P. R. Kannan Rajkumar ¹, P. T. Ravichandran ¹, J. K. Ravi ¹, L. Krishnaraj ¹

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur - 603203, Tamil Nadu, IN

Abstract

Background/Objectives: Cement particles disperse due to the flow character of the cement paste which also controls the quality of concrete. Cement particles also disperse due to the addition and action of Super-plasticizers (SPs) and this influences the high fluid paste behaviour. In the development of High Performance Concrete the Super-plasticizers and mineral admixtures such as fly ash plays an important role. SPs are normally adsorbed on the cement particles and sometimes the adsorption will not be even and slightly erratic. This is due to the clinker composition of cement and the type of SP used. Various combinations of materials including mineral admixtures affect the behaviour of the cement–based system and become incompatible like slump loss, delayed setting of concrete etc. Methods: In this study an attempt is made to explore maximum benefits of the compatibility between cement, Fly-ash and super-plasticizers (SP). The Flow table and marsh cone tests were conducted to determine the optimum dosage of the mixture. The different combination was tried in the cement mortar and the improvements in compressive strength were studied. Findings: Results show that the cement with 20% Fly-ash has the better compatibility with Poly carboxylate ether with optimum dosage of 0.9% by weight of cement. Improvement: The investigation shows that the polycarboxylate type superplasticizer has better compatibility with the different types of cement considered in this study.

Keywords

Flyash, Flow Table, Marsh Cone, Poly Carboxylate Ether, Super-Plasticiser.

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U. P. Vijay ¹, P. R. Kannan Rajkumar ², P. T. Ravichandran ²

Affiliations
1 Engineering Manager, EDRC, L&T Construction, Chennai - 600025, IN
2 Department of Civil Engineering, SRM University, Kattankulathur – 603203, Tamil Nadu, IN

Abstract

The study investigates the effect of ViscoElastic (VE) dampers on the overall increase in damping ratio of RCC structure significantly and hence improving the global performance of dynamically sensitive structures. A parametric study is carried out on the proposed Hospital building located at Delhi using VE dampers. The building is chosen such that it is a life line structure and located in a highly seismic prone zone. Finite element analysis was employed using the program ETABS version 9.7.2. In order to show the effectiveness of damper a comparative study on the lateral load resisting behavior between bare(without damper) and damped structures has been studied analytically. The brace type damping mechanism has been modeled as a linear spring and dash-pot in parallel for the ViscoElastic damper. The earthquake events used in this study has been applied as response spectrum acceleration. A number of analyses were carried out to gain a comprehensive understanding of the effectiveness of strategic damper placement in this structure to achieve maximum damping ratio. This study indicates that the dynamic characteristics of ViscoElastic damper have improved the damping ratio additionally by 2% when compared to RCC structure. The effectiveness of adding the ViscoElastic damper reduced the seismic response (drift, displacement, shear and overturning moment) of the structures to about 4 to 20% and control of seismic responses facilitates the optimum design of shear wall without increasing the size of walls by which the net floor area increases about 0.5%.

Keywords

Damping Ratio, Response Spectrum Analysis,ViscoElastic Dampers

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V. Umamaheswaran ¹, C. Sudha ¹, P. T. Ravichandran ², P. R. Kannan Rajkumar ¹

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur – 603203, Tamil Nadu, IN
2 Department of Civil Engineering, SRM University, Kattankulathur – 603203, Tamil Nad, IN

Abstract

Due to rapid development in urban area, use of high strength concrete in the construction industry is increasing rapidly. Mineral admixtures such as Ground Granulated Blast furnace Slag (GGBS), Metakaolin, Silica fume and Alccofine are become unavoidable in high strength concrete because of their effects in hardened concrete properties. Replacing the Ordinary Portland Cement (OPC) by mineral admixtures is retaining the natural resources for future generation. In present scenario, replacement of river sand with manufactured sand is almost mandatory due to scarcity of the river sand. Superplasticizers are used to improve the workability of concrete at low water-cement ratio and increase the compressive strength by reducing it. In urban infrastructure development, the high strength concrete is mandatory to reduce the size of structural member, and to increase the utility space to carry heavier load. In this study M100 grade concrete mix was designed with replacement of OPC by different types of mineral admixtures using river sand and manufactured sand along with Polycarboxylate Ether (PCE) based superplasticizer. The Compressive strength, flexural strength and split tensile strength at various curing periods such as 28 and 56 days. The durability properties such as Rapid Chloride Penetration test, Water penetration test and water absorption test were carried out on the specimens at 28 and 56 days. Also, the Drying shrinkage of the concrete was tested at 14 days. From the experimental test results it is observed that, all the mixes were achieved the target mean strength, among these the Alccofine with Manufactured sand combination has achieved 21% higher than the target strength at age of 56 days and other strength parameters such as split tensile and flexural strength also slightly increased in this combination comparatively. The durability tests (Rapid chloride penetration, water penetration and drying shrinkage) were conducted and the obtained values at the age of 56 days are within permissible limit as per the codal provisions and the concrete with manufactured sand shows slightly higher value than concrete with river sand.

