REACTIVE POWDER CONCRETE.doc

REACTIVE POWDER CONCRETE

SEMINAR REPORT

On

“REACTIVE POWDER CONCRETE” A DEVELOPING ULTRA HIGH STRENGTH CONCRETE

SUBMITTEDTO

VIVESWARAIAH TECHNOLOGICAL UNIVERSITYBELGAUM

FOR THE PARTIAL FULFILLMENT OF M-TECH (STRUCTURAL ENGINEERING)

BYDIVAKAR.Y

Reg. No: -1st Semester M-Tech Structures

Under The Guidance of:Prof. K.JAYARAM

Prof. & HeadDepartment of Civil Engineering

BANGALORE INSTITUTE OF TECHNOLOGY(Affiliated To Visveswaraiah Technological University)

Bangalore-560004

DEPARTMENT OF CIVIL ENGINEERING- BIT


BANGALORE INSTITUTE OF TECHNOLOGYBANGALORE -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 1st 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.JAYARAMProf. & Head

Department of Civil Engineering



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.Y1st Semester M-TECH (STRUCTURES)

BANGALORE INSTITUTE OF TECHNOLOGY



CONTENTS

1. INTRODUCTION

2. COMPOSITION OF RPC

3. MECHANICAL PERFORMANCE AND DURABILITY OF RPC

4. MIXTURE DESIGN OF RPC AND HPC

5. RESULTS5.1 Fresh Concrete Properties5.2 Compressive Strength5.3 Flexural Strength5.4 Water Absorption5.5 Resistance to Chloride Ion Penetration5.6 Water Permeability

6. THE BENEFITS

7. STATUS

8. LIMITATIONS OF RPC

9. DISCUSSIONS

10. CONCLUSIONS

11. PHOTOGRAPHS



12. REFERENCES

REACTIVE POWDER CONCRETEA 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



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. Enhancement of homogeneity by elimination of coarser aggregates.

2. Enhancement of compacted density by Optimization of the granular mixture.

3. Enhancement of the microstructure by Post-set heat-treatment4. Enhancement of ductility by addition of small-sized steel fibres5. Application of pressure before and during setting to improve

compaction6. Utilization of the pozzolanic properties of silica fume. 7. The optimal usage of superplasticizer to reduce w/c and

improve workability



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 strengthProperty of RPC

Description Recommended Values

Types ofFailure eliminated

Reduction inAggregate size

Coarser aggregates are replaced by fine sand with a reduction in the size of the coarsest aggregate by a factor of about 50

Maximum size of the fine sand is 600microns

Mechanical, chemical & thermo-mechanical

Enhanced mechanicalProperties

Improved mechanical properties of the paste by the addition of silica fume

Young’s modulus values in 50-75 GPa range

Disturbance of mechanical stress field

Reduction in aggregate to matrix ratio

Limitations of sand content Volume of the paste is at least 20% greater than the voids index of non-compacted sand

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.

Table 2- Selection parameters for RPC components



Components SelectionFunction

parametersParticle

Types

Sand

Good hardnessReadily

available at low cost

Gives Strength as

Aggregate

150µm to 600µm

Natural crushed

Cement

C3 S: 60%C2S: 22%C3A: 3.8%C4AF:7.4%

Binding material production of

primary hydrates

1µm to 100µm

OPC medium fineness

Quartz FinenessMaximum

reactive during heat-treating

5µm to 25µm

Crystalline

Silica fumeVery less

quantity of impurities

Filling the voids, enhances rheology (flow ability), production of secondary hydrates

0.1µm to1µm

Procured from Ferro-silicon industry (highly refined)

Steel fibreGood aspect ratio

Improve ductilityL:3-25mmDia:0.15-0.2mm

Straight

Super-Plasticiser

Less retarding characteristic

Reduce w/c ------Polycrylate 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.



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

Portland Cement

Silica Fume

Fly Ash

Blast Furnace Slag

CaOSiO2AL2O3Fe2 O3MgOSO3Na2OK2O

63.020.0 6.3 3.6 2.4 1.5 0.15 0.5

4.15 93.0

0.2 0.05 0.51

0.05 0.2

0.22

2.552.528.210.5 1.6 0.2 0.04 0.9

42.4 32.3 13.3 0.3 6.4 2.1 - -



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.

