application of externally bonded inorganic matrix composites to existing masonry structures

Fabric-reinforced cementitious matrix (FRCM) and composite-reinforced mortar (CRM) are recently introduced inorganic-matrix composites that have shown promising results as externally bonded reinforcement (EBR) of existing masonry structures. FRCM and CRM comprised high-strength fiber textiles embedded within inorganic matrices. Different fibers and matrices can be used, which lead to a large number of systems characterized by different properties. In this paper, different techniques employed to strengthen the existing masonry structures with EBR. FRCM and CRM composites are presented and discussed

Mortar-based systems for externally bonded strengthening of masonry

Mortar-based composite materials appear particularly promising for use as externally bonded reinforcement (EBR) systems for masonry structures. Nevertheless, their mechanical performance, which may significantly differ from that of Fibre Reinforced Polymers, is still far from being fully investigated. Furthermore, standardized and reliable testing procedures have not been defined yet. The present paper provides an insight on experimental-related issues arising from campaigns on mortar-based EBRs carried out by laboratories in Italy, Portugal and Spain. The performance of three reinforcement systems made out of steel, carbon and basalt textiles embedded in inorganic matrices has been investigated by means of uniaxial tensile coupon testing and bond tests on brick and stone substrates. The experimental results contribute to the existing knowledge regarding the structural behaviour of mortar-based EBRs against tension and shear bond stress, and to the development of reliable test procedures aiming at their homogenization/standardization

Late Endosomal Cholesterol Accumulation Leads to Impaired Intra-Endosomal Trafficking

Background Pathological accumulation of cholesterol in late endosomes is observed in lysosomal storage diseases such as Niemann-Pick type C. We here analyzed the effects of cholesterol accumulation in NPC cells, or as phenocopied by the drug U18666A, on late endosomes membrane organization and dynamics. Methodology/Principal Findings Cholesterol accumulation did not lead to an increase in the raft to non-raft membrane ratio as anticipated. Strikingly, we observed a 2–3 fold increase in the size of the compartment. Most importantly, properties and dynamics of late endosomal intralumenal vesicles were altered as revealed by reduced late endosomal vacuolation induced by the mutant pore-forming toxin ASSP, reduced intoxication by the anthrax lethal toxin and inhibition of infection by the Vesicular Stomatitis Virus. Conclusions/Significance These results suggest that back fusion of intralumenal vesicles with the limiting membrane of late endosomes is dramatically perturbed upon cholesterol accumulation

Diversity of Raft-Like Domains in Late Endosomes

BACKGROUND: Late endosomes, the last sorting station in the endocytic pathway before lysosomes, are pleiomorphic organelles composed of tubular elements as well as vesicular regions with a characteristic multivesicular appearance, which play a crucial role in intracellular trafficking. Here, we have investigated whether, in addition to these morphologically distinguishable regions, late endosomal membranes are additionally sub-compartmentalized into membrane microdomains. METHODOLOGY/PRINCIPAL FINDINGS: Using sub-organellar fractionation techniques, both with and without detergents, combined with electron microscopy, we found that both the limiting membrane of the organel and the intraluminal vesicles contain raft-type membrane domains. Interestingly, these differentially localized domains vary in protein composition and physico-chemical properties. CONCLUSIONS/SIGNIFICANCE: In addition to the multivesicular organization, we find that late endosomes contain cholesterol rich microdomains both on their limiting membrane and their intraluminal vesicles that differ in composition and properties. Implications of these findings for late endosomal functions are discussed

Damaging of frcm composites through a micro-scale numerical approach

Aim of this paper is to proposed a micro-scale numerical approach for the evaluation of the mechanical behavior of Fiber Reinforced Cementitious Mortar (FRCM) composites. As a matter of fact, the FRCM constitutive behavior is affected by micro-mechanisms, such as the cracking of the mortar and the slippage of the fibers within the mortar. The repetitive structural geometry of the FRCMs, due to the presence of the mesh grid, allows to identify a representative unit cell. This element is made by different constituent materials, i.e. fiber and mortar, and composed by three layers, i.e. two external layers of mortar and one inner layer made with fibers and mortar. In the framework of 2D plane stress state, the numerical approach consists in modeling the constituents as linear elastic materials and accounting for the material non-linearities through the implementation of suitable interface elements. In the interface model, the damage, the friction effects and the unilateral contact are taken into account. This numerical approach is used for reproducing the tensile behavior of the FRCM composites. It is successfully validated with available experimental results and a parameter sensitivity analysis is performed

Bond behavior of FRCM composites applied on concrete and masonry

I materiali compositi FRCM (\u201cFiber Reinforced Cementitious Matrix\u201d) sono stati recente-mente introdotti nelle applicazioni di ingegneria civile per il rinforzo di elementi in muratura e c.a. Lo scopo dello studio sperimentale \ue8 quello di valutare il comportamento, in termini di aderenza, di materiali compositi FRCM in carbonio e vetro, nella forma di reti bidirezionali o tessuti unidirezionali, applicati su diversi supporti utilizzando una malta cementizia e un promotore di adesione. Le evidenze sperimentali ottenute sulla muratura utilizzando malta a base cementizia sono state confrontate con i risultati derivanti dagli stessi sistemi di rinforzo applicati con malta a base calce. Tutti i campioni sono stati sottoposti a prove di aderenza, in modo da valutare le possibili modalit\ue0 di crisi, la capacit\ue0 massima e il comportamento globale in termini di spostamenti e deformazioni (grazie alla tecnica della Digital Image Correlation). I risultati sperimentali hanno evidenziato le buone prestazioni dei sistemi di rinforzo testati se applicati in combinazione con il promotore di adesione.Fiber Reinforced Cementitious Matrix (FRCM) composite materials have been recently introduced in civil engineer-ing applications for the strenthening of masonry and reinforced concrete elements. The aim of the presented experimental study is to evaluate the bond behavior of carbon and glass FRCM composite materials, in the form of bidirectional grids or unidirectional sheets, applied on different substrates by using a cementitious mortar together with an adhesion promoter. Experimental outcomes obtained on masonry using a cementitious mortar have also been compared with the results coming from the same strengthening sys-tems applied with lime mortar. All specimens were subjected to single-lap shear tests until failure, in order to evaluate failure modes, maximum bond capacity and the whole samples behavior in terms of displacement and strain maps (thanks to Digital Image Correla-tion technique). Experimental outcomes highlighted the good performance of the strengthening systems tested when applied in com-bination with the adhesion promoter