|Basics of Concrete Roofing Elements (SKAT)|
In a small workshop
The production of MCR and of FCR Elements is labour intensive. It can take place close to the point of use and in a small workshop. A minimum of infrastructure, equipment and at least 2-3 workers are needed to work with one vibrating table.
By men and women
Both production and mounting of the MCR or FCR Elements can be made on the spot and by local (male and female) workers. So the cost of transportation of the finished product can almost be eliminated.
Training is a must
The simplicity of the technology makes it easy though inevitable to acquire the requisite technical skills in a relatively short period of training time. Professional training is offered by regional MCR/ FCR centres and by suppliers of equipment.
Preparing the mortar
The first step of production is similar to the process of mortar preparation in basic masonry practice. For FCR the fibre is chopped up to a length of about 15-25 mm and mixed with the basic ingredients (sand, cement, water and fibre) into a concrete mortar.
Forming the tile
One of the most demanding and skill-intensive aspect of MCR and FCR production is the transformation of the fresh mortar into tiles or sheets. This involves spreading the fibre concrete mix on a vibrating table, compacting it by vibration and then lifting the wet concrete screed and casting it on a mould.
Curing and drying
On the mould it is dried for 24 hours. The green tiles are then placed into a tank filled with water for a curing period of two weeks. After the curing the hard tiles are dried for another two to three weeks before they can be used for installation on the roof.
Since fibre concrete is a brittle material it has to be handled and laid with care. Whenever possible the tiles should be transported directly from the workshop to the building site. The transport vehicle must be specially prepared, e.g. with a bed of sand on the platform, so as to guarantee a smooth Journey.
It is a sound technique...
The production of MCR and FCR is a sound technique and much practical experience is available. Failures can be identified and are usually due to production errors. Ongoing research and development as well as the evaluation of experiences will lead to the necessary improvement of know-how.
... if professional training is provided
Tile making can be started in most places with a fair chance of success, if professional training is provided and if the appropriate method is chosen. Beginning production should take into account the history and the state-of the-art and not simply be in the spirit of appropriate technology enthusiasm, trying to reinvent the wheel by making the same mistakes many others already have.
The four steps of title production