RPC 200

RPC 800

Compressive strength (using Quartz sand) MPa 170-230 490-680Compressive strength (using Steel aggregate) MPa

------- 650-810

Flexural strength MPa 30-60 45-141Heat-Treating 20-90 250-400

Table -4 Comparison of RPC 200 and RPC 800

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

HPC (80MPa)

RPC 200

Compressive strength MPa 80 200Flexural strength MPa 7 40Modulus of elasticity GPa 40 60Fracture toughness J/m2 <103 30x103



RPC has ultra-high durability characteristics resulting from its extremely low porosity, low permeability, limited shrinkage and increased corrosion resistance. In comparison to HPC, there is no penetration of liquid and / or gas through RPC (Mr. Dauraic C, May 9,1997). The characteristics of RPC given in table 6 (Mr. Bickley J.A and Mr. Mitchell D, 2001) enable its use in chemically aggrasive environments and where physical wear greatly limits the life of other concretes.

Table 6- Durability of RPC compared to HPC

Abrasive wear 2.5 times lowerWater absorption 7 times lowerRate of corrosion 8 times lowerChloride ions diffusion 25 times lower

4 MIXTURE DESIGN OF RPC AND HPC

The process of mixture selection of RPC and HPC is given below.

1. Considerable numbers of trial mixtures were prepared to obtain good RPC and HPC mixture proportions.

2. Particle size optimization software, LISA (Elkem website) was used for the preparation of RPC and HPC trial mixtures.

3. The selection of best mixture proportions was on the basis of good workability and ideal mixing time.

4. Finalized mixture proportions of RPC and HPC are shown in Table 8 (Mr. Dili and Mr. Santhanam, 2004)



Table 7- Mixture proportions of RPC and HPC

Materials Mixture proportionsRPC RPC-

FibreHPC HPC-

FibreCement 1.00 1.00 1.00 1.00Silica fume 0.25 0.25 0.12 0.12Quartz powder 0.31 0.31 --- ---Standard sand grade 2

1.09 1.09 --- ---

Standard sand grade 3

0.58 0.58 --- ---

River sand 2.40 2.4020mm aggregate 1.40 1.4010mm aggregate 1.50 1.5030mm steel fibre 0.2036mm steel fibre 0.20Water 0.25 0.25 0.4 0.4

Workability and density were recorded for the fresh concrete mixtures. Some RPC specimens were heat cured by heating in a water bath at 900 C after setting until the time of testing. Specimens of RPC and HPC were also cured in water at room temperature

The performance of RPC and HPC were monitored over time with respect to the following parameters.

1. Compressive strength (as per IS 516 on 50mm cubes for RPC, 100mm cubes for HPC), flexural strength (as per IS 516 on 40x40x160 mm prisms for RPC, 100x100x500 cm beams for HPC)

2. Water absorption (on 150 mm cubes for both RPC and HPC), confirming to BS 1881:122-1983

3. Non destructive water permeability test using German instruments (on 150mm cubes for both RPC and HPC),

4. Resistance to chloride ions penetration test (on discs of diameter 100mm and 50mm as per ASTM C 1202)

5 RESULTS

The laboratory experiment conducted by Mr. Dili and Mr. Santhanam (2004), based on the mix proportions given in table 6 has obtained the following results.



5.1 Fresh Concrete PropertiesThe workability of RPC mixture (with and without fibre) measured using the mortar flow table test as per ASTM C 109 was in the range of 120-140 mm. On the other hand, the workability of HPC mixture (with and without fibre), measured using the slump test as per ASTM C 231,was in the range of 120-150mm.The density of fresh RPC and HPC mixtures was found to be in the range of 2500-2650 kg/m3.

5.2 Compressive Strength The compressive strength test shows that RPC has higher compressive strength than HPC shown in Fig 1. Compressive strength at early ages is also very high for RPC.Compressive strength is one of the factors linked with the durability of a material. The maximum compressive strength of RPC obtained from this study is high as 200 MPa, while the maximum strength obtained for HPC is 75 MPa. The incorporation of fibre and use of heat curing was seen to enhance the compressive strength of RPC by 30 to 50 percent. The incorporation of fibre did not affect the compressive strength of HPC significantly.

Fig-1 Compressive Strength of RPC & HPC

5.3 Flexural Strength

Plain RPC was found to possess marginally higher flexural strength than HPC.Table 9 clearly explains the variation in flexural strength of RPC and HPC with the addition of steel fibres. Here the increase of flexural strength of RPC with the addition of fibre is higher than that of HPC.

