Browsing by Author "Rajeeva, S.V."

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Analysis of shape parameters of coarse aggregate and their effects on packing density by DIP technique
(2006) Nagendra, R.; Dhabale, A.K.; Bai, H.S.; Rajeeva, S.V.
In this paper the particle shape parameters are analysed using a sophisticated technique called Digital Image Processing (DIP). The effects of shape parameters on the packing density are studied. The packing density determines the amount of cement paste required to fill the voids between aggregate particles. In this paper the details of experimental investigations carried out on coarse aggregates are presented. Aggregate samples from seven different sources have been used for experimental investigation. The shape parameters determined by DIP technique are correlated with packing density.
Analysis of shape parameters of coarse aggregate and their effects on packing density by DIP technique
(2006) Nagendra, R.; Dhabale, A.K.; Bai, H.S.; Rajeeva, S.V.
In this paper the particle shape parameters are analysed using a sophisticated technique called Digital Image Processing (DIP). The effects of shape parameters on the packing density are studied. The packing density determines the amount of cement paste required to fill the voids between aggregate particles. In this paper the details of experimental investigations carried out on coarse aggregates are presented. Aggregate samples from seven different sources have been used for experimental investigation. The shape parameters determined by DIP technique are correlated with packing density.
Effect of binder chemistry on sulphate resistance of fly-ash blended cement concrete mixes
(Institute of Physics Publishing helen.craven@iop.org, 2020) Nazeer, M.; Narasimhan, M.C.; Rajeeva, S.V.
The chemical durability of concretes exposed to sulphate environment largely depends on the quality and quantity of products of cement hydration. Certain hydration products are readily reactive with the sulphate ions and form expansive products such as gypsum and ettringite. On the other hand, some sulphate compounds participate in reducing the cementing property of hydration products. These reactions cause expansion and deterioration of strength of concrete. Sulphate resistance of concrete can be improved by the incorporation of Supplementary Cementitious Materials (SCMs). Reduced water-binder ratio and proper curing can make concrete more durable in sulphate environment. This paper reports the details and results of an investigation of effect of chemical composition of binder materials on the sulphate resisting property of concrete exposed to a rich MgSO4 solution. The effect of initial curing is also investigated so that it may be possible to suggest the mix compositions for typical field applications of concrete. The variables investigated in this report are the oxide composition of binder components and the initial curing conditions. A set of concrete mixes, all with a constant binder content and water-binder ratio are used in the investigation. Â© 2020 Published under licence by IOP Publishing Ltd.
High temperature performance of self-compacting high-volume fly ash concrete mixes
(2011) Amrutha; Nayak, G.; Narasimhan, M.C.; Rajeeva, S.V.
Quite often, concrete in structures is likely to get exposed to high temperatures, including an incident of fire. The strength-retention properties of concrete after such an exposure are of great importance in terms of the serviceability of buildings. This paper presents an experimental study on the strength retention and impermeability aspects of a set of self compacting, high-volume fly ash concrete mixes under elevated temperatures. Five selfcompacting concrete mixes with a higher 60% level of cement replacement with fly-ash, are designed and the effects of elevated temperatures, in the range of 200-800 C, on the physical, mechanical and durability properties of these mixes are assessed. The assessment is in terms of the weight losses and the reduction in the compressive strengths of concrete cubes and split tensile strengths of concrete cylinders. The durability characteristics are assessed in terms of RCPT test results on these mixes. Performances of these self compacting concrete mixes (SCC) at elevated temperatures are also compared with two normally-vibrated concrete mixes (NCs) of an equivalent M30 strength grade. Test results indicate that weight of the specimens significantly get reduced with an increase in the level of elevated temperature, with sharp variations beyond 600 C. The experimental results also show that large improvements against chloride-ion penetration and better strength-retention at higher temperatures can be realized with self-compacting high-volume fly-ash concrete mixes additionally admixed with GGBFS and silica fume.
High temperature performance of self-compacting high-volume fly ash concrete mixes
(2011) Amrutha; Nayak, G.; Narasimhan, M.C.; Rajeeva, S.V.
Quite often, concrete in structures is likely to get exposed to high temperatures, including an incident of fire. The strength-retention properties of concrete after such an exposure are of great importance in terms of the serviceability of buildings. This paper presents an experimental study on the strength retention and impermeability aspects of a set of self compacting, high-volume fly ash concrete mixes under elevated temperatures. Five selfcompacting concrete mixes with a higher 60% level of cement replacement with fly-ash, are designed and the effects of elevated temperatures, in the range of 200-800 C, on the physical, mechanical and durability properties of these mixes are assessed. The assessment is in terms of the weight losses and the reduction in the compressive strengths of concrete cubes and split tensile strengths of concrete cylinders. The durability characteristics are assessed in terms of RCPT test results on these mixes. Performances of these self compacting concrete mixes (SCC) at elevated temperatures are also compared with two normally-vibrated concrete mixes (NCs) of an equivalent M30 strength grade. Test results indicate that weight of the specimens significantly get reduced with an increase in the level of elevated temperature, with sharp variations beyond 600 C. The experimental results also show that large improvements against chloride-ion penetration and better strength-retention at higher temperatures can be realized with self-compacting high-volume fly-ash concrete mixes additionally admixed with GGBFS and silica fume.
Study of the properties of SCC with quarry dust
(2009) Gowda, M.R.; Narasimhan, M.C.; Karisddappa; Rajeeva, S.V.
Granite fines or rock dust is a by-product obtained during crushing of granite rocks and is also called quarry dust (QD). This paper deals with using quarry dust as an alternative to fine aggregate (FA) in SCC and reports the strength behaviour and hardened properties of such SCCs. Although in normal concretes, introducing QD increases the water demand, in SCC, it has been successfully used for increasing the deformability and passing ability of fresh concrete. Also, it was noted that by increasing the pouring heights of an SCC, the compressive strength and splitting tensile strength of concrete were unaffected.
Study of the properties of SCC with quarry dust
(2009) Gowda, M.R.; Narasimhan, M.C.; Karisddappa; Rajeeva, S.V.
Granite fines or rock dust is a by-product obtained during crushing of granite rocks and is also called quarry dust (QD). This paper deals with using quarry dust as an alternative to fine aggregate (FA) in SCC and reports the strength behaviour and hardened properties of such SCCs. Although in normal concretes, introducing QD increases the water demand, in SCC, it has been successfully used for increasing the deformability and passing ability of fresh concrete. Also, it was noted that by increasing the pouring heights of an SCC, the compressive strength and splitting tensile strength of concrete were unaffected.