Study of the effect of Water-Cement Ratio and Metakaolin on Corrosion of Concrete Reinforcements in Splash Zone in Persian Gulf Region
Mohammad
Shekarchi Zadeh
استاد دانشکده مهندسی عمران و سرپرست انستیتو مصالح ساختمانی دانشکده فنی دانشگاه تهران
author
Rayehe
Khaghanpour
کارشناسی ارشد مهندسی عمران، گرایش سازه، دانشکده فنی دانشگاه تهران
author
Mohammad Hossein
Tadayon
دانشجوی دکترای مهندسی عمران،گرایش سازههای دریایی، دانشکده فنی دانشگاه تهران
author
Atiye
Farahani
دانشجوی دکتری مهندسی عمران،گرایش سازه، دانشکده فنی دانشگاه تهران
author
text
article
2016
per
Marin environments such as Qheshm Island, are the most destructive environments for reinforced concrete structures. Concrete quality is one of the important factors in corrosion. Nowadays use of pozzolanic materials is one of the methods to improve the concrete qualities. In this study, by placing specimens with different water to cement ratios and different amounts of Metakaolin in splash zone and measuring the rate of corrosion and half-cell potential using GalvaPulse method, the effect of these factors on corrosion of reinforcements during 32 month is evaluated. The test results indicate that the specimen with lower water to cement ratio has lower likelihood of corrosion. Increasing the water to cement ratio from 0.35 to 0.45, decreases the time-to-corrosion to 50%. Using Metakaolin also reduces the rate of corrosion.
Concrete Research
University of Guilan
8
v.
1
no.
2016
5
14
http://jcr.guilan.ac.ir/article_1520_593eda9448b849a37f3c8d5ab81c0ecb.pdf
Evaluation of Pure Shear Strength in Reactive Powder Concrete and its comparison with Normal Concrete
A.
Toofani Milani
کارشناس ارشد مهندسی عمران، دانشگاه صنعتی سهند
author
H.
Afshin
دانشیار دانشکده مهندسی عمران، دانشگاه صنعتی سهند
author
Y.
Aliloo
دانشجوی دکترای مهندسی عمران، دانشگاه صنعتی سهند
author
H.
Naseri
کارشناس ارشد مهندسی عمران، دانشگاه صنعتی سهند
author
text
article
2015
per
Reactive Powder Concrete (RPC) is one of the latest achievements in concrete technology. Development and application of this concrete depends on the knowledge on its specifications and characteristics. Shear strength is one of the most important specifications in design of RC structures. One of the effective methods to determine the shear strength of concrete is to estimate this strength using concrete’s compressive strength. In this study, RPC and normal concretes with different mixture designs and using the existing materials in Iran were produced. Than their compressive and shear strengths evaluated. Two methods (JSCE G553, Afshin Aliloo’s) were used to measure the shear strength. The result show that there are difference between reactive powder concrete shear properties and normal concrete. Also, shear strength that measured by either of two methods is close together. Using the results of the experiments, an equation is developed to estimate the shear strength of RPC using its compressive strength.
Concrete Research
University of Guilan
8
v.
1
no.
2015
15
25
http://jcr.guilan.ac.ir/article_1528_041d967216cefcd248940753d89d5b83.pdf
Prediction of Plastic Hinge Length at the RC Bridge Piers using Artificial Neural Networks Algorithm
A.
Khalili
کارشناسی ارشد مهندسی سازه، دانشکده مهندسی عمران، دانشگاه سمنان
author
M.
Ahmadi
دانشجوی دکتری مهندسی سازه، دانشگاه سمنان، دانشکده مهندسی عمران
author
E.
Emami
مربی دانشکده مهندسی عمران، دانشگاه پیام نور
author
A.
Kheyroddin
استاد دانشکده مهندسی عمران، دانشگاه سمنان
author
text
article
2015
per
According to significant of bridges as infrastructures, and need for serviceability after earthquakes, it is necessary to design this group of structures adequately. In this way the determination of the location of nonlinear response in these structural systems is an important step to predict the performance of the system under different loading conditions. In reinforced concrete bridge piers, these nonlinear deformations generally occur over a finite hinge length. A model of hinging behavior in reinforced concrete bridges pier will help guide, detailing and drift estimates for performance-based design. In this paper, by using experimental results that conducted on the reinforced concrete bridges piers and also applying artificial neural networks algorithm, predict the plastic hinge length of reinforced concrete bridges pier. The results show that the accuracy of artificial neural networks algorithm for predicting of this parameter in compare with other formulations that were proposed as for calculated error is appropriate.
