REACTIVE POWDER CONCRETE.doc

February 17, 2017 | Author: Sujay Raghavendra N | Category: N/A
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REACTIVE POWDER CONCRETE

SEMINAR REPORT On

“REACTIVE POWDER CONCRETE” A DEVELOPING ULTRA HIGH STRENGTH CONCRETE SUBMITTED TO VIVESWARAIAH TECHNOLOGICAL UNIVERSITY BELGAUM FOR THE PARTIAL FULFILLMENT OF M-TECH (STRUCTURAL ENGINEERING)

BY DIVAKAR.Y Reg. No: 1st Semester M-Tech Structures Under The Guidance of: Prof. K.JAYARAM Prof. & Head Department of Civil Engineering

BANGALORE INSTITUTE OF TECHNOLOGY (Affiliated To Visveswaraiah Technological University) Bangalore-560004

DEPARTMENT OF CIVIL ENGINEERING- BIT

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REACTIVE POWDER CONCRETE

BANGALORE INSTITUTE OF TECHNOLOGY BANGALORE -560004

CERTIFICATE This is to certify that Mr. DIVAKAR.Y bearing university USN has submitted the seminar report on “REACTIVE POWDER CONCRETE A DEVELOPING ULTRA HIGH STRENGTH CONCRETE” in partial fulfillment of the 1 st semester M-Tech course in structural engineering as prescribed by the Visveswaraiah Technological University during the academic year 2006-2007, under the guidance of Prof. K. JAYARAM

Prof. K.JAYARAM Prof. & Head Department of Civil Engineering

DEPARTMENT OF CIVIL ENGINEERING- BIT

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ACKNOWLEDGEMENT

I express my deep sense of gratitude to PROF. K.JAYARAM professor & Head, Department of Civil Engineering, BIT, for his guidance and help through out this seminar work. I will remain thankful to all the faculty members of Department of Civil Engineering, BIT for their support during the course of this work. Finally I express gratitude to my family and friends.

DIVAKAR.Y st

1 Semester M-TECH (STRUCTURES) BANGALORE INSTITUTE OF TECHNOLOGY

DEPARTMENT OF CIVIL ENGINEERING- BIT

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REACTIVE POWDER CONCRETE

CONTENTS 1. INTRODUCTION 2. COMPOSITION OF RPC 3. MECHANICAL PERFORMANCE AND DURABILITY OF RPC 4. MIXTURE DESIGN OF RPC AND HPC 5. RESULTS 5.1 Fresh Concrete Properties 5.2 Compressive Strength 5.3 Flexural Strength 5.4 Water Absorption 5.5 Resistance to Chloride Ion Penetration 5.6 Water Permeability 6. THE BENEFITS 7. STATUS 8. LIMITATIONS OF RPC 9. DISCUSSIONS 10. CONCLUSIONS 11. PHOTOGRAPHS 12. REFERENCES DEPARTMENT OF CIVIL ENGINEERING- BIT

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REACTIVE POWDER CONCRETE A DEVELOPING ULTRA HIGH STRENGTH CONCRETE ABSTRACT Concrete is a versatile and critical material for the construction of infrastructure facilities throughout the world. A new developing material known as reactive powder concrete (RPC) is available that differs significantly from traditional concretes. RPC has no large aggregates, and contains small steel fibres that provide additional strength and in some cases can replace traditional steel reinforcement. Reactive powders concrete (RPC) will allow the concrete industry to optimize material use, generates economic benefits, and build structures that are strong and durable. A comparison of the physical mechanical and durability properties of RPC and high performance concrete (HPC) shows that RPC possesses better (both compressive and Flexural strength) and lower permeability compared to HPC. HPC leads the way to the achievement of the maximum compressive strength of the order of say 120-150 MPa or so. However, at such a level of strength, the coarse aggregate becomes the weakest link in concrete. In order to increase the compressive strength of concrete even further, the only way is to remove coarser aggregate. This philosophy has been employed in what is today known as reactive powder concrete

