دانلود مقالات سومین کنفرانس بین المللی بتن و توسعه

STUDY OF NEW GROUTING TECHNIQUES IN REPAIR AND
STRENGTHENING OF SOFT SOILS
S. Kazemian, Bujang. B. K. Huat, A. Asadi, V. Ghiasi
Department of Civil Engineering, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
ABSTRACT
Demands for soft land strengthening and contaminated soil solidification have been
increased due to the explosion population, development of technology, industry,
and transportation systems.
Deep mixing methods (DMMs) are conventional methods for strengthening the soft
soils. Cement (or binder) with soil have being mixed in this method. Injection of
cement and additives with a high pressure and displacing the gases and liquids
from within soil grains in combination with DMMs is a new wedding technique for
increasing the efficiency of soil stabilization.
In this paper, different kinds of deep mixing methods (conventional and new
techniques) were studied. By considering the type and alternative layers of soil,
load size, the situation, cost and type of project selecting the right stabilizing
method for repair and strengthening of soft soils recommended and it is believed
that it could prompt engineers to resolve soil strengthening difficulties from the
geotechnic-al view point.
Keywords: grouting, stabilizing, injection, mixing, soft soil, cement and binder

لینک دانلود: http://persiandrive.net/24937

INTERNAL STEEL BRACING OF RC FRAMES
M.R. Maheri
Professor of Civil Engineering, Shiraz University, Shiraz, Iran
ABSTRACT
Steel bracing systems can be used effectively for seismic retrofitting of existing RC
buildings as well as for seismic design of new buildings. Although adaptation of
bracing to upgrade the lateral load capacity of existing RC frames has been the
subject of a number of successful studies, guidelines for its use in newly
constructed RC frames need to be further developed. This paper reports on some
recent experimental and numerical work conducted by the author and his
colleagues on internal bracing of RC frames using direct connections between the
bracing system and the frame. The effects of X-bracing and knee bracing on
enhancing the seismic capacity of the frames are investigated experimentally
through pushover tests as well as cyclic tests. A compression release device has
also been introduced and tested to enhance the seismic performance of the bracing
system by avoiding the buckling of the compression member. An important
consideration in the design of steel-braced RC frames is the level of interaction
between the strength capacities of the RC frame and the bracing system. In this
paper, results of experimental and numerical investigations aimed at evaluating the
level of capacity interaction between the two systems are also discussed. It is found
that the capacity interaction is due primarily to connections overstrength. Based on
the numerical results the connection overstrength has been quantified and
guidelines for the seismic design of the internally braced RC frames with direct
connections are provided.

لینک دانلود: http://persiandrive.net/619999

بخش هفتم:
بتن های ویژه

THE STUDY OF VELOCITY AND FREQUENCY OF PASSING
WATER THROUGH A MAGNETIC FIELD AND ITS EFFECT ON
THE COMPRESSIVE AND TENSILE STRENGTH OF CONCRETE
H. Safaye Nikoo
Faculty member of Chabahar Maritime University, Chabahar, Iran
ABSTRACT
Concrete is a material which can have a range of different strengths with using
different ratio s of its composites. In this regard, every factor that can help us reach
better mechanical properties and other characteristics of concrete is worth studying.
In our study, regarding above information, we study the effects of water properties
(considering magnetizing water) of concrete on some of the mechanical features of
concrete containing microsilica such as compressive and tensile strength at
different curing ages. The water in concrete has been passed through magnetic field
with velocities such as Q, Q/2, Q/3, Q/6 and with 1, 3 and 6 passing times. The
results indicate that increasing the number of times water is passed (from 1 to 6),
improves the compressive and tensile strength of concrete, and decreasing the
velocity of passing water through magnetic field in one cycle (from Q to Q/6) has a
similar result. The improvement of decreasing the velocity in one cycle is more
significant than the improvement caused by passing water through a number of
times, and the compressive and tensile strength will be improved substantially. the
compressive and tensile strength of concrete will be increased up to 15 % .This
method is considered very economical and does not need special equipments in
industry.
Keywords: microsilica, magnetic water, superplasticizer, compressive

