Terrazzo and agglomerated stone flooring are increasingly being used as alternatives to natural stone flooring; however, there are a number of commonly held misconceptions with these materials:
- Terrazzo tiles are two-part (facing and backing); agglomerated tiles are not two-part
- Terrazzo tiles use cement as a binder; agglomerated tiles use resin
- Terrazzo tiles are cast or pressed; agglomerated tiles are cut from a larger block
- Aggregate is always marble
Definitions in the relevant standards show that:
Terrazzo tiles can be single or dual-layered and they can be either manufactured individually or cast as large sheets or blocks before being cut to size.
Single-layered terrazzo tiles are made in a single homogeneous layer of aggregate embedded in a paste of grey or white cement and water
Dual-layered terrazzo tiles are made up of a facing or wear layer whose composition is similar to single-layered terrazzo tiles and a second layer known as backing or base concrete layer whose surface is not exposed during normal use
The aggregate used can be ‘Natural stone or another aggregate’.
Reference: BS EN13748-1&2 Terrazzo tiles for internal and external use
Agglomerated stone is an industrial product manufactured from a mixture of aggregates of various sizes sometimes mixed with other compatible materials, additions and binder.
Aggregates consist of natural and/or recycled stones and/or different additions such as crushed ceramics, glass or mirrors. The natural aggregates can be of carbonate-based, e.g. marble, limestone, etc., of silica, e.g. quartz, sandstone, granite, etc. or a combination of the two. They are bound via resin and filler or hydraulic cement and water or a mixture of both.
The semi-finished product manufactured from agglomerated stone is into the form of blocks or slabs, which can be transformed in finished slabs, tiles, vanity tops or similar elements. A modular tile is defined as a piece of agglomerated stone in standard sizes, with dimensions (<600 mm) x (<600 mm) and nominal thickness from 6 mm to 20 mm.
Reference: BS EN 14618 Agglomerated stone — Terminology and classification, BS EN15285 Agglomerated stone — Modular tiles for flooring and stairs (internal and external), BS EN 14617 series of standards, Agglomerated stone – Test Methods.
Terrazzo tiles are specified in terms of three main properties (strength, absorption and abrasion) with the addition of slip resistance for external use.
Sandberg can carry out the testing required to assess compliance:
- Breaking load and breaking strength
- Abrasion (using the ‘wide wheel’ method)
- Capillary and total water absorption
- Slip resistance (using the pendulum tester)
All of these tests are UKAS accredited.
Other tests such as drying shrinkage, wetting expansion or thermal expansion can also be determined.
The classification agglomerated tiles for flooring and stairs is based on water absorption, flexural strength, abrasion resistance and chemical resistance.
Slip resistance can also be determined where necessary.
Performance Assessment and Failure Investigation
Sandberg can monitor the in-situ performance of such properties as slip resistance and carry out investigations where tiles have failed. The latter would involve site inspection, forensic removal of tiles to allow inspection of bedding and to provide samples for laboratory examination and testing.
For more information contact our in-house expert: