Forum Message



Name:   
Heading: 1.2.1.1Concrete Modulus of Elasticity
Message:
It is great to have the Forum up and operating again.

Can anyone help me with ascertaining a relationship between compressive strength of concrete and MOE, or, any characterisitcs of the concrete or concrete materials that influence MOE, ie, W/C ratio, or any characterisitics of the aggregates, sand or cements etc.

Thanks.


---------------------------------------------
BARRY HUDSON


barry
elasticity modulus of concrete is related to its compressive strength
there are many ways to calculate the elastic modulus
of concrete from a stress / strain curve  results can differ!

ACI 318 or the CEP-FIB Model

high long term E modulus means high rigidity and therefore reduced buckling of beams and decks
high early age E modulus means higher potential for cracking (shrinkage or thermal) as little deformations can induce (from Hooke’s law) high stresses when tensile strength of the material is still low
for this reason massive pours at risk for thermal cracking should be cast with low to very low elasticity modulus concrete

if you need to understand it will i can send youmore

ashraf

---------------------------------------------
ahmad ahmad


Ashraf already gives a good answer on the forum. I could add the following:

The European Eurocode 2 (EN 1992-1-1) gives an indicative relationship between the compressive strength and the modulus of elasticity for general applications. Please see paragraph 3.1 (especially paragraphs 3.1.2 and 3.1.3 and table 3.1) of this standard.

It gives the relationship between the mean cylinder compressive strength at 28 days (fcm) and the secant modulus of elasticity at 28 days (Ecm) (sc between 0 and 0,4*fcm):

Ecm = 22*[(fcm)/10]^0,3
Fcm in MPa
Ecm in GPa

The variation of the modulus of elasticity with time can be estimated by:

Ecm(t) = [(fcm(t) / fcm)^0,3]*Ecm
See paragraph 3.1.2, point (6) for the relationship between fcm and fcm(t).

The standard also gives multipiers for aggregates different from quartz.

So, the modulus of elasticity at 28 days is dependant on the compressive strength at 28 days. Of course this compressive strength is influenced by the type of binder, the water-binderratio, the type of aggregate and the amount of air.

I hope I helped you with this information. If you have any more questions, please let me know.

Best regards,
Marique Ruijs
B|A|S Research & Technology
The Netherlands

---------------------------------------------
Marique Ruijs


I leave others to answer Barry's question but disagree with Ashraf's advice to use v low E for mass pour concrete. E depends on strength and on E value of coarse agg. Strength is determined by other considerations, so not an available parameter. Cement content (therefore temp rise) can be limited by high PFA content rather than low strength.
---------------------------------------------
Ken Day
 
   Click Here to Reply    Areas
Advertise Here