• Constructed from cement concrete or reinforced concrete slabs • Grouted concrete roads are in the category of semi-rigid pavements. • The design of rigid pavement is based on providing a structural cement concrete slab of sufficient strength to resists the loads from traffic. • The rigid pavement has rigidity and high modulus of elasticity to distribute the load over a relatively wide area of soil.
PARTS OF RIGID PAVEMENT
CHARACTERISTICS OF RIGID PAVEMENT • It consists of one layer Portland cement concrete slab or relatively high flexural strength. • It is able to bridge over localized failures and area of inadequate support. • Its structural strength is provided by the pavement slab itself by its beam action. • Flexural strength of concrete is a major factor for design. • It distributes load over a wide area of subgrade because of its rigidity and high modulus of elasticity. • Temperature changes induce heavy stresses in rigid pavements. • Any excessive deformations occurring due to heavier wheel loads are not recoverable
• Sufficient thickness to spread loading to a pressure intensity tolerable by sub-grade • Sufficiently strong to carry imposed stress due to traffic load • Sufficient thickness to prevent the effect of frost susceptible subgrade • Pavement material should be impervious to penetration of surface water which could weaken subgrade and subsequently pavement • Pavement surface should be skid resistant
• Reduce and distribute the traffic loading so as not to damage the subgrade • Provide vehicle access between two points under all weather conditions • Provide safe, smooth and comfortable ride to road users without undue delays and excessive wear & tear . • Limited noise and air pollution • Reasonable economy
Advantages of Rigid Pavement: • • • •
It is very easy to clean and practically dust free. The resistance to traffic is low. When clean, it is not slippery. When properly designed and constructed, it has long life and comparatively low maintenance cost. • It can withstand any amount of traffic.
Disadvantages of Rigid Pavement: • High initial costs • Joints required for contraction and expansion • Generally rough riding quality • High repair costs
TYPES OF FAILURE IN RIGID PAVEMENT The following 5 form of failures are commonly found in rigid pavement • • • • •
Scaling of cement concrete Shrinkage cracks Joint spalling Warping cracks Pumping
Scaling of rigid pavement simply means, peeling off or flaking off of the top layer or skin of the concrete surface. This may be due to the following reasons • • • •
1. SCALING OF CEMENT CONCRETE
Improper mix design Excessive vibration during compaction of concrete Laitance of concrete Performing finishing operation while bleed water is on surface
2. SHRINKAGE CRACKS
• Formation of hairline shallow cracks on concrete slab is the indication of shrinkage cracks. • Shrinkage cracks develop on concrete surface during the setting & curing operation. These cracks may form in longitudinal as well as in transverse direction.
3. JOINT SPALLING Joint spalling is the breakdown of the slab near edge of the joint. Normally it occurs within 0.5 m of the joints. The common reasons for this defect are • • • •
Faulty alignment of incompressible material below concrete slab Insufficient strength of concrete slab near joints Freeze-thaw cycle Excessive stress at joint due to wheel load
4. WARPING CRACKS • In hot weather, concrete slab tends to expand. Therefore the joints should be so designed to accommodate this expansion. When joints are not designed properly, it prevents expansion of concrete slab and therefore results in development of excessive stress. This stress cause formation of warping cracks of the concrete slab near the joint edge. • This type of crack can be prevented by providing proper reinforcement at the longitudinal and transverse joints. Hinge joints are generally used to relieve the stress due to warping.
5. PUMPING When material present below the road slab ejects out through the joints or cracks, it is called pumping. When soil slurry comes out it is called mud pumping. The common reasons for this defect •Infiltration of water through the are joints, cracks or edge of the pavement forms soil slurry. Movement of heavy vehicles on pavement forces this soil slurry to come out causing mud pumping. •When there is void space between slab and the underlying base of subgrade layer •Poor joint sealer allowing infiltration of water •Repeated wheel loading causing erosion of underlying material
• A four-level partial turbine interchange in Makati, Metro Manila • It serves as the junction between the South Luzon Expressway (SLEx) and Epifanio de los Santos Avenue (EDSA) • An interchange between the 2 train lines of Metro Manila, the MRT-3, which is over EDSA, and the PNR Metro Commuter, beside SLEx.
• The Interchange was poorly designed, however, and in 2010, several pipe leaks was discovered under the interchange, that is why the Metropolitan Manila Development Authority closed down its outer lanes. It was reopened in 2011.
• Magallanes Interchange was maintained by Department of Public Works and Highways (DPWH). • Series of repair works done in stages at Magallanes Interchange which has an overall accomplishment of 82 percent will restore the structural integrity of the bridges for the safety of travelling public. • To restore structural integrity of Magallanes Interchange, retrofitting activities includes epoxy injection on top and bottom of slab and application of glass fiber and skim coat at 2nd level structure for Stages 1, 3, and 4 and 3rd level structure for Stages 2 and 5.
PROBLEMS:
SOLUTION:
• Heavy volume of vehicles at the interchange • Accident prone • Traffic gridlock • Poorly design
• Road reblocking • Road rehabilitation • Closing of some portion to reduce the number of accidents • Department of Public Works and Highways will build roads with thicker concrete pavement to make them “more durable” and give them “better riding quality.”
QUEZON CITY
TRECE MARTIREZ, CAVITE
BENGUET
BAGUIO