quality inspection of a concrete pavement feb2013 presentation1

QUALITY INSPECTION OF A CONCRETE PAVEMENTAS PER RMS SPECIFICATION RN 83

BULAHDELAH BYPASSUPGRADING OF THE PACIFIC HIGHWAY

QUALITY INSPECTION 21/02/13

Quality inspection of concrete pavement with RMS Tony Compton and RMS Dave Murphy.

TRANSVERSE JOINT

Damage to backing rod. This compressible material must be maintained to prevent incompressible materials from entering the joints.

BACKER ROD

Backer rod is pushed back into the joint.

SURFACE DEFECTDamaged area near longitudinal joint. May not have to be repaired as its well away from the wheel path. Repair will involve cutting it square to prevent feather edges. Repair materials sometimes also do not have the required design life and patch will need to be maintained.

STITCH BAR REINFORCEMENTRMS Dave Murphy with a metal detector along the longitudinal joint. Each panel requires 5no. 1m long bars across the joint. Bars should be 200mm away from transverse joint, so as not to induce unwanted transverse cracking.

OMITTED REINFORCEMENT BARS

Areas where bars are missing are marked. Bars may have to be “stitched in” or may be left in…

OMITTED REINFORCEMENT BARS

Four – 4- number bars were left out of this slab, as can be seen marked on the side the pavement.

LONGITUDINAL JOINT

Longitudinal black filler/ backing rod is out of the joint. This will allow incompressibles to enter the joint which may result in the joint ceasing up and cracking the pavement.

TRANSVERSE TEXTURECross texture will increase the noise as vehicles pass over. Transverse textures are to be parallel to the transverse joints. This results in clean edges, free of ravelling, when the transverse joints are cut.

LOSS OF TEXTURERain has resulted in a loss of texture on this section. A closer look will show how smooth the surface is. Results? Aquaplaning can result as a smooth surface with water flowing over it will not allow traction. The texture can be reinstated via diamond groove cutting.

TRANSERVSE JOINT DETAILSThe compressible filler should extend right through the sawcut joint and sealant placed on top should fill and cover the edge completely to prevent fines from shoulder concrete entering the edge of the joint and resulting in joint failure. A crack will propagate diagonally from the top and cross both adjacent slabs. This will result in failure of the slabs. Tony explained that it took 3months of investigation on a previous project to understand this defect cause and consequent diagonal crack.

TRANSVERSE JOINT DETAILSAs on the previous slide, the compressible material is pushed al the way down into the cut joint to prevent lateral ingress of incompressibles from the shoulder pour. Sealant should also not be excessively applied at the edge to prevent ingress, as a blob of sealant will result in a hollow – or weak zone in the shoulder pavement. The shoulder pavement edges will then fail locally as loading is applied.

JOINT INTERSECTIONA number of points to note. Note the corrugated material? This is termed a biscuit. Its inserted after the transverse joint has been cut and it provides support when the longitudinal joint is cut, such that ravelling does not occur where the joints meet. In this case it appears that the concrete may have been too green/ not adequately set, when the joints were cut. Once the corners ravel, and are subjected to dynamic traffic loading, further spalling can result. This material may damage the sealant and then enter the joints – resulting in joints ceasing.

JOINT INTERSECTION

The contracting staff immediately removed the loose material and replaced the compressibles.

CONSTRUCTION JOINTConstruction joint. This joint should be square and straight. Sometimes the crew is unfocused at the end of a long day and do not finish off the edge neatly. The edges may be feathered and vehicle loading can result in damage at this interface.

CONSTRUCTION JOINT - NCR

A solution would be to sawcut along the joint, 20mm wide and up to 80mm deep. As the joint is not straight, this could be tricky…

LEVEL OF THE FINISHED PAVEMENT

A 3m long straight edge is used to check that the finished surface is within the tolerance range. At no point should the surface be away from the straight edge by more than 5mm.

A calibrated wedge is used to check gaps below the straight edge.

THE END

CONCEPTS:JointsSealingTextureLevel toleranceShrinkageSawcutAquaplaning