ما هو الفرق بين كل من expansion joint and contraction joint في slab on grade?

 الفرق بين الاثنتين في طريقة عملها  ومكوناتها معلش رح اكتب بالأنجليزي عشان الشرح يكون ادق    concrete as you know expands and contract according to ambient temperatures and humidity levels in the atmosphere , the expansion joint is an assembly designed to absorb the force of expanding concrete without  damaging the slab or any structure for that mater it is usually made of a shock absorbing rubber material , it works sort of like a shock absorber for the concrete so it doesn't crack.

a contraction Joint is just a small  space made  when pouring the concrete at certain intervals to facilitate the contraction of concrete with out it cracking ,concrete tends to shrink more  specially in cold weather this will lead to cracks in the surface of the slab , when you  divide  the slap  in to smaller units by making the contraction joint each unit of the concrete will contract at smaller lengths , therefore reducing cracking of each individual unit of the slap .  الفرق بين الاثنتين في الهدف منها وطريقة عملها اخي الكريم