Development and corroboration of a novel Natural Textile Reinforced Mortar System for masonry retrofitting

Project Information

NaTeRM

Grant agreement ID: 101038078

DOI

10.3030/101038078

Project closed

EC signature date 19 April 2021

Start date 1 February 2022

End date 11 May 2024

Funded under

• SPREADING EXCELLENCE AND WIDENING PARTICIPATION

Total cost

€ 147 815,04

EU contribution

€ 147 815,04

Coordinated by

UNIVERSIDADE DO MINHO
Portugal

Periodic Reporting for period 1 - NaTeRM (Development and corroboration of a novel Natural Textile Reinforced Mortar System for masonry retrofitting)

Reporting period: 2022-02-01 to 2024-01-31

Summary of the context and overall objectives of the project

The NaTeRM project addresses the pressing need for effective structural retrofitting solutions for aged and historic masonry structures, which are widespread across Europe. These structures are particularly vulnerable to damage, especially from seismic activity, and often do not comply with modern safety standards. Current reinforcement methods face significant challenges, including compatibility with heritage materials, cost-effectiveness, and environmental sustainability. The preservation of historical buildings and ensuring the safety of older structures is vital for protecting cultural heritage, maintaining public safety, and promoting economic stability. Sustainable retrofitting solutions that align with eco-friendly practices play a crucial role in reducing carbon emissions in the construction industry and contribute to the European Green Deal's objectives for climate neutrality. Enhancing the durability and resilience of these structures supports disaster risk reduction, extends their service life, and enables energy-efficient improvements.

The primary goal of the NaTeRM project was to develop and validate an innovative, natural fiber-based Textile Reinforced Mortar (TRM) system tailored for sustainable retrofitting of masonry structures. This effort focused on designing a lime-based matrix with mechanical properties suitable for integration with natural fibers and common masonry substrates, ensuring long-term durability and resistance to moisture-driven decay. Another critical aim was to create composite systems with optimized fiber-to-matrix bond efficiency while assessing their durability under various conditions. The project included conducting pilot applications to evaluate the effectiveness of the developed TRM systems in improving the mechanical properties and seismic performance of masonry walls. In addition, analytical tools were formulated to assist in the practical design of natural TRM systems and to inform computational analyses for structural improvements.

The NaTeRM project has pushed the boundaries of current technology by providing sustainable, cost-effective solutions that contribute to heritage conservation and encourage the use of renewable resources in the construction sector. The results promise significant socio-economic impacts, supporting cultural preservation, enhancing public safety, reducing the carbon footprint of construction practices, and promoting resilience in the built environment.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The NaTeRM project made significant progress in developing and validating an innovative natural Textile Reinforced Mortar (TRM) system for strengthening masonry structures. Through extensive lab work, lime-based mortars were optimized, resulting in six trial mixtures, with two chosen for their excellent mechanical properties, including compressive strength above 10 MPa and flexural strength over 3 MPa. Over 20% of the lime binder was replaced with sustainable additives like silica fume, boosting eco-friendliness.
Three types of natural fiber-reinforced TRM systems were created: lime mortar with flax fibers, a lime-pozzolan TRM with coated hemp textiles, and a hybrid combining both fibers. Tests showed high textile-to-matrix bond efficiency, over 90%, and confirmed their multi-cracking and strain-hardening abilities using advanced strain analysis.
Pilot tests on retrofitted masonry showed impressive results. The Fiber Reinforced Mortar (FRM) increased shear strength by 210%, while the TRM with hemp textiles improved shear strength by 200% and tripled ductility, demonstrating the systems’ effectiveness in enhancing structural resilience.
The computational phase shifted from complex modeling to practical analytical methods, applying mechanics theories to create tools for calculating optimal fiber volume and spacing. This approach informed efficient TRM design.
Results were shared through open-access publications, conference presentations, and public outreach, including university lectures and events like Researchers' Night. A project webpage and social media updates kept stakeholders informed.
Outcomes included the development of high-performance TRM composites surpassing initial targets, a new engineering design method for TRM systems, and improved masonry retrofitting capabilities. The project also advanced the researcher's career, leading to a partnership with FibreNet SPA as their technical representative.
Future work includes more publications and steps to increase the TRM system's readiness for industrial use. The collaboration among the University of Minho, the researcher, and FibreNet SPA lays a foundation for further research and commercialization. The project supports the European Green Deal’s goals, promoting sustainable building practices and safer, eco-friendly retrofitting solutions.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The NaTeRM project achieved significant progress beyond the state of the art by developing an innovative natural Textile Reinforced Mortar (TRM) system for retrofitting masonry structures. High-performance, lime-based eco-friendly matrix materials were created. Over 20% of the lime binder was substituted with sustainable additives like silica fume, boosting both performance and sustainability. By integrating both dispersed flax fibers and hemp textiles composites with enhanced tensile performance were developed.
A notable theoretical contribution was the development of a first-order analytical design method for TRM composites, enabling more accurate engineering calculations for fiber volume and matrix properties, surpassing the empirical methods previously used. Pilot tests validated the TRM systems' effectiveness, with diagonal compression tests showing a 210% increase in shear strength for fiber-reinforced mortar and a 200% increase for textile-reinforced systems, alongside a threefold boost in ductility. These results confirmed the system's practical application potential in masonry retrofitting.
The project’s socio-economic impact is significant, offering a cost-effective, sustainable solution for retrofitting that could lower repair and maintenance costs. It supports green industry growth by using natural fibers and eco-friendly matrices, fostering a circular economy. Enhanced seismic resilience of buildings improves public safety and aids in preserving historical structures, especially in earthquake-prone areas. Environmentally, NaTeRM contributes to climate action goals by using renewable fibers and sustainable binders, reducing carbon emissions and dependence on non-renewable resources. It promotes heritage conservation, ensuring cultural identity is maintained for future generations.
NaTeRM’s results align with European policies, supporting the European Green Deal by advocating for energy-efficient, sustainable construction practices. The project’s cost-effective solutions enhance infrastructure affordability and safety, contributing to an economy that works for people. It also aligns with EU sustainability strategies, promoting renewable resources and innovative, low-impact construction techniques that foster a climate-conscious future.

Diagonal compression test on masonry specimen retrofitted with natural TRM

Tensile stress-strain behavior of hybrid composite combining dispersed flax fibers and hemp textile

Variation of axial strains at different stages of a tensile test performed on natural TRM specimen