Key Engineering Materials Vol. 898

Abstract: Historic masonry buildings experience a high seismic vulnerability: innovative intervention strategies for strengthening, based on the use of fibre-based composite materials are gradually spreading. In particular, the coupling of fibre-based materials with mortar layers (Fibre Reinforced Mortar technique - FRM) evidenced a good chemical and mechanical compatibility with the historical masonry and proved to be effective for the enhancement of both in-plane and out-of-plane performances of masonry, contrasting the opening of cracks and improving both resistance and ductility. The resistant mechanisms that arise in FRM strengthened masonry walls subjected to in-plane horizontal actions are analyzed in the paper and a practical design approach to evaluate their performances is illustrated, evidencing the dominant collapse mode at the varying of the masonry characteristics. Some masonry walls are analyzed numerically and analytically, as “case study”.

Abstract: With the increase of graffiti since the beginning of the 1970s, the interest in proper removal and high-quality protection systems also have grown. To protect affected objects and buildings from damage caused by graffiti, anti-graffiti systems (AGS) can be used. In practice, it has already been shown that no AGS is suitable for all kind of surfaces. In this study, the effects of permanent anti-graffiti systems on various concrete surfaces are specifically investigated and evaluated with test series under natural weathering (over 3 years). The focus is put on functionality (visual influences) and durability (surface properties of the concrete).

Abstract: This paper describes the issue of sealing cement-based materials. These materials can also include concrete elements or cement fiber boards. For the purposes of this work, a cement fiber material is selected, namely glass. This material has good effects in terms of small dust particles on the surface, which damage the bonding sealant and the substrate. Focus on its suitability for sealing cement-based substrates. The method for determining the properties of the sealant and the properties of the stylistic joint between the sealant and the base material is the tensile test. For the purpose of this test, one representative of neutral silicones, one representative of acetate silicones and one representative for acrylic sealants shall be selected. From the results of the tensile test, it is clear that with a suitable choice of the combination of bonding sealant and primer, it is possible to seal such a problematic substrate with good results.

Abstract: This paper deals with the study of chemical resistance of new cement-based grout for invert grouting. The aim of this work is to verify new mixtures with specific admixtures. The study monitors resistance to external sulphate attack. Specimens were placed into sulphate solution 29.8 g∙l^-1 (44 g∙l^-1 Na₂SO₄) according to DIN19753 standard. Based on the results gained, new mixtures will be designed and optimized by addition of suitable secondary raw materials (fly ash, waste foundry sand, waste glass, waste filers).

Abstract: The polymeric adhesives for the installation of basalt elements on a metal base are designed primarily for environments with increased chemical and mechanical stress. They are composed of polymer resins (epoxy, polyurethane) as binders, as well as organic additives and mineral admixtures that mainly fulfill the function of filler. In all sectors of today's construction industry, maximum efficiency in the production of materials is required for sustainability purposes, which, however, must never be at the expense of the quality or the required performance. Due to these requirements, great emphasis is placed on the maximum use of secondary raw materials. Talc is used as the primary filler for polymer adhesives. Sawdust, tire rubber, and fly ash are used as secondary raw materials. The use of these in building supplies can positively affect some physical and mechanical properties of polymeric adhesives. Also, the use of secondary raw materials has the above-mentioned ecological benefit. Basic properties, such as bulk density and adhesion to both metallic and basalt elements, were monitored. The details of the cohesion of the adhesive with the bonded material, as well as the distribution of secondary raw materials in the polymer matrix, were assessed microscopically.

Abstract: In the last years, the interest in eco-sustainable composites has consistently increased. Such innovative materials are actually a promising sustainable solution for structural strengthening since they can be an alternative to petroleum‐based materials, which are frequently used for masonry retrofitting. This work describes an experimental campaign dedicated to investigating the behavior of Fabric-Reinforced Cementitious Matrix (FRCM) with natural fibers (NFRCM) made with eco-sustainable materials. Experimental tests are performed on unreinforced masonry panels (URM) and reinforced ones (RM), for characterizing their mechanical behavior. URM samples are compared with RM ones accounting for their response under shear actions.

Abstract: The objective of presented research was to verify and evaluate whether the treated hazardous waste (HW) can be used as filler in polymer coatings based on epoxy (EP) and polyurethane resin (PUR). The end product created by the incineration of municipal waste and cement dusts from cement kiln bypasses were chosen for solidification. The hazardous waste used was solidified by a homogenisation method using filter fly ash from fluidized bed combustion of lignite and silica flour as the solidifying agents. The aim was to use as much hazardous waste as possible and incorporate it into the polymer matrix of the coatings. The usability of the filler prepared in this way was verified by testing the tensile properties of polymer coatings, the surface hardness and the adhesion to the concrete. The cohesion of the coatings with concrete was observed using a digital optical microscope. It has been found that the PUR-based coatings with HW content show better properties than the coatings containing only the silica flour as a filler.

Abstract: Oils, e.g. linseed oil, has been used as mortar admixtures or components of lime-oil mastic since ancient times. The reason was either to increase the mortar durability and/or to prolong the mortar/mastic workability. Historic mortars are conventionally analyzed by means of X-ray diffraction and thermal analysis, but these methods are not able to detect the organic compounds directly. The goal of the present research was to evaluate the applicability of thermal analysis, infra-red spectroscopy, solid state NMR spectroscopy and gas chromatography for detection and possible quantification of linseed oil in prepared mortar containing, beyond the oil, just lime and calcite. Both applied spectroscopies were able not only detect the presence of oil but may be used also for study of the oil chemical transformation in the alkaline environment of the lime mortar. Thermal analysis is not able to identify kind of organic admixture, but when it is known that it is e.g. linseed oil, its quantification by help of Evolved Gas Analysis is very good. The results of gas chromatography of mortar’s extract are affected by the polymerization of oil in mortar. The total organic content analysis is providing good information about the total amount of organics in mortar. There in not any single method, which could provide all information about the oil admixture in mortar (kind of oil, content of oil, fate of oil after mortar’s mixing) by itself; the combination of techniques must be used.

Abstract: One of the methods of curing (Cured-In-Place Pipe) CIPP pipes is the curing using ultraviolet (UV) light. The main difference from common CIPP types is in the structure of the liner material. In terms of material, it is a woven fiber glass fabric which is saturated with vinyl ester or polyester resin. In general, these pipes are more resistant to chemicals and achieve higher values of flexural properties. The paper focuses on the investigation of the short-term mechanical properties using three-point bending test and structure of UV cured CIPP liners. The computed tomography (CT) was used for the analysis of CIPP internal structure and composition.