Waste management strategies for concrete

Recycling and reuse of waste such as building rubble, concrete lumps, etc. generated at construction and demolition sites form part of a wider, complex issue, primarily relating to improving supplies of construction material and solving problems of disposal of waste construction material. Within the framework of the sustainable development of the environment, the use of waste materials with minimum environmental impact has received much attention. The conversion of a large amount of demolished waste into an alternative resource will conserve the depleting natural resources of building materials. Demolished waste is mainly used as a non-stabilized base or sub-base in highway construction. The present paper discusses the recycling process and makes an effort to assess a safe and economic use of recycled concrete as a structural grade material for the construction industry. Extensive tests of structural properties such as compressive strength, flexural strength and split tensile strength of recycled concrete were carried out, in which cement and similarly fine aggregate were partially replaced by demolished waste to obtain recycled concrete and recycled aggregate concrete whose properties were compared with results for the conventional concrete.     

Future research directions and data requirements for developing ambient ozone guidelines or standards for agroecosystems

The ambient air quality in Central Europe appears to have the potential to adversely affect the productivity of the agroecosystems in that geographic area. Therefore, there is a need to develop, validate, and apply air pollutant exposure-plant response models to explain the relationships between the stochastic chemical climate and ecosystem responses. Such models will have to include numerical terms for the effective air pollutant exposure regime to account for the fluxes of matter, energy and information within the ecosystem and its components. The structure and function of the ecosystem which are influenced by the air pollutant flux can be described by a combination of empirical and mechanistic models. A discussion of such an approach is presented in this paper.     

Factors affecting alkaline nature of rain water in Agra (India)

Rain water was collected and analysed from a reference site, Dayalbagh and Taj Ganj, near the Taj Mahal in Agra. The ionic components Ca, Mg, Na, K, NH(4), Pb, Fe, Zn, SO(4), HCO(3), Cl and F were analysed along with pH, alkalinity and conductance. The average pH of rain water at both sites is 7.05. There is a dominance of alkaline components, particularly Ca. The rain water chemistry shows the importance of calcareous soil-derived materials in controlling the pH of rain water.