Concrete highway slabs are poured in lengths of 9.00m .

Question

Part A
How wide should the expansion gaps between the slabs be at a temperature of 22∘C to ensure that there will be no contact between adjacent slabs over a temperature range of -25 ∘C to 48∘C?

Answer 1

α=12•10⁻⁶ K⁻¹
T₁=22° T₂=-28°, T₃= 48°
ΔT₁ = T₃-T₂ = 48-(-25) = 73°
ΔT₂ =48-22 = 26°
ΔL₁=L αΔT₁=9•12•10⁻⁶•73=0.0079 m
If the slabs are in contact at 48° =>
they are at 0.0079 mm at -25°
ΔL₂=L αΔT₂ = 9•12•10⁻⁶•26=0.0028 m
ΔL= ΔL₁-ΔL₂=
=0.0079-0.0028=0.0051 m=5.1 mm (at 22°)