Field Testing of Reinforced Concrete Structures (with references to International Standards) F.Papworth Buildings Mines Industrial Historical

Expected Outcomes – Site Surveys  Understand what sort of job you can do yourself with minimal risk  Understand what sort of information can be obtained  Understand when you should get help  Have a little background in the common tests  You may be able to use with minimal training  Testing companies may use on site Lets take a closer look at this …

Corrosion Testing Potentials Resistivity Polarisation Resistance Embedded Half Cell Carbonation Depth Chloride Penetration Visual Inspection Magnifier Gauge Deformation Monitor Strain Camera Buried Defects Impact Echo Pulse Echo Thermography Radar Nuclear Cover Quality Sorptivity Air Permeability Water Permeability Coatings Peel Tester Pull off Thickness Embedment Cable Tension Bolt Pull Out Cover Surface Flatness/Levelness Abrasion Resistance Dusting Insitu Strength Schmidt Rebound Pundit Break off Pull out Maturity

Corrosion Reaction Cathodic Reaction 4(OH)- Electrolyte Current Anodic Reaction Secondary Reaction H2OH2O 2Fe(OH) 2 O2O2 2Fe ++ 4e - WaterChlorideOxygen Fe 2 O 3 H 2 O (Rust) 4e - Electron Transfer H2OH2OO2O2

Strength Assessment – Early Age  Why Early Age Assessment  Check before lifting/stripping  Check before applying prestress  Check to stop curing Water retaining code = 75% f’c Bridges Code = 60% 60% f’c  Schmidt Hammer Method  Repetitive so establish conversion curve Accurate to 10-15% If 8MPa required lift safe to lift at 10MPa  Surface strength only  Maturity Measurement Method  Doubles as temperature measurement Cylinder strengths underestimate insitu strength 7 or 14 day specs overstate requirements

Strength Assessment  Check Old Structures  Check capacity for increased load Floor slabs when changing usage Buildings where heavy equipment to be located Bridges for increased capacity  Check continued capacity of historic structures Where no design information available  Check for progressive weakening Leaching of water retaining structures  Schmidt Rebound  No conversion curves available  Surface hardening due to carbonation  ±25% with carbonation allowance, ±50% no carbonation allowance

Strength Assessment  Rebound Hammer Rebound Hammer  Ultrasonics  Maturity  Pull off tests