Universitat Politècnica de Catalunya. Departament d'Enginyeria Civil i Ambiental, Universitat Politècnica de Catalunya. ATEM - Anàlisi i Tecnologia d'Estructures i Materials
This study addresses the evaluation of the confinement effect in the experimental determination of compressive strength in solid fired clay units. The experimental campaign has focused on two different types of solid fired clay bricks, namely mechanically extruded and handmade, with a total amount of 458 specimens. The research considers different standard specimens, such as whole or half brick, and 100 × 100 × 40 mm3 specimen, and nonstandard 40 × 40 × 40 mm3 specimen, subjected to different standard bearing surface treatments, i.e. grinding, capping with cement mortar or gypsum plaster, placing with birch plywood or fibreboard. Additionally, two novel bearing surface treatments are proposed, i.e. covering with gypsum powder, and placing two oiled PTFE leaves. The experimental campaign has focused on four main aspects. First, the evaluation of the compressive strength value in specimens with hardening response. Second, the influence of the cross section’s aspect ratio, defined as the ratio between the specimen’s length and width. Third, the influence of the bearing surface treatment on the determination of the compressive strength. Fourth, the evaluation of the standard compressive strength through the comparison amongst reference standards. The results highlight and quantify the different factors that influence the confinement, while detecting differences depending on the manufacturing process of the unit. In addition, the results reveal the use of oiled PTFE leaves as a promising and fast possibility of low boundary friction to obtain the strength regardless of the specimen shape. The authors gratefully acknowledge the financial support from the Ministry of Science, Innovation and Universities of the Spanish Government (MCIU), the State Agency of Research (AEI) as well as that of the ERDF (European Regional Development Fund) through the project SEVERUS (Multilevel evaluation of seismic vulnerability and risk mitigation of masonry buildings in resilient historical urban centres, ref. Num. RTI2018-099589-B-I00). Support from MCIU through a predoctoral grant awarded to the first author is also gratefully acknowledged.
