Abstract

In the manufacture of Roller Compacted Concrete Pavement (RCCP) materials, various types of aggregates are used, namely crushed stone as coarse aggregate and river sand as fine aggregate. The main purpose of adding aggregate in RCCP is to achieve higher flexural strength. In the present experimental work, use of manufactured sand(M-Sand) with river sand as partial replacement (50%) was investigated along with the Pozzolanic effect of fly ash on RCC. Six levels of partial replacement of cement with fly ash were considered such as 10%, 20%, 30%, 40%, 50% and 60%. 50% of river sand was replaced with M-Sand. The various strength indices like specific strength (SP_RCC ), specific strength of Pozzolanic effect (SP_FA ), specific strength ratio (R), contribution percentage of Pozzolanic effect to strength (P) and index of specific strength were examined. Finally the results indicate that

• The strength of RCCP at early ages with fly ash and M-Sand (50%) was poor.
• At 90 days of curing, the contribution of fly ash effect to strength of RCCP reaches upto 68%.

Abstract

An analytical study has been carried out to investigate the seismic behaviour of multi-storey buildings resting on normal and sloping grounds in different seismic zones with and without base isolators. Totally 160 multi-storey building models with rectangular configuration in plan of 12 x 16 m size have been analysed. The building models considered ranges from 1 storey height to 10 storey heights, and assumed to be located in seismic zones II, III, IV and V as per Indian standard code under two different terrain conditions viz. plain and sloping grounds with and without seismic base isolators. Response spectrum method of dynamic analysis has been performed using STAAD Pro software for all the building models, and the dynamic response quantities such as fundamental time period, base shear, top floor displacement and inter-storey drift were obtained for all the models. Seismic analysis results of building models indicate that for a given seismic zone and terrain condition, the introduction of seismic base isolators at base level of building increases fundamental natural time period, but reduce base shear, top floor displacement and inter-storey drift of the building. The results also indicate that for a given base (i.e. support) condition and terrain nature the base shear, top floor displacement and inter-storey drift increase as the seismic zone level increases. Furthermore, the results indicate that the introduction of seismic base isolation system at the base of building makes the structure behave like a rigid structure.

Abstract

Strength of concrete had been given more significance in past but no attention was paid on durability of concrete. Further it is recognized that strength of concrete alone is not sufficient. Resistance against harshness of environmental conditions to which the concrete is exposed over its entire design period is also equally important. Generally, permeability is one of the parameters of durability of concrete. At the aggregate-paste interface, porous transition zones are formed which affect the pore size distribution. In the initial stage, micro cracks are so small that may not cause higher permeability. But the drying shrinkage, thermal shrinkage and externally applied load causes propagation of micro cracks with time. Permeability is the responsible factor for volume change. Ca(OH)2, a by-product of hydration of cement paste of concrete can be reduced so that the concrete pore structure is to be densified. Therefore, the present investigations are done on High Volumes of Slag Concrete which consists of Cement: GGBFS in the ratio 50:50. Cylinders were cast for different water binder ratios (0.55 to 0.27). The Chloride permeability is tested for 28 days, 90 days and 180 days of curing. The Chloride permeability was observed to be very less in the case of specimens cured for later ages.

Abstract

As the production of cement increases, its adverse impact on the environment also increases. With cement being the second most consumed substance after water, the need to reduce its production is the need of the hour. Replacement of cement by supplementary cementitious materials results in less usage of cement. In this study, cement is partially replaced with reactive microfine, namely Alccofine and the effect of this replacement on the basic properties like standard consistency, initial setting time, final setting time and compressive strength of cement mortar were analyzed. Addition of Alccofine upto 20% has resulted in increase of compressive strength of the mortar cubes, with consistency and setting time values being within the specified limits.

Abstract

Relative stiffness of beam and column plays an important role in design and analysis of any building. This paper presents the effect of varying stiffness in terms of cross section and moment of area of beam and column, and on shear lag phenomenon. Variation of axial force in the column is affected by the variation of stiffness of beam as well as column. It has been observed that the beam stiffness has more significant impact on the variation of the axial force and base bending moment of the tubular buildings. This impact of the beam stiffness may be understood in the terms of additional bending moment which is generated in the flange panel of the tubular buildings. Effect of increasing column stiffness has increased base bending moment in both flange and web columns due to increased rigidity of the building.