Cement Energy and Environment

mixes. Tests were conducted for basic strength properties like compression, split tension and flexure. From the results of the investigation important conclusions on the role of light weight aggregates in optimizing the weight of concrete, the behavior of concrete with fibers and light weight aggregates (pumice) are drawn. Recommendations are made. Use of Admixtures and Fibers in Concrete Many researchers have tried to modify the properties of conventional concrete to suit the individual needs. The modifications were tried on quality of the concrete making materials. To start with many additives and admixtures were tried instead of altering the conventional materials used. Though the use of admixtures and additives is being frowned upon by some technologists , there are many, on the contrary, who highly recommend and foster the use and development of admixture as it imparts many desirable characteristics and effects economy in concrete construction. Attempts were also made to improve the tensile strength and dynamic properties of concrete by addition of fibers. The fiber reinforced concrete (FRC) is gaining rapid importance in the field of concrete technology. Necessity of Light Weight Concrete The obvious characteristics of light weight concrete are its low density. There are many advantages of having low density. It helps in reduction of dead load, increases the progress of building and lowers the haulage and handling costs . The use of light weight has made it possible to proceed with construction of tall and heavy structures on soils with low bearing capacities. In framed structures, if floors and walls are made up of light weight concrete, it will result in considerable economy. Another most important characteristic of light weight concrete is its relatively low thermal conductivity, a property which improves with decreasing density. Hence in extreme climatic conditions and also in case of buildings with air conditioning, the use of light weight concrete with low thermal conductivity will be of considerable advantage from the point of view of thermal comforts and lower power consumption. The adoption of light weight concrete gives an outlet for industrial wastes such as cinder, fly ash , slag etc. which otherwise create problem for disposal. Necessity of Fibrous Light Weight Concrete With the advent of systems building techniques in concrete construction and the ever increasing trend towards seeking new and non - traditional areas of application of concrete, a need has arisen for the development of a high strength and low unit weight concrete. The development of such a concrete will facilitate the use of thinner and lighter structural system and thereby reducing fright, lift and connection expenses. Further the overall dead weight of structures will be reduced and the need for providing elaborate and expensive foundations, especially for tall buildings can be eliminated or minimized. The availability of high strength, thin member structural systems of concrete can also provide architects with new vistas for developing different architectures for the twenty first century. Triple Blending The process of replacing cement by some other pozzolanic materials is known as triple blending. These materials are even finer than cement. It is done for successively filling the voids between cement grains which can increase the packing density of the cementitious materials and reduces the volume of voids to be filled with water. This would release more water to increase the flow ability at same water/cementatious materials (W/CM) ratio or allow the W/CM ratio to be lowered to increase the strength at same flow ability requi rement. Various mineral admixtures like fly ash, condensed silica fume, GGBS, Metakaoline etc, can be tried for ripple blending. Types of Light Weight Aggregates With alarming increase of construction industry, availability of natural aggregate became scarce and need to create artificial aggregate became very much essential around the globe. The socio-economic and ecological problems of mankind forces one to encourage the artificially made ag£!regates . Light aggregates can be broadly classified use of weight into 2 categories namely natural light weight aggregates and artificial light weight aggregates. Natural Light Weight Aggregates There are a number of natural light weight aggregates available. Prominent among them are: Pumice, Diatomite, Volcanic cinders, Saw dust. 47