Reactive powder concrete A Seminar Report Submitted in partial fulfillment of the requirements of the degree of BACHELOR OF TECHNOLOGY IN CIVIL ENGINEERING

ByD. Siddhartha(UG101218)

DEPARTMENT OF CIVIL ENGINEERINGNATIONAL INSTITUTE OF TECHNOLOGY, WARANGAL2013-2014

Table of ContentsAbstract31. Introduction41.1 Defining Reactive powder concrete41.2 History and development of RPC41.3 Scope of RPC42. Composition of RPC52.1 Introduction52.2 RPC components52.2.1 Cement52.2.2 Sand52.2.3 Quartz powder62.2.4 Silica fume62.2.5 Steel fibers62.2.6 Super plasticizer62.2.7 Table showing components of RPC62.3 Mix proportion of RPC73. Properties of RPC83.1 Introduction83.2 Typical properties of RPC 20093.3 Typical properties of RPC 80093.4 Comparison of RPC and HPC103.5 Fresh concrete properties103.6 Compressive strength113.7 Flexural strength113.8 Water absorption123.9 Water permeability123.10 Resistance to chloride ion penetration134. Factors effecting strength of RPC144.1 Silica Fume Percentage144.2 Quartz Powder144.3 Curing Regime144.4 Compressive and tensile properties of RPC at elevated temperatures144.5 Effect of pre-setting pressure145. Advantages156. Limitations157. Structures built using RPC168. Case study168.1 THE SIDEWALK SYSTEM OF THE QINGHAI-TIBET RAILWAY BRIDGE168.2 Pedestrian bridge in Sherbrooke179. References18

Abstract Reactive Powder Concrete (RPC) is catching more attention now days because of its high mechanical and durability characteristics. RPC mainly comprises of cement, silica fume, silica sand, quartz powder and steel fibers. RPC has been able to produce with compressive strength ranging from 200 MPa to 800 MPa with flexural strength up to 50 MPa and in some cases can replace traditional steel reinforcement. RPC will allow the concrete industry to optimize material use, generates economic benefits, and build structures that are strong and durable. Present seminar mainly discusses on composition and Mix proportion of RPC, properties and factors effecting RPC and comparison between High performance concrete (HPC) and RPC and limitations of RPC and few case studies.

1. Introduction 1.1 Defining Reactive powder concreteReactive powder concrete (RPC) is ultra high strength and high ductile composite material with advanced mechanical properties. Reactive powder concrete is a concrete without coarse aggregate, but contains cement, silica fume, sand, quartz powder, super plasticizer and steel fiber with very low water binder ratio. The absence of coarse aggregate was considered by inventors to be key aspect for the microstructure and performance of RPC in order to reduce the heterogeneity between cement matrix and aggregate.1.2 History and development of RPCThe concept of reactive powder concrete was first developed by P. Richard and M. Cheyrezy and RPC was first produced in the early 1990s by researchers at Bouygues laboratory in France. The worlds first Reactive Powder Concrete structure, the Sherbrooke Bridge in Canada, was erected in July 1997. The addition of supplementary material, elimination of coarse aggregates, very low water/binder ratio, additional fine steel fibers, heat curing and application of pressure before and during setting were the basic concepts on which it was developed. Compressive strength of RPC ranges from 200 to 800 MPa, flexural strength between 30-50 MPa and Youngs modulus up to 50-60 GPa. There is a growing use of RPC owing to the outstanding mechanical properties and durability. RPC structural elements can resist chemical attack, impact loading from vehicles and vessels, and sudden kinetic loading due to earthquakes. Ultra high performance is the most important characteristic of RPC. RPC is composed of more compact and arranged hydrates. The microstructure is optimized by precise gradation of all particles in the mix to yield maximum density. It uses extensively the pozzolonic properties of highly refined silica fume and optimization of the Portland cement chemistry to produce highest strength hydrates.1.3 Scope of RPCRPC will be suitable for pre-stressed application and for structures acquiring light and thin components such as roofs of stadiums, long span bridges, space structures, high pressure pipes, blast resistance structures and the isolation and containment of nuclear wastes. In India the work on RPC has started from last few years. The utility of RPC in actual construction is minimal or nil in India, it is because of non-availability of sufficient experimental data regarding production and performance of RPC. 2. Composition of RPC2.1 Introduction RPC is composed of very fine powders (cement, sand, quartz powder and silica fume), steel fibers and super plasticizer. The super plasticizer, used at its optimal dosage, decreases 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 800 MPa.Richard and Cheyrezy indicate the following principles for developing RPC:1. Elimination of coarse aggregates for enhancement of homogeneity2. Utilization of the pozzolonic properties of silica fume3. Optimization of the granular mixture for the enhancement of compacted density4. The optimal usage of super plasticizer to reduce w/c and improve workability5. 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 ductilityApplication of these principles without steel fibers produces a matrix with very high compressive strength, but with ductility no better than that of conventional mortar. The inclusion of fibers improves tensile strength, and also makes it possible to obtain the required level of ductility.2.2 RPC components2.2.1 CementCement is binding material for production of primary hydrates. Its particle size ranges from 1m to 100m. Optimum cement properties are C3S: 60% C2S: 22% C3A: 3.8% C4AF: 7.4%2.2.2 SandCoarse aggregates are replaced by fine sand. It gives strength to the concrete. Maximum size of sand is 600m. Size ranges from 150m to 600m. It eliminates mechanical chemical and thermo mechanical failures.2.2.3 Quartz powderIts particle size ranges from 5m to 25m. It must be in crystalline form.2.2.4 Silica fumeSilica fume is used for filling voids and enhance rheology and for production of secondary hydrates. Its particle size ranges from 0.1m to 1m . 2.2.5 Steel fibersIt should have good aspect ratio and should be able to improve ductility. Its length ranges from 13mm to 25mm. It should be straight. 2.2.6 Super plasticizer A copolymer of acrylic ester (CAE), a polynaphtalene Sulfonate (PNS) and a polymelamine sulfonate (PMS) are normally employed for the purpose. These admixtures are synthetic polymers.2.2.7 Table showing components of RPCComponent

Selection parameter Function Particle size

Sand Good hardnessReadily available and low cost.Gives strength150 m to 600 m

Cement C3S: 60% C2S: 22% C3A: 3.8% C4AF: 7.4%Binding material,Production of primary hydrates1 m to 100 m

Quartz powderFineness Max. reactivity during heat-treating5m to 25m

Silica fumeVery less quantity of impuritiesFilling the voids,Enhance rheology,Production of secondary hydrates0.1m to 1m

Steel fibersGood aspect ratioImprove ductilityLength 13mm to 25mmDia. 0.15 0.2 mm

Super plasticizerLess retarding characteristicReduce w/cPolyacrylate based

Table 1 Components of RPC2.3 Mix proportion of RPCThe RPC family includes two types of concrete, designated RPC 200 and RPC 800. Mix proportion (by weight) given by P. Richard and and M. Cheyrezy. RPC 200 RPC 800

Non fibered Fibered Silica aggregatesSteel aggregates

Portland cement111111

Silica fume0.250.230.250.230.230.23

Sand1.11.11.11.10.5-

Quartz powder-0.39-0.390.390.39

Super plasticizer0.0160.0190.0160.0190.0190.019

Steel fibre L=12 mm--0.1750.175--

Steel fibre L=3 mm ----0.630.63

Steel aggregates