This floor is water-proof, dustless, jointless, acid-proof and attractive in appearance and as such becoming popular these days. This floor is also non-slippery and noiseless.
Construction of this flooring consists of following two operations.
Preparation of Mastic Asphalt
Asphalt which is generally available in drums is broken into pieces and put in an iron pot known as ‘cauldron’. The iron pot is heated by lighting fire under it. Due to heating, asphalt starts melting.
The mass is continuously heated and stirred till whole of the mass melts. Once the whole mass acquires uniform consistency (i.e., whole mass has melted) clean sharp sand or grit it added in proportion of two parts of sand or grit to one part of asphalt.
This mixture of sand and asphalt is continued to be heated till it starts emitting light brown coloured smoke. At this stage the mixture which is also known as compost, acquires such a consistency that it can drop freely from the stirrer. At this temperature, the mix or compost is considered fit for use.
Compost should not be heated further as otherwise, it may get over-burnt and its properties undergo marked change which are unfavourable for a good floor finishing.
Read Also: Different Types of Flooring
Laying of Asphalt
The hard and unsinkable base is prepared by 10 cm to 15 cm thick layer of lean cement concrete or lime concrete. The surface is thoroughly cleaned and dried. The mastic asphalt prepared as above is poured on the prepared base with the help of iron ladles and spread evenly on the surface in thickness varying from 13 mm to 25 mm.
Before the mastic asphalt becomes hard on cooling, very fine sand is shifted on the surface. The surface is then rubbed with the help of trowel or hand float. The asphalt floor is put to use after it has hardened.
In case mastic is to be laid in two layers instead of one, sand should not be shifted over the bottom layer. Second layer should be laid before the bottom layer solidifies. Second layer of mastic should be covered with fine sand and finished by trowelling before mastic becomes hard.
In old days asphalt floors were not favoured because of bad smell and ugly colour of the asphalt. Nowadays asphalt flooring can be made in a variety of colours. Floors may be made from asphalt tiles, which are manufactured from natural asphalt, asbestos fibres and mineral pigments. Asphalt floors may also be formed from asphalt terrazzo which is manufactured by mixing marble, chips to coloured asphalt.