Keywords

Alccofine, Durability, High Performance Concrete, High Strength Concrete, M Sand, Metakaolin, Silica Fume

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Bobby A. Mathew ¹, C. Sudha ¹, P. R. Kannan Rajkumar ¹, P. T. Ravichandran ¹

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur – 603203, Tamil Nadu, IN

Abstract

This paper focuses on the analytical and experimental investigations carried out on the tensile properties of High Strength Steel Fibre Reinforced Concrete (HS-SFRC). The steel fibres used here are circular double-end hooked steel fibres and the grade of concrete used is M60. The High Strength concrete is prepared using Silica Fume and Fly Ash as admixtures, along with a Super Plasticizer. The direct tensile tests have been carried out on specimens with different fibre combinations, viz., 0.5% and 1% as well as controlled concrete specimens. The analytical investigations were carried out using the Finite Element Analysis software ABAQUS (Version 6.10). The steel fibres were modelled using the geometry module before distributing and orienting them vertically based on the calculated fibre composition along critical failure zones identified within the concrete specimen. The plain concrete specimen was assigned a linear elastic property prior to analysis. Another model with a homogenous material property has also been generated and analysed for tensile loading. The results obtained from analysis were correlated using the experimental results.

Keywords

Fibre Volume Fraction, Heterogeneous Modelling, High Strength Steel Fibre Reinforced Concrete, Hooked Steel Fibres, Ultimate Tensile Strength

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C. Sudha ¹, K. Divya Krishnan ¹, P. T. Ravichandran ¹, P. R. Kannan Rajkumar ¹

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur, Chennai - 603203, Tamil Nadu, IN

Abstract

Background/Objectives: The construction industry mainly aims at sustainable construction with the available natural resources by reducing the negative environmental impacts on environment. Over a period of time, the scarcity of fine aggregate has become one of the most complex and challenging problem in the construction field. In India, the escalation in the price of natural river sand leads to the demand in the alternate construction material by considering Manufactured Sand (M sand) as a fine aggregate which solve the problem of scarcity. The focus of the present investigation is to assess the potential of using Manufactured sand as a replacement to fine aggregate in M60 grade concrete. Fly ash and silica fume also used to reduce the cement content and as a voids filler material. Methods Statistical Analysis: In the present investigation, it is aimed at to study 0, 25, 50, 75 and 100% of traditional fine aggregate replaced with M- sand. The test results are obtained by conducting compressive strength test, split tensile strength test and flexural strength test after 3, 14, 28 and 60 days of curing. Findings: The strength characteristics of concrete shows higher its strength with the partial and 100% replacement of M-sand in fine aggregate for all the curing period studied. An increase of 6.27% and 14.65 % in compressive and split tensile strength is observed by the full replacement of river sand with M- sand at the curing period of 28th day. Application/Improvements: Use of Manufactured sand in high strength concrete serves better alternative for the river sand. The utilization of manufactured sand in concrete as fine aggregate reduces the problem in scarcity of natural sand and reduces the time delay and cost of the construction.

Keywords

Compressive Strength, High Strength, Manufacatured Sand, River Sand.

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L. Krishnaraj ¹, P. T. Ravichandran ¹, P. R. Kannan Rajkumar ¹, P. Keerthy Govind ¹

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur - 603203, Tamil Nadu, IN

Abstract

Background/Objectives: The cement industry is seeking ways to reduce the energy resource consumption and environmental load due to cement production. The usage of Supplementary Cementitious Material (SCMs) as a partial replacement of ordinary Portland cement can reduce its environmental load as well as the reduction in construction cost. Methods: In this work it is intended to analyze the mortarcube compressive strength by replacing the cement by 50% of Raw Fly ash and Sieved fly ash, with silica 10, 30% with 12 M Sodium Hydroxide and with and without the addition of lime 10, 30% in one series. Similarly, another set of studied with the ratio of 1:2.5 Sodium Hydroxide 12 M and Sodium Silicate asalkali activators to know the characteristics of the modified mortar. The mortar specimens curedin oven for 24 hrs at 60°c and then left for air curing for predetermined ages at 3, 7, 14, 28 days of curing. The micro structural test was conducted to know their morphological characteristics, particle size and their chemical compositions of cement, Raw fly ash and Sieved fly ash. Findings: Results from the work showed that modified mortar prepared using Sieved fly ashgave 9% increase in compressive strength than RFA. The higher percentage of replacements oflime is observed to increase the strength of Sieved Fly Ash (SFA) mortars. SEM results show that SFA sample taken at different resolution indicate smallest particle size to be 106.4 nm, and EDX results show that reducing the particle size has reduced the carbon content by 10% improved the properties of fly ash. Application/Improvements: Use of sieved fly ash, increases the strength in geopolymer properties is more advantageous in the construction industry for utilizing the fly ash in largequantity and thereby reducing the use of cement content also minimize the CO2 emission during the production in the cement industry.

Keywords

Alkali Activated Mortar, Compressive Strength, Nano Structure Materials, Oven Curing, Sieved Fly Ash

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P. T. Ravichandran ¹, K. Divya Krishnan ¹, Manisha Gunturi ¹, C. Sudha ¹, P. R. Kannan Rajkumar ¹

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur - 603203, Tamil Nadu, IN

Abstract

Background/Objectives: Problematic soils cause more damage to structures which are resting over it due to less strength to support the loads acting on them during the construction as well as in service periods. A proper treatment of the subgrade soil is required for providing a stable working area for the construction of structures. In geotechnical point of view, soil stabilization with suitable admixtures fulfils the improvement in the soil characteristics for construction of foundation for light structures and pavements. Methods/Statistical Analysis: In this study an attempt is made to analyse the effect of soil stabiliser RBI grade 81 on two different soils treated with varying percentages of admixture for different curing periods. The strength properties are studied by conducting the UCC and CBR test for treated soils with 2%, 4% and 6% of RBI for specific curing of 7, 28 and 60 days. Microstuctural studies by Scanning electron microscopy had done on untreated and treated soils shows the relevant structural changes which promotes the strength attainment with the addition of admixtures while curing period increases. Findings: This study shows a substantial improvement in problematic soils by treated with RBI grade 81 shows the increasing value of UCC ranging from 1.5 to 11 times and California Bearing Ratio values shows an increase of 65% and 41% from 2% and 2.19% for the both the soils with the addition of 6% RBI additives at the curing period of 60 days. Improvement/Applications: Use of RBI 81 in soil stabilisation renders a better stabilizing agent making the soils capable of meeting the constructional requirements with improved engineering properties.

Keywords

CBR, RBI 81, Soil Stabilisation, UCS

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K. Francis Yakobu ¹, P. T. Ravichandran ¹, C. Sudha ¹, P. R. Kannan Rajkumar ¹

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur - 603203,Tamil Nadu, IN

Abstract

Limestone and clay which are the major ingredients of the cement production are non-renewable resources. Therefore, it is essential to identify a sustainable material to replace cement. The by-product from the steel plant is subsequently granulated to desired fineness and is termed as Ground Granulated Blast furnace Slag (GGBS). Superplasticizers (SP) are used to improve the workability of concrete at low water-cement ratios and increase the compressive strength by reducing it. But, this workability is sometimes lost rapidly as time progresses after contact between the cement and water. Therefore, it is necessary to understand the mechanisms that influence the cement-super plasticizer interaction for selecting an appropriate type of admixture at an optimum dosage. In this present research the compatibility study, between six combinations of cement using different percentages of GGBS with two different SPs were investigated. The optimum dosage was found using marsh cone test. The cement mortar flow test was conducted to find out the setting time and compressive strength of the mortar. It is found that the increase in addition of GGBS decreases the dosage of Superplasticizers to achieve the desired workability. The target mean strength of the M40 concrete was achieved with replacement of 50% GGBS using PCE based SP.

Keywords

GGBS, Saturation Dosage of SPs, Slump Retention

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L. Krishnaraj ¹, P. T. Ravichandran ², P. R. Kannan Rajkumar ²

Affiliations
1 Department of Civil Engineering, SRM University, Kattankulathur - 603203, Tamil Nadu, IN
2 Department of Civil Engineering, SRM University, Kattankulathur - 603203, Tamil Nadu

Abstract

Background/Objectives: Many synthetic additives have been using for improve cement mortar and concrete characteristics, but natural additive is a friendly environment option.In this work, the attempt is made to study, to reduce the pollution from cement production and other materials used in the construction by replacing of Secondary Cementitious Materials. Methods: In this study, the effects of cementitious materials like Ultra-Fine Fly Ash (UFFA) and Nano Silica (NS) on strength development, water permeability of mortar and the optimum use of UFFA and NS in mortars are investigated. Class C Fly Ash which is used as partial replacement of cement was subjected to ball milling for a total duration of 2 hours to obtain UFFA. The NS is a by product obtains from the silicon industries are also used as a replacement material of cement. Cement was partially replaced with four percentages (15%, 30%, 45% and 60%) of UFFA and NS by weight. The specimens used to determine the compressive strength and split tensile strength at the age of 3, 7, 14 and 28 days. Crystallite phase and grain size of UFFA and NS were determined by using X-ray diffraction test and the shape and texture was studied using SEM analysis. Findings: The test results show that strength increases with increase of secondary cementitious materials up to 30% of replacements of cement. Test results indicates that the physical, chemical, mechanical and durability properties of the cement are also enhanced with the influence of the secondary cementitious material. Application/Improvements: Increase in use of fly ash in cement mortar in the construction industry reduces the consumptions of cement as well as the cost of construction.

Keywords

Compressive Strength, Durability Properties, Fly Ash, Micro Structural Study

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