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Results from 45 bond tests conducted using the so-called direct tension pullout specimen type are presented. Anchorages of steel bars with machined deformations were tested so as to enable a targeted study of the straight bar, bent-up bar and headed bar on bond behaviour, tests were conducted with or without the combined presence of external confinement over the embedded length. The novel specimen form presented in the paper was designed to simulate the state of stress and strength arising in usual bar anchorages in the tension zones of flexural members where both cover concrete and bar are stressed in tension. This development was motivated by the need to eliminate spurious influences of the test setup on specimen behaviour, which are known to interfere with bond mechanics. Additional parameters studied in the experimental program were the development length, the cover thickness, the effect of confinement, and the tensile strength of concrete.
This Paper Presents the Compressive strength of high performance concrete with the replacement of cement with Alccofine and Fly ash, and also with natural sand to manufactured sand. The necessity of high performance concrete is increasing because of demands in the construction industry. Efforts for improving the performance of concrete over the past few years suggest that cement replacement materials along with Mineral & chemical admixtures can improve the strength and durability characteristics of concrete. Alccofine (GGBS) and Fly ash is pozzolanic materials that can be utilized to produce highly durable concrete composites. The concrete specimens were cured on normal moist curing under normal atmospheric temperature. The compressive strength was determined at 3, 7 and 28 days. The addition of Alccofine shows an early strength gaining property and that of Fly- ash shows long term strength. The ternary system that is Ordinary Portland cement-fly ash-Alccofine concrete was found to increase the compressive strength of concrete on all ages when compared to concrete made with fly ash and Alccofine alone.