Concrete Research
University of Guilan
8
v.
1
no.
2015
27
40
http://jcr.guilan.ac.ir/article_1529_951d4bf1fde7c0cc6d72061b51e5ab53.pdf
Investigation of effect of steel fibers on fresh and hardened properties of self-compacting lightweight concrete with Scoria
Malek Muhammad
Ranjbar
استاد یار گروه مهندسی عمران، دانشکده فنی دانشگاه گیلان
author
S.Hosein
Ghasemzadeh Mosavinejad
استاد یار گروه مهندسی عمران، دانشکده فنی دانشگاه گیلان
author
Shahin
Chatkhtab
مربی گروه مهندسی عمران، مؤسسه آموزش عالی دیلمان
author
M.Ebrahim
Zakeri
کارشناس ارشد مهندسی عمران سازه، مؤسسه آموزش عالی دیلمان
author
Mohammad
Arayeshgar
کارشناس ارشد مهندسی عمران سازه، دانشکده فنی دانشگاه گیلان
author
Soroush
Easapour
کارشناسی مهندسی عمران، دانشکده فنی دانشگاه گیلان
author
text
article
2015
per
This paper evaluates the impacts of the addition of steel fibers with two different percentage by weight, on flow ability parameters and hardened properties of self-compacted lightweight concrete containing lightweight aggregate of Scoria. For this purpose, was used from the steel fibers with a length of 50mm the amount 20&40 kg/m3.With a good mix design, fresh and hardened properties of each plans was evaluated. Fresh properties such as slump flow, V-funnel, and L-box and physical properties such as, density measurements, compressive strength, splitting tensile strength, flexural strength, ultrasonic pulse velocity (UPV), flexural toughness, and dry unit weight were determined in hardened conditions. The samples were stored in water until the age 7, 14, 28, 42 and 90 days.
From the result, it is clear that fibers decrease flow ability of fresh concrete, however mixeswereinthe acceptable range of EFNARC. The results of hardened concrete indicate, all mixes are in the range of structural lightweight concrete too. Moreover, the addition of fibers significantly increases tensile strength, flexural strength and flexural toughness.
Concrete Research
University of Guilan
8
v.
1
no.
2015
41
54
http://jcr.guilan.ac.ir/article_1530_9a59ecdf7a85aacc780909211d5fc851.pdf
High Temperatures and Nano-Silica Effects on Mechanical Properties of Structural Lightweight Concrete
Seyed Hamid
Hashemi
استادیار، دانشکده فنی و مهندسی، گروه مهندسی عمران، دانشگاه اراک
author
Ali
Noroozi Arkavini
دانشجوی کارشناسی ارشد سازه، دانشکده فنی و مهندسی، دانشگاه اراک
author
text
article
2015
per
The behavior of light weight concrete at elevated temperature is of significant importance in providing safety of structures in response to certain accidents or particular service conditions. This paper deals with the physical and mechanical properties of light weight concrete “containing leca” such as: compressive strength, water absorption, mass loss and spalling. Specimens with different amount of Nano Silica by applying the Taguchi method for an optimal mix design had been made and after curing for 28 days and being subjected to 200, 400 and 600˚C specimens had been compared with the specimen without Nano silica and cured at room temperature. It was found that by increase temperature to 600˚C physical properties of light weight concrete like water absorption goes bad and in some condition an improvement in mechanical properties like compressive strength had been emerged surprisingly.
Concrete Research
University of Guilan
8
v.
1
no.
2015
55
69
http://jcr.guilan.ac.ir/article_1531_553e5a9d52eb782964c6eb7cac18e4f8.pdf
Assessment of Effects of the Number of Spans on Static Capacity of Six-Meter Plain Concrete Arch Bridges
M.
Yazdani
دانشجوی دکتری سازه، دانشگاه تربیت مدرس، تهران، ایران
author
M.S.
