| Popis: |
The construction industry is currently dealing with a number of major issues. These include of shortage of river sand and large amount of energy required for manufacturing of cement produces free CO2 in air, accordingly use of manufactured sand and industrial waste in concrete increases. In construction of hilly topography long carrying of concrete is required, In outside location providing of concrete from inner mixing place, in construction of road, in lengthy tunneling work, manual transportation of concrete by labor, directly affect the flow property and concrete get stiff at the time of casting on real site work and in several conditions concrete get rejected by engineers. The paper discusses effects of replacing cement with 20% of industrial waste silica fumes and partially replacing natural sand with manufactured sand in the context of properties of retempered concrete like flow, water absorption, sorptivity, tensile, compressive, flexural, shear, impact strengths and chloride permeability. The work demonstrates that the flow property inversely proposition with retempering time. Water absorption, sorptivity and chloride permeability for retempered concrete made by 20% substitute of cement by silica fume with additional 5% cement and water are lesser up to 60 min of retempering time. Compression, tension and flexural, shear, impact strengths for retempered concrete made by 20% substitute of cement by industrial waste silica fume with additional 5% cement and water are increased up to 60 min of retempering time, having strong microstructure than in the reference concrete. The prospect of substituting manufactured sand for natural sand and industrial by-products silica fume for cement has significant technical, economic, and environmental benefits, all of which are critical in today's construction climate also Instead of squandering bulk concrete, retempering using industrial waste and manufactured sand is advised. |
