Pozzolana

Pozzolana is a material of interest for civil engineers. It is used in building construction. It consists of amorphous silica or a mixture of amorphous silica and alumina. Pozzolana when mixed with calcium hydroxide at ambient temperature in the presence of moisture, becomes a cementitius material. The mixture is called lime-pozzolana cement. Pozzolana can be derived from powdered burnt clay, fly ash or rice husk ash. Amount of sand should be minimized while burning clay since sand does not react with lime. Fly ash as pozzolana is usually obtained from thermal power stations where pulverized coal is used as the fuel. Fly ash is nothing but the very fine particles of burnt coal which contain significant amounts of amorphous silica and alumina. Rice husk ash is a natural source of silica. There are many methods of production of lime-pozzolana cement. They are wet grinding using lime-surkhi mortar, dry blending of lime and pozzolana and wet blending of lime and pozzolana.

Automatic guided vehicles

Automatic guided vehicle or AGV is widely used as a material handling device in flexible manufacturing systems. AGV is a battery powered vehicle. AGV can move and transport materials from one place to another. They are not physically tied to the production line. On-board controllers mounted on AGV helps to execute complicated tasks, complex paths and loading/unloading operations. This helps in easy dispatching, easy routing, traffic control and collision avoidance. Flexibility is the main advantage of an AGV system. It can be monitored in real time and fine control of the system possible. Safety point of view also, AGV is far superior to its counterparts. AGV is more cost effective than modifying fixed conveyor lines or rail guided vehicles. There is a provision to incorporate warning lights and fire safety interlocks in an AGV.