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CONTENTS
Volume 3, Number 3, September 2015
 

Abstract
FRP confining is a widely used method for seismic retrofitting of concrete columns. Several studies investigated the stress-strain behavior of FRP confined concrete prisms with square and rectangular sections both experimentally and analytically. In some studies, the monotonic stress-strain behavior of confined concrete was investigated and compressive strength models were developed. To study the reliability of these models, thorough statistical tests are required. This paper aims to investigate the reliability of the presented models using statistical tests including t-test, wilcoxon rank sum test, wilcoxon signed rank test and sign test with a level of significance of 5%. Wilk Shapiro test was also employed to evaluate the normality of the data distribution. The results were compared for different cross section and confinement types. To see the accuracy of the models when there were no significant differences between the results, the coefficient of confidence was used.

Key Words
compressive strength; statistical tests; FRP confined concrete; square and rectangular sections

Address
Farid Hosseinpour and Adel E. Abdelnaby: Department of Civil Engineering, The University of Memphis, Memphis, TN 38152, USA

Abstract
The present study addresses about the development of sustainable concrete utilizing recycled coarse aggregates manufactured form waste concrete and colloidal Nano-Silica. Experimental investigations are carried out to determine compressive and tensile strength of concrete mixes designed with recycled coarse aggregates and different percentages of Nano-Silica. Moreover, water absorption, density and volume voids of concrete mixes are also examined to ascertain the influence of Nano-Silica on behavior of recycled aggregate concrete. The outcomes of the research depict that properties of concrete mixes are significantly affected with the introduction of recycled coarse aggregates in place of the natural coarse aggregates.However, the study reveals that the depletion of behavior of recycled aggregate concrete could be restored with the incorporation of little amount (3%) of Nano-Silica.

Key Words
recycled aggregate concrete; colloidal Nano-Silica; mechanical properties; water absorption; density; volume of voids

Address
Bibhuti Bhusan Mukharjee: Department of Civil Engineering, Veer Surendra Sai University of Technology,Burla, Sambalpur, Odisha, India
Sudhirkumar V Barai: Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India

Abstract
This paper presents the results of a study undertaken to investigate the enhancement of concrete strength using Silpozz and Rice Husk Ash (RHA). The total percentage of supplementary cementitious material (SCM) substituted in this study was 20%. Six different concrete mixes were prepared such as without replacement of cement with silpozz and RHA (0% silpozz and 0% RHA) is treated as conventional concrete, whereas in other five concrete mixes cement was replaced by 20% of silpozz and RHA as (0% silpozz and 20% RHA), (5% silpozz and 15% RHA), (10% silpozz and 10% RHA), (15% silpozz and 5% RHA) and (20% silpozz and 0% RHA) with decreasing water-binder (w/b) ratio i.e. 0.375, 0.325 and 0.275 and increasing super plasticiser dose. New generation polycarboxylate base water reducing admixture i.e.,Cera Hyperplast XR-W40 was used in this study. The results of this research indicate that as w/b decreases,super plasticiser dose need to be increased so as to increase the workability of concrete. The effects of replacing cement by silpozz and RHA on the compressive strength, split tensile strength and flexural strength were evaluated. The concrete mixture with different combination of silpozz and RHA gives higher strength as compared to control specimen for all w/b ratios and also observed that the early age strength of concrete is more as compared to the later age strength. It is also observed that the strength enhancement of concrete mixture prepared with the combination of cement, silpozz and RHA is higher as compared to the concrete mixture prepared with cement and silpozz or cement and RHA.

Key Words
rice husk ash (RHA); silpozz; compressive strength; flexural strength; split tensile strength

Address
K.C. Panda: Department of Civil Engineering, ITER, SOA University, Bhubaneswar, Odisha, India, 751030
S.D. Prusty: Post Graduate Student, Department of Civil Engineering, ITER,SOA University, Bhubaneswar, Odisha, India

Abstract
Concrete is the most widely used material of construction. Concrete gained the popularity as a construction material due to the easy availability of its component materials, the easy formability, strength and rigidity upon setting and curing.In construction industry, strength is a primary criterion in selecting a concrete for a particular application. Now a days, the substantial amount of waste materials,containing the properties of the Pozzolana, is being generated from the major industries; and disposal of such industrial wastes generated in abundance is also the serious problem from environmental and pollution point of view. On this backdrop, an efforts are made by the researchers for the exploring the possibility utilization of such waste materials in making the sustainable construction material. The present paper reports the experimental investigation to study the strength characterization of the concrete made from the pozzolanic waste materials. For this purpose, the pozzolanic materials such as fly ash and ground granulated blast furnace slag were used as a cement replacing materials in conjunction with ordinary Portland cement. The equal amounts of these materials were used in eight trial mixes with varying amount of cement. The waster cement ratio was also varied. The chemical admixture was also added to improve the workability of concrete. The compressive strengths for 7, 28, 40 and 90 days

Key Words
concrete, strength, pozzolanic materials, fly ash, ground granulated blast furnace slag (GGBFS)

Address
H.S.Chore and M.P. Joshi: Department of Civil Engineering, National Institute of Technology Calicut, Kerala, India

Abstract
Beam-column joints are highly vulnerable locations which are to be designed for high ductility in order to take care of unexpected lateral forces such as wind and earthquake. Previous investigations reveal that the addition of steel fibres to concrete improves its ductility significantly. Also, due to presence of slab the strength and ductility of the beam increases considerably and ignoring the effect of slab can lead to underestimation of beam capacity and defiance of strong column weak beam concept. The influence of addition of steel fibres on the strength and behaviour of steel fibre reinforced high performance concrete (SFRHPC) interior beam-column-slab joints was investigated experimentally. The specimens were subjected to reverse cyclic loading. The variable considered was the volume fraction of crimped steel fibres i.e., 0%, 0.5% and 1.0%. The results show that the addition of steel fibres improves the first crack load, strength, ductility, energy absorption capacity and initial stiffness of the beam.

Key Words
beam-column-slab joint; energy absorption capacity; high performance concrete; high performance steel fibre reinforced cement concrete; reverse cyclic loading; stiffness degradation

Address
N. Ganesana, Nidhi M. and P. V. Indira: Department of Civil Engineering, National Institute of Technology Calicut, Kerala, India

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