Experimental assessment of Textile Reinforced Sprayed Mortar strengthening system for brickwork wallettes

This work explores the feasibility of strengthening masonry with Textile Reinforced Mortar (TRM) by projecting it to save application time. Nineteen tests on masonry samples strengthened with TRM have been carried out to assess this new application method. Different mortars and fibre grids were considered for studying their influence and applicability with this new technique. Three points bending tests have been performed on the specimens to compare the flexural strength between cases with manually applied mortar (TRM) and sprayed application (TRSM) of the mortar layer. It was noticed that the strengthening mortar has a significant influence on the failure mode. Results show a remarkable (between 2 and 6 times more) productivity increase when using TRSM and a load-bearing capacity rise for the cases with larger grid spacing and projectable mortar when using TRSM instead of TRM. Greater ductility values were also observed for the TRSM cases in comparison with the analogue TRM cases (same grid and mortar). (C) 2013 Elsevier Ltd. All rights reserved.Peer ReviewedPostprint (author’s final draft

Masonry Walls Strengthened with Vegetal Fabric Reinforced Cementitious Matrix (FRCM) Composites

Fabric-reinforced cementitious matrices (FCRMs) are promising composite materials for the retrofitting and reinforcement of existing structures. In this study, vegetal meshes consisting of hemp and cotton coated with epoxy were manufactured and combined with a cementitious matrix to strengthen masonry walls. A synthetic glass fibre mesh was also tested. Several walls were manufactured, strengthened, and tested under cyclic loading. The results allow us to compare the performances of different mesh configurations in terms of size and materials. All strengthening solutions significantly increased shear strength capacity and the ability to dissipate energy compared to unreinforced walls. Further, all strengthened walls exhibited multi-track pattern distributions and achieved distortion capacity improvements of up to 300%. Indicators of stiffness, energy dissipation, damping, residual deformation, and damage allow us to compare the strengthening performances of different solutions. The vegetal solutions provided superior efficiency compared to the glass-FRCM strengthened walls. Additionally, the use of a larger volume of vegetal fibres reduces the consumption of cement and can provide a sustainable solution. The main failure mechanism of the vegetal-FCRMs was debonding, which can be remedied by improvements to material interfaces

Comparación entre los sistemas de refuerzo TRM y FRP en la prevención del colapso por pandeo de muros de fábrica

Fibre Reinforced Polymer (FRP) and Textile Reinforced Mortar (TRM) have been studied, compared and applied to strengthen brick masonry walls. The comparison of their performance against second order bending effects is addressed in this paper for the first time. Experimental and analytical data from previous researches and new analytical data for TRM cases are summarised, ordered and systematically compared to analyse the structural response of strengthened brick masonry walls. The results show a similar performance for both systems in terms of load bearing capacity and in-plane response. However, TRM strengthened cases showed greater lateral deformation than FRP ones.Materiales tipo Fibre Reinforced Polymer (FRP) y Textile Reinforced Mortar (TRM) han sido estudiados, comparados y aplicados para reforzar muros de fábrica de ladrillo. La comparación de su comportamiento frente a efectos de flexión de segundo orden se abordada en este artículo por primera vez. Datos experimentales y analíticos de investigaciones previas y nuevos datos analíticos para los casos de TRM son resumidos, ordenados y sistemáticamente comparados para analizar la respuesta estructural de los muros de fábrica de ladrillo reforzados. Los resultados muestran un comportamiento similar de los dos sistemas respecto su capacidad de carga y su respuesta en el plano. Los casos reforzados con TRM mostraron desplazamientos laterales superiores a los reforzados con FRP

