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MCR Technology Evolution
A report on improvements in the package Lokesh Hubbali and V Sriraman
It has been realised that among MCR practitioners, the demand for high quality conscious segment of the market is increasing day by day. Customers, today, are willing to pay for quality. The up-market segments in urban and peri-urban areas pose higher demand on value-added (coloured) and high quality tiles. In South India, Mangalore pattern tiles have been predominantly used as the roofing material for more than 100 years. Prevalence of such a roofing material pushes up the expectations of the market on tile and roof quality. It is therefore mandatory to boost the quality of technology package in terms of the tile production process, equipment and ultimately technical know-how in order to attract big commercial players. With this intention, the Technology, Development and Consultancy Unit (TDCU) within Development Alternatives aims to look into various aspects of MCR technology for further improvements and continued research and development for its technological evolution.Several technical aspects that need to be resolved were prioritised by MCR practitioners and experts. The most important issue identified was Dampness and seepage in MCR tiles and roofs, especially in heavy rainfall areas of our country. South India and the West coast areas receive rainfall in the order of magnitude of 3000 mm annually. The task of providing solutions to the dampness and seepage problems by conducting experiments in a systematic way after studying the problem has been taken up by the TDCU. It is linked with the water-cement ratio, and there is a need to bring down the water input without losing workability of cement mortar. With this idea, experiments have been conducted with concrete admixtures such as Plasticizers, Air entrainers and Integral Water Proofing compounds (IWP). The objective was to come up with appropriate mix proportion and methodology for production of dampness-resistant tiles. The various admixtures tried out are furnished in Table.1 A batch of 15-20 experimentation tiles was produced for each admixture combination. The raw material proportion was kept constant at 1:3 (cement : sum of fine and coarse aggregates) in order to assess the effect of admixture. Tiles were evaluated for the following parameters : Strength, Water seepage through rainfall test, Dampness, and Cost. (The results are shown in Figure 1 and Figure 2.) In high rainfall areas, tiles are prone to seepage and dampness due to continuous or longer duration and intensity of rainfall. The admixtures can arrest dampness, but, as in such high rainfall zones, rainfall is invariably coupled with speedy winds, the water splashing on roof surface enters through gaps between tile overlaps. Experiments were conducted to solve these problems and promising results have been obtained. Sealants were applied and their performance in arresting water entry was evaluated by simulating the conditions of rainfall using spray test. The results obtained in these experiments are tabulated in Table 2. For water spray test, the discharge was three litres per minute or equivalent to 100mm rainfall per hour. The test results are based on experiments conducted under controlled conditions. The project intends to validate these results in a field situation. In its mandate, TDCU takes up specific problems faced by MCR practitioners, individual entrepreneurs and technology promoters. Customised solutions for technical problems in tile production and roof construction could be provided by TDCU on commercial terms. q
(For more details, contact V Sriraman, TDCU, Development Alternatives, Bangalore.)
The authors are Junior Engineer and Technology Development Engineer, respectively.
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