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CONTENTS
Volume 6, Number 1, February 2018
 

Abstract
An experimental investigation has been carried out on the use of an environmentally sustainable material, bamboo, in the construction of precast concrete structural wall panels. The strength and behaviour of three prototype bamboo reinforced concrete wall panel specimens under two-way in-plane action was studied. The specimens with varying aspect ratio and thinness ratio were tested to fail under a uniformly distributed in-plane load applied at an eccentricity of t/6. The aspect ratio of the specimens considered includes 1.667, 1.818 and 2 and the thinness ratio includes 12.5, 13.75 and 15. The influence of aspect ratio and thinness ratio of bamboo reinforced concrete wall panels, on its strength and behaviour was discussed. Varnished and sand blasted bamboo splints of 20 mm width and thickness varying from 8 to 15 mm were used as reinforcement in concrete. Based on the study, an empirical equation was developed considering the geometrical parameters of bamboo reinforced concrete wall panels for predicting its ultimate strength under two way in-plane action.

Key Words
bamboo reinforced concrete; two way; in-plane action; wall panels; slenderness ratio; aspect ratio; thinness ratio

Address
N. Ganesan, P.V. Indira and P.R. Himasree: Department of Civil Engineering, National Institute of Technology Calicut, 673601, Kerala, India

Abstract
In the present investigation, influence of various material parameters on the cavitation erosion resistance of concrete was investigated on the basis of laboratory experiments. As there is no wellestablished laboratory test method for evaluating the cavitation resistance of concrete, a test set up called \'cavitation jet\' was specially established in the present study in order to simulate the cavitation phenomenon experienced in the hydraulic structures. Various mixtures of concrete were designed by varying the grade of concrete, type and quantity of pozzolana, type of aggregates and cement type to develop good cavitation resistant concrete constructed using marginal aggregates. Three types of aggregates having three different Los Angeles abrasion values (less than 30%, between 30% and 50% and more than 50%) were employed in this study. To evaluate the cavitation resistance a total of 60 cylindrical specimens and 60 companion cubes were tested in the laboratory respectively. The results indicate that cavitation resistance of concrete degrades significantly as the L.A. abrasion value of aggregates goes beyond the 30% value. Incorporation of pozzolanic admixtures was seemed to be beneficial to enhance the cavitation resistance of concrete. Influence of other material parameters on the cavitation resistance of concrete was also noted and important observations have been made in the paper.

Key Words
hydraulic structures; concrete; cavitation erosion; material properties

Address
G.B. Ramesh Kumar and Umesh Kumar Sharma: Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee, India
Arjit Bhardwaj: Department of Civil Engineering, Punjab Engineering College, Chandigarh, India

Abstract
This paper investigates the effect of inclusion of glass fibers on mechanical and fracture properties of binary blend geopolymer concrete produced by using fly ash and ground granulated blast furnace slag. To study the effect of glass fibers, the mix design parameters like binder content, alkaline solution/binder ratio, sodium hydroxide concentration and aggregate grading were kept constant. Four different volume fractions (0.1%, 0.2%, 0.3% and 0.4%) and two different lengths (6 mm, 13 mm) of glass fibers were considered in the present study. Three different notch-depth ratios (0.1, 0.2, and 0.3) were considered for determining the fracture properties. The test results indicated that the addition of glass fibers improved the flexural strength, split tensile strength, fracture energy, critical stress intensity factor and critical crack mouth opening displacement of geopolymer concrete. 13 mm fibers are found to be more effective than 6 mm fibers and the optimum dosage of glass fibers was found to be 0.3% (by volume of concrete). The study shows the enormous potential of glass fiber reinforced geopolymer concrete in structural applications.

Key Words
geopolymer concrete; glass fiber; fracture properties; flexural strength

Address
M.S. Midhun, T.D. Gunneswara Rao and T.Chaitanya Srikrishna: Department of Civil Engineering, National Institute of Technology Warangal, Telangana, India

Abstract
This article reports the utilization of fly ash (FA) waste product from industry and silpozz which is an agro-waste from agriculture as an environmental friendly material in construction industry. The evaluation of strength and durability study was observed using FA and silpozz as a partial replacement of Ordinary Portland Cement (OPC). The studied parameters are compressive strength, flexural strength, split tensile strength and bond strength as well as the durability study involves the acid soluble chloride (ASC), water soluble chloride (WSC), water absorption and sorptivity. Scanning electron microscopy (SEM) and XRD of selected samples are also done. It reveals from the test results that the deterioration factor (DF) in compressive strength is 4% at 365 days. The DF of split tensile strength and flexural strength is 0.96% and 0.6% at 90 days respectively. The minimum slip is 1mm and 1.1mm after 28 days of testing bond strength for NWC and SWC sample respectively. The percentage decrease in bond strength is 10.35% for 28 days SWC samples. The pre-cast blended concrete samples performed better to chloride diffusion. Modulus of elasticity of SWC samples are also studied.The water absorption and sorptivity tests are conducted after 28 days of curing.

Key Words
blended cement concrete; bond strength; fly ash; super plasticizer; silpozz; sorptivity

Address
T. Jena and K.C. Panda: Department of Civil Engineering, Siksha \'O\' Anusandhan (Deemed to be University), Bhubaneswar, 751030, Odisha, India

Abstract
In order to provide sufficient stability and resistance against bleeding and segregation during transportation and placing, mineral admixtures are often used in self-compacting concrete mixes (SCC). These fine materials also contribute to reducing the construction cost and the consumption of natural resources. Many studies have confirmed the benefits of these mineral admixtures on properties of SCC in standard curing conditions. However, there are few published reports regarding their effects at elevated curing temperatures. The main objective of this study is to investigate the effect of three different mineral admixtures namely limestone powder (LP), granulated blast furnace slag (GS) and natural pozzolana (PZ) on mechanical properties and porosity of SCC when exposed to different curing temperatures (20, 40, 60 and 80oC). The level of substitution of cement by mineral admixture was fixed at 15%. The results showed that increasing curing temperature causes an improvement in performance at an early age without penalizing its long-term properties. However the temperature of 40oC is considered the optimal curing temperature to make economical and high performance SCC. On the other hand, GS is the most suitable mineral admixture for SCC under elevated curing temperature.

Key Words
SCC; mineral admixture; curing temperature; mechanical strength; modulus of elasticity; porosity

Address
Boukhelkhal Djamila and Kenai Said : Geomaterials Laboratory, Department of Civil Engineering, University of Blida, Blida, Algeria
Boukendakdji Othmane : LME Laboratory, University of Medea, Medea, Algeria
Kadri El-Hadj : L2MGC Laboratory, University of Cergy Pontoise, Cergy Pontoise, France

Abstract
Utilization of waste tires may be considered as one of the solution to the problems faced by the local authorities in disposing them. Reclaimed rubber (RR) is being used in concrete for replacing conventional aggregates. This research work is focused on the strength prediction of reclaimed rubber concrete using a Genetic Algorithm (GA) for M40 grade of concrete and comparing it with experimental results. 1000 sets were taken and 100 iterations were run during training of GA models. A base study has been carried out in this research work partially replacing cement with three types of fillers such as Plaster of Paris (POP), Fly Ash (FA) and Silica Fume (SF). A total of 243 cubes were cast and tested for compression using a Universal Testing Machine. It was found that SF produced maximum strength in concrete and was used in the main study with reclaimed rubber. Tests were conducted on 81 cube samples with a combination of optimum SF percent and various proportions of RR replacing coarse aggregates in concrete mix. Compressive strength tests of concrete at 7, 14 and 28 days reveal that the maximum strength is obtained at 12 percent replacement of cement and 9 percent replacement of coarse aggregates respectively. Moreover the GA results were found to be in line with the experimental results obtained.

Key Words
Plaster of Paris; fly ash; silica fume; compressive strength; reclaimed rubber; genetic algorithm

Address
Kanmalai C. Williams : Department of Civil Engineering, St. Peter\'s University, Tamil Nadu, India
P. Partheeban : Department of Civil Engineering, St. Peter\'s College of Engineering and Technology, Avadi, Chennai, 600054, India


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