ICOLD Bulletin: The Physical Properties of Hardened Conventional Concrete in Dams
Section 2 (Strength properties)
As submitted for ICOLD review, march 2008 Section 2-1
2 STRENGTH PROPERTIES
2 STRENGTH PROPERTIES ................................................................. 1
2.1 GENERAL.............................................................................................................2
2.2 CONCRETE TESTING..........................................................................................2
2.2.1 Testing of concrete strength for new dams................................................2
2.2.1.1 Testing in stages................................................................................................. 2
2.2.1.2 Testing program.................................................................................................. 3
2.2.1.3 Sample Sizes ......................................................................................................5
2.2.1.4 Wet screening..................................................................................................... 7
2.2.2 Testing of concrete strength in existing dams............................................8
2.2.2.1 General ............................................................................................................... 8
2.2.2.2 Semi-destructive or non-destructive methods...................................................... 8
2.2.2.3 Ratio between core diameter and MSA............................................................... 9
2.2.2.4 Length-to-diameter ratio.................................................................................... 10
2.2.2.5 Core size........................................................................................................... 10
2.2.2.6 Core vs. laboratory strength .............................................................................. 11
2.2.3 Nominal age of concrete strength ............................................................12
2.2.4 Test Equipment........................................................................................16
2.2.5 Evaluation of Strength Testing.................................................................16
2.2.6 Generic Uncertainty in Test Procedures ..................................................18
2.3 COMPRESSIVE STRENGTH .............................................................................20
2.3.1 Effects of porosity and w/c-ratio on concrete strength .............................20
2.3.2 Effects of maximum size of aggregate (MSA) ..........................................22
2.3.3 Effects of aggregate properties................................................................23
2.3.4 Effects of curing .......................................................................................24
2.3.5 Effect of mineral admixtures and blended cements .................................25
2.3.6 Effect of sustained loading.......................................................................26
2.3.7 Multiaxial compressive stress domain in a dam .......................................28
2.4 TENSILE STRENGTH.........................................................................................29
2.4.1 Tensile loading in the dam .......................................................................29
2.4.2 Type of tensile testing ..............................................................................30
2.4.3 Tensile strength ratios..............................................................................31
2.4.4 Size effect ................................................................................................32
2.4.5 Tensile strain capacity in dams................................................................32
2.4.6 Tensile strength at joints ..........................................................................33
2.4.7 Tensile strength criteria............................................................................34
2.4.8 Use of tensile strength in mathematical models.......................................36
2.4.8.1 Linear elastic analysis ....................................................................................... 36
2.4.8.2 Non linear analysis............................................................................................ 37
2.5 SHEAR STRENGTH ...........................................................................................39
2.6 DYNAMIC STRENGTH .......................................................................................41
2.6.1 Dynamic Compressive Strength...............................................................42
2.6.2 Dynamic Tensile Strength........................................................................43
2.6.3 Dynamic Shear Strength..........................................................................45
2.7 REFERENCES....................................................................................................46