Researchers Rehabilitate Thin Concrete Walls With New Techniques

Researchers from the engineering faculty of the Universidad del Valle (Univalle), in collaboration with an Italian company, have shown how to reinforce thin concrete walls —found in many residential buildings in Colombia— so that they have better seismic performance.

Roger Ortega, postgraduate researcher at the School of Civil Engineering and Geomatics explained that in the research group they subjected a thin reinforced concrete wall to cyclic lateral load until it failed, and then repaired the wall by injecting its cracks with epoxy resin to then subject it to the same type of test, again.

"One of the purposes of the research is to propose a reinforcement alternative for the walls of the buildings of this type that may present a seismic performance outside expectations," Ortega explained.

The tests were implemented in the MaP-H Lab. The group Research Group in Seismic, Wind, Geotechnical and Structural Engineering (G-7) is led by Profesor Peter Thomson, with the support and management of Profesor Johannio Marulanda Casas, the current dean of the Faculty of Engineering at Univalle.

Foto: Inyección de grietas. Crédito: Grupo de Investigación en Ingenierías Sísmica, Eólica, Geotécnica y Estructural (G-7) – Universidad del Valle

Simulating Damage

Thin concrete walls are found in residential buildings in the 4 to 15 floor range, such as Colombia, Peru, Ecuador and Bolivia. There are regions of these countries with high seismic activity, for example, in Cali, Colombia.

"The experimental results of tests of typical walls of this system suggest that some of these buildings may present significant seismic vulnerability, especially constructions prior to 2018," said Ortega, adding that the current work is part of an experimental campaign since 2017 developed by the G-7 Group. 

For the most recent project, the researchers carried out two full-scale wall tests, resembling those found in the walls of buildings, and the expected behavior of these structures when facing a seismic event.

The first test consisted of subjecting a thin wall 10 centimeters wide, a little more than the length of a credit card and 2.4 meters high, with a "T" section, to the lateral load test until the moment of its failure to assess its behavior and how it failed.

Ortega explained that according to the damage observed in the wall, a rehabilitation proposal was proposed: repair and also reinforcement with thin metal plates attached to the faces of the walls.

“For the execution of this rehabilitation, we had the support of MAPEI, the company that supplied the materials to anchor the reinforcement, the replacement of the base concrete, the epoxy resin to inject cracks and anchor the bolts, and the adhesive epoxy to attach the plates, and confine the cracks for injection,” Ortega said.

The second test consisted of replicating the lateral load test, to which the original wall (without damage) was subjected, in the rehabilitated wall, this to evaluate the effect of the reinforcement by comparing the experimental response of the wall without damage versus the intervened wall.

"The results show that it is possible to increase the deformation capacity of the wall and improve the behavior of the wall under seismic load, which indicates that the reinforcement proposal is viable for existing buildings that may have a seismic vulnerability," Ortega said.

Read more from the School of Civil y Geomatic Engineering: Tearing Down Walls For Science in Cali, Colombia  

Photo: Cyclic lateral load test on the original wall without damage. Credit: Research Group in Seismic, Wind, Geotechnical and Structural Engineering (G-7) – Universidad del Valle

Working With an International Company

The Italian company that supplied the materials to anchor the reinforcement is called MAPEI, it has 79 factories in 34 countries on 5 continents and first arrived in Colombia in 2017.

The Technical Sales Manager Colombia for MAPEI Colombia, Ing. Jorge Eduardo Rodriguez explained that Univalle is recognized as the main institution of higher education in the south-west of the country, with high quality institutional accreditation and is ranked as the largest research center in the region and one of the most important in the country.

“In the field of Structural Engineering, it has stood out in the contribution of research and within its group of graduates and teachers it has highly recognized professionals who, like Mapei, are joined in a permanent interest in contributing to the development of engineering at a national and international level,” Rodriguez said.

In 2019, Lauren Güiza Mera, Technical Advisor from MAPEI Colombia participated in the IX Congress of Earthquake Engineering, representing the company's structural reinforcement product line.

Güiza Mera explained that the Universidad del Valle was the host of the event and presented papers from Master's and Doctorate research projects for related to structural effects.

"MAPEI had an opportunity to present itself as rehabilitation solutions, for which the company is an expert in the field worldwide," said Güiza Mera, adding that the company began sponsoring the group's project in 2020.

She stated that the exchange of knowledge between the different research and development teams of the MAPEI group and the constant updating of knowledge through joint research projects with the scientific community was “the backbone of the organization.”

If you would like to contact the researchers or learn more about the projects, write to the Communications Office of the Faculty of Engineering: comunicaingenieria(at)correounivalle.edu.co.

Banner Photo: Repair of the wall subjected to a high level of damage, replacement of the concrete and the fractured reinforcement. Credit: G-7/Universidad del Valle