Marefat
استاد دانشکده مهندسی عمران، دانشگاه تهران، ایران
author
text
article
2015
per
There are a large number of old arch bridges in Iran designed to carry the service loads that have been increased in the past decades. Capacity assessment of these bridges has become a vital need. Due to their complex behavior, essential field and loading tests are required. An accurate and appropriate modeling of these types of bridges was the first key paid attention to, in this research. Parameters such as number, length and geometry of spans and strength of materials are the most significant features to achieve this goal. Field load testing of old railway bridge in km–24 of Tehran–Qom railway have revealed important characteristics of the bridge such as primary stiffness, rigidity and pattern of fraction. The bridge is a plain concrete arch with five identical six-meter spans. The effect of number of spans on the yielding strength of the bridge has been carried out using ANSYS software. Based on the results obtained, a plain concrete arch bridge with a single span has a totally different behavior with the multi span ones. Also it has been revealed that bridges with more number of spans have less yielding strength and higher amount of crown displacement value. At last, novel relations for computing the yield strength and displacement value of six-meter span plain concrete bridges have been suggested.
Concrete Research
University of Guilan
8
v.
1
no.
2015
71
84
http://jcr.guilan.ac.ir/article_1532_54bf87c3ebe3700964d4dbc7886b8e6b.pdf
Performance and Properties of Concrete with Magnetic Water
Mohammad Ali
Rahgozar
هیئت علمی دانشگاه اصفهان
author
Mohsen
Zamani
کارشناس ارشد مهندسی عمران
author
text
article
2015
per
When subjected to a magnetic field, the hydrogen bonds between water molecules become weakened, and the water molecule clusters break down into smaller ones. This allows for the water to more easily penetrate into cement particles, causing a faster and more effective hydration process. In order to assess the effect of magnetic water on curing and workability of cement past and wet concrete, also the compressive strength of condensed cement as well as concrete, first, a magnetic treatment device was designed and built in this study. The magnetic water produced was mixed with cement to make cement pastes with different water-to-cement (w/c) ratios. Curing time, workability, and compressive strength of such cement pastes were investigated. Then, using well balanced aggregates, magnetic water, cement with different proportions, and micro-silica, concrete with different mix designs were made and tested. Among the results from this study are: 1) The optimized magnetic field intensity for producing magnetic water is 0.8 to 1.0 tesla. 2) Magnetic water reduces the primary and secondary curing of cement by 50% and 19%, respectively. 3) The best compressive strengths are obtained if the water is circulated through the magnetic field for about 15 minutes, and the best workability is obtained if this time is about 65 minutes. 4) For higher proportions of cement in mix design and the application of magnetic water, the resulted concrete compressive strength may be increased by 20% and even higher. 5) In addition to enhancing the level of cement hydration, application of magnetic water takes more advantage of micro-silica in improving concrete strength. For example, the simultaneous application of micro-silica and magnetic water increases the 7-day-strength by 46% and the 28-day-strength by 39%. It is noteworthy that if one were to choose either application of micro-silica or the magnetic water for enhancing the concrete compressive strength, results here show that the application of micro-silica is slightly more effective. In general, the application of magnetic water increases the speed of concrete strengthening and/or the hydration process. In fact the rate of this strengthening for the 7-day-concrete is much more than that for the 28-day-concrete.
Concrete Research
University of Guilan
8
v.
1
no.
2015
85
99
http://jcr.guilan.ac.ir/article_1533_a555923587ff303b8213dcf64eb28454.pdf
Effect of Steel Fibers and Concrete Strength on Mechanical specifications of Steel Fiber Reinforced Concrete
Mehrollah
Rakhshani mehr
استادیار دانشکده فنی و مهندسی، دانشگاه الزهرا
author
Hossein
Bakhshi
استادیار گروه مهندسی عمران دانشکده فنی و مهندسی، دانشگاه حکیم سبزواری
author
text
article
2015
per
In order to select the most suitable concrete for the construction of high-rise buildings, method of analytic hierarchy process (AHP) based on expert knowledge has been used.
