While the components and installation process varies by the type

of Terrazzo system, all Terrazzo floors (except Rustic Terrazzo)

follow the same grinding and finishing process.

3/8” Epoxy Terrazzo 1/4” Epoxy Terrazzo 3” Sand Cushion Terrazzo 2” Bonded Terrazzo 1/2” Monolithic Terrazzo 3/8” Polyacrylate Modified Cement Terrazzo Rustic Terrazzo Grinding & Finishing

3/8” Epoxy Terrazzo

A nominal 3/8” thick resin matrix veneer placed upon an interior concrete slab or over a double layer of exterior-grade plywood.  Epoxy Terrazzo will have three times the chemical, stain, and crack resistance of the cementitious thin-set Terrazzo. When compared to traditional Terrazzo, the slightly less labor intensive process for epoxy Terrazzo translates into time saved on the jobsite. • The concrete slab must have an effective (10 mils or better) vapor barrier placed directly below the slab for all on or below grade installations or a manufacturer approved moisture mitigation system must be used • Control joints in the concrete slab are acknowledged with back “L” strips • Additional divider strips (of 1/4”,  1/8”, or 1/16”) are only decorative and/or to provide method to change Terrazzo color • Terrazzo finish is placed directly on the prepared slab or plywood substrate • The Terrazzo finish is comprised of an epoxy resin and aggregates (traditionally marble chips - sizes #0, #1, and #2 may be used) • Exotic aggregates such as glass, mother of pearl, or recycled ceramics can be used to create unique visual effects • Epoxy Terrazzo is available in any color of the rainbow, just like epoxy paint • Once installed and cured the Terrazzo is ground and finished.  See Grinding & Finishing  • Epoxy Terrazzo takes a great polish and the hard surface is easier to maintain than cementitious Terrazzos • DePaoli Mosaic recommends the 3/8” Epoxy Terrazzo over the thinner 1/4” Epoxy Terrazzo for added crack resistance and traditional appearance. • Allows for the use of crack isolation membranes for slab remediation or to preserve Terrazzo artwork • At 3-4lbs per square foot, its light weight and design flexibility make it ideal for renovations and multi-story use      

1/4” Epoxy Terrazzo  

Nominal 1/4” thick resin matrix veneer placed upon an interior concrete slab or over a double layer of exterior-grade plywood.  Because the 1/4" system is so thin aggregate sizes are limited.  The 1/4” Epoxy will have three times the chemical and stain resistance of cement Terrazzo; however the crack resistance is only twice that of the cementitious thin-set Terrazzo. • The concrete slab must have an effective (10 mils or better) vapor barrier placed directly below the slab for all on or below grade installations or a manufacturer approved moisture mitigation system must be used. • Control joints in the concrete slab are acknowledged with back “L” strips • Additional divider strips are only decorative and/or to provide method to change Terrazzo color • Terrazzo finish is placed directly on the prepared slab or plywood substrate • The Terrazzo finish is comprised of an epoxy resin and aggregates (traditionally marble chips - sizes #0 and #1 only may be used) • Exotic aggregates such as glass, mother of pearl, or recycled ceramics can be used to create unique visual effects (again, only in size #0 and #1) • The smaller chip size will result in a change in the texture of the Terrazzo finish • Epoxy Terrazzo is available in any color of the rainbow, just like epoxy paint • Once installed and cured the Terrazzo is ground and finished See Grinding & Finishing  • Epoxy Terrazzo takes a great polish and the hard surface is easier to maintain than cementitious Terrazzos • Allows for the use of crack isolation membranes for slab remediation or to preserve Terrazzo artwork • At 3-4lbs per square foot, its light weight and design flexibility make it ideal for renovations and multi-story use

3” Sand Cushion Terrazzo

The best cement Terrazzo system and historically the most crack resistant.  A 3” system comprised of a 2 1/2” wire-reinforced, concrete underbed topped by a 1/2” Terrazzo finish.  Each divider strip in this system acts as a control joint to take care of anticipated shrinkage and/or movement at control joints in the slab.  This means that spaces develop between the Terrazzo finish and the divider strips rather than a random crack. • A dusting of sand is spread on the slab to act as ball bearings • Polyethylene is put down as a slip sheet • A reinforced underbed is installed to within 1/2” of the finish floor elevation • 1 1/4” divider strips are anchored into the setting bed with the top edge at the finished floor elevation to form panels no larger than 6’-0” per side • The 1/2” Terrazzo finish (pigmented Portland cement and marble chips) is poured the next day to a level slightly above the finished floor elevation set by the strips and then cured for 4 to 5 days • The use of mineral pigments in cement Terrazzo restrict the color choices to neutrals & pastels • Once installed and cured the Terrazzo is ground and finished.  See Grinding & Finishing  • This system weighs 25-30lbs per square foot and requires a 3” slab depression

2” Bonded Terrazzo

A 2” system comprised of a 1 1/2” concrete underbed topped by a 1/2” Terrazzo finish.  Similar to the typical mud-set ceramic or quarry tile.  With a bonded Terrazzo floor the divider strips act like score marks in a concrete sidewalk to control shrinkage and casual movement in the vicinity of the divider strip.  However, concrete movement in the center of a panel will result in a crack. • An underbed is installed 1 1/2” thick over the slab with the 1 1/4” divider strips installed directly over the concrete control joints to within 1/2” of the finish floor elevation (as in the Sand Cushion system) • Panel size should not exceed 8’-0” per side • The 1/2” Terrazzo finish (pigmented Portland cement and marble chips) is poured the next day to a level slightly above the finished floor elevation set by the strips and then cured for 4 to 5 days • The use of mineral pigments in cement Terrazzo restrict the color choices to neutrals & pastels • Once installed and cured the Terrazzo is ground and finished.  See Grinding & Finishing  • A 2” bonded Terrazzo floors weighs 18-22lbs per square foot and requires a 2” slab depression

