A. S. Santhi

Bio: A. S. Santhi is an academic researcher from VIT University. The author has contributed to research in topics: Fly ash & Compressive strength. The author has an hindex of 9, co-authored 21 publications receiving 207 citations. Previous affiliations of A. S. Santhi include A.V.V.M Sri Pushpam College.

Effect of Ternary Cementitious system on compressive strength and resistance to Chloride ion penetration

Abstract: Portland cement is a highly energy intensive material. Therefore, considerable effort is being made to find substitutes for partial replacement of cement in concrete. This paper reports the results from experimental studies on the compressive strength and resistance to chloride ion penetration of concrete containing ternary blends of Portland cement, silica fume (SF) and wide range of fly ash (FA) Class C fly ash is used in this study in various proportions (i.e.) 30%, 40% and 50% and that of silica fume by 6% and 10% by weight of cement. The mix proportions of concrete had constant water binder ratios of 0.4 and super plasticizer was added based on the required degree of workability. The concrete specimens were cured on normal moist curing under normal room temperature. The compressive strength was determined at various ages and the resistance to chloride-ion penetration was measured at different ages up to 90 days. The results indicate that the concrete made with these proportions generally show excellent fresh and hardened properties since the combination is somewhat synergistic. The addition of silica fume with fly ash was found to increase the compressive strength of concrete at early age when compared to concrete made with fly ash alone. Moreover the incorporation of fly ash and silica fume in concrete increases the resistance to chloride ions and produced concrete with low permeability.

Empirical Relationship between the Impact Energy and Compressive Strength for Fiber Reinforced Concrete

Abstract: In this study, an empirical relationship between the impact energy and compressive strength is developed using regression analysis. For this, simple, practical, and economical drop weight test was performed on fiber reinforced concrete which was based on the testing procedure recommended by ACI committee 544. Crimped steel fiber of 50 mm length and an aspect ratio of 50 was used as the reinforcing material in four different volume fractions such as 0%, 0.5%, 1.0% and 1.5% with water cement ratio of 0.42. The test results indicated that increasing volume fraction of fiber increased the impact resistance of concrete specimen. It is also found that the empirical relationship obtained from the regression analysis is accurate and preferable to evaluate the impact energy by using compressive strength of fiber reinforced concrete thus eliminating the drop weight test.

Simulation of Brick Infill and Effect of Openings on RC Frames Using ANSYS

Abstract: An infill frame is defined as a dual system, which consists of bricks or concrete blocks filling the inter-planar voids between lower and upper beam and space between side columns of reinforced or steel frame. Despite the fact that infill enhances both strength and stiffness of the moment resisting frames; their role is ignored in the design due to insufficient knowledge of the composite behaviour of infill and frames. It is credible, that a major portion of the lateral load is shared by the infill. This paper deals with translating existing experimental data into analytical methods. To understand the behaviour of brick masonry, a G+1 structure was modelled in ANSYS and results were obtained. The present study is also aimed at finding the effect of openings in brick walls and captive column effect. When infill walls are omitted in the bottom storey, a soft storey is formed compared to stiffer stories at top. By response spectrum analysis it has been proved that the structural time period for frame with infill decreases by 2 to 3 times compared to frames without infill. The results showed that the soft storey building frame attracts 40% more shear force than frame excluding soft storey effect. The variation in time period at different mode shapes, with and without infill is presented in the paper. The phenomenon of captive column was replicated and formation of short column is shown in the pilot study.

Study on Strength Development of High Strength Concrete Containing Fly ash and Silica fume

Abstract: This paper presents the results of an experimental investigation carried out to evaluate the compressive strength of High Strength Concrete. High Strength Concrete is made by partial replacement of cement by fly ash (FA) and silica fume (SF). In this study the Class C fly ash used in various proportions 30%, 40% and 50% and that of silica fume by 6% and 10% by weight of cement. The mix proportions of concrete had a constant water binder ratio of 0.4 and super plasticizer was added based on the required degree of workability. The total binder content was 450 kg/m. The concrete specimens were cured on normal moist curing under normal atmospheric temperature. The compressive strength was determined at various ages up to 90 days. The results indicate the concrete made with these proportions generally show excellent fresh and hardened properties since the combination is somewhat synergistic. The addition of silica fume shows a early strength gaining property and that of fly ash shows a long term strength. The ternary system that is Portland cement-fly ash-silica fume concrete was found to increase the compressive strength of concrete on all age when compared to concrete made with fly ash and silica fume alone.

A self-reinforced cementitious composite for building-scale 3D printing

Abstract: A design scheme for self-reinforced cementitious composites to be used for building-scale 3D printing processes is introduced. The design is based on that of engineered cementitious composites, which include dispersed short polymer fibers to generate robust tensile strain-hardening. The mechanical property profile of these printable ECC materials is meant to eliminate the need for steel reinforcement in printed structures, providing more freedom and efficiency for building-scale 3D printing processes. The fresh state rheological properties have been systematically manipulated to allow printability. Effects on fresh state workability of several compositional ingredients and processing parameters are investigated herein. To maintain consistent printing performance with a batch mixing approach, thixotropy in the fresh state is exploited to temporarily decouple hardening behavior from the processing timeline. Minimal workability loss under continued shear agitation is achieved. Mechanical properties of the printable materials are characterized and the printability of the materials is demonstrated.