By
Kaushal Kishore
Materials Engineer
Roorkee

INTRODUCTION:
SCREENERS companies near Dehradun and elsewhere have set up highly sophisticated as well as, eco-friendly screening and washing plants for the production of uncrushed (Shingle) coarse aggregates and coarse sand direct from river bed. These plants are producing and supplying uncrushed (Shingle) aggregates of sizes 40 mm, 20 mm, 12.5 mm and river coarse sand, which complies to the specifications of
IS : 383-19702.

Our construction sites, particularly Govt. Departments hesitates in the use of uncrushed coarse aggregate as so far they are being supplied to them direct from river bed or by manual sieving without washing them with water. Thus neither they are clean nor properly graded. This draw back is not with the uncrushed aggregates produces and supplied from SCREENERS modern plants with regular quality control. In this booklet the readers will find that when quality uncrushed aggregates are available not only economically but locally, our construction sites particularly Govt. Departments should not hesitate in the use of uncrushed aggregates from the river bed and save our environment, as crusher generate pollution. Further in all the Civil Engineering Codes uncrushed aggregates from river bed has been specified to be used in our all Civil Engineering Construction.
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By
A.K. Jain
Lecturer, Civil Engineering (Selection Grade), S.V. Polytechnic College, Bhopal M.P. 462-002, India

S.S. Goliya
Asst. Professor SATI (Degree) Vidisha M.P.464001, India

Dr. J.S. Chouhan
Professor and Head, Civil Engineering Deptt, SATI (Engineering College) Vidisha, M.P. 464-001, India

Abstract:
This paper presents the laboratory results of the study undertaken to determine the effect of shapes and size of aggregates on porosity, unit weight, strength and permeability of pervious concrete. Shape of aggregate is measured in terms of their angularity number. Angularity or absence of rounding of the particles of an aggregate is a property which is of importance because it affects the porosity, surface area in contact with each other in the matrix of ingredients and ease of handling of a mixture of aggregate and binder. It is a laboratory method intended for comparing the properties of different aggregates for mix design purposes. The result indicates that various properties of pervious concrete vary as a function of angularity number of aggregates used. It is found that for all sizes of course aggregates used in the study, aggregate with less angularity number produce mix with average compressive strength greater then the aggregate with higher angularity number. The study suggest that angularity number of aggregates may be considered as an important parameter in deciding the suitability of course aggregate to prepare pervious concrete mix in order to achieve better strength and permeability.

Keywords:
Angularity number; pervious concrete; compressive strength.
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By
O. James ,P.N.Ndoke and S.S.Kolo
Department Of Civil Engineering, Federal University Of Technology.
Minna.

ABSTRACT
Normal concrete was prepared with a water-cement ratio of 0.50. cube specimens were cast for testing the compressive strength at 7 and 28 days of curing respectively using three curing methods namely immersion, sprinkling and Plastic sheeting, curing to cure the cube specimens until the day of testing. Test results indicates that water curing (WAC) as well as sprinkling (spraying) curing provided much better results than membrane (Plastic Sheeting) method of curing. The rate of drying was significant when the specimens were subjected to membrane (Plastic sheeting) method of curing. This thus hampered the hydration process and thus affected the compressive strength property of the hardened concrete. The overall finding of this study suggests that concrete should be cured by water curing to achieve a better compressive strength.

Keywords:
Curing method, compressive strength, concrete
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By Narasingha Mohanta
(Research Officer, Zonal Laboratory (R&B) Balangir)

Abstract:
IS:10262 is the code specified by Bureau of Indian Standards for Concrete Mix Design. The code came to existence in the year 1982. Keeping pace with the advancing technology the code has been revised in December 2009. Significant changes have been made in the revised version and a brief discussion is presented in this paper comparing the two versions of IS:10262. The basic points where the guidelines have been modified are discussed. Besides one numerical example has been solved using guidelines of both the versions to understand the differences. Though the 2009 version encourages mixing of mineral admixtures to meet greater challenges of modern concreting, a simple example is considered with use of no additives.

Introduction
Mix Design of Concrete is the process of deciding the proportions of the ingredients of concrete so as to be produced most economically, that would satisfy the desired properties of fresh and hardened concrete as well. In simpler words, the concrete should be well workable when fresh and the designed compressive strength as well as durability should be achieved at hardening.
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By
Prof. V.D.Gundakalle, Professor ,Department of Civil Engineering, K.L.E. College of Engineering and Technology, Belgaum, Karnataka, (India)

Prof.Abhishek.S.Pathade, Professor, Department of Civil Engineering, K.L.E. College of Engineering and Technology, Belgaum, Karnataka, (India).

Mubashar Munshi Post Graduation Student, K.L.E. College of Engineering and Technology, Belgaum, Karnataka, (India).

Abstract
The actual earthquake force in considerably higher than what the structures are designed for. We cannot design the structures for the actual value earthquake intensity because the cost of construction will be too high. The actual intensity of earthquake is reduced by a factor called response reduction factor ‘R’. The value of ‘R’ depends on how we design the frame members. From previous study it is noted that the ‘R’ factor depends on ductility factor (Rµ), strength factor (Rs), structural redundancy (RR) and damping associated with structure. The objective of this work is to evaluate the response modification factor (R) for RC elevated water tanks supported on framing system are considered having staging height of 15m and 21m with varying capacities and staging configuration. These tanks are designed for gravity as well as seismic loads. A non-linear pushover analysis is used to calculate the base shear capacity and ductility of tanks. Two different cases of collapse criterion are used for defining ultimate stage on the capacity curve. It is observed that the Rµ are increasing with time period but the variation is not consistent. RS is higher for lower staging height.

Key words
Response reduction factor, Seismic design, static nonlinear pushover analysis
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