Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

C Do’s and Don’ts
Do’s Don’ts
1. Use lime with purity not less than 70% by weight of
CaO. Where lime of the minimum specified purity
is not locally available, the total amount of lime to
be added shall be proportionately increased with the
approval of the Engineer ensuring that the amount
of CaO in the total amount of lime added is not lower
than the specified value.
2. Ensure uniformity of mixing of lime with soil by
mechanical means like tractor-towed rotavator.
3. Look for soft patches, if any, and rectify them by
removing or adding fresh material and compacting
the same thoroughly.
404. CEMENT TREATED SOIL SUBBASE AND BASE
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Quality Assurance Handbook for Rural Roads
1. Do not allow the spread lime to be blown away.
2. Do not accept the completion of the mixing process if
any white streaks or pockets of lime are visible.
3. Slaked lime supplied in airtight bags should not be
stored for more than 3 months.
4. Do not allow any traffic other than mixing equipment
to pass over the spread lime till mixing has been
completed.
5. Do not allow traffic until the lime treated layer is cured
for atleast 7 days.
For soils which do not respond to lime treatment and where comparatively higher and faster development
of strength and durability characteristics is needed, especially for waterlogged and high rainfall areas,
soil stabilization with cement is resorted to. Granular and sandy soils are most suitable for cement
stabilization
A. Methodology
1. Mix Design should be worked out to determine the optimum quantity of cement to be added to
soil for stabilization. A minimum laboratory 7-day unconfined compressive strength of 2.76 MPa
is required for use in base courses, whereas in sub-base courses, a minimum laboratory 7-day
unconfined compressive strength of 1.7 MPa is considered acceptable.
2. By way of broad guidelines, the requirements of cement content for different soil types are as
under:-
Sands/Sandy soils/Soil-Gravels 3 to 5 percent
Silts/Silty clays of low P1 (30), pre-treatment with lime is resorted to in the first stage to reduce
plasticity and to facilitate pulverization.
3. The pulverization of soil clods, meeting the requirements of Table 404.1 and mixing of pulverized
soil should be accomplished by tractor-towed implements.
TABLE 404.1: SOIL PULVERIