Mechanical Properties of a 3D Printed Wall Segment Made with an Earthen Mixture

This paper is part of the research on 3D printing of earthen housing modules, made with earth taken in situ. Previous studies have already led to the definition of 3D printed earthen elements for the external cladding of single-story wooden load-bearing structures. With this work, we intend to take a step forward in the use of 3D printed earthen elements, studying their load-bearing capacity for vertical loads. The goal is to create load-bearing structures entirely in earth, with two or more floors. To this end, the present work investigates two of the major presumed criticalities of 3D printed elements under vertical load, namely the detachments due to poor cohesion between extruded layers and the detachments between internal infill and external coating. The uniaxial compression test on a specially 3D printed wall segment did not actually show any particular danger for the stability of the structure, due to detachment phenomena. Rather, the experimental results showed some quite anomalous mechanical behaviors for a brittle construction material (studied at the mesoscale), especially as regards Poisson’s modulus and volumetric strain. The main experimental finding concerns the contribution of the internal infill, which seems to have a structural function and not just a filling function.

Evaluation of Freeze-Thaw Durability of Silica Fume Concrete with Spraying Inorganic Coating Using Ultrasonic Testing

To study the antifreezing durability of internal coating silicon fume concrete with different external coatings, fast freeze-thaw (FT) cycle testing was performed for three types of external coatings applied to the internal coatings of silicon fume concrete. Using ultrasonic testing and compressive strength tests, we analysed the relationships between the ultrasonic pulse velocity and the mechanical and physical properties of concrete under freeze-thaw action. The results show that the compressive strength and pulse velocity of the studied concrete changed little before the first 100 FT cycles but varied significantly after being subjected to 100 FT cycles and diminished linearly with increasing FT cycles. The dynamic elastic parameters of the concrete were inferred using pulse velocity calculations, and the dependence on FT cycles was very similar to that of ultrasonic pulse velocity. The concrete strength was strongly and positively correlated with ultrasonic pulse velocity. The linear regression model of between ultrasonic pulse velocity, kinetic coefficient, and compressive strength of concrete was also established. The damage incurred to the external coating material (XT-HPA + XT-SS and XT-HPS) was small, and the good performance of the concrete with the added inorganic coating after freeze-thaw cycles indicates good frost resistance.

Ergonomic analysis of biomechanical overloading: external coating activity using mortar

The economic growth of a country is directly linked to the growth of several sectors, in which the construction sector is prominent. The objective was to investigate by means of ergonomic analysis the external coating activity performed on building façades, due to its high degree of difficulty. The methodological approach was composed by a review of the literature and quantitative research using the OCRA checklist method, highlighting the biomechanical overload risk analysis of the external coating activity in mortar based on International Standard ISO 11228-3: 2009. The data collection took place in construction sites in Brazil in the cities of Ponta Grossa-PR and Porto Alegre-RS applying the mentioned method. The results of demand illustrate the concepts presented in the review, as well as the confirmation of the incidence of pain and lesions in the upper limbs and the repetitiveness in the analyzed activities. The results indicate that: a) the analysis of the chosen activity resulted in a high level of risk applying the immediate intervention, with improvements; b) proof by calculating the risk of biomechanical overload to implement improvements in the company; c) evidence that the improvements resulted in a reduction of ergonomic risks by more than 50%, with improvement in posture and strength requirements. In turn, the relevance of this work is highlighted, as it enables the development of public and private policies in the area of ergonomics with the purpose of developing the sector. In the end, the work opens up possibilities for the continuity of the research on the addressed topic.

Packaging Covered with Antiviral and Antibacterial Coatings Based on ZnO Nanoparticles Supplemented with Geraniol and Carvacrol

The purpose of the study was to obtain an external coating based on nanoparticles of ZnO, carvacrol, and geraniol that could be active against viruses such as SARS-Co-V2. Additionally, the synergistic effect of the chosen substances in coatings was analyzed. The goal of the study was to measure the possible antibacterial activity of the coatings obtained. Testing antiviral activity with human pathogen viruses, such as SARS-Co-V2, requires immense safety measures. Bacteriophages such as phi 6 phage represent good surrogates for the study of airborne viruses. The results of the study indicated that the ZC1 and ZG1 coatings containing an increased amount of geraniol or carvacrol and a very small amount of nanoZnO were found to be active against Gram-positive and Gram-negative bacteria. It is also important that a synergistic effect between these active substances was noted. This explains why polyethylene (PE) films covered with the ZC1 or ZG1 coatings (as internal coatings) were found to be the best packaging materials to extend the quality and freshness of food products. The same coatings may be used as the external coatings with antiviral properties. The ZC1 and ZG1 coatings showed moderate activity against the phi 6 phage that has been selected as a surrogate for viruses such as coronaviruses. It can be assumed that coatings ZG1 and ZC1 will also be active against SARS-CoV-2 that is transmitted via respiratory droplets.

No Pipe Body Downgrades - Improved Corrosion Mitigation Coating System Provides Significant Operator Savings

Objectives/Scope Tubulars used in completion and intervention riser applications are exposed to both the marine environment and corrosive oilfield chemicals, including salt-based completion brines. Eight years of field history from one company shows a loss of $24.3 million from pipe body downgrades due to corrosion and pitting in these salt-based environments. Methods, Procedures, Process This paper documents an extensive development effort spanning over eight years including: research of completion parameters and environments, evaluation of 18 potential external coating/salt neutralization products, multiple lab tests, field trials, as well as testing surface preparation methods, coating application, dry time and adhesion tests. The development of application procedures and construction of an external coating facility are discussed as are rig pipe washing systems and corrosion mitigation procedures. Results, Observations, Conclusions The result is an improved corrosion mitigation coating system. A modified epoxy phenolic internal coating combined with a metallic-based, moisture-cure polyurethane encapsulating external coating. Since 2015, over 1,700,000 feet, 44,000 joints, of completion and intervention tubulars utilizing this system have been deployed with zero pipe body downgrades due to corrosion or pitting, and zero operational issues. In addition to reducing replacement cost and loss of capital, this system provides the ability for longer deployment of the pipe on a multiple well program reducing logistics costs. Novel/Additive Information Extensive research, testing, field trials, and successful field deployments have resulted in an improved corrosion mitigation coating system providing significant savings to operators. Pipe body downgrades due to pitting and corrosion have been eliminated. Improved corrosion resistance has allowed multiple-well deployments reducing shipping, inspection, and repair costs. Ultimately this results in longer life of the tubulars reducing total cost of ownership.

Research on coating technology with wet-process sprayed mortar: waste and productivity

The mechanical application of mortar is as an adequate solution to minimize the problems in the execution of internal and external coating of the buildings. However, few scientific studies address the gains in efficiency afforded by mechanization as well as the scarce parameters of waste, productivity and quality that could contribute to choosing this technology. This article aims to characterize the presented constructive technology and to investigate the waste of mortar (percentage of losses and consumption) and the productivity of the labor in the execution of internal and external coating for sealing in the application of wet-process sprayed mortar. Investigations were carried out in 08 construction works, which presented results of up to 150% and 0.18h/m2 for, respectively, loss of industrialized mortar and labor productivity. Thus, the present research contributes to the advancement of the knowledge about the wet-process sprayed mortar by increasing the understanding of the technology. Other important contributions are the indicators of losses and productivity and their detailed measurement, which are efficient tools to assist the companies in the decision-making by adopting this technology as well as in the management of the activities during the execution process.