The durability factor
A LARGE number of the over 700 mud houses built by the Karnataka Housing Board (KHB) at Yelahanka near Bangalore are showing signs of falling apart. This is a major setback to a project that described by V Suresh, a HUDCO director who was then KHB chairman, once described as a "glowing demonstration of the durability of stabilised mud blocks".
The efficacy of mud blocks depends crucially on mixing the right proportions: 4 to 5 per cent cement, 25 to 30 per cent sand and a fixed proportion of lime. Because the exact quantity of cement and sand is determined according to the soil composition, proper soil testing is essential before mud blocks are made. K S Jagdish, who heads Centre for the Application of Science and Technology to Rural Areas (ASTRA) unequivocally blames the KHB and HUDCO for launching the project without carrying out proper tests or considering its viability for Bangalore city. "The idea of using these blocks is to save energy and we have never propagated this technology as a cost-saving device," said Jagdish "In fact, in Bangalore we may even have to get suitable mud from outside the city and it may work out to be as expensive as brick buildings." Furthermore, Jagdish contended, the KHB hired contractors who did not care about the technology and saved on cement, sand and lime. "The KHB did not use the technology developed by ASTRA, nor was there any mention of ASTRA when the KHB first publicised the project in 1989," said Jagdish. "Now that things have gone wrong, we are blamed."
However, stabilised mud blocks have also been found appropriate for rural Karnataka and voluntary agencies such as MYRADA and Gramashrama are using them to build houses in the Coondapur taluka in south Kanara district, an area prone to heavy rain.