Influence of aggregate type on strength and abrasion resistance properties of concrete
Aolfazl
Hassani
author
Behrooz
Shirgir
author
text
article
2009
per
This paper investigated the influence of aggregate type on the strength characteristics and abrasion resistance of high strength silica fume concrete. Five different aggregate types (gabbro, basalt, quartzite, limestone and sandstone) were used to produce concrete containing silica fume. Silica fume replacement ratio with cement was 15% on a mass basis. Water-binder ratio was 0.35. The amount of hyper plasticizer was 4% of the binder content by mass. Gabbro concrete showed the highest compressive and flexural tensile strength and abrasion resistance, while sandstone showed the lowest compressive and flexural tensile strength and abrasion resistance. High abrasion resistant aggregate produced a concrete with high abrasion resistance. Three-month compressive strengths of concretes made with basalt, limestone and sandstone were found to be equivalent to the uniaxial compressive strengths of their aggregate rocks. However, the concretes made with quartzite and gabbro aggregate showed lower compressive strength than the uniaxial compressive strength of their aggregate rocks. The results of the current investigation show how aggregate strength limits the compressive and flexural tensile strengths of a concrete, how transition zone strength limits the compressive strength of concrete, and how aggregate types influence abrasion resistance of concrete.
Concrete Research
University of Guilan
2
v.
2
no.
2009
21
30
http://jcr.guilan.ac.ir/article_796_0a8005f5594bd67041f88c6196192646.pdf
Mechanical Characteristics of Concrete with Limestone Powder
A.R.
Habibi
author
text
article
2009
per
In this study, effects of adding limestone powder on mechanical characteristics of concrete are surveyed. Objective of this research is to study interactive effects of water-cement & powder-cement ratios on compressive strength, tensile strength and modulus of elasticity of concrete at the ages of 7, 28 and 90 days. The used samples in the experiment were made using different values of cement and powder. The performed elementary experiments in this research showed that substitution of limestone powder by fine and coarse aggregate in concrete simultaneously, has the good improvement on mechanical characteristics of concrete. The results of experiments showed that addition of limestone powder to concrete has variative effects on mechanical characteristics of concrete and in high values of water-cement ratios, increasing compressive strength of concrete can be expected by adding powder to concrete.
Concrete Research
University of Guilan
2
v.
2
no.
2009
71
84
http://jcr.guilan.ac.ir/article_797_0a8005f5594bd67041f88c6196192646.pdf
Evaluation Mechanical Properties and Durability of Concretes incorporating Rice Husk Ash (RHA)
mehdi
mehdikhani
author
Ali Akbar
Ramezanianpour
author
pouya
Pourbeik
author
GholamHosein
Ahmadibeni
author
text
article
2009
per
There are several years that concrete has exhibited particular roles as most consuming materials among civil engineers. Through these years, several factors in concrete have been studied. Durability of concrete is one of these factors that affect the service life of concrete structures. Recently, the properties of Rice Husk Ash (RHA) as high-quality artificial pozzolanic materials are important issues that specialists are concerned with, especially in East Asia and North America. It is not widely produced and used due to lack of adequate experiments on this material. In this research, in order to supply typical RHA, for the first time in the Middle East, an special furnace was designed and constructed in Amirkabir University of Technology. This furnace was built in a pilot size having the ability to control the conditions of combustion. Then various experiments were carried out to determine mechanical properties and durability of concretes incorporating RHA. The results show that RHA as an artificial pozzolanic material has increased the strength and durability of concretes.
Concrete Research
University of Guilan
2
v.
2
no.
2009
http://jcr.guilan.ac.ir/article_798_0a8005f5594bd67041f88c6196192646.pdf
Probabilistic modeling of civil engineering problems with Monte Carlo simulation
Jafar
Sobhani
author
text
article
2009
per
Modeling of the problems in engineering scienc -es requires some effective tools that reliably predict the governing behaviors. In this paper, the Monte-Carlo Simulation (MCS) is introduce -ed as one of the most effective numerical methods for the simulating of the complex problems in the civil engineering area. The MCS, through the generation of the random numbers and probabilistic analysis is capable to simulate the experimental tasks in the environment of personal computers which reliably predicts the behavior of considered problems. Moreover, the application of MCS in the probabilistic failure analysis of civil enginee -ring problems such as structural analysis and the service life prediction of reinforced concrete structures were explained.
Concrete Research
University of Guilan
2
v.
2
no.
2009
59
70
http://jcr.guilan.ac.ir/article_799_0a8005f5594bd67041f88c6196192646.pdf
Investigation and Comparison of Brick Infilled Frames with Shear Walls in Elevated Concrete Structures as Shear Connective Member
M.
Khanzadi
author
Amin
Massoumi Goudarzi
author
Morteza
Zahedi
author
text
article
2009
per
In the past years, use of infilled frames had only been confined as filler and separator while its major role neglected for the amendment of vibration behavior of structures through earthquakes occurrence. Though, since 1967, some researches have been accomplished by Benjamin, Malik, Dow & Young, Zarnik, Moghaddam and Shahian et al.
that could stride fundamental steps to introduce the application of the rigidity and dynamic specifications of composite system of infilled frame-shear wall on the vibration behavior of structures through earthquakes occurrence. The researches can also be applied for the strengthening and optimization of available structures.
