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# Mean value of axial tensile strength of concrete at an age of t days, fctm(t)

## Eurocode 2 part 1-1: Design of concrete structures \$(document).ready(function () { var freeExample = \$("#freeExample").length; \$("#mainMenu li#nav-appCate, #mainMenu li#nav-appEC211").addClass("active"); var proUser = false === true || false === true || freeExample !== 0; if (!proUser) { \$('#Input input').keyup(function(){ \$('#AlertSubscribe').modal(); }); \$('#Input select').change(function(){ \$('#AlertSubscribe').modal(); }); }; var tempInput = \$("#tempInput").text(); if (tempInput != "") { \$("#Input").parent("form").deserialize(tempInput); if (proUser) { \$("#acceptBtn").trigger("click"); } }; });  3.1.2 (9)

The mean value of axial tensile strength of concrete an age of t days is:

 fctm(t) = (βcc(t))α⋅fctm (3.4)

where:

fctm
is the mean value of axial tensile strength of concrete at 28 days, see Table 3.1
βcc(t)
is a coefficient which depends on the age of the concrete t:
 βcc(t) = exp { s [1 - (28/t)1/2] } (3.2)

with

t
the age of the concrete
s
a coefficient which depends on the type of cement:
= 0,20 for CEM 42,5 R, CEM 52,5 N and CEM 52,5 R (Class R)
= 0,25 for CEM 32,5 R and CEM 42,5 N (Class N)
= 0,38 for CEM 32,5 N (Class S).
α
= 1 for t < 28 days
= 2/3 for t ≥ 28 days.

This application calculates the mean tensile strength fctm(t) from your inputs. Intermediate results will also be given.

Input
days

Output
fctm
MPa
βcc(t)
α
the mean tensile strength fctm(t)
MPa (3.4)