Question
For rigid pavement, what is recompense of using lean concrete sub-base instead of traditional granular sub-base?
Answer
There are some shortcomings of using granular sub-base in concrete carriageway-
(i) As sub-base is permeable, water know how to seep from side to side sub-base and soil particles will be pumped out through contraction or expansion joints when subject to traffic load. So, voids are formed underneath pavement structure and concrete pavement may crack under severe traffic loading.
(ii) Lean concrete increases strength and renders roads capable of carrying heavy traffic loads.
(iii) Because of workmanship problem, it could have uneven distribution of sub-base and these results in cracking of concrete carriageway when question to severe traffic loading.