Sand is an inert element essential in the composition of concrete; its use ensures granular continuity between the cement and gravel for better cohesion of concrete. This paper presents the results of a study that inv...Sand is an inert element essential in the composition of concrete; its use ensures granular continuity between the cement and gravel for better cohesion of concrete. This paper presents the results of a study that investigated the influence of sand quality on the properties of fresh and hardened SCC （self-compacting concrete）. The dune sands are very fine materials characterized by a high intergranular porosity, high surface area and low fineness modulus; on the other hand crushed （manufactured） sand has a high rate into thin and irregular shapes which influence the workability of concrete. The amount of dune sand varies from （0%, 50% to 100%） by weight of fine aggregates. The results show that the rheological properties favour the use of dune sands; however the mechanical properties support the use of crushed sand.展开更多
Concrete is multicomponent composite material, consisting of coarse aggregate, fine aggregate, cement and water. Natural aggregates, as well as aggregates obtained after the reprocessing of buildings＇ demolition wast...Concrete is multicomponent composite material, consisting of coarse aggregate, fine aggregate, cement and water. Natural aggregates, as well as aggregates obtained after the reprocessing of buildings＇ demolition waste, can be used as coarse and fine aggregates. Characteristics of the hardened concrete depend on the raw materials, used for the preparation of concrete mixture, and their characteristics. The objective of the research is to analyse the sources of demolition waste, to describe the reprocessing technology of concrete waste, to investigate the production of the aggregate from the concrete waste, to analyse the main properties of these aggregates -- particles＇ density, bulk density, granulometric composition, hollowness and other properties, as well as to compare the obtained results with the requirements applicable to the aggregates based on natural materials.展开更多
文摘Sand is an inert element essential in the composition of concrete; its use ensures granular continuity between the cement and gravel for better cohesion of concrete. This paper presents the results of a study that investigated the influence of sand quality on the properties of fresh and hardened SCC （self-compacting concrete）. The dune sands are very fine materials characterized by a high intergranular porosity, high surface area and low fineness modulus; on the other hand crushed （manufactured） sand has a high rate into thin and irregular shapes which influence the workability of concrete. The amount of dune sand varies from （0%, 50% to 100%） by weight of fine aggregates. The results show that the rheological properties favour the use of dune sands; however the mechanical properties support the use of crushed sand.
文摘Concrete is multicomponent composite material, consisting of coarse aggregate, fine aggregate, cement and water. Natural aggregates, as well as aggregates obtained after the reprocessing of buildings＇ demolition waste, can be used as coarse and fine aggregates. Characteristics of the hardened concrete depend on the raw materials, used for the preparation of concrete mixture, and their characteristics. The objective of the research is to analyse the sources of demolition waste, to describe the reprocessing technology of concrete waste, to investigate the production of the aggregate from the concrete waste, to analyse the main properties of these aggregates -- particles＇ density, bulk density, granulometric composition, hollowness and other properties, as well as to compare the obtained results with the requirements applicable to the aggregates based on natural materials.
