Question

1. What are the possible reasons for the following pavement distresses? What are the appropriate procedures that should be followed for repair in each case? a. Rutting b. Stripping c. Fatigue cracking d. Thermal cracking e. Faulting f. Scaling

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Answer 1

Rutting - Rutting are two types (1) Mix Rutting (2) subgrade Rutting due to consideration due to lateral movement of material due to traffic loading due to insufficient compaction of HMA Repair First identify the reason behind the Rutting less than 1/3 inch deep ruts left centreated and deeper cuts is levelled and overload. (b) stripping stripping occurs due to Bond between aggregrates and aspnalt binders. In stripping first the bottom layer of HMA is and progress upward. Rightarrow water in HMA lead to moisture damage Rightarrow poor aggregates used. Repair rightarrow Identify the root cause. Stripped pavement needs to be removed and rep-lace after correction of root cause (C) Fatigue cracking rightarrow fatigue cracking occurs when stress applied is more than its Bearing capacity rightarrow for long time applied stress. \r\n rightarrow stress concentration Rightarrow overload Rightarrow residual stress Rightarrow loss of subbase Repair rightarrow Removing sections of cracked pavement by replacing the poor subgrade.