HYDRAULIC CONCRETE FOR BRIDGES

 HYDRAULIC CONCRETE FOR  BRIDGES

This was a discussion held through the internet in 2012.

Hydrophobic impregnation and painting should be scheduled to re-application. Of course the mix design will be most crucial. Life 365 is not the best software for such prediction. Typical mix design is

Cement (Kgr/m3) 320

Water /CB 0.40

Silica Fume (Kgr/m3) 25 (i.e. SikaFume HR)

Max. Aggregate (25mm) (Kgr/m3) 310

Medium Aggregate (10-13mm) (Kgr/m3) 501

Fine Aggregate (4-8mm) (Kgr/m3) 257

Sand ( down to US Sieve 50) 740

Crystal Growth System (Kgr/m3) 2.7 (i.e. Penetron Admix)

Slump (mm) 100-135

HRWR (Kgr/m3) 4.8 (i.e. SIKA Sikament 240, BASF Glenium 3400 NV)

Predicted Total Charge Passed (Coulombs)

AASTHO T277 514-600

Predicted Water Permeability (cm/sec) ASTM D5084 6.57-7.54 x 10-11

Predicted Sealing Resistance Rating ASTM C672 1

Predicted Compressive Strength 7 days (MPa) 29.2-31.4

Predicted Compressive Strength 28 days (MPa) 41.8-43.2

Estimated Final Temperature (oC) 29.2

Estimated Concrete Density (kg/m3) 2325

Estimated Effective Water to Binder Ratio 0.431

Estimated Time To Critical Attack 30mm cover (years) 56

Estimated Time To Critical Attack 50mm cover (years) 112.7

Posted by Chris Rodopoulos

NOTE: ON THIS BRIDGE THEY USED STAINLESS STEEL REINFORCING BARS.(TO EXTEND THE LIFE OF THE REBAR)

MY SUGGESTION IS TO CONNECT “ALL” METALS TO A SACRIFICE ANODE AND KEEP CONTROL OVER IT,

SEAL THE CONCRETE WITH CLEAR EPOXY SEALER (*)AND THEN INSTALL A RUBBERIZED ASPHALT  ON TOP

OF THE CONCRETE, THESE COATS WILL PROTECT FROM HUMIDITY INSIDE THE CONCRETE. IN MY EXPERIENCE I HAVE CONSTRUCTED 17 FERROCEMENT BOATS ( 45’ TO 80’) AND WE HAVE USED NORMAL REBAR OR GALVANIZED REBAR AND INCLUDED ON THE WATER FOR THE CONCRETE MIX A

CALCIUM HIPOCLORITE MIX TO INHIBIT THE REACTION OF THE WATER WITH THE REBAR.

IF USING NORMAL STEEL REBAR, IT CAN BE COATED WITH "ARMATEC" FROM SIKA

(*) The concrete sealer must be applied after the 28 day concrete cure

Also if there is going to be ice present don’t forget “air inclusive agent”


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