Course: CAEE $330($Construction Materials $\backslash$& Methods$)$

Assignment $\backslash$#$3$

Problem $\backslash$#$1($Total $100)$

A concrete mix for the following conditions and constraints using the absolute volume method will be designed.

Design Environment

$-$ Bridge footing with reinforced concrete exposed to freezing and thawing in a moist condition $($footings are not considered flatwork$).$

$-\backslash (\backslash$quad $\backslash )$ Required design strength $\backslash (=4000\backslash$mathrm$\{$psi$\}\backslash )$

$-$ Minimum dimension $\backslash (=18\backslash )$ in$.$

$-$ Minimum space between rebars $\backslash (=6\backslash )$ in

$-$ Minimum cover over rebars $\backslash (=6\backslash )$ in$.$

$-$ Standard deviation of compressive strength of $375$ psi is expected $($more than $30$ samples$)$

$-$ Only air entrained is allowed

$-$ Slump $2"$

Available Materials

Cement

$-$ Moderate Exposure

$-$ Air Entrainer

$-$ Manufacturer specification $\backslash (0\mathrm{.}25\backslash$mathrm$\{$fl$\}\backslash$mathrm$\{$oz$\}/1\backslash \%\backslash )$ air$/100$ lb cement

Aggregate Fineness Modulus: $2\mathrm{.}40$

Coarse aggregate

$-1$ in$.$ nominal maximum aggregate size, river gravel $($round$)$

$-$ Bulk oven dry specific gravity $\backslash (=2\mathrm{.}88\backslash ),$ absorption $\backslash (=2\mathrm{.}6\backslash \%\backslash )$

$-$ Oven dry$-$rodded density $\backslash (=130\backslash$mathrm$\{$pcf$\}\backslash )$

$-$ Moisture content $\backslash (=2\mathrm{.}2\backslash \%\backslash )$

Fine aggregate

$-$ Natural sand

$-$ Bulk oven$-$dry specific gravity $\backslash (=2\mathrm{.}30\backslash ),$ absorption $\backslash (=4\mathrm{.}0\backslash \%\backslash )$

$-$ Moisture content $\backslash (=4\mathrm{.}5\backslash \%\backslash )$

Determine the following:

a$.$ Water cement ratio

b$.$ Calculate the volume of coarse aggregate

c$.$ Find the air content

d$.$ Calculate the desired water content

e$.$ Calculate the cement content

f$.$ Calculate the weight of the sand

g$.$ Calculate the adjusted mix water $($extra credit$)$