Advantages of Full Depth Recycling

Transcription

1 Definition of FDR re-use existing asphalt, base and subgrade material 6 12 ( mm) to produce a new base course a new wearing surface is applied a stabilizer can be incorporated

2 Advantages of Full Depth Recycling Technical Advantages Eliminate base and surface problems simultaneously Improve the load bearing capacity of the pavement The profile of the road remains unchanged On widening projects, materials will be uniform across the new road's width Economical Advantages Cut costs by re-using existing roadway materials Save time by using in-place construction techniques Minimize traffic disruption, detours, and downtime Minimize traffic of construction trucks Environmental Advantages No new aggregates needed for the base No material for disposal Reduce dust contamination Save in energy use

3 Building for the future Roads have evolved from gravel roads at some time in the past. In some cases the materials that were left in place to form the base course were not suitable for the job. Stabilization can help improve its performance.

4 Increased Rigidity Spreads Loads 100 psi 100 psi 4 psi 15 psi Unstabilized Granular Base Cement-Stabilized Base Soil-Cement Cement-Treated Base FDR with cement

5 Eliminates Rutting Below Surface Unstabilized Base Cement-Stabilized Base Rutting can occur in surface, base, and subgrade of unstabilized bases due to repeated wheel loading Cement-stabilized bases resist consolidation and movement, thus virtually eliminating rutting in all layers but the asphalt surface.

6 Reduced Fatigue Cracking Asphalt Surface Unstabilized Base Cement-Stabilized Base High deflection due to low base stiffness Results in high surface strains and eventual fatigue cracking Higher stiffness of cement-stabilized base produces lower deflections Resulting in lower surface strains and longer pavement life

7 Reduced Moisture Susceptibility Unstabilized Granular Base High water table Cement-Stabilized Base Moisture infiltrates base: Through high water table Capillary action Causing softening, lower strength, and reduced modulus Cement stabilization: Reduces permeability Helps keep moisture out Maintains high level of strength and stiffness even when saturated

8 Steps in the process Site investigation Mix design Select road width and thickness Cost analysis (Life-cycle analysis) Construction

9 Steps in the construction Simple and Fast Process! Pulverization (Reclaimer) Adding aggregate (if needed) Adding stabilizer (cement) Adding water (if needed) Mixing (Reclaimer) Compaction Curing Surfacing

10 Pulverization Pulverize mat to appropriate gradation

11 Inside a Reclaimer

12 Aggregate Adjustment (if necessary)

13 Cement Spreading (Slurry)

14 Blending and Moisture Addition Cement is blended into pulverized, recycled material Water is added to optimum moisture

15 Grading Material is graded to appropriate plan line, grade, and cross-sections Excess material is removed from roadway (rare occasions)

16 Compaction Material is compacted

17 Curing Bituminous Compound Water

18 Surfacing Surface course is applied last Chip Seal Asphalt Conventional Concrete Roller Compacted Concrete Bituminous Overlay

19 Completion: Rehabilitation of asphalt pavements

20 Summary The FDR with portland cement FDR w/pc is a durable and rapid method of rebuilding roadways (it is faster than traditional methods). The pavement is structurally upgraded and ready for the increasing traffic. Advantages reduction of costs of construction, re-usage of old asphalt and base materials, preservation of the environment, conservation of energy. Types of roads to recycle deteriorated county and secondary roads