave propagation velocity was measured in three orthogonal directions on cubic samples, oriented according to rift surface (known in quarry works like the preferential partition surface visible in the blocks). Vp was measured on dry and water saturated samples. All the dry samples showed an anisotropic behaviour of Vp. Models of microcrack network distribution and possible mineral grain orientation were developed based on the obtained data.

The tests of Brazilian Standard NBR 15575: 2013 are part of the knowledge of the civil construction industry, but the heat and thermal shock test is innovative and does not have a consolidated history. The research objective is to analyze the testing critically and present proposals based on data meta-analysis. Results showed that the test is very inaccurate in describing the procedure and equipment. This study proposed adjustments and innovations in the test to provide more reliable results, but it does not make propositions regarding visual inspection and the number of cycles. The study concluded that the lack of information on the testing has direct responsibility for the results and that the suggested proposals have the potential to be incorporated.

The above-ground performance of decking treated with two alternative copper-based preservative formulations is being evaluated at a test site near Madison, Wisconsin, USA. Southern pine sapwood lumber specimens (38 mm by 140 mm by 910 mm) were pressure treated with 0,93 %, 1,40 % or 2,34 % (oxide basis) actives concentrations of a boron-copper formulation (BC) composed of 7,2 % copper hydroxide and 92,8 % sodium tetraborate decahydrate. Similar specimens were pressure-treated with 0,66 % or 1,32 % actives concentrations of a copper-zinc formulation (CZDP) composed of 18 % copper (CuO basis), 12 % zinc (ZnO basis), 14 % dimethylcocoamine and 56 % propanoic acid. In both cases untreated specimens and specimens treated with a 1% concentration of chromated copper arsenate Type C (CCA-C) were included for comparison. The specimens were installed on racks approximately 760 mm above the ground and periodically evaluated for extent of fungal decay and surface microbial growth. After 18 years in test specimens treated with the lowest solution concentration of BC (0,93 %) suffered substantial degradation and all but three replicates have failed. Obvious decay has not yet been detected in specimens treated to the highest BC concentration (2,34 %), but decay is suspected in one of these specimens. Decking specimens treated with CZDP exhibited no evidence of decay until year 17 when a fruiting body was observed on one specimen treated with a 0,66 % solution concentration. There has been no evidence of decay in specimens treated with 1,32 % CZDP or in either set of specimens treated with 1 % CCA-C. Both BC and CZDP-treated specimens were at least as effective as 1 % CCA-C in minimizing noticeable surface microbial growth. These decking studies confirm that relatively low copper concentrations can provide substantial protection for decking exposed in a moderate climate, and that the CZDP formulation is potentially more effective than the BC formulation. However, caution is warranted in extrapolating these findings to more severe climates and to construction designs that are more likely to trap moisture.

About a decade of research carried out at IIT Madras on cementitious systems has shown that the partial replacement of portland cement with supplementary cementitious materials (SCMs) has benefits as well as limitations. The SCMs do not adversely affect the long-term compressive strength and drying shrinkage of concretes, though there may be some compromise in workability and the resistance against plastic shrinkage cracking. Through the assessment of the chloride ingress rate in concrete and chloride threshold of steel, it is evident that the use of SCMs could significantly enhance the service life under chloride attack, though there is a reduction of the carbonation resistance. More importantly, SCMs can lead to significant reduction of the carbon footprint of concrete, and hence, are essential to achieve sustainability.

In this research, the synergetic effect of a super-absorbent polymer in combination with a calcium nitrite corrosion inhibitor were evaluated as a combined technology to improve concrete durability in High Performance Concrete. For this purpose, Portland cement mortars with a water/cement ratio of 0.4 and a substitution of 9.5% of cement by silica fume were produced. The effect of this technologies was evaluated by measuring the following parameters: autogenous and drying shrinkage, surface electrical resistivity and the non-steady-state chloride migration coefficient. The results indicate that the synergistic effect of SAP + CNI improves autogenous shrinkage and surface electrical resistivity.

Fibre-reinforced concrete (FRC) allows reduction in, or substitution of, steel-bars to reinforce concrete and led to the commonly named structural FRC, with steel fibres being the most widespread. Macro-polymer fibres are an alternative to steel fibres, being the main benefits: chemical stability and lower weight for analogous residual strengths of polyolefin-fibre-reinforced concrete (PFRC). Furthermore, polyolefin fibres offer additional advantages such as safe-handling, low pump-wear, light weight in transport and storage, and an absence of corrosion. Other studies have also revealed environmental benefits. After 30 years of research and practice, there remains a need to review the opportunities that such a type of fibre may provide for structural FRC. This study seeks to show the advances and future challenges of use of these polyolefin fibres and summarise the main properties obtained in both fresh and hardened states of PFRC, focussing on the residual strengths obtained from flexural tensile tests.