1 INTRODUCTION RPC with trade name ‘DUCTAL’ was developed in France by researchers Mr.Richard and Mr. Cheyrezy in the early 1990s at Bouygues, laboratory in France. The world’s first RPC structure, the Sherbrooke Bridge in Canada, was constructed in July 1997. RPC is an ultra high-strength and high ductility cementitious composite with advanced mechanical and physical properties. It is a special concrete where the microstructure is optimized by precise gradation of all particles in the mix to yield maximum density. It extensively uses the pozzolanic properties of highly refined silica fume and optimization of the Portland cement chemistry to produce the highest strength hydrates. RPC was nominated for the 1999 nova awards from the construction innovation forum. RPC has been used successfully, for isolation and

DEPARTMENT OF CIVIL ENGINEERING- BIT

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containment of nuclear wastes in Europe due to its excellent impermeability. This new material demonstrates greatly improved strength and durability characteristics compared with traditional or even high-performance concrete. Classified as Ultra-High Performance Concrete (UHPC), or Reactive Powder Concrete (RPC). The improved properties of RPC are obtained by improving the homogeneity of the concrete by eliminating large aggregates, increasing compactness of the mixtures by optimizing packing density of fine particles, and using fine steel fibres to provide ductility The HPC used for nuclear waste containment structures of Indian concrete power plants are having moderate compressive strength, moderate E value, uniform density, good workability, and high durability. There is a need to evaluate RPC regarding its strength and durability to suggest its use for nuclear waste containment structures.

2 COMPOSITION OF RPC RPC is composed of very fine powders (cement, sand, quartz powder, steel aggregates and silica fume), steel fibres (optimal) and a superplasticizer. The superplasticizers, used at its optimal dosage, decrease the water to cement ratio (w/c) while improving the workability of the concrete. A very dense matrix is achieved by optimizing the granular packing of the dry fine powders. This compactness gives RPC, ultra-high strength and durability. Reactive powder concretes have compressive strengths ranging from 200 MPa to 810 MPa Mr. Richard and Mr. Cheyrezy indicate the following principles for developing RPC. 1. 2. 3. 4. 5. 6. 7.

Enhancement of homogeneity by elimination of coarser aggregates. Enhancement of compacted density by Optimization of the granular mixture. Enhancement of the microstructure by Post-set heat-treatment Enhancement of ductility by addition of small-sized steel fibres Application of pressure before and during setting to improve compaction Utilization of the pozzolanic properties of silica fume. The optimal usage of superplasticizer to reduce w/c and improve workability

DEPARTMENT OF CIVIL ENGINEERING- BIT

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Table1 (Mr. Dili and Mr. Santhanam, Indian concrete journal, April 2004) lists salient properties of RPC, along with suggestions on how to achieve them Table 1 - Properties of RPC enhancing its homogeneity and strength Property of RPC

Description

Reduction in Aggregate size

Coarser aggregates are replaced by fine sand with a reduction in the size of the coarsest aggregate by a factor of about 50 Improved mechanical properties of the paste by the addition of silica fume

Enhanced mechanica l Properties Reduction Limitations of sand content in aggregate to matrix ratio

Recommended Values

Types of Failure eliminated

Maximum size Mechanical, of the fine sand chemical is 600microns thermomechanical Young’s modulus values in 50-75 GPa range Volume of the paste is at least 20% greater than the voids index of noncompacted sand

Disturbance of mechanical stress field By any external source (Eg: Form work

Table 2 Describes the different ingredients of RPC and their selection parameters. The mixture design of RPC primarily involves the creation of a dense granular skeleton. Optimization of the granular mixture can be achieved either by the use of packing models or by particle size distribution software such as LISA .For RPC mixture design, an experimental method has been preferred. The major parameter that describes the quality of the mixture is its water demand (quantity of water for minimum flow of concrete). In fact the voids index of the mixture is related to the sum of water demand and entrapped air.

