Restrained Shrinkage-Induced Cracking of Light Weight High Performance Fiber Reinforced Cementitious Composites

Problem statement: Shrinkage induced cracking cause damage to reinforced concrete structures. An experimental study was conducted on restrained shrinkage test of cement mortar and light weight High Performance Fiber Reinforced Cementitious Composites (HPFRCC). Approach: Two types of light weight HPFRCC and a premix mortar containing small amount of fiber were included in the experiment. Results: Results showed the multiple cracks, as many as 49, in light weight HPFRCC specimens compared to few cracks (about six cracks) in the premix mortar specimen. At the end of shrinkage test, the width of the cracks in the mortar specimen was more than 250 μm with the largest crack width of about 400 μm. However, the scenario was quite different in light weight HPFRCC specimens, where the width of almost all cracks was less than 100 μm. Conclusion: The higher number of multiple cracks with small cracks width in light weight HPFRCC specimens due to drying shrinkage was due to their strain hardening and ductile behavior compared to quasi brittle behavior of premix mortar where less number of wide cracks was observed

A review on durability properties of strain hardening fibre reinforced cementitious composites (SHFRCC)

This paper reviews and presents various durability properties of strain hardening fibre reinforced cementitious composites (SHFRCC). Published research results show that, due to its tight crack width properties compared to ordinary concrete and ordinary fibre reinforced concrete, SHFRCC significantly resists the migration of aggressive substances in to the concrete and improves the durabilityof reinforced concrete (RC). It is also reported that, due to the strain hardening and multiple cracking behaviours, SHFRCC meets the tight crack width limits for durability of RC structures proposed by different design codes. Based on the reviewed durability properties it is argued that SHFRCC materials can be used in selected locations of RC structural members to improve their overall durability performances

Quantification of Crack Formation Using Image Analysis and its Relationship with Permeability

In this study a relationship between permeability of concrete and fractal dimension of crack is established. For this purpose four series of specimens of fiber reinforced cementitious composites are prepared. Specimens are subjected to uniaxial tension in order to create targeted damage (cracking) prior to permeability test. Image analysis is done on the cracked surface and fractal dimension of cracks are calculated using box counting method. Maximum crack width is found to have correlation with the coefficient of permeability. However, such correlation was observed neither between coefficient of permeability and crack area nor between coefficient of permeability and crack density. Relationships of fractal dimension of cracks is established with the maximum crack width, crack area and crack density. Trilateral relationship among coefficient of permeability, the maximum crack width and fractal dimension are established

Experimental analysis of self-healing cement-based materials incorporating extruded cementitious hollow tubes

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: N.M.P. is supported by the European Research Council (ERC Starting Grant Ideas 2011 BIHSNAM No. 279985 on ‘‘Bio-inspired hierarchical supernanomaterials,’’ ERC Proof of Concept (PoC) 2013-1 REPLICA2 No. 619448 on ‘‘Large-area replication of biological anti-adhesive nanosurfaces,’’ ERC PoC 2013-2 KNOTOUGH no. 632277 on ‘‘Super-tough knotted fibres’’), by the European Commission under the Graphene Flagship (WP10 ‘‘Nanocomposites,’’ No. 604391), and by the Provincia Autonoma di Trento (‘‘Graphene nanocomposites,’’ No. S116/2012-242637 and regional deliberation No. 2266)

Intolerance of uncertainty and mental wellbeing: serial mediation by rumination and fear of COVID-19

The novel coronavirus-2019 (COVID-19) pandemic has become globally widespread with millions of confirmed cases and many countries implementing various levels of quarantine. Therefore, it is important to investigate the psychological consequences of this process, given the unique situation that has been experienced globally. Therefore, the present study examined whether intolerance of uncertainty was related to mental wellbeing and whether this relationship was mediated by rumination and fear of COVID-19. The sample comprised 1772 Turkish individuals (aged between 18 and 73 years) from 79 of 81 cities in Turkey, who completed measures of mental wellbeing, intolerance of uncertainty, rumination, and fear of COVID-19. Results of serial mediation analyses showed that intolerance of uncertainty had a significant direct effect on mental wellbeing. Rumination and fear of COVID-19, in combination, serially mediated the association between intolerance of uncertainty and mental wellbeing. The findings are discussed within the framework of the psychological consequences of the COVID-19 pandemic and related literature

Iridoids and Anthraquinones from the Malaysian Medicinal Plant, Saprosma scortechinii (Rubiaceae)

A further investigation of the leaves and stems of Saprosma scortechinii afforded 13 compounds, of which 10 are new compounds. These were elucidated as the bis-iridoid glucosides, saprosmosides G (1) and H (2), the iridoid glucoside, 6-O-epi-acetylscandoside (3), and the anthraquinones, 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone (4), 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone 3-O-β-primeveroside (5), 1,3-dihydroxy-2-carbomethoxy-9,10-anthraquinone 3-O-β-primeveroside (6), 1,3,6-trihydroxy-2-methoxymethyl-9,10-anthraquinone (7), 1-methoxy-3,6-dihydroxy-2-hydroxymethyl-9,10-anthraquinone (8), 1,3,6-trihydroxy-2-hydroxymethyl-9,10-anthraquinone 3-O-β-primeveroside (9), and 3,6-dihydroxy-2-hydroxymethyl-9,10-anthraquinone (10). Structure assignments for all compounds were established by means of mass and NMR spectroscopies, chemical methods, and comparison with published data. The new anthraquinones were derivatives of munjistin and lucidin