Carbonation is a deleterious concrete durability problem which may alter concrete microstructure and yield initiation of corrosion in reinforcing steel bars. Previous studies focused on the use of Artificial Neural Networks (ANN) for the prediction of concrete carbonation depth and to minimize the need for destructive and elaborated civil engineering laboratory tests. This study aims to provide improved accuracy of simulation and prediction of carbonation with an ANN architecture including eighteen input parameters employing alternative Scaled Conjugate Gradient (SCG) function. After ensuring a promising value of the coefficient of correlation as high as 0.98, the influence of proposed input parameters on the progress of carbonation depth was studied. The results of this parametric analysis were observed to successfully comply with the conventional civil engineering experience. Hence, the employed ANN model can be used as an efficient tool to study in detail and to provide insights into the carbonation problem in concrete.

Glass materials based on lithium zinc silicate system of the composition 24Li2O–20ZnO–56SiO2 LZS (mol%) were prepared and converted to glass–ceramics using controlled heat-treatment schedules. The LZS base glass system was modified by addition of Al2O3 and MO/ZnO replacements where MO = CaO, CdO and SrO oxides. Several crystalline phases were developed, including lithium zinc orthosilicate, α-quartz, β-spodumene solid solution, lithium meta and disilicate, Ca-wollastonite, Cd or Sr metasilicate, and Sr-zinc silicate of hardystonite type. The effects of crystallization process on some properties, like thermal expansion coefficient (TEC), chemical stability, and density of glass–ceramics were evaluated. The TEC of crystalline samples varied from 72 × 10−7 to 149 × 10−7 K−1, 25–600 and density values in the range, 2.67–3.29 g/cm3. The addition of Al2O3 and MO/ZnO replacements in the base glass led to improve the chemical durability of the glass–ceramics samples. As a result of the thermal and physico-chemical properties of the studied glass–ceramic, the materials acquire excellent properties and can be used to seal a variety of different metals and alloys.

Earth mortars are present in several building materials markets because of numerous advantages, particularly economic and ecological. Portugal has a vast earthen built heritage and these mortars are the most suitable for their rehabilitation and conservation. However, although some studies have been carried out on the behaviour of this type of mortars, little is known about their durability when applied outdoors. This study aims to assess the influence of adding low amounts of limes (air lime or natural hydraulic lime) and using washed sand on the durability of earth-based mortars applied as external wall renders. The results obtained did not show any improvement on the mechanical and physical characteristics of earth mortar renders with these additions and the washed sand. Therefore, to improve the performance of this material, namely towards liquid water, other additions, admixtures or surface protections should be studied.

The study investigated the joint effect of freeze–thaw attack and ultraviolet (UV) radiation on concrete. Mass loss ratio, relative dynamic modulus of elasticity (RDME) and flexural strength of concrete were experimentally investigated. A two-way ANOVA was used to analyse the effect of UV radiation on the test results. Water–binder ratio significantly affected the mass loss ratio, RDME and flexural strength. Meanwhile, UV radiation only had a significant effect on mass loss ratio but had no evident effect on RDME and flexural strength. Concrete microstructure was demonstrated by microscopic analysis via scanning electron microscope to explore the insight into the damage evolution of concrete under the joint effect. Prediction models of the damage degree of concrete were proposed by incorporating the results in this investigation. Comparison results showed that the prediction values were consistent with the experimental values.

In this project is required to determine if there is any result variation in durability indexes due to size effect in sizes of mortar specimens. Cubes 5 x 5 cm, 5 x 10 cm and 10 x 20 cm cylinders for each mortar type were considered. It was found that in certain indexes (WER, TVC, and CS) results did not depend on specimen´s geometry. Nonetheless, UPV index result presented differences up to 17.5 % between the cubes and the 10 x 20 cm cylinders. εeff index result showed an interesting difference between the cubes and the 5 x 10 cm cylinders used in full length. Therefore, it is recommended to restrict the height of the specimen to a standard value

Alternative and higher value uses are needed for residual materials generated from wood products processing. Western redcedar sawdust contains an array of unique chemicals and has the potential to be used to alter the appearance, stability and durability of non-durable timbers. Here it was hypothesized that impregnation of Western redcedar heartwood extractives into Pacific silver fir would decrease shrinkage, hygroscopicity, and susceptibility to decay. Western redcedar hot water extracts were obtained from sawdust and used to pressure-treat Pacific silver fir blocks. Extractive impregnation enhanced the wood’s appearance and gave it a more cedar-like brown colour. Impregnated samples had reduced shrinkage, but were not as dimensionally stable as Western redcedar heartwood. Pacific silver fir blocks impregnated with water-soluble extractives were also highly susceptible to leaching, and leached samples had similar shrinkage values to untreated controls. In contrast, leaching had little effect on the hygroscopicity of the Western redcedar heartwood. Extractive-impregnated Pacific silver fir blocks had increased resistance to decay by two brown-rot fungi, and showed resistance similar to that of Western redcedar heartwood. However, leached blocks did not have the same decay resistance.

