No abstract

No abstract

Self consolidating concrete (S.C.C.) is a type of concrete which need not be provided any kind of external work for compaction and gets consolidated by own weight and thereby providing a lot of economic and technical benefits. It flows under own weight to completely fill forms and pass without segregation, through closely spaced reinforcement. Alccofine is a pozzolanic material and the ultrafine particles of Alccofine provide better workability, strength as well as the economy. Properties of M40 S.C.C. control mix was compared with S.C.C. mixes incorporating 1% of glass fiber and replacing different percentages (0%, to 15% by weight) of cement with Alccofine was studied. Optimum replacement of cement was assessed by studying properties in the fresh state and in the hardened state, and then comparing results with properties of control mix. Fresh state properties of S.C.C. were assessed by L box test, slump-flow test and V funnel test. Compressive strength, flexural strength, and splitting tensile strength tests were done to assess hardened state properties. Properties of S.C.C. in Fresh and hardened state were seen to be enhanced by addition of Alccofine and Glass fiber.

No abstract

Concrete is a composite construction material composed of cement, fine aggregate, coarse aggregate and water. Aggregate occupy 70-75% of the total volume of concrete. Concrete is designated as "high strength concrete" on the basis of its compressive strength measured at a given age. Concrete mix that show 40MPa or more compressive strength at 28-days are designated as high-strength concrete. Now a days, 60-100 MPa concrete mixes are commercially developed. Unfortunately, production of cement involves emission of large amounts of carbon-dioxide gas a major contributor for green house effect and global warming. Hence it is inevitable to search either for a substitute to cement or partially replace it by some other material. Mineral admixtures such as blast furnace slag powder can be used as partial replacement to cement by 5 to 30%. From earlier days onwards river sand is used as fine aggregate. Nowadays, M-sand, pit sand etc. are also used. Since pit sand is available only at certain regions and due to the scarcity of river sand and M-sand, it has become necessary to find an alternative material, as fine aggregate. The alternative material selected here is fine aggregate from Weathered Crystalline Rock. This type of rock is abundantly available at low cost in tropical areas. This paper discusses the fresh state & mechanical properties of high strength concrete using weathered crystalline rock sand as fine aggregate.