Table 9 Flexural strength (as per IS 516) at 28 days, MPa

RPC RPC-Fibre HPC HPC-FibreNC HWC NC HWC NC HWC11 12 18 22 8 10

NC-Normal Cured; HWC-Hot water curing

According to Mr. Blais P.Y (1994) literature view RPC should have an approximate flexural strength of 40 MPa. The reasons for low flexural strength is due to the fibre used (30mm) were long and their diameters were relatively very higher. Fibre reinforced RPC (with appropriate fibre) has the potential to be used in structures without any addition of steel reinforcement. This cost reduction in reinforcement can compensate the


5.2 Compressive Strength

Compressive

Strength Mpa

Time days


increase in the cost by the elimination of coarse aggregates in RPC to some extent

5.4 Water Absorption

Fig 2 represents a comparison of water absorption of RPC and HPC. A common trend of the water absorption with age is seen for both RPC and HPC. The percentage of water absorption of RPC however is very low compared to that of HPC. This quality of RPC is one among the desired properties of nuclear waste containment materials.

The incorporation of fibres and use of heat curing are seen to marginally increase the water absorption. The presence of fibre possibly leads to creation of channels at the interface between the fibre and paste that promote the uptake of water. Heat curing, on the other hand, leads to the development of a more open microstructure (compared to normal curing) that could result in an increased absorption.

5.5 Resistance to Chloride Ion Penetration

Penetration of chloride increases when heat curing is done in concrete. Even though heat cured RPC shows a higher value than normal-cured RPC, it is still extremely low or even negligible (<100 coulombs). This property of RPC enhances its suitability for use in nuclear waste containment structures. The addition of steel fibre leads to an increase in the permeability, possibly due to increase in conductance of the concrete. The HPC mixture also showed very low permeability, although higher compared to RPC.

5.6 Water PermeabilityThe non-destructive assessment of water permeability using the German instrument equipment actually only measures the surface permeability and not the bulk permeability like in conventional test methods. A


5.4. Water absorption

Water

absorptio

n percent

Time daysFig 2 Water absorption of RPC &HPC


comparison of the surface water permeability of RPC and HPC is shown in Fig 3.

Fig3 Surface water permeability of RPC and HPC

It can be seen from the fig 3 the water permeability decreases with age. The 28-day water permeability of RPC is negligible when compared to that of HPC (almost 7 times lower). As in the case of water absorption, the use of fibre increases the surface permeability of both types of concrete.

6 THE BENEFITSThe Benefits of Reactive Powder Concrte are as follows.1. RPC is a better alternative to High Performance Concrete and has

the potential to structurally compete with steel. 2. Its superior strength combined with higher shear capacity results in

significant dead load reduction and limitless structural member shape.

3. With its ductile tension failure mechanism, RPC can be used to resist all but direct primary tensile stresses. This eliminates the need for supplemental shear and other auxiliary reinforcing steel.

4. RPC provides improve seismic performance by reducing inertia loads with lighter members, allowing larger deflections with reduced cross sections, and providing higher energy absorption.


Water permeability, 0.0001mm/sec

0

0.5

1

1.5

2

2.5

3

3.5

RPC Fibered RPC HPC Fibered HPC

14thday

28thday

Type of concrete

5.6 - Water permeability


5. Its low and non-interconnected porosity diminishes mass transfer making penetration of liquid/gas or radioactive elements nearly non-existent. Cesium diffusion is non-existent and Tritium diffusion is 45 times lower than conventional containment materials.

7 STATUS

The firm HDR Engineering Inc. is responsible for the development and promotion of RPC in North America. An application of RPC can be seen in the Pedestrian Bridge 197m span, 3.3m wide, 3.0m deep, 30mm thick slab, in the city of Sherbrooke, Quebec, Canada. Seonyu foot Bridge ,120m span, 4.4m wide, 1.3m deep, 30mm thick slab, in Seoul, Korea, Sakata Mirai footbridge, in Japan and Canopy at Shawnessy Light Rail Transit Station, Calgary, Canada. RPC has also been used for isolation and containment of nuclear waste of several projects in Europe and also for Producing Sewer, Culvert and Pressure Pipes in Army engineer waterways experiment station, Vicksburg MS., This product was nominated for the 1999 Nova Awards from the Construction Innovation Forum

8 LIMITATIONS OF RPC

In a typical RPC mixture design, the least costly components of conventional concrete are basically eliminated or replaced by more expensive elements. In terms of size scale, the fine sand used in RPC becomes equivalent to the coarse aggregate of conventional concrete, the Portland cement plays the role of the fine aggregate and the silica fume that of the cement. The mineral component optimization alone results in a substantial increase in cost over and above that of conventional concrete (5 to 10 times higher than HPC). RPC should be used in areas where weight savings can be realized and where some of the remarkable characteristics of the material can be fully utilized. Owing to its high members where durability issues are at stake (for example, in marine condition). Since RPC is in its infancy,

the long-term properties are not yet known. Applying pressure to mix and applying heat treatment in the field has got technological difficulties and cost.

