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Execution and repair of masonry structures using mortar reinforced with natural fibers in a cementitious matrix

Abstract:

Masonry structures that are built in Ecuador use a cementitious mortar, either in the joints of the blocks or in the plaster, and the mortar is made of water, sand and cement only, on a ratio of 3 to 1. Such mortar has a good compression behavior but a poor tension behavior of the elastic-fragile type. Therefore, under seismic forces the masonry walls suffer different types of collapse, either of the panels or of the plaster. This construction typology using mortar with the addition of natural fibers from the bamboo plant (guadua angustifolia) gives to the masonry an increment of the tensile strength with some ductility avoiding the collapse of the explosive type. A theoretical and experimental research on the fiber reinforced mortar was carried out in order to verify its real behavior. The natural fibers obtained from the bamboo plant have also a good durability, due to the inherent properties of these species, and therefore are acceptable with reference to the life expectancy of the structure. In order to define the characteristics of the mechanical behavior, many diagonal compression tests were conducted in masonry panels of 120 x 120 cm, using clay blocks and mortar reinforced with short and long fibers of the bamboo plant (guadua angustifolia). Such tests were confronted with similar tests of previous research in which carbon and basalt fibers were used under the form of a mesh reinforcing the plaster. The results can be considered positive also under the cost-benefit aspect, and therefore this type of reinforcement is recommended for the execution of new masonry structures or for the repair of the masonry damaged by seismic events.