لینک دانلود: http://persiandrive.net/784335

MIX DESIGN OF STRUCTURAL SELF-COMPACTING
CONCRETE USING VOID-BULK DENSITY METHOD
N. Abdizadeh1, A.A. Zekavati2, H. Afshin3
1M.Sc Student, Civil Eng. Faculty, Sahand University of Technology, Tabriz, Iran
2M.Sc Student, Civil Eng. Faculty, Sahand University of Technology, Tabriz, Iran
3Associated professor in Civil Eng. Faculty, Sahand University of technology, Tabriz, Iran
ABSTRACT
Self Compacting Concrete (SCC) was firstly developed in Japan in 1987.
(Alternative: Pioneering works on Self Compacting Concrete returns to 1980s in
Japan) In recent years, much research has been conducted in other to achieve a
reasonable and also suitable mix design method for controlling the compaction
experiment and determination of the compliance particular trait of SCC. But, just a
few researches have been done in to propose a mix design method that can have
both of highly fluid state and good viscosity, simultaneously. SCC is a special kind
of concrete that can flow through and fill the gaps of reinforcement and corners of
molds without any need for vibration and compaction during the placement
process. In this paper Void-Bulk Density mix design method for structural SCC is
investigated. In this method, firstly, the relationship between the void volume (or
density of combined aggregates) and coarse-to-total aggregate volume ratio is
established by packing different amounts of coarse and fine aggregates following
ASTM C 29/C 29M, using the void volume of the dry binary aggregate (fine and
coarse), is determined. Then, based on the optimum ratio that results from
minimum void of aggregate and minimum bulk density, mix design is
accomplished and finally in order to increase the flowability of the concrete have
been added, some excess paste via reducing ratio of volume aggregate in unit
volume concrete. Obtained results of the experiments on fresh concrete (Slump
flow, L-box, V-funnel) and hardened concrete (compressive strength, tensile
strength, elastic moduli and durability) show that this method is appropriate for
SCC. In this study nine different SCC mixtures having the volume of paste and the
ratio between sand and gravel as variables were compared with eight different
mixtures of conventionally vibrated concrete (CVC).
Keywords: Self-compacting concrete, compressive Strength, Durability, elastic
moduli, Mix design

لینک دانلود: http://persiandrive.net/711782

ENGINEERING PROPERTIES OF GEOPOLYMER CONCRETE
BASED ON ALKALI ACTIVATED NATURAL POZZOLAN
D. Bondar1, C.J. Lynsdale2, N. Milestone3, N. Hassani4, A.A. Ramezanianpour5
1Ph.D. candidate of Sheffield University and P.W.U.T. Research Associate
2Dept. of Civil and Structural Engineering, (c) Dept. of Material Engineering Univesity of Sheffield,
Mappin Street, Sheffield, S1 3JD, UK
3Research Center of Natural Disasters in Industry, P.W.U.T., Tehran, Iran
4Dept. of Civil Engineering, Amir Kabir University, Tehran, Iran
ABSTRACT
The development of alkali activated binders with superior engineering properties
and longer durability have emerged as an alternative to OPC. It is possible to use
alkali-activated natural pozzolans to synthesize environmental friendly sound
geopolymeric cementitious construction materials. The main benefit of geopolymeric
cement is the reduction in environmental impact in harmony with the
concept of sustainable development. This paper presents a comprehensive
summary of the extensive studies conducted on the results of experimental
investigations on the engineering properties of geo-polymer concrete using
activated Iranian natural pozzolan namely, Taftan. Experimental work was
conducted to determine mechanical strength; modulus of elasticity; ultrasonic pulse
velocity and shrinkage of different concrete mixtures. Test data are used to identify
the effects of salient factors such as water to binder ratios and curing conditions
that influence the properties of the geopolymer concrete. The results show that
mortar and concrete made with alkali activated natural pozzolan develop moderate
to high mechanical strength and modulus of elasticity and shrink much less than
ordinary Portland cement (OPC) concrete.
Keywords: alkali-activated binder; geopolymeric cement; natural pozzolan

