Fibre and micro concrete tiles
• were developed to overcome most of the problems encountered in producing and installing corrugated FC sheets (previous example);
• are made most efficiently on a small vibrating table (hand powered or run by electricity, ea. a car battery), which can be operated by a single trained worker;
• can be made thinner (6 mm) than FC sheets (10 mm), and their cement: sand ratio (between 1: 2 and 1: 3) is less than for FC sheets (1: 1), so that the cement used for making tiles is only between 5 and 7 kg per m2 of roofing;
• are easy to handle when fresh and to cure in water tanks; do not tend to break as easily as sheets during transport and installation, and minor inaccuracies in the supporting structure have no negative effects; are easily torn off by strong wind forces, if they are not well fixed to the substructure.
Further information: RAS c/o SKAT, Vadianstrasse 42, CH-9000 St. Gall, Switzerland; Bibl. 11.03,11.05,11.07,11.08, 11.15.
Production of FC/MC tiles
Materials and equipment
• Cement: same as for FC sheets, but about 0.4 kg per 6 mm thick pantile of 50 x 25 cm, corresponding to cement: sand ratio of 1: 3.
• Sand: same as for sheets, but 1.2 kg per tile.
• Fibre: same as for sheets, but 0.02 kg per tile, used in FC tiles only.
• Aggregate: for MC tiles aggregate is used instead of fibre. The ratio sand to aggregate is between 2:1 and 1:1.
• Water and admixtures: same as for sheets.
• Screeding machine: comprising a vibrating screeding surface and interchangeable, hinged frame (for products of different shapes and thicknesses), whereby the vibrating mechanism is either powered by a 12 volt car battery or hand-powered. (A variety of models, depending on different user requirements and desired output rates are available from the Intermediate Technology Workshops, United Kingdom).
• Setting moulds: these are part of the pantile production kit, and are generally made of impact-resistant pvc, with rib markings (for accurate positioning of the tile edge) and supporting frame for stacking.
• Other equipment: same as for sheets.
Moulding and curing
• The wet mix is trowelled onto the polythene interface sheet on the screeding machine and, under vibration, smoothed with a trowel to the same level as the surrounding steel frame. At a predetermined spot at the top end of the tile, a matchbox-size nib is formed and a wire loop pushed into it (required for fixing to the roof).
• The steel frame is lifted off the screeding surface and the polythene sheet slowly pulled over the pvc setting mould, ensuring correct positioning of the tile edge to achieve uniform curvature.
• The mould with the fresh tile is then placed on a stack of moulds for initial setting and curing (24 hours), after which the tiles can be demoulded and cured for 2 weeks in wafer tanks or in an airtight container with vapour saturated air (vapour curing).
Pantiles and Roman tiles
Two types of tiles are common:
• The pantile : is of a sinouscourve like shape and can easily be placed on a slightly uneven roof.
• The Roman tile: gives a neater roof surface but requires an even roof structure.
Production of FC/MC Ridge Tiles
• Materials and equipment: same as for tiles, but with a different steel frame and setting moulds.
• Moulding and curing: same as for tiles, but with nibs and wire loops fitted after the tile is placed on the setting mould.
Installation of FC/MC Roofing
The FC/MC tiles are laid on timber laths (spaced at 40 cm centres) in the same way as clay roof materials. Slight inaccuracies do not cause major problems especially in the case of pantile. The tiles are fixed with wire loops, nailed or tied onto the timber laths.
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