3. 3
INTRODUCTION
• Water proofing of roads is most important to increase the life of the
pavement.
• Potholes form in a road surface when water enters cracks within a road
surface. Freeze-thaw action widens these cracks, which weaken the
surface and eventually cause it to break open, leaving a
pothole. Potholes are responsible for many accidents, injuries and
vehicle damage every year, with local councils spending a large portion
of their budgets patching them.
• Water proof roads restricts potholes formation by preserving the
structural integrity of the highway surface. It improve the longevity of
roads.
4. 4
MATERIALS FOR WATERPROOFING
• The following are some materials or admixtures used globally for
waterproofing of cement concrete roads as well as bituminous
roads.
• For cement concrete roads:
1. Calcium stearate,
2. Aluminium stearate,
3. Butyl stearate,
4. Petroleum wax emulsion.
5. 5
MATERIALS FOR WATERPROOFING
• For bitumen road:
1. Petroleum wax emulsion mixed in bitumen,
2. Rubber crumbs,
3. Mastic asphalt polymer,
4. Paving fabrics.
• But to make the road pavement water proof ensure that the mix is
proper and provide enough camber to remove water from the road
surface. It is the cheapest and most economical method to make
pavement water proof.
6. 6
CALCIUM STEARATE
• Calcium stearate is produced by heating stearic acid and calcium
oxide: Ca(C18H35O2)2
• It can be added 0 to 2.85% by the weight of cement, the addition of calcium
stearate at 1 kg/m3 in self-compacting concrete (SCC) with 10% fly ash, the
mechanical and physical properties of SCC can be improved significantly.
• The compressive strength of the concrete when adding calcium stearate is
relatively stable. Moreover, the use of calcium stearate will clearly reduce the
water absorption capability of concrete. Also corrosion of concrete can be
reduced by using calcium stearate. Hence, calcium stearate is a good
candidate to improve the mechanical and physical properties of concrete.
9. 9
RUBBER CRUMBS
• The Government is aware of the problem of disposal of rubber tyres
and also benefits from its use in bituminous pavement courses. Normal
bitumen modified with crumb rubber & other additives has improved
performance compared to normal bitumen.
• Crumb rubber is usually recycled rubber which is obtained from waste
tyres. In the recycling process, the steel and the tyre cords are
removed and tyre rubber is separated. This is done either mechanically
or by using cracker mill. Crumb rubber is very suitable to be the used
as an additive in pavement because it has the characteristic that can
support the weakness of asphalt. It not only enhances the properties of
bitumen but also addresses serious environmental pollution issues.
10. 10
RUBBER CRUMBS
• Crumb rubber bituminous concrete showed improvement in strength and stability values.
It shows an increasing trend till 12 percent addition of rubber content. Addition of 12%
crumb rubber to 5% bitumen content gives satisfactory results and can be used for
construction of road pavements.
• It can be done by dry method and wet process. Dry method gives better performance
results as compared to Wet process.
• Overall, using the crumb rubber in bituminous mixture helps to:
1. Utilization of crumb rubber waste.
2. Water proofing of roads
3. Reduction in the use of bitumen by around 10%.
4. Increase in the strength and performance of the road.
5. Reduce the cost.
11. 11
PAVING FABRICS
• Since the late ’60s, paving fabrics have been used in overlay
systems of hot-mix asphalt—primarily to reduce or delay the rate
of reflective cracking through a new overlay.
• Waterproofing is now being viewed as a potential benefit of paving
fabrics. Although many engineers think the paving fabric system is
mainly used as a stress-relieving interlayer to retard reflective and
fatigue cracking, a principal function of the system is
waterproofing.“
12. 12
PAVING FABRICS
• To apply a fabric system, an existing asphalt pavement typically is first
milled to remove cracks. A leveling course of hot-mix asphalt (HMA) is
applied. Sprays about 1.1 liter/sq meter of hot asphalt tack coat onto
the surface. A non-woven fabric is laid into the tack coat and an HMA
overlay is placed on top of the fabric.
• The heat and pressure of the overlay reactivate the asphalt tack coat,
drawing it up into the fabric and bonding it to the overlay. The resultant
interlayer is a fairly thick asphalt-saturated fabric-reinforced layer.
• When paving fabric is placed between the layers of pavement, the
bond that is established between the old and new pavement become
the waterproof and stress absorbing layer that reduces reflective
cracking of the new asphalt surface layer