Floor screeds

FERFA, 241 Fligh Street, Aldershot, Hants GU11 1TJ, Guide No. 4, Synthetic Resin Floor Screeds, Guide No. 6, Polymer Floor Screeds. 

Figure 4.6 Section showing the application of polyurethane floor screed on a concrete base. Reproduced with permission from Fosroc...

Most countries have their own specifications for sand used in mortars. In Europe, work is well in hand to produce a standard (see section 8.8.1). In the UK, the relevant standards are BS 1199 (for plastering and rendering mortars) [8.13] and BS 1200 (for masonry mortars) [8.14]. Sands for floor screeds are specified in BS 882 [8.2] and in BS 1199 [8.13]. 

Air entrainers used to achieve very low densities, say down to 500 kg/m, for floor screeds and thermal insulation are more usually known as foaming agents. 

Uses Acrylic for hydraulically setting systems, PCC-mortars, plasters for trowel applies., primers, sealers, floor screeds/self-leveling compds., industrial floorings, building adhesives Features Free from film-forming aids, soivs., and plasticizers Properties Whitish liq. ammonia odor dilutable in water dens. 1.05-... 

Anhydrite reacts much more slower than plaster, particularly if it contains an appreciable proportion of free lime. Accelerators such as potassium or aluminum sulfate can then be added. Anhydrite is often used in floor screed compositions. 

B.S. 8000 specifies workmanship on building sites. Pt.ll specifying a code of practice for ceramic, terrazzo, mosaic and natural stone tiles. Pt.9 specifies floor screeds Pt.6 slating and tiling of roofs. B.S. 5980 is the specification for wall tile adhesives. Proper specification of appropriate adhesives and fixing methods, and a high standard of workmanship are essential to the success of tiling. 

WRAP [63] has also funded a project that uses rubber from waste tyres to product new flooring screed and plaster products. The products are generically known as Rubbercrete, with the plaster products containing 70% rubber crumb and the flooring screed 30% crumb. Rubbercrete is also available in a rapid set mix design, which has a crumb content of 35% and dries within two to three hours. 

They are appHed in bridge decking and airport runway apphcations, in repair applications, where the mortar layer can be as much as 5-8 cm thick, in industrial floor screeds, where up to a 5 cm layer is appHed over standard concrete, in fine screeds or patching compounds, where up to 1.5 cm of repair mortar is appHed on floors, in self-leveHng underlayments, where thickness from 2-3 cm to feather edging are common. 

Self-leveling These are generally based on solvent-free epoxy and there are a number of proprietary products available. Generally, they are 3-8 mm thick, but if the base floor is too rough, it is advisable to first level this with a cement/resin screed. 

Panel widths ranged from 8 to 10 feet, lengths were 8 to 12 feet, and nominal thickness was 4 inches. The desirable approach is to deliver a full width of mixed material at the beginning to the panel and sustain a delivery rate to maintain full width ahead of the screed. Screeds used were wood equipped with a vibrator, either electrical or air-powered, the latter being preferred by these operators. Once the screed starts, it is preferable to continue in one single sweep to the completion of the panel. Figure 6 shows a floor section after screeding. 

Polymeric overlays are used on concrete pavements to protect them from dust, excessive wear, cracking, crazing, spalling and to provide an attractive appearance. These materials are applied on concrete pavements in the form of screeds, self-levelling material or floor coatings. Epoxies, polyurethanes and acrylics are commonly used, epoxies being the most commonly chosen. Table 1.4 gives the suitability of these materials for different environments. 

Conductive floors provide effective control of static electricity Available in the form of screeds, self-levelling floors and floor coatings Water resistant... 

Major construction applications include adhesives, concrete bonding compounds, crack injections and screed floors. They are also finding use as modifiers to cycloaliphatic and aliphatic amine curing agents (Air Products, undated). 

Epoxies have an excellent resistance to abrasion. The abrasion resistance of a particular system depends upon the type of formulation and conditions. For example coatings have the capacity to resist abrasion from rubber wheels, whereas screed floorings, repair mortar and self-levelling floors can resist thousands of cycles from steel wheels. 

Floor topping A polymeric material applied on concrete floors for a specific reason. Screed floorings and self-levelling floors are included in this category. 

Screed A system based on polymeric binder and sand aggregates. Such systems are applied by trowel as industrial floorings. 

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