1/2” Monolithic Terrazzo

The least expensive Terrazzo system.  Although the Terrazzo will crack if the slab cracks, cracks are not a disaster or a failure.  Cracks are easily grouted to match the matrix.  Cracks are most likely to develop in the first year of building occupancy. • The slab is shot blasted (no dustproofer/sealer/hardener compounds should be used) • Control joints in the concrete slab are acknowledged with back “L” strips 1/2” high • Additional divider strips are only decorative and/or to provide method to change Terrazzo color • DePaoli always uses an epoxy or latex bonding agent to promote adhesion between the 1/2” Terrazzo finish and the concrete slab • The Terrazzo finish is comprised of pigmented Portland cement and marble chips (same as in 2” and 3” systems) • The use of mineral pigments in cement Terrazzo restrict the color choices to neutrals & pastels • Once installed and cured the Terrazzo is ground and finished.  See Grinding & Finishing • This system weighs 5-7lbs per square foot and generally does not require a slab depression

3/8” Polyacrylate Modified Cement Terrazzo

Similar to the 1/2” Monolithic Terrazzo in price, installation, and lack of crack-resistance.  The water is replaced with an acrylic (polyacrylate) emulsion and the same emulsion is used as a latex bonding agent.  The Polyacrylate additive adds strength and enables the cementitious floor to be thinner to accommodate height and weight restrictions.  The Polyacrylate Terrazzo system is vulnerable to bastardization.  Thirty-two percent solids emulsion (the recommended strength) looks exactly the same as the sixteen percent solids emulsions (thus, one that has been cut fifty percent with water). • Control joints in the concrete slab are acknowledged with back “L” strips 3/8” high directly over the joint in the concrete • Additional divider strips are only decorative and/or to provide method to change Terrazzo color • DePaoli always uses an latex bonding agent to promote adhesion between the 3/8” Terrazzo finish and the concrete slab • The Terrazzo finish is comprised of pigmented Portland cement, acrylic emulsion, and marble chips (same as in 2” and 3” systems) • The use of mineral pigments in cement Terrazzo restrict the color choices to neutrals & pastels • Once installed and cured the Terrazzo is ground and finished.  • this system weighs 4 1/2lbs per square foot and does not require a slab depression See Grinding & Finishing  

Rustic Terrazzo

Rustic Terrazzo offers a unique alternative to exterior paving.  The unpolished surface of Rustic Terrazzo allows the stones to stand out and provides excellent slip-resistance.  Rustic Terrazzo is a durable finish that allows the great design flexibility one might expect from Terrazzo.  • Rustic Terrazzo can utilize any cementitious Terrazzo system and varies in thickness from 1/2” to 3” over a concrete slab and up to 5” over compacted fill • In lieu of metal divider strips, wood strips are typically used as placeholders until the floor is finished and joints are filled with a flexible sealant.  Joints should be placed directly over the concrete control joints (if install over a concrete slab) and should run the full thickness of the Terrazzo system. • Typical aggregates used in Rustic Terrazzo include marble chips, granite chips, and river pebbles • After installation, Terrazzo is wet-cured for a minimum of 7 days.  When the Terrazzo is sufficiently cured, it is acid-washed and scrubbed with a stiff brush to remove laitance and expose the aggregate • Finally, the surface is cleaned and sealed

Grinding & Finishing 

Regardless of the type of Terrazzo used, all floors are ground and polished using the same process. • The floor is allowed to cure (4-5 days for cement and 24-48 hours minimum for epoxy) and is then ground with a Terrazzo grinding machine using carborundum or equivalent diamond impregnated stones. • #24 grit is used to first cut down to the level of the divider strips.  This is called the Rough Grind. • #80 grit is used to remove deep scratches • The floor is then grouted to fill air and/or water voids (same as voids along the sides of a core sample from concrete slab).  Epoxy Terrazzo floors are grouted with epoxy while cementitious Terrazzo floors use cement grout.  In either case, the grout is tinted to match the matrix (background) color.  Grout leaves a skim coat on the surface and the Terrazzo is sometimes left in this condition while other messy work is completed.  The skim coat protects against casual scratching but not heavy construction work or traffic. • Final polish is done using either #110 or #220 stones • The Terrazzo is then washed  with a pH neutral cleaner and sealed with three coats of a water-based acrylic floor finisher and sealer that is UL-Listed for slip resistance and ADA- compliant with a minimum co-efficient of friction of 0.6. • From this point the building owner should institute a regular maintenance program using products formulated for Terrazzo.

TECHNICAL INFORMATION

Descriptions of each Terrazzo system along with requirements and weights for each system are below.  The full NTMA technical specifications are also available by clicking here.   Please use the links below to learn more.  If you have questions or require additional information please contact us at info@depaolimosaic.com

Contact Us

If you still have questions or if you would like to discuss Terrazzo options for your upcoming project, please contact our office.