Durability of FRP Immersed in Water. Changes in Mechanical Properties

Fibre Reinforced Polymers (FRP) have been widely used to strengthened construction structural elements in the last years because of their mechanical pros. However, the durability of these materials is always controversial. In particular, the effect of long-term contact with water on the mechanical properties of FRPs is studied in this research throughout the implementation of accelerated degradation tests. Samples of Carbon FRP and Glass FRP were immersed into supply water, water with salts and surfactants and highly chlorinated water. In all cases, electrical current passing through the samples was also imposed. Tensile tests on pristine and degraded samples were carried out to determine the influence of these aggressive environments on the tensile strength and the Young‘s modulus of the specimens. Finally, superficial (ATR) FT-IR analyses were conducted to assess possible chemical changes in the samples surfaces. Results indicated that the chemical composition of used resins was not modified due to the water exposure. No hydrolysis process took place during testing time on the surface. However, mechanical properties were reduced, especially when samples were exposed to plain supply water, which may be related to the physical degradation caused by moisture intake by diffusion

Non-Destructive Techniques for Characterising Earthen Structures

Earthen architecture is one of the most relevant building technologies among heritage structures. However, mechanical properties are commonly obtained from destructive tests. To contribute at changing this trend, two non-destructive mechanical techniques (ultrasound and modal analysis) are studied to determine their ability at characterizing earthen materials and their possible correlation. To achieve these purposes, twenty cubic-shaped earthen specimens were produced for testing the capability of ultrasound transmission method to control moisture content and its evolution during drying process at different environments. Additionally, a real-scale rammed earth wall was built to assess the feasibility of using ultrasound technique to determine elastic dynamic Young modulus. This analysis was validated by indirect comparison with experimental modal analysis test results. The most important findings are that the relationship between moisture content and ultrasound transmission speed is linear. This information is useful to control the drying process of earthen materials and to control the moisture content distribution on larger in-service structures. Finally, numerical simulation using ultrasound transmission data as input information allow to predict the vibrational response of the tested wall with an error around 3%

In-plane behavior of cavity masonry infills and strengthening with textile reinforced mortar

The seismic vulnerability of masonry infilled reinforced concrete (rc) frames observed during past earthquakes in some south European countries resulted in losses of human lives and huge repair or reconstruction costs, justifies the need of deeper study of the seismic behavior of masonry infills enclosed in rc frames. Therefore, the main goals of this study are related to: (1) better understanding of the cyclic in-plane behavior of traditional brick infills built in the past decades as enclosures in rc buildings in Portugal; (2) analysis of a strengthening technique based on textile reinforced mortar (TRM) aiming at enhancing the in-plane behavior. To accomplish the objectives, an extensive experimental campaign based on in-plane static cyclic tests on seven reduced scale rc frames with masonry infill walls was carried out. The performance of strengthening of masonry infill based on textile reinforced mortar was also evaluated experimentally. Among the conclusions of this research, it should be stressed that: (1) the presence of infill inside the bare frame could significantly enhance the in-plane stiffness and resistance of bare frame; (2) TRM technique could enhance the in-plane behavior of infilled frames by improving the lateral strength and by reducing significantly the damage of the brick infill walls.The authors would like to acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the research project ASPASSI – Assessment of the safety and strengthening of masonry infill walls subjected to seismic action (POCI-01-0145-FEDER-016898) (PTDC/ECMEST/3790/2014).info:eu-repo/semantics/publishedVersio

Applications and Properties of Hemp Stalk-Based Insulating Biomaterials for Buildings: Review

There has been increasing interest in green and recyclable materials to promote the circular economy. Moreover, the climate change of the last decades has led to an increase in the range of temperatures and energy consumption, which entails more energy expenditure for heating and cooling buildings. In this review, the properties of hemp stalk as an insulating material are analyzed to obtain recyclable materials with green solutions to reduce energy consumption and reduce noise to increase the comfort of buildings. Hemp stalks are a low-value by-product of hemp crops; however, they are a lightweight material with a high insulating property. This study aims to summarize the research progress in materials based on hemp stalks and to study the properties and characteristics of the different vegetable binders that could be used to produce a bio-insulating material. The material itself and its microstructural and physical aspects that affect the insulating properties are discussed, as is their influence on durability, moisture resistance, and fungi growth. Research suggests using lignin-based or recyclable cardboard fiber to develop a bio-composite material from hemp stalk, but long-term stability requires further investigation