--- title: "Maintenance, rehabilitation, reconstruction; rigid failures" subject: "Transportation Engineering II" chapter: 4 key: "semester_7/transportation_engineering_ii:maintenance-rehab-reconstruction-rigid-failures" source: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/maintenance-rehab-reconstruction-rigid-failures site: BCT Engineering --- # Maintenance, rehabilitation, reconstruction; rigid failures Transportation Engineering II · Chapter 4: Highway Maintenance, Repair, and Rehabilitation - Asked in: 2080 Bhadra, 8 marks - Video: [Pavement rehabilitation](https://www.youtube.com/watch?v=RlxW52fLK1c) — hannie michelle intrepido - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/maintenance-rehab-reconstruction-rigid-failures - Whole chapter: https://www.bctengineer.com/md/semester_7/transportation_engineering_ii/chapter-4 ## Question Describe the term maintenance, rehabilitation and reconstruction. Describe the typical types of rigid pavement failure with sketches where possible. ## Short answer Maintenance preserves serviceability (patching, sealing). Rehabilitation restores structural strength (overlay, recycling). Reconstruction builds new pavement. Rigid failures: transverse cracking (shrinkage, late sawing), corner breaks (pumping, unsupported corner), faulting (step at joint, poor load transfer), pumping, spalling, blow-up (blocked expansion joints). ## Answer #### Maintenance, rehabilitation and reconstruction | Term | Meaning | Examples | Aim | |---|---|---|---| | **Maintenance** | Regular works to keep the road in serviceable condition without improving the original design | Patching, crack sealing, drain cleaning, resealing, regravelling | Preserve the existing condition and slow deterioration | | **Rehabilitation** | Works that restore the structural strength and extend the life of an existing pavement, usually after major distress | Structural overlay (by deflection/IRC:81), recycling, partial reconstruction of failed areas, widening | Raise the load capacity to carry the traffic of the next design period | | **Reconstruction** | Complete or near-complete removal and rebuilding of the pavement layers (and sometimes the geometry) at the end of its life | Removing all pavement layers and rebuilding to a new design | Provide a new pavement with a full design life | #### Typical failures of rigid pavement Typical types of failure of a cement concrete pavement: | Failure | Description | Cause | |---|---|---| | **Transverse cracking** | Cracks across the slab | Late sawing of joints, joint spacing too long, thin slab, restrained shrinkage | | **Longitudinal cracking** | Cracks along the lane | Differential settlement, warping, thin slab, poor subgrade support | | **Corner break (corner crack)** | A triangular piece cut off at the slab corner by a crack meeting both edges, usually within about 1.5 m of the corner | Load at an unsupported corner, loss of support (pumping), poor load transfer | | **Diagonal cracking** | Crack at about 45 degrees | Heavy corner loads, settlement | | **Punch-out / shattered slab** | Slab breaks into many pieces | Heavy repeated loads, weak sub-base | | **Faulting** | Step between slabs at a joint | Pumping, poor load transfer (dowel failure) | | **Pumping** | Ejection of water and fines at joints | Water under the slab, loose subgrade, heavy traffic | | **Spalling** | Breaking of joint edges | Incompressible material in joints, weak concrete, dowel misalignment | | **Blow-up (buckling)** | Slab lifts and shatters in hot weather | Blocked expansion joints, insufficient expansion gap | | **Scaling and crazing** | Flaking and map cracks on the surface | Over-finishing, poor curing, freeze-thaw | | **Joint seal failure** | Loss of sealant, weeds in joints | Aged sealant, poor installation | ```text Faulting at a joint Corner break ______ +-------------+ ______| step | | joint | | | crack -> / +-----------/-+ ``` Remedies include full-depth repair, slab replacement, dowel retrofit, grinding of faults, crack and joint resealing, undersealing (grouting) to fill voids, and improving drainage. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which works are rehabilitation rather than maintenance? A. Pothole patching B. Drain cleaning C. Structural overlay or recycling to restore strength D. Crack sealing Answer: C. Rehabilitation restores or raises structural strength; maintenance preserves existing condition. (Key point: Maintenance vs rehabilitation) 2. Reconstruction means: A. Complete or near-complete removal and rebuilding of pavement layers at end of life B. Filling small potholes C. Resealing cracks D. Cleaning culverts Answer: A. Reconstruction gives a new pavement of full design life by rebuilding the layers. (Key point: Reconstruction) 3. A corner break in a concrete slab is caused by: A. Loads at an unsupported corner, loss of support and poor load transfer B. Late curing only C. Over-finishing D. Excess sealant Answer: A. Heavy load on an unsupported corner, often after pumping, breaks a triangular piece within about 1.5 m of the joint. (Key point: Corner break) 4. Which is a remedy for rigid pavement failures? A. Full-depth repair, undersealing grout and dowel retrofit B. Applying prime coat C. Increasing tyre pressure D. Removing joints Answer: A. Remedies include full-depth repair, slab replacement, dowel retrofit, grinding, resealing and undersealing. 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