REACTIVE POWDER CONCRETE

ABHIRAM R 0209-1019

INTRODUCTION

RPC is an ultra high strength and high ductility cementitious composite with advanced mechanical and chemical properties.

Mixture of fiber reinforced, super plasticized, silica fume, cement & quartz sand with very low water cement ratio.

First developed by P. Richard and M. Cheyrezy and RPC was first produced in the early 1990’s by researchers at Bouygues laboratory in France.

RPC COMPOSTION

CEMENTS SILICA FUMES SAND QUARTZ POWDER STEEL FIBERS WATER SUPER PLASTICIZERS

RPC Composition

RPC is able to obtain its improved properties by using a very dense mix, consisting of fine particles and fibers.

o Low w/cm ratio : 0.16 to 0.24 (as low as 0.13)o Cement with low C3A content give better result (C3A-

1%-8%)o Silica fume (25% by weight)o High dosages of super plasticizer.o Fine quartz sand (150-600μm) (SG=2.75)o Steel fibers (2.5-10% by volume) for tougheningo No rebar neededo Cured in steam bath for 48 hrs @ 190ºF (88ºC) after

initial set, placed under pressure at the molding stage.

COMPONENTS WITH FUNCTION PARAMETERS

COMPONENTS

SAND CEMENT QUARTZ POWDER

SILICA FUME STEEL FIBERS SUPER PLASTICIZERS

FUNCTION PARAMETERS Strength to

aggregates. Binding material Maximum reactivity

during heat treating. Filling the voids. Improve ductility. Reduces water

binding.

PRINCIPLES OF DEVELOPING RPC

Elimination of coarse aggregate for enhancement of homogeneity.

Utilization of pozzolanic properties of silica fume.

Optimal usage of super plasticizer to reduce W/C and at the same time improves compaction.

Post- set heat treatment for enhancement of the microstructure.

Addition of small sized steel fibers to improve ductility.

TYPICAL COMPOSITION OF RPC 200

Portland cement-type V Fine Sand (150-400

micron) Silica fume (18m2/gram) Precipitated silica(35 m2/g) Super plasticizer

(polyacrylate) Steel fibers Total water Compressive

strength(cylinder) Flexural strength Young’s modulus

955 kg/m31051 kg/m3229 kg/m310 kg/m313 kg/m3191 kg/m3153 kg/m3170-230 MPa25-60 MPa54-60 GPa

TYPICAL COMPOSITION OF RPC 800

Portland cement-type V Fine Sand (150-400

micron) Ground Quartz (4 microns) Silica fume (18m2/gram) Super plasticizer

(polyacrylate) Steel fibers Total water Compressive

strength(cylinder) Flexural strength Young’s modulus

1000kg/m3500kg/m3390 kg/m3230 kg/m318 kg/m3630 kg/m3180 kg/m3490-680 MPa45-102 MPa65-75 GPa

PROPERTIES OF RPC

COMPRESSIVE STRENGTH FLEXURAL STRENGTH WATER ABSORPTION WATER PERMEABILITY HOMOGENITY COMPACTNESS MICROSTRUCTURE MATERIAL DUCTILITY

COMPRESSIVE STRENGTH

Higher compressive strength than HPC

Compressive strength: 200- 800 MPa

Max Compressive strength of HPC: 75 Mpa.

It is one of the factors linked with the durability of a material.

FLEXURAL STRENGTH

Plain RPC is found to possess marginally higher flexural strength than HPC.

The increase of flexural strength of RPC with the addition of steel fibers is higher than that of HPC.

Flexural strength at first cracking is higher than ultimate flexural strength of normal concrete.

Comparison of HPC (80 MPa) and RPC 200

Property HPC (80 MPa) RPC 200

Compressive strength

80 MPa 200 MPa

Flexural strength 7 MPa 40 MPa

Modulus of Elasticity

40 GPa 60 GPa

Fracture Toughness <10³ J/m² 30*10³ J/m²

WATER ABSORPTION & PERMEABILITY

The percentage of water absorption of RPC is very low compared to that of HPC.

This quality of RPC is one among the desired properties of nuclear waste containment materials.

Incorporation of fibers and use of heat curing marginally increase the water absorption.

The permeability of RPC is almost 7 times lower than that of HPC.

HOMOGENITY

Improved by eliminating all coarse aggregates.

Replaced by fine sand ( 600μm maximum)

Reduction in aggregate/matrix ratio.

COMPACTNESS: Application of pressure before and during

concrete setting period.

MICROSTRUCTURE:Microstructure of the cement hydrate can be

changed by applying heat treatment during curing.

MATERIAL DUCTILITY:Material ductility can be improved through the

addition of short steel fibres

RPC APPLICATIONS:

Used in nuclear waste containment structures due to lower water absorption and low permeability.

Used for heavily loaded structures like bridges due to its ultra high strength and durability.

Used for marine structures due to high sulphate resistance.

RPC APPLICATIONS

First bridge that used RPC-pedestrian bridge in Sherbrooke, Quebec, Canada. (230MPa) It was used during the early days of RPC production. Has prompted bridge building in North America, Europe, Australia, and Asia.

Portugal has used it for seawall anchors

Australia has used it in a vehicular bridge

France has used it in building power plants

Qinghai-Tibet Railway Bridge.

Sherbrooke pedestrian bridge, in Canada.

Qinghai-Tibet Railway Bridge.

ADVANTAGES:

As fracture toughness is higher, RPC exhibits high ductility.

Since RPC is an Ultra dense micro structure, porosity and permeability is less and therefore can be used for waste storage holding facility.

RPC has limited shrinkage, increased corrosion resistance and so can be used in aggressive chemical environments.

LIMITATIONS:

Least costly components of conventional concrete are replaced by more expensive elements.

Since RPC is in its infancy, a long term properties are not yet known.

CONCLUSIONS:

It has immense potential in construction due to its superior, mechanical &durability properties.

RPC has ultra dense micro structure , giving advantageous water proofing &durability characteristics.

RPC is a better alternative to High Performance Concrete and has the potential to structurally compete with steel.

REFERENCES:

Development of a lightweight reactive powder concrete, journal of advanced concrete technology, No. 3, vol. 2

A.S Dili and Manu Santhanam, investigation on RPC:A developing ultra high strength technology, The Indian concrete journal, April 2004.

M S Shetty , concrete technology S. Chand & company LTD, Ram Nagar New Delhi.

 The Seattle Daily Journal of Commerce. Purdue university website.

The concrete portal.com