A concrete highway is built of slabs 12 m long .How wide should be the expansion cracks between the slabs at 15 Celsius to prevent buckling

Question

A concrete highway is built of slabs 12 m long .How wide should be the expansion cracks between the slabs at 15 Celsius to prevent buckling if the range of temperature is -30 to 50 Celsius?

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Gerda 3 years 2021-09-02T01:34:06+00:00 1 Answers 0 views 0

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  1. mit
    0
    2021-09-02T01:35:48+00:00
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    Answer:

    x=4.2\ mm

    Explanation:

    Given:

    • length of the concrete slab, l=12\ m
    • temperature of observation, T_o=15^{\circ}C
    • we’ve the coefficient of linear expansion for concrete, \alpha=10^{-5}\ ^{\circ}C^{-1}
    • lower temperature limit, T_l=-30^{\circ}C
    • upper temperature limit, T_u=50^{\circ}C

    Change in length due to temperature can be  given as:

    \Delta l=l.\alpha.(T_u-T_l)

    \Delta l=12\times 10^{-5}\times (50-(-30))

    \Delta l=0.0096\ m=9.6\ mm

    Now at temperature 15°C:

    \Delta l'=12\times 10^{-5}\times (15-(-30))

    \Delta l'=0.0054\ m=5.4\ mm

    Hence the expansion crack between the slabs at this temperature must be:

    x=\Delta l-\Delta l'

    x=9.6-5.4

    x=4.2\ mm

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