In this study conducted a series of laboratory works, to compare the effect of steel fibers used in various categories of resistance on concrete behavior parameters. Mixing the samples is set for the three categories of resistance 25, 35 and 45 MPa. Strength parameters that are chosen to identify concrete actions are tensile strength, impact strength, compressive strength and flexural strength. Also the samples in each resistance category are made with four fibers quantity: without fibers, 15, 25 and 35 kg fibers per cubic meter. The results suggest that using of steel fibers, increases the impact resistance, time of the first crack and ultimate strength of concrete significantly. Also the addition of this type of fibers, increases tensile strength and flexural strength but don’t have significant effect on the compressive strength of concrete.
Concrete Research
University of Guilan
8
v.
1
no.
2015
101
112
http://jcr.guilan.ac.ir/article_1534_7aeacd0edd4780afd4001e203cbd022b.pdf
Determination of Optimal Reinforcement Layout for Shear Wall with Opening Via Strut-and-Tie Approaches
Reza
Morshed
استادیار دانشکده عمران، دانشگاه یزد
author
Mohammad
Kamalodini
دانش آموخته کارشناسی ارشد سازه، دانشگاه یزد
author
Nima
baghadam
دانشجوی کارشناسی ارشد سازه، دانشگاه یزد
author
text
article
2015
per
Determination of optimal steel reinforcement layout for shear wall with opening is an important topic in designing this structural member.Strut-and-Tie Method (STM) is one way to design such members, where steel reinforcement is arranged based on the selected model.In this study, a strategy was introduced to determine optimal Strut-and-Tie model by selecting a good volume fraction in continuum topology optimization problem.The elastic strain energy was selected as the objective function to achieve the optimal pattern, and the modified Solid Isotropic Material with Penalization (SIMP) with continuous penalty function was used to prevent local minimum solution. Finally, By using Nonlinear Finite Element and defining qualitative and quantitative conditions for optimal STM, the resulting models, obtained with topology optimization for three shear wall with various opening, were compared with previous models and models with manufacturing constraint.The results show that, topology optimization models have the best ultimate load to steel weight ratio and get the optimal steel reinforcement layout for shear wall with opening.
Concrete Research
University of Guilan
8
v.
1
no.
2015
113
127
http://jcr.guilan.ac.ir/article_1535_18cc624ca29b55054a7cc4dec4f2ec7e.pdf
The Effects of Polypropylene, Steel and Glass Fibers on Compressive and Flexural Strength of Concrete Samples Using the Aggregates in Bushehr
Mohammad
Vaghefi
دانشیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه خلیجفارس، بوشهر، ایران
author
Alireza
Pouladi
کارشناس ارشد مهندسی عمران، دانشگاه آزاد اسلامی بوشهر
author
text
article
2015
per
Using concrete reinforcement fibers improves the concrete desirable features including its strength, and sometimes provides the engineers with very light materials by reducing the concrete’s weight. In the current study, type 2 Dashtestan cement, polypropylene, steel and glass fibers, and Superplasticizer were used in 9 mixture patterns to make the concrete. After they were built, concrete samples were kept in a regular water tank. Then, compressive and flexural strength of samples were measured in 7, 28, and 90 days. Results indicated that polypropylene fiber reinforced concrete’s compressive strength curve, which was ascending at 1 percent range of fibers (the curve was upward), and descending at 2 to 3 percent fiber range (the curve was downward). In addition, Propylene fiber reinforced concrete’s flexural strength curve which was ascending at 1 and 2 percent range of fibers (the curve was upward). At 3 percent range of fiber, it was descending (the curve was downward) and the highest compressive and flexural strength occurred at 1 and 2 percent range of polypropylene fiber respectively. Steel and glass fibers cause an increase in concrete samples compressive and flexural strength. The compressive strength of steel and glass fibers reinforced concrete at 1 to 3 percent range of fiber with an upward curve. The flexural strength of steel fiber reinforced concrete at 1 to 2 percent range of fiber with an upward curve, and at 3 percent range it had a downward curve, and the curve of flexural strength of glass fiber reinforced concrete at 1 to 3 percent of fiber with an upward curve. The highest compressive and flexural strength in steel fiber reinforced concrete occurred at 2 and 3 percent range of fiber respectively, and for glass fiber reinforced concrete, it was at 3 and 3 percent range of fiber respectively.
Concrete Research
University of Guilan
8
v.
1
no.
2015
129
142
http://jcr.guilan.ac.ir/article_1536_29629b251f1fda4f828fd83f21611182.pdf