Cementitious terrazzo that’s severely cracked, spalled, eroded, or damaged is commonly replaced during restoration projects and not repaired. Replacement of sections between divider strips or wholesale replacement need to be determined based on the level of damage. In some cases, it’s appropriate to replace cementitious terrazzo with an epoxy terrazzo system. This alternative system replaces the cementitious matrix with an epoxy-based matrix. Refer to our new terrazzo page for additional information on this system. 

New terrazzo should generally be replaced to mimic the existing system. Terrazzo was typically poured-in-place onsite, or pre-cast offsite and later installed. For poured-in-place floor installation, concrete slab preparation, underbed, and metal divider strips would be installed. For wall installation, metal lathe, scratch coat, and mortar underbed and metal divider strips would be installed. Once the terrazzo mix was placed and cured, the surface would be successively ground smooth. A slurry coat of portland cement would be applied to fill pin holes, and ground smooth after. Stair treads, risers, stringers, wall base, and plinth blocks were often precast. After installation is complete, the floor would be gently cleaned and sealed.  

If cracks, spalls, or delaminations in the topping exist, they can be repaired in situ. Small batches of terrazzo topping are formulated to match the existing and installed in the prepared repair area. Care should be given to matching the cementitious or epoxy matrix and stone chips as closely as possible in aesthetic, size, gradation, and type. Depending on the size and shape of the repair area, it may require hand-placing stone chips to match and blend with the existing terrazzo.  

Cementitious terrazzo that has severe scratches, scuffs, or coatings can be reground, grouted, and polished to restore the surface to its original appearance. However, if resurfacing is necessary, this can be carried out by buffing the surface with a fine grit diamond pad.  

If stripping and resealing is necessary, it’s important to understand the terrazzo topping composition, existing sealer chemistry, if the existing sealer can be removed, and what stripping materials are appropriate and designed for terrazzo floor surfaces. After floors are stripped and cleaned, a compatible sealer is applied, and the floor is repolished.  

Daily dust mopping and vacuuming reduces grit that can act as an abrasive, helping preserve the terrazzo surface. Cleaning spills, damp mopping, and wiping down terrazzo with warm water prevents deep staining over time. For terrazzo floors, deep cleaning with an electric floor scrubber and pH neutral cleaner, followed by spray buffing, can restore the shine lost due to foot traffic and reduces the need for more aggressive cleaning or stripping and resealing. Abrasive and chemical treatments that damage terrazzo surfaces are inappropriate and can leave terrazzo open to accelerated weathering and lower resiliency. For more information on terrazzo cleaning and maintenance, take a look at the NTMA Terrazzo Maintenance Guide. 

With repair and restoration projects, it’s important to understand the properties of the existing terrazzo, composition, and condition prior to selecting new repair materials. The following field and laboratory testing may be needed for terrazzo evaluation. 

FIELD TESTING:

LABORATORY TESTING: