Of all building materials used for construction, artificial ones, like Cement Mortars & Concretes, are the most widely used. Biological decay of mortars & Concrete is one of the serious problem, as approximately 30% of visible alteration on building materials occurs due to due to microbial impact.
Effects of microorganisms (Algae & Fungi) on building facades are responsible for aesthetic, bio-geophysical and bio-geochemical deterioration. Even the Buildings of cultural heritage are discolored and degraded by the growth and activity of living & multiplying micro-organisms. Historical structures and buildings have however obviously survived for centuries and it may be suggested that they therefore have an inherent resistance to such decay and deterioration processes.
Procedures for preventing bio-deterioration include intervention methods. Chemical methods, like the use of biocides, are frequently applied as a conservation treatment for historic monuments recently, however, the use of biocides is not being well accepted, as these products do not promote a long term protection, (most frequently due to the development of resistance mechanisms by micro organisms and also rain water washings), and therefore need to be repeatedly applied. Besides the short-time durability of biocides treatment, the application of these products involves other sort of problems as they are toxic and can induce environmental and public health harms. Therefore, new scientific concepts of ecological treatments are needed.
In the tropical climatic conditions in India, where plain or reinforced concretes are used for building material, covering surfaces of many irrigation channels, water treatment structures, water storage tanks these concreted water bodies get exposed to the prevailing conditions that are ideal for growth of microorganisms. Lack of understanding and non availability of application oriented cementitious products in the country further aggravates the problem of microorganism attacks on concrete structures.
This paper reviews the trends of research and analyses the results achieved in the areas of use of natural as well as synthetic biocides in historic as well as modern construction applications. The paper also discusses further the experimental data generated at the author’s laboratory as a part of exploratory work carried out on the performance of experimental Biocidal Cements , in terms of resistance to Microbial growth .The Paper was p[resented and published at 12th-NCB-Int-Seminar