PRESENTATION ON

REACTIVE POWDER CONCRETE (RPC)AS

ULTRA HIGH STRENGTH AND

HIGH PERFORMANCE CONCRETEBY: Mahesh Raj Bhatt

ME in Structural Engineering Kathmandu University

1:CONCRETE:

• Composite material /artificially built up stone composed of:

I. Cement(binding)II. aggregate(inert/strength)III. water (hydration)IV. Admixtures (chemical/minerals) fig: composition of concrete

• High compressive strength but weak in tensile.

2:CLASSIFICATION BASED ON STRENGTH:

– Low Strength (<2000psi), 20Mpa– Normal strength (2000-6000psi),20-60 Mpa– High Strength (HPC) (>6000psi), >60 Mpa– Ultra High Strength (UHPC/RPC) ,>200 Mpa

• High strength concrete(HSC)Lower w/c ratio (<=0.35)Silica fume is added(to prevent CaOH2 formation)Less workable? BUT super plasticizers are added

Methods of production (HSC)a. High speed slurry mixing -cement water paste + then aggregate addedb. Use of cementitious aggregates-high strength aggregatec. Re-vibration-1% porosity reduce = 5% strength gaind. Use of admixtures/to reduce w/c ratioe. Sulphur filling or impregnation/increase

strength.f. Preventations of cracks/inhibition.

• High performance concrete(HPC)

HIGH : strength/workability/imperm-ability/elasticity/ chemical attack resistance/dimensional stability AND durability.

• Ultra high strength/ultra high performance concrete produced by:a. Compaction by pressureb. Helical bindingc. Polymerizationsd. Reactive powder concrete (RPC)(FURTHER……..)

3: REACTIVE POWDER CPNCRETE (RPC)

• Need of High Strength /durability and ductility concrete.• Eliminated flaws of other types of concrete and use of

coarse aggregates.• Consists of very fine powders of Cement, Micro Silica Sand,

Quartz Powder, Minimum Water and Steel fibers for ductility.

• Ultra high strength range in compression: 200-800 Mpa.• Developed by P Richards and M Cheyrezy Bouygues, construction, in the early 1990s. (Paris)• w/c ratio 0.16-0.24 (sometime 0.13 too)

3.1: Ingredients of RPC

Components parameters function Particle size(μm)

Types

Sand Good hardness available at low cost

Gives strength 150-600 Natural crushed

Cement C3S 60%,C2S22%C3A3.8%,C4A47.4%

Binding and hydration

1-100 OPC fineness

Quartz powder Fineness Maximum reactivity during Heat treating

5-25 microns

Crystalline

Silica fumes Very low impurities Fills voids, produces secondary hydrates

0.1 – 1 micron

Highly Refined25% weight

Steel fibers Good aspect ratio Improves ductility L: 13-25 mmDia: 0.15 – 0.20 mm

Straight3-10%

super plasticizers

Less retarding Nature Reduce W/C ratio Polyacrylate

3.2:RPC MIX and PLACING

• Can be mixed and produced in a ready-mix truck and still have similar strengths to those made in a central mixer.

• Self-placing, requires no internal vibration.• Despite its composition, the large amount of super plasticizer still makes

it workable.

Function parameters

• Give strength to aggregate • Binding material • Maximum reactivity during heat-treating • Filling the voids • Improve ductility • Reduce water binding

3.3: PRINCIPLES:

Chard and Cheyrezy gave following principles for developing RPC:1. Elimination of coarse aggregates for enhancement of

homogeneity 2. Utilization of the pozzolanic properties of silica fume 3. Optimization of the granular mixture for the enhancement of

compacted density 4. The optimal usage of super plasticizer to reduce w/c and

improve workability 5. Application of pressure (before and during setting) to improve

compaction6. Post-set heat-treatment for the enhancement of the

microstructure7. Addition of small-sized steel fibers to improve ductility

3.4: PROPERTIES OF RPC• Compressive strength(>100 Mpa in 24 hours of initial set)• Flexural strength• Water absorption• Water permeability• Resistance to chloride ion penetration• Homogeneity• Compactness• Micro-structure• Material ductility• Almost no shrinkage or creep • Light weight • Long life • Aesthetic possibilities

a. compressive strength • Higher compressive (200-800MPa)

b. Flexural Strength• Plane RPC possess high flexural strength than HPC

(Up to 100mpa)• By introducing steel fibers, RPC can achieve high

flexural strength. c. Water Absorption -less than 7-10 times of HPCd. Water permeability-28th day water permeability of RPC is negligible.-7 times less than HPC-fiber increase surface water permeability

e..Resistance to chloride ion penetration• Increases when heat curing is done in concrete• Heat cured RPC show higher value than normal cured RPC. • This property of RPC enhances its suitability for use in nuclear waste

containment structures.f. Homogeneity• Improved by eliminating all coarse aggregates• Dry components for use in RPC is less than 600 micro meter. g. Compactness:• Application of pressure before and during concrete setting period.h. Microstructure:• Microstructure of the cement hydrate can be changed by applying

heat treatment during curing.i. material ductility:• Material ductility can be improved through the addition of short steel

fibers.

3.5: RPC APPLICATIONS Light weight ,high span bridges, multi story

buildings, high strength and in seismic region, inside water structures etc.

Real structures: First bridge in Sherbrook, Quebec, Canada. (230MPa)

• 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. • Shawnee's Light Rail Transit Station.

Basically, structures needing - light and thin components, -things like roofs for stadiums, -long bridge spans, extra safety or security such as blast resistant structures.

Qinghai-Tibet Railway Bridge

3.6:BENEFITS:

• It has the potential to structurally compete with steel.• Superior strength combined with higher shear capacity result in significant dead load reduction.• RPC can be used to resist all but direct primary tensile stress. Tensile strength up to 50 MPa• Improved seismic performance by reducing inertia load with lighter member.• Low &non-interconnected porosity diminishes mass transfer, making penetration of liquid/gas non-existent.

Fig: showing bending stress

3.7:LIMITATIONS:

• RPC mixture design, the components are more expensive elements.

• No code ( no any formal worldwide documents but is under research )

• 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(lack) that of the cement.

• The mineral component causes cost (5 to 10 times higher than HPC).

3.7:CONCLUSIONS:

• Owing to its high durability, RPC can even replace steel in compression members where durability issues are at stake (e.g. in marine condition).

• Since RPC is in its developing stage, the long-term properties are not known.

• It would be under research what if using other ashes rather than silica fume e.g. Pulverized fly ash etc.

Bibliography:1. Concrete technology B.L Gupta & Amit Gupta2. Concrete technology M.S.Shetty .3. Objective guides for civil engineers D. Prasad4. Properties of Concrete, A.M. Neville5. http://elearning.vtu.ac.in/12/enotes/Adv_Conc_Stru/Unit7-KK.pdf6. http://www.slideshare.net/shruthicivil/7. http://www.slideshare.net/vickynandhu/reactive-powder-concrete-41

6119738. http://www.slideshare.net/MohamedAbdelkhalekAt/reactive-powder-

concrete2-57310486

• Examples:

Qinghai-Tibet Railway

Shawnessy Light Rail Transit Station in Iowa (2004) First UHPC Bridge in U.S.

Sherbrooke pedestrian bridge, in Canada.

THANK YOU!!!!

ANY QUARIES??

WE ARE WAITING SUCH CONCRETES!!!!!!!