DEPARTMENT OF CIVIL ENGINEERING- BIT

&

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Table 2- Selection parameters for RPC components

Components

Sand

Cement

Quartz

Silica fume

Steel fibre SuperPlasticiser

Selection Good hardness Readily available at low cost C3 S: 60% C2S: 22% C3A: 3.8% C4AF:7.4%

Function parameters

Particle

Gives Strength as Aggregate

150µm to 600µm

Natural crushed

Binding material production of primary hydrates

1µm to 100µm

OPC medium fineness

Maximum 5µm to Fineness reactive during 25µm heat-treating Filling the voids, enhances Very less rheology (flow 0.1µm to quantity of ability), 1µm impurities production of secondary hydrates L:3-25mm Good aspect Improve ductility Dia:0.15ratio 0.2mm Less retarding Reduce w/c -----characteristic

Types

Crystalline Procured from Ferrosilicon industry (highly refined)

Straight Polycrylat e based

After selecting a mixture design according to minimum water demand, optimum water content is analyzed using the parameter of relative density (Do / Ds). Here Do and Ds represent the density of the concrete and the compacted density of the mixture (no water or air), respectively. Relative density indicates the level of packing of the concrete and its maximum value is one. For RPC, the mixture design should be such that the packing density is maximized.

DEPARTMENT OF CIVIL ENGINEERING- BIT

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Heat curing does microstructure enhancement of RPC. Heat curing is by simply heating (normally at 90 C) the concrete at normal pressure after it has set properly. This considerably accelerates the pozzolanic that have formed. Pre-setting pressurization has also been suggested as a means of achieving high strength. The high strength of RPC makes it highly brittle. Steel micro fibres are generally added to RPC to enhance its ductility. Straight steel fibre used typically are about 13mm long, with a diameter of 0.15mm.The fibre are introduced into the mixture at a ratio of between 1.5 and 3 percent by volume. The cost-effective optimal dosage is equivalent to a ratio of 2 percent by Volume. Table 3 Comparison of oxide composition of different pazzalonic material, we can notice that Sio2 presence in silica fumes is very high Table 3 - Oxide composition of Cementations Materials (Concrete Technology by M.L.Ghambir page 36) Oxide Composition, % by Weight CaO SiO2 AL2O3 Fe2 O3 MgO SO3 Na2O K2O

Portland Cement 63.0 20.0 6.3 3.6 2.4 1.5 0.15 0.5

Silica Fume 4.15 93.0 0.2 0.05 0.51 0.05 0.2 0.22

DEPARTMENT OF CIVIL ENGINEERING- BIT

Fly

2.5 52.5 28.2 10.5 1.6 0.2 0.04 0.9

Blast Furnace Slag 42.4 32.3 13.3 0.3 6.4 2.1 -

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3 MECHANICAL PERFORMANCE AND DURABILITY OF RPC The RPC family includes two types of concrete, designated RPC 200 and RPC 800, which offer interesting implicational possibilities in different areas. Mechanical properties for the two types of RPC are given in Table 4(Mr. Dili and Mr.Santhanam, 2004). The high flexural strength of RPC is due to the addition of steel fibres. Table -4 Comparison of RPC 200 and RPC 800

Compressive strength (using Quartz sand) MPa Compressive strength (using Steel aggregate) MPa Flexural strength MPa Heat-Treating

RPC RPC 800 200 170-230 490-680 ------650-810 30-60 20-90

45-141 250-400

Table 5- Shows mechanical properties of RPC compared to a conventional HPC having compressive strength of 80 MPa. (Bickley J.A and Mitchell D, 2001). As fracture toughness, which is a measure of energy absorbed per unit volume of material to fracture, is higher for RPC, it exhibits high ductility. Apart from their exceptional mechanical properties, RPCs have an ultra-dense microstructure, giving advantageous waterproofing and durability characteristics. These materials can therefore be used for industrial and nuclear waste storage facilities. Table 5 Comparisons of HPC (80 MPa) and RPC 200

Compressive strength MPa Flexural strength MPa Modulus of elasticity GPa Fracture toughness J/m2

DEPARTMENT OF CIVIL ENGINEERING- BIT

HPC (80MPa) 80 7 40
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