لینک دانلود: http://persiandrive.net/58327

AN INVESTIGATION ON EFFECT OF USING PP FIBERS AND
DIFFERENT CEMENTITIOUS MATERIALS ON MECHANICAL
PROPERTIES OF EPS CONCRETE
A. Sadrmomtazi1, M.A. Mirgozar Langeroudi 2, A. Fasihi3, A.K. Haghi4
1Assistant professor, Dept of Civil Engg, Faculty of Engg, University of Guilan, Rasht, Iran
2,3M.S. Student, Dept of Civil Engg, Faculty of Engg, University of Guilan, Rasht, Iran
4Professor, Dept of Textile Engg, Faculty of Engg, University of Guilan, Rasht, Iran
ABSTRACT
The use of lightweight concrete in many applications of modern construction is
increasing, owing to the advantages that lower density results in decreasing the
magnitude of dead load of the structure which lead to smaller cross sections for load
bearing elements. Expanded polystyrene (EPS) beads are a type of artificial
lightweight nonabsorbent aggregates which can be used to produce low density
concretes by replacing with normal aggregates, either partially or fully, depending
upon the requirements of density and strength. Also plastic shrinkage is the
dimensional change that occurs in all fresh cement based materials within the first
few hours after it has been placed which is not unacceptable in itself, but it is some
times accompanied by development of cracks that are unsightly and objectionable.
Polypropylene and other synthetic fibers are added to concrete as secondary
reinforcement in order to control this plastic shrinkage. On the other hand, the
addition of fibers affects on the properties of hardened concrete like compressive and
tensile strength, elastic modulus and toughness. The present study covers the use of
polypropylene fibers at contents equal to 0.1%, 0.3%, 0.5% and 1% by volume of
EPS concrete in order to study about the effects of its addition into the EPS concrete
matrix on mechanical properties. Also the effects of using Silica fume and Rice husk
as two supplementary cementitious materials were investigated.
Keywords: EPS concrete, PP fibers, silica fume, rice husk, mechanical properties

لینک دانلود: http://persiandrive.net/496639

AN INVESTIGATION ON EFFECT OF USING PP FIBERS AND
DIFFERENT CEMENTITIOUS MATERIALS ON MECHANICAL
PROPERTIES OF EPS CONCRETE
A. Sadrmomtazi1, M.A. Mirgozar Langeroudi 2, A. Fasihi3, A.K. Haghi4
1Assistant professor, Dept of Civil Engg, Faculty of Engg, University of Guilan, Rasht, Iran
2,3M.S. Student, Dept of Civil Engg, Faculty of Engg, University of Guilan, Rasht, Iran
4Professor, Dept of Textile Engg, Faculty of Engg, University of Guilan, Rasht, Iran
ABSTRACT
The use of lightweight concrete in many applications of modern construction is
increasing, owing to the advantages that lower density results in decreasing the
magnitude of dead load of the structure which lead to smaller cross sections for load
bearing elements. Expanded polystyrene (EPS) beads are a type of artificial
lightweight nonabsorbent aggregates which can be used to produce low density
concretes by replacing with normal aggregates, either partially or fully, depending
upon the requirements of density and strength. Also plastic shrinkage is the
dimensional change that occurs in all fresh cement based materials within the first
few hours after it has been placed which is not unacceptable in itself, but it is some
times accompanied by development of cracks that are unsightly and objectionable.
Polypropylene and other synthetic fibers are added to concrete as secondary
reinforcement in order to control this plastic shrinkage. On the other hand, the
addition of fibers affects on the properties of hardened concrete like compressive and
tensile strength, elastic modulus and toughness. The present study covers the use of
polypropylene fibers at contents equal to 0.1%, 0.3%, 0.5% and 1% by volume of
EPS concrete in order to study about the effects of its addition into the EPS concrete
matrix on mechanical properties. Also the effects of using Silica fume and Rice husk
as two supplementary cementitious materials were investigated.
Keywords: EPS concrete, PP fibers, silica fume, rice husk, mechanical properties