9 DISCUSSIONS


http://www.stormingmedia.us/corpauthors/ARMY_ENGINEER_WATERWAYS_EXPERIMENT_STATION_VICKSBURG_MS.html

http://www.stormingmedia.us/corpauthors/ARMY_ENGINEER_WATERWAYS_EXPERIMENT_STATION_VICKSBURG_MS.html


A laboratory investigation carried out by Mr. Dili and Mr. Santhanam gave the following conclusion.

1. A maximum compressive strength of 198 MPa was obtained. This is in the RPC 200 range (175 MPa -225 MPa)

2. The maximum flexural strength of RPC obtained was 22 MPa, lower than the values quoted 40 MPa. A possible reason for this could be the higher length and the diameter of fibre used in this study.

3. A comparison of the measurements of the physical, mechanical and durability properties of RPC and HPC shows that RPC shows better strength (both compressive and flexural) and lower permeability compared to HPC,

4. The extremely low levels of water and chloride ion permeability indicate the potential of RPC as a good material for storage of nuclear waste. However, RPC needs to be studied with respect to its resistance to the penetration of heavy metals and other toxic wastes emanating from nuclear plants (such as Cesium 137 ion in alkaline medium) to qualify for use in nuclear waste containment structures.

10 CONCLUSIONS

RPC is an emerging technology that lends a new dimension to the term “high performance concrete”. It has immense potential in construction due to superior mechanical and durability properties than conventional high performance concrete, and could even replace steel in some applications. The development of RPC is based on the application of some basic principles to achieve enhanced homogeneity, very good workability, high compaction, improved microstructure and high ductility. RPC has an ultra-dense microstructure, giving advantageous waterproofing and durability characteristics. It could, therefore be a suitable choice for industrial and nuclear waste storage facilities.

11. PHOTOGRAPHS




530kg470 kg110 kg130 kgWeight

700 mm

700 mm

360 mm360 mm Section depth

RCCPSCSteelRPC X-Shaped

Section parameters

Flexural Strength or Fracture Energy?Impact Resistance

– Drop Hammer Test -



Impact resistance of:Reactive Powder Concrete (RPC)

Impact resistance of:Reactive Powder Concrete (RPC)



Pedestrian Bridge,Sherbrooke, Canada.


12. REFERENCES:

RICHARD P and CHEYREZY M “Composition of Reactive Powder Concrete, Cement and Concrete Research”, 1995, Vol 25

AICTIN P.C. “Cements of yesterday and today: Concrete of tomorrow, Cement and Concrete Research”, 2000, Vol 30.

BLAIS P.Y and COUTURE M. “Precast, Prestressed pedestrian bridge-World’s first Reactive Powder Concrete structure, PCI journal” 1999,Vol 44

DAURAIC C “Special concrete may give steel stiff competition: Building concrete. The seattle Daily Journal of Commerce”, May 9, 1977.

BASU P.C “Performance requirements of HPC for Indian NPP structure. The Indian

BONNEAU O, VERNET C, MORANVILLE M. and AITCIN P C “Characterization of granular packing and percolation threshold of Reactive Powder Concrete, Cement and Concrete Research” 2000 ,


Shawnessy Light Rail Transit Station, Calgary, Canada


Vol 30

GOLTERMANN P, JOHNSAN V and PALBOL L “Packing of aggregates: An alternate tool to determine the optimal aggregate mix, ACI Materials Journal”, September – October 1997.

MATTE V and MORANVILLE M “Durability of reactive powder composites: Influence of silica fume on the leaching properties of very low w/b pastes, Cement and Concrete Composites”, 1999, Vol 21.

STAQUET S and EPISON B “Influence of cement and silica fume type on compressive strength of reactive powder concrete, 6th International Sympoium on HPC,University of Brussels ,Belgium”, 2000.

BICKLEY J.A and MITCHELL D “A state of art review of high performance concrete structures built in Canada”, 1990-2000(2001)

Dili and Santhanam,”The Indian concrete journal”, April 2004

Website on Reactive powder concrete


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