This research confronts the following concrete properties: water absorptions (by immersion and capillarity), electrical resistivity and compressive strength. Concrete mixtures with two types of cement were tested. Results showed that concretes with higher content of pozzolan had higher resistivity and greater absorption by capillarity, for water/cement ratios lower than 0,60. This behavior is attributed to reduced pore diameters and microstructure densification. However, for water/cement ratio of 0,60, concrete with lower content of pozzolan presented higher absorption by capillarity. It was observed that the compressive strength and the electrical resistivity behaved inversely proportional to the water/cement ratio, and the absorption by immersion and capillarity are directly proportional to the water/cement ratio. Correlations with high determination coefficients were found between tests.

Many wood processing industries use short rotation teak, which has lower quality especially in durability and dimensional stability. Heat treatment is an eco-friendly method to improve dimensional stability and durability of wood. The objectives of the study were to investigate the effects of thermal modification on chemical composition, colour, dimensional stability and durability as well as coating’s performance after accelerated weathering of short and long rotation teak for exterior utilization. In this study, the samples were heated in oven at 220 °C for 20 h under nitrogen atmosphere. Results showed that independently of growth conditions teak woods underwent hemicelluloses degradation and an increase of lignin content after heat treatment. Extractives contents were lower in short rotation than in long rotation teak, and decreased in all cases after heat treatments. Dimensional stability was considerably improved as indicated by anti-swelling efficiency values of 64.9% and 58.9% for short and long rotation teak, respectively. Heated teak woods were more resistant against Trametes versicolor and the durability of short-rotation teak increased from moderate to very durable. Coatings on heat treated teaks had better bonding quality and better photo-stability when compared to unheated. Heated short rotation teak could be considered for exterior application.

The purpose of this study was to isolate microorganisms associated to surface-affected concrete structures and to measure the in vitro dissolution of concrete based on the release of elements such as calcium and silicon. Although many microorganisms were detected only a fungus was capable of significantly decreasing the culture medium pH and releasing both elements. The molecular characterization allowed to identify the microorganism as Aspergillus carbonaurius, a citric-acid producing fungus that dissolved concrete in the in vitro test. After seven days of incubation, the soluble calcium concentration in the uninoculated culture medium containing concrete was 172.3 mg/L, while in the inoculated medium it was 525.0 mg/L. The soluble silicon concentration in the uninoculated medium was 10.3 mg/L, while in the inoculated medium it was 50.1 mg/L. These findings showed that plants and microorganisms rendered a synergistic effect accelerating the biodeterioration of concrete.

We evaluated the consolidating capacity of ethyl silicate in three types of bricks fired at 800, 950 and 1100 °C. We chose two concentrations of product, at 25% and 50%, diluting the product in white spirit to estimate whether greater dilution enables the product to penetrate deeper into the bricks, or whether a higher concentration leads to better consolidation of bricks. The application of ethyl silicate caused bricks porosity to decline and their compactness to increase. These changes were more accentuated as the concentration of the product increased. The pore size distribution not changed substantially except that there were fewer of the smallest pores. The color and the lightness of the pieces changed after application of the consolidant, albeit slightly. The durability of bricks improved as manifested by the results of the salt crystallization test. In general, the longest-lasting pieces were those treated with 25% ethyl silicate.

Flat roofs are inverted when the insulation material is placed over the waterproofing membrane. This widely-used constructive system sets materials which may interact easily with each other causing their deterioration. The incompatibilities and the materials that may interact with each other are not completely described, the elements currently used to separate the materials are not totally efficient to avoid deterioration. This paper intends to enlarge the knowledge regarding the materials that are incompatible for inverted flat roofs, the conditions were interactions take place and the efficiency of some alternative solutions to separate the materials. The ethylene propylene diene monomer (EPDM) waterproofing membranes are incompatible with the extruded polystyrene (XPS). The interactions between incompatible materials increase with the pressure.

The application of self-cleaning coatings presents one of the most effective ways to protect the surfaces of the building materials. The effect of TiO2/kaolin based coatings applied to three types of substrates: non-porous, porous and highly porous, was investigated. Mechanical activation was applied for the impregnation of the active TiO2 component (in content of 3 and 10 wt. %) into the kaolin support. Surface properties (roughness, hydrophilicity and micro-hardness) and functional properties (photocatalytic activity and self-cleaning efficiency) were studied in order to define the optimal formulation of the applied coatings. The effect of the photocatalytic behavior of the coated substrates in terms of self-cleaning ability was assessed by the photodegradation of Rhodamine B, performed before and after durability tests. The results obtained in this paper showed that photocatalytic activity of the TiO2/kaolin composite coating generally depends on the procedure of TiO2 impregnation into the kaolin clay and the loaded TiO2 content.

This paper presents an analysis of experimental data from conventional concrete regarding sorptivity and penetrability under pressure comparing these parameters to chloride diffusion rate determined in the laboratory and in actual marine environment. Prescriptions for durability assurance of reinforced concrete structures is based on the qualitative characterization of transport properties. For the specific case of the marine environment, it is required to assess the resistance of concrete to chloride ingress. The results show the limitations of both parameters as prescriptive indexes, with capillary absorption rate showing some advantages over water penetration under pressure.