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The reinforced concrete slab is a universally accepted technology for roofing and flooring systems. In fact, in recent times, villagers in India have enthusiastically taken to reinforced concrete instead of tiled roofing. However, there are some disadvantages of RC slab which affects its affordability and ecological soundness. The problems may be listed as follows; (a) In RC slab of 12.5 cms thickness, the bottom portion of 6–7 cms will be under tension. Hence, the concrete using a high cement content remains cracked and ineffective. Its only function is to provide a good lever arm between the steel and the centre of compression. (b) Secondly, the in situ nature of concrete slab construction needs an elaborate and time consuming formwork to support the fresh concrete. (c) When the RC slab is used as a roof it picks up a lot of solar heat and radiates it into the interior for several hours after sunset. This can be especially problematic in hot and dry areas. An alternative to the RC slab must explore ways of replacing expensive concrete at the bottom by a less expensive and insulating material. The problem of formwork has to be solved by looking at partial or completely prefabricated components. This study deals with such a solution which may be named as the composite T-beam.

There are innumerable examples of masonry vaults all over the world constructed centuries ago. Perhaps, the builders of those times had some empirical approaches in arriving them. The mechanics of vaults was explored only after the advent of classical theories of structures and elasticity. Later, several researchers contributed to the understanding of vaults. Masonry vaults continue to be adopted in modern construction, both for architectural purposes and to minimize the use of steel and concrete. Also, it uses minimal supporting system. The recent work on stress analysis of masonry cylindrical shells at Indian Institute of Science needs a special mention, whereas the analysis was based on two assumptions, viz. (i) the material is isotropic and (ii) a simple boundary condition at the springing level with no shear. However, it is well known that brick masonry is orthotropic in behaviour due to the nature of disposition of bricks along and across the bed joints. The orthotropic strength and elastic properties of various brick masonry are also now available. Hence, the present study looks at two aspects: (i) adopting the orthotropic properties for the analysis and (ii) modified boundary conditions by considering zero longitudinal displacements at the springing level. The studies were aimed at trying to understand and compare the stress resultants with that of the results from the earlier studies. It has been found that the results are somewhat different, and it is suggested that such an approach is better suited for the current material properties and practices.

Depletion of natural resources and restriction due to environmental considerations leads to scarcity of good quality river sand. Also sand procurement has become a major concern especially in large cities like Bangalore, India. Nearby sources have been exhausted; therefore, it is very essential to optimize the consumption of natural river sand as well as to develop alternative sources. In this paper, an attempt is made to investigate the potential use of filtered sand and its implication as a substitute for river sand in mortar and concrete. Filtered sand is facing the concerns of environmentalist and engineers due to its alleged poor engineering properties, higher clay and silt content, improper or crude methods adopted for filtering the sand etc. If these issues are addressed, then filtered sand may be used as an alternative to river sand, provided the source of filtered sand is from a barren land and not fertile earth. The present investigation deals with the use of filtered sand as an alternative to natural fine aggregates in concrete and cement-mortar. Two types of filtered sand samples (FS-1 and FS-2) available near Bangalore were collected and physical properties of these samples were studied. Natural sand was replaced partially/fully with filtered sand in different percentages of replacement. Specimens of cement mortar in the ratio 1:6 was cast, cured, and tested for determining the density, compressive strength, and modulus of elasticity, while concrete cube specimens with mix proportion 1:1.5:3 were cast to determine its compressive strength, split tensile strength and flexural strength as per the Indian standard code of practice. The results on comparison with those of conventional concrete and cement-mortar specimen indicated that with the usage of filtered sand, the performance of both the concrete and mortar improved.