Traditional masonry (brick, block, stone) and older concretes can be brittle, meaning they crack and lose strength abruptly during earthquakes. High-ductility seismic concrete addresses this by using a fiber-reinforced mix that yields gradually and holds cracked sections together. ZRETE’s Seismic High-Ductility Masonry Concrete is one such material, formulated with special fibers and admixtures to achieve high toughness. Notable characteristics include:

• High Toughness & Energy Absorption: Toughness is measured by the area under the stress-strain curve in bending; this seismic mortar provides a much higher toughness than normal concrete. For instance, it maintains significant load even after initial cracking, with an Equivalent Bending Toughness on the order of 80–160 kJ/m² at 60 days (depending on grade). This means the material can absorb a lot of energy as it cracks, protecting the structural integrity.

• Controlled Cracking: The fiber reinforcement (usually polymer, steel, or specialized mineral fibers) within the mix distributes throughout the concrete. When stress occurs, many tiny cracks form instead of one large crack, and the fibers bridge these cracks. This controlled micro-cracking prevents catastrophic failure. The material can maintain a degree of load-bearing even with cracks, which is critical for masonry walls in earthquakes to avoid collapse.

• Ease of Application: This high-ductility concrete can be applied as an overlay (e.g., adding a few centimeters layer on an existing wall or slab), or used to fill slots or coats on masonry surfaces. The process typically involves wetting the substrate, mixing the fiber concrete (often provided as a pre-mixed blend of cement, fibers, and additives), and applying it by pouring or troweling. It’s designed to be workable (sometimes self-compacting) without needing vibration, and it bonds well to substrates. ZRETE’s product, for example, is mixed from component A (powder) and component B (fiber pack) with water, then applied – it is self-leveling and non-segregating for uniform performance.

• Multi-Purpose Retrofit: Beyond seismic retrofit, the high-ductility mortar can also patch and strengthen areas with defects (cracks, honeycombs, exposed rebars) and increase cover thickness. It improves durability by providing a new protective layer with enhanced properties (freeze-thaw resistance F≥300, low permeability P≥12, etc.). This means it not only strengthens but also protects the existing structure from environmental damage.

Using this material on masonry or concrete elements results in a composite action: the old wall plus the new ductile layer work together to resist loads. During an earthquake, the ductile layer takes on deformation, preventing the brittle core from shattering. Think of it as giving an old rigid wall a flexible outer armor. This approach has been effectively used in retrofitting unreinforced masonry buildings to meet modern codes without altering their appearance drastically.

Product:

• Seismic High-Ductility Masonry Concrete – A fiber-reinforced cementitious composite for seismic strengthening. It significantly increases a wall’s bending toughness and crack resistance, allowing the structure to maintain integrity even when bent during earthquakes. Suitable for masonry retrofits, structural concrete repairs, and enhancing the ductility of various elements.

(This high-ductility concrete is a key part of ZRETE’s earthquake-resistant reinforcement lineup. It is often used in conjunction with other systems – for example, applying it over a wall that also has fiber mesh embedded (FRCM) for ultimate strength, or using it to encase columns after wrapping with FRP fabric, etc. By using compatible materials like this, engineers can achieve a holistic seismic retrofit that addresses both strength and ductility.)