لینک دانلود: http://persiandrive.net/718938

DAMPER CONCRETE FOR SEISMIC WAVES
H. Khoshroo1, F.Sinaeian2
1Apply Research Office of NAJA
2Building and Housing Research Centre (BHRC). I.R.Iran
ABSTRACT
When an earthquake happens, different kinds of compression and shear waves are
produced. Structures in direction of compression waves P (sense's weight of
structure) have good enforcement and main loss of structures is in sense of shear
(sense of propagation S waves). By reducing amplitude of seismic waves, we can
reduce damages to the building. Nowadays, one of the most important difficulties
in front of engineering structure is finding ways for reducing side movement of
structure and vibrations caused by the device measuring earthquakes in buildings
especially high structures for adding to their factor of safety. Seismic waves are
among mechanic waves and for propagation need material environment and their
reduction has opposite environment's density. So, reducing density of propagation
environment is one of ways for reducing amplitude of waves. On the other side,
liquids do not have a stiffness shear and cannot effect and propagation S waves. So,
in this plan, we have tried using this specifications and installing sphere full of
fluid in the sample environment of ordinary concrete, make new concrete and
evaluate its behavior so that has considerable reduce against shear waves.
For considering the made sample behavior and comparing it with ordinary concrete,
cubic samples with sizes 10x20x20 and 10x20x60cm are made and were put under
impulse loads. Comparing test results, it was observed that amplitude of registered
wave on the concrete sample with fluid compare to sample of ordinary concrete has
reduced on average %50. So, by using this damping concrete, we can reduce the
seismic energy and acceleration effected to the structure and considering amount of
this reduction, the structure weight is also reduced. Reduction of structure weight
caused reduction of secondary seismic force.
Keywords: damper, shear wave, fluid

لینک دانلود: http://persiandrive.net/880528

APPLICATION OF HYBRID FIBER REINFORCEMENT AND
HIGH VOLUME COARSE FLY ASH IN SELF COMPACTING
CONCRETE
A.A. Mounesan1, K. Siamardi2, M.M. Khodavirdi Zanjani2
1Civil Engineer, Sharif University of Technology, Head Manager of Atisaz Company
2Civil Engineer, Concrete Research Center, Atisaz Company
ABSTRACT
Self compacting concrete is termed as a concrete with high flow ability and
cohesiveness which can fill its mold without the need of any extra vibration effort.
Fiber inclusion to concrete enhances the mechanical properties, while making the
concrete less workable. This article presents a study on the fresh and mechanical
properties of a fiber reinforced self compacting concrete incorporating highvolume
fly ash that does not meet the fineness requirements of ASTM C 618. A
poly carboxylic based superplasticizer was used in combination with a viscosity
modifying admixture. In mixes containing fly ash, 50% of cement by weight was
replaced with fly ash. Two different types of steel fibers were used in combination,
keeping the total fiber content constant at 60 kg/m3. Slump flow time and
diameter, V funnel, and air content were performed to assess the fresh properties of
the concrete. Compressive strength, split tensile strength, and ultrasonic pulse
velocity of the concrete were determined for the hardened properties. It can be
concluded that high-volume coarse fly ash could successfully be used in producing
fiber reinforced SCC. Even though there is some reduction in the concrete strength,
because of the use of high-volume coarse fly ash, it is possible to achieve self
compaction with considerable fiber inclusion.
Keywords: self compacting concrete, fiber reinforcement, high volume coarse fly
ash, fresh properties, ultrasonic test

لینک دانلود: http://persiandrive.net/961929