Effective section on grapevine plants (Vitis vinifera L.) attacked by Xylotrechus arvicola Olivier (Coleoptera: Cerambycidae) grubs: Influence and effects on its resistance.

Xylotrechus arvicola Olivier 1795 (Coleoptera: Cerambycidae) is an insect pest that affects Vitis vinifera L. 1753 (Vitales: Vitaceae) plants in the main wine-producing regions of Spain. X. arvicola larvae bore into grapevine wood, causing both direct damage (ingestion of vascular tissues) and indirect damages (introduction of wood fungi) to the plant. The aim of research was to evaluate the effective section of wood damaged by larvae and assess its resistance capacity through compression tests and loading and breaking times. Compressive tests (on trunks) and flexural tests (on branches) were performed to evaluate the effective section. Trunk samples exhibited a higher effective section than branches samples, with effective section percentages ranging from 91.49 % to 93.53 % in trunks and decreasing from 84.91 % to 86.95 % in branches. Both loading times (Time 1) and breakage times (Time 2) increased with the effective section of the wood, although these times were lower in damaged wood samples of both trunks and branches. Additionally, significant differences were observed in the interactions between loading time x effective section and breakage time x effective section in dry trunks. This indicates a stronger relationship between the effective section and increased resistance in trunks. The results suggest that, in 'Tempranillo' variety, branches with a lower effective section are more prone to breakage when affected by X. arvicola larvae, whereas trunks, with a greater effective section, maintain better stability. This research should be continued with the evaluation of other vine varieties and different years of X. arvicola attacks, as the current findings are based on a single variety ('Tempranillo') over a period of ten years.

Performance of graphene oxide as a water-repellent coating nanomaterial to extend the service life of concrete structures.

Surface treatments help to protect the built heritage against damage (environmental, accidental, etc.), reducing repair and restitution costs and increasing the useful life of building materials. The use of nanomaterials is currently the most important field of research in surface treatment technology for the preservation of building materials and, more specifically, to improve their durability and prevent their deterioration, extending their useful life. This paper studies the influence of a graphene oxide (GO) suspension as a surface treatment on the properties of concrete. The results indicate that, at best, surface treatment with GO can decrease both the water absorption and capillary absorption of concrete by about 15 %. The increase in the amount of GO deposited as a surface treatment leads to a further reduction in concrete water absorption. It is shown that, at best, GO coating also reduces water penetration at low and high pressures by approximately 20 % and 60 %, respectively. In addition, scanning electron microscopy analysis shows that GO surface treatment facilitates the hydration process and densifies the concrete microstructure. A simple aqueous suspension of GO is revealed as a tool with a high potential to protect concrete surfaces in a fast and cost-effective way, thanks to the easy application by spraying and the small amount of material needed to obtain great results.

Biotreatments Using Microbial Mixed Cultures with Crude Glycerol and Waste Pinewood as Carbon Sources: Influence of Application on the Durability of Recycled Concrete.

Two eco-friendly healing bioproducts generated from microbial mixed cultures (MMC) for the production of polyhydroxyalkanoates (PHA) were used as surface treatments, with two residual materials used as the substrates, namely crude glycerol and pinewood bio-oil. Their ability to improve the durability of concrete samples containing recycled aggregates was assessed. To determine this protective capacity, 180 samples were analyzed using different tests, such as water penetration under pressure, capillary absorption, freeze-thaw and water droplet absorption test. Three types of conditions were used: outdoor-indoor exposure, re-application of biopolymers and application in vertical exposure conditions. The results showed reductions of up to 50% in the water penetration test and a delay in the water droplet absorption test of up to 150 times relative to the reference. The surface application of these bioproducts significantly reduced the degree of water penetration in recycled concrete, increasing its useful lifespan and proving to be a promising treatment for protecting concrete surfaces.

Use of Mixed Microbial Cultures to Protect Recycled Concrete Surfaces: A Preliminary Study.

One approach to tackle the problems created by the vast amounts of construction and demolition waste (CDW) generated worldwide while at the same time lengthening concrete durability and service life is to foster the use of recycled aggregate (RA) rather than natural aggregate (NA). This article discusses the use of polyhydroxyalkanoates (PHAs)-producing mixed microbial cultures (MMCs) to treat the surface of recycled concrete with a view to increase its resistance to water-mediated deterioration. The microorganisms were cultured in a minimal medium using waste pinewood bio-oil as a carbon source. Post-application variations in substrate permeability were determined with the water drop absorption and penetration by water under pressure tests. The significant reduction in water absorption recorded reveals that this bioproduct is a promising surface treatment for recycled concrete.

Recycled Precast Concrete Kerbs and Paving Blocks, a Technically Viable Option for Footways.

The linear economy paradigm in place to date has to be seriously challenged to give way to a new school of thought known as the circular economy. In this research work, precast kerbs and paving blocks made with recycled concrete (RACC-mixture) bearing 50 wt% mixed recycled aggregate (masonry content of 33%) and an eco-efficient cementitious material as 25 wt% conventional binder replacement were evaluated to assess their intrinsic potential to replace traditional raw materials, in keeping with circular economy criteria. Therefore, precast products were subjected to mechanical strength, durability and microstructure tests and were compared to conventional concrete units (CC-mixture and commercially available precast elements). Although a class demotion was observed for water absorption and some decreases in flexural strength (26%), splitting tensile strength (12.8%) and electrical resistivity (45%) and a lower class water absorption were registered, and the recycled mixture also exhibited a greater performance in terms of compressive strength (6%), a better abrasion resistance classification and a comparable porosity and microstructure, which ensures a good concrete durability. In any case, the results showed that precast pieces were European standard-compliant, thus supporting the viability of the mixed recycled aggregates and eco-efficient cementitious replacement in footways.

Use of Bioproducts Derived from Mixed Microbial Cultures Grown with Crude Glycerol to Protect Recycled Concrete Surfaces.

The large increase in the world population has resulted in a very large amount of construction waste, as well as a large amount of waste glycerol from transesterification reactions of acyl glycerides from oils and fats, in particular from the production of biodiesel. Only a limited percentage of these two residues are recycled, which generates a large management problem worldwide. For that reason, in this study, we used crude glycerol as a carbon source to cultivate polyhydroxyalkanoates (PHA)-producing mixed microbial cultures (MMC). Two bioproducts derived from these cultures were applied on the surface of concrete with recycled aggregate to create a protective layer. To evaluate the effect of the treatments, tests of water absorption by capillarity and under low pressure with Karsten tubes were performed. Furthermore, SEM-EDS analysis showed the physical barrier caused by biotreatments that produced a reduction on capillarity water absorption of up to 20% and improved the impermeability of recycled concrete against the penetration of water under pressure up to 2.7 times relative to the reference. Therefore, this bioproduct shown to be a promising treatment to protect against penetration of water to concrete surfaces increasing its durability and useful life.

Bioautography and GC-MS based identification of piperine and trichostachine as the active quorum quenching compounds in black pepper.

In the search of new and safe antibacterial compounds, the quorum sensing system (QS) modulation by natural products has been studied. As a result, many plant-derived compounds have been identified as potent quorum sensing inhibitors. Piper nigrum L. (black pepper) ethanolic extract inhibits the QS in some Gram-negative bacteria but the active components have not been previously identified. Thus, the objective of this work was to identify the P. nigrum peppercorns main components that block the QS, applying bioassay and chromatographic techniques. Piperine and trichostachine were identified as the main components responsible for the quorum quenching (QQ) activity of P. nigrum peppercorns extract. Piperine at 30 mg/L, decreased the violacein production by Chromobacterium violaceum CV026 by 35%, without affecting bacterial growth. Piperine concentration of 40 mg/L decreases violacein production by C. violaceum CV026 by 70% and growth in only 4.34%. Trichostachine at 50 mg/L decreases violacein production by C. violaceum CV026 by 12%, without affecting bacterial growth. P. nigrum extract concentration of 0.5 g/L decreased violacein production in 40 % and no effects on growth were observed. Neither P. nigrum extract, piperine, nor trichostachine did affect QS of Pseudomonas aeruginosa PAO1. Data here described exhibit the potential of piperamides as modulators of QS, not previously reported.

Influence of the use of External Carbon Fiber Reinforcement on the Flexural Behavior of Prismatic Concrete Test Specimens. An Application for Repairing of Deteriorated Agricultural Structures.

This manuscript reports a study of the capacity of polymer composites to increase flexural strength in concrete. The polymer composites reinforced with carbon fiber and bonded with epoxy adhesive were used in prismatic test specimens of mass concrete corresponding to two different morphologies. The aim was to simulate the restoration of deteriorating concrete agricultural structures in order to explore the viability of this alternative against replacing them. An increase was found in the strength of the elements tested, with a higher strength being observed in those test specimens presenting a modified geometry.

Paving with Precast Concrete Made with Recycled Mixed Ceramic Aggregates: A Viable Technical Option for the Valorization of Construction and Demolition Wastes (CDW).

This research aimed to prove the feasibility of producing two types of precast elements widely used in construction, such as curbstones and paving blocks, using recycled concrete made with a 50% substitution of the natural gravel by recycled mixed aggregates with a significant ceramic content (>30%). In order to prove the quality of such mass concrete recycled precast elements, two different mixes were used: the first one was a conventional concrete mix provided by Prefabricados de Hormigón Pavimentos Páramo S.L., one of the collaborating companies in this study, and the other was a mixture in which wt 50% of the natural coarse aggregates were substituted for recycled mixed aggregates ceramic (RMAc). This recycled aggregate is a heterogeneous mixture of unbound aggregates, concrete, ceramic, etc., used as a secondary recycled aggregate and commonly produced in a lot of recycling plants in many European countries. This material was supplied by Tecnología y Reciclado S.L., the other collaborating company. Both mixtures were representative in order to establish the comparative behavior between them, taking into account that smaller percentages of replacement of the natural with recycled aggregates will also produce good results. This percentage of substitution represents a high saving of natural resources (gravel) and maintains a balanced behavior of the recycled concrete, so this new material can be considered to be a viable and reliable option for precast mass concrete paving elements. The characterization of the recycled precast elements, covering mechanical, microstructural, and durability properties, showed mostly similar behavior when compared to the analogous industrially-produced pieces made with conventional concrete.

Ceramic ware waste as coarse aggregate for structural concrete production.

The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

Overview regarding construction and demolition waste in Spain.

The construction sector comprises a number of activities that may result in environmental impacts of considerable magnitude, waste generation being one of the major negative effects of this industry due to the large streams generated. Proper knowledge of the environmental problem caused by the sector is of great importance in order to achieve an effective waste management. Thus, this paper analyse the Spanish situation regarding construction and demolition waste (CDW) compared with other European Union countries; which sets out the current figures of the CDW scenario (legislation, generation, composition, treatment and market) as well as the difficulties encountered when handling this residue.

Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard.

Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW.

Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture.

The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique.