|Basics of Concrete Roofing Elements (SKAT)|
The basic raw materials required for the production of MCR and FCR are cement, sand, eventually fibre and water. Optionally, colorants in the form of standard natural or chemical pigments, such as those already in use by the concrete industry, can be added.
Ordinary Portland cement is the type used for MCR and FCR. In order to achieve the desired results in strength and durability, it is essential that the quality of cement measures up to the standards required for normal concrete and masonry practice. In some cases the use of pozzolanic binders may be taken into consideration.
The chopped fibre plays its main role in giving a better cohesion to the fresh mix and it enables the moulding of corrugated products. It is possible to use many types of natural fibres in concrete roofing elements as long as they are clean. Coconut husk, stem fibre as for example jute or leaf fibre such as sisal are the most common examples of vegetable fibres which have been used with success.
Recent research has shown that tiles can be produced without fibres. This technology, named Micro Concrete Roofing (MCR), requires more care in the selection of raw materials (e.g. grading of sand). However the quality of MCR is compatible to that of FCR.
Normally any type of clean sand which is suitable for cement mortars can be used for MCR and FCR. Sand with particle sizes between 0.125 mm and 2 mm is suitable. Aggregates up to 4 mm may be added in MCR elements.
The production of good quality MCR and FCR requires good quality water, preferably standard potable water.