Laboratory Tests on Hydraulic Lime Mortar Reinforced With Jute Fibres

Background: Considering the high seismic vulnerability of masonry buildings located in the Italian territory, the implementation of seismic retrofit programs is strongly needed.. With consideration for sustainable interventions, it is evident that the retrofit techniques to protect the historical heritage should be carried out with innovative green compound materials, such as mortars reinforced with natural fibres. Objective: In the current paper, laboratory tests on lime mortars strengthened with raw jute fibres have been performed. Methods: The workability of the fibre-reinforced mixture has been assessed through shaking table tests, and the mechanical resistances of standard specimens have been evaluated by bending and compression tests. Results: Considering the hygroscopic nature of jute, it has been identified that the optimal water/lime ratio and the maximum water percentage are absorbed by jute fibres. From the results, how the spreading of the mixture, which is indicative of the mortar consistency, changes with the water/lime ratio, has been evaluated. From bending tests, the effective behaviour of fibres, which provide a stitching effect of the failure crack in the investigated fibre-reinforced lime mortars, has been observed. Conclusion: Finally, the results of compression tests have shown that the examined fibre-reinforced mortars can be effectively used as building products according to the actual Italian technical code NTC 2018.

Influence of an Impregnation Treatment on the Morphology and Mechanical Behaviour of Flax Yarns Embedded in Hydraulic Lime Mortar

The increasing attention toward environmental aspects has led, also in the sector of construction materials, to the need for developing more eco-friendly solutions. Among several options, the employment of low energy raw materials appears as an efficient solution intended to enhance the sustainability of building structures. One of the applications moving in this direction is the use of plant fibers as a reinforcement in cement-based composites, hence named as natural textile reinforced mortar (NTRM) composites. Although representing a promising technique, there are still several open issues concerning the variability of plant fibers properties, the durability, and the mechanical compatibility with the mortar. This study aims at investigating the influence of an impregnation process on the thread’s morphology and on the mechanical response. Therefore, the geometry of dry and impregnated flax threads is identified by using scanning electron microscope (SEM) images analysis, and their mechanical response in tension is assessed. In addition, the fibers-to-mortar bond behavior is investigated by means of pull-out tests. The proposed results show that the impregnation procedure employed, although not improving the fibers-to matrix bond, leads to a standardisation of the threads morphology and reduces the thread’s deformability in tension, and paves the way for further investigations on a larger scale.

Chemical analysis of mortars of archaeological samples from Mediana locality, Serbia

Mineralogical and chemical composition of mortar from the floor, ceiling and wall of Stibadium B, from the archaeological site of Mediana (Serbia) have been analysed using ICP-OES, F?IR and XRD-spectroscopy and chemical analysis. The results show that hydraulic lime mortar was used with crushed bricks as artificial puzzolanic aggregate. Large contribution of silicon- and aluminum-oxides, indicate the presence of quartz and phyllosilicate minerals derived from the aggregate, river sand and crushed bricks. Also, high content of Pb and Cu was observed in investigated samples.

Experimental Analysis on Bond Behavior of GFRCM Applied on Clay Brick Masonry

External bonded reinforcements (EBR), made by fibrous meshes embedded in a cementitious/hydraulic lime mortar, are getting a great deal of attention, mostly for strengthening, retrofitting and repair existing structures. In this context, the interest versus the FRCM (Fiber Reinforced Cementitious Matrix) is growing. The mechanical performance of these mortar-based reinforcements is not well known at the date and it needs to be investigated in terms of bond and tensile strength, strain and stiffness, in relation to the type of both substrate and fibers. The present work reports the results of an experimental study, still in progress, on different pre-cured GFRP grids embedded in inorganic matrices and applied on clay brick masonry. First, the mechanical properties of both pre-cured GFRP grid and GFRCM reinforcements were obtained through tensile tests. Then, the experimental investigation on bond behavior was carried out by direct shear bond test. The test results were collected and processed to evaluate bond strength, failure mode, load-slip relationship.