Methods Of Curing

-1.Water Curing

-a.Immersion

-b.Ponding

-c.Spraying/Fogging

-d.Wet Covering

-2.Membrane Curing

-3.Application Of Heat

-a.Steam Curing

-b.Infra Red Radiation Curing

-c.Electrical Curing

Immersion Curing

Ponding Curing

Spraying Curing

Wet Covering Curing

Membrane Curing

Steam Curing

Reasons For Curing

-Laboratory tests show that concrete can lose 50% strength if it is in dry environment

-Higher Temperature = Early Strength Gain

-Better surface hardness

-Makes concrete more water tight

-Better appearances

Curing Of Concrete

-Maintaining of an adequate moisture content & temperature

-Develop such properties it was designed to achieve

-Begins immediately after placement & finishing

-Concrete may get its desire strength

-Cementitious material in concrete cannot react to form a quality product without adequate supply of m/c

-Drying may remove the water needed for hydration

-Rate of hydration & strength development is faster at higher temperatures

-Temperatures should be higher than 10C

-Uniform temperature should be provided

Compacting Factor Apparatus

-Determine the workability

-Compacting factor apparatus is used

-1.Weigh the empty cylinder

-2.Place fresh concrete in upper hopper

-3.Open the gate & allow concrete to fall into lower hopper

-4.Open gate of lower hopper so that it falls into cylinder

-5.Cut off excess concrete from top of cylinder & weigh the cylinder containing concrete

-6.Deduct the weight of empty cylinder & new weight is called as the weight of partially compacted concrete

-7.Cylinder is filled again with fresh concrete & vibrated or tamped to obtain full compaction

-8.Concrete in cylinder is weight again & this is called as weight of fully compacted concrete

• Compacting Factor = Wt. Of partially compacted conc./Wt. Of fully compacted conc.

                                                                   

Measurement Of Workability

-Many different methods to measure workability

-Most common are Slump Cone Test & Compacting Factor Test

-Ball Penetration

-Flow Table Test

-Vebe Test

7.Use Of Admixture

-Most Important Factor which affects the workability

-Plasticizers, Super-Plasticizers

6.Grading Of Aggregates

-Maximum influence on workability

-Well graded aggregate has least amount of voids

-Better grading>Less Void Content>Higher Workability