In this research, additionally to take into account the criteria which to be observed for executing infilled frames, four 20-story reinforced concrete buildings with bending frame system consisting shear walls and infilled frames (composite system of infilled frame-shear wall) are modeled in accordance with the Iranian common codes by ETABS (V 9.0.1) software which has the ability of modeling of historic behavior of reinforced concrete members and infilled frames Results of this research in 28 curves show that the application of composite system of infilled frame-shear wall can positively affect the dynamic behavior of the structure especially within higher stories and can distribute forces onto the stories.
Use of infilled frames within higher stories causes
to absorb lateral forces and hence those forces are less transported to the beams and columns. Accordingly, displacements are reduced within the higher stories therewith. Right in where shear wall can not reduce the displacement by its modal change, composite system of infilled frame-shear wall especially within higher stories will have an essential role for improving vibration behavior of frames.
Concrete Research
University of Guilan
2
v.
2
no.
2009
45
58
http://jcr.guilan.ac.ir/article_800_0a8005f5594bd67041f88c6196192646.pdf
EFFECT OF PASTE VOLUME ON WORKABILITY OF SELF-COMPACTING CONCRETE
M.
Tadaion
author
M.
Khanzadi
author
Gholamreza
Ghahremani
author
text
article
2009
per
In addition to influential parameters on rheology of Self-compacting concrete such as paste rheology and aggregate properties, paste volume factor can also be mentioned. The paste present in Self-compacting concrete can decrease interparticle friction of aggregates by increasing the distance between them, thus changing the fresh and hardened properties of Self-compacting concrete. Here by keeping the water cement ratio equal to 0.45, aggregates grading, admixture cement ratio percent, vma cement ratio percent fixed and only by changing the consumed paste volume, we assessed the effect of paste volume on workability of eight samples of Self-compacting concrete. Workability of different mixtures were assessed by undergoing slump-flow, j-ring, l-box (without bar), l-box, u-box, v-funnel and v-funnel (after 5 min) tests. Results in the mentioned range show improvement on workability of Self-compacting concrete due to increase of paste volume
Concrete Research
University of Guilan
2
v.
2
no.
2009
97
106
http://jcr.guilan.ac.ir/article_801_0a8005f5594bd67041f88c6196192646.pdf
Limitation of equation for prediction the ultimate capacity of RC beams strengthened with CFRP in the case of premature failures
hamid
Varastepour
author
text
article
2009
per
In recent years, the method of external bonding of carbon fiber reinforced polymer (CFRP) is used for retrofing and strengthening of reinforced concrete beams. To determine the ultimate capacity of these beams we can\'t use classical method because of failure mode, nonlinear behavior of material and interface effect. For calculating load capacity, determination of premature failure mode is very important. In this paper we present a method to determine premature failure mode and ultimate capacity of RC beams strengthened with CFRP. Also we dispute about the limitations of applica -tion of proposed equation.
Concrete Research
University of Guilan
2
v.
2
no.
2009
85
95
http://jcr.guilan.ac.ir/article_802_0a8005f5594bd67041f88c6196192646.pdf
The role of nano-particles in sustainable development of concrete industry
Payam
Hosseini
author
hadi
Bahadori
author
ebrahim
Eslami
author
text
article
2009
per
Most of the environmental investigators believe that the recent changes in climatic condition around the world arise from greenhouse gases. The detrimental effect of these gases on ozone layer leads to warmer climatic conditions and causes undesired climatic changes whose most obvious results are drought and famine. Carbon dioxide is one of the most important greenhouse gases forming almost 82% of these harmful substances. On the other hand, since approximately 5% of the annual mass of CO2 made by human activities is a direct product of the process of manufacturing clinker in cement factories, this process is one of the producing sources of CO2 on the earth. The nano-science and technology, which is called a scientific revolution, is serving us in different forms helping in our routine life. This issue can be seen clearly in the application of nano-technology in the development and construction of a high range of substances and materials. Alongside, nano-particles which are a result of nano-technology, combined with cementitious materials, have succeeded to affect the structure and develop the properties of cement based materials. Accordingly, by awareness of the data previously discussed, the objective of this research is reducing the amount of cement in high strength concrete by using nano-particles as a replacement of cement. Reduction of cement usage is a symbol of sustainable development and application of nano-particles is a mark of nano-technology helping us in the same direction to make a brighter future. In this study, the properties of concretes made by reduction of cement (including 10%, 20% and 30% of cement content) and combination of silica nano-particles (including 1%, 2% and 3% of cement content) are investigated. The conducted tests include measuring the fresh concrete density, compressive strength, splitting tensile strength and microstructure of Interfacial Transition Zone (ITZ).
Concrete Research
University of Guilan
2
v.
2
no.
2009
31
43
http://jcr.guilan.ac.ir/article_803_0a8005f5594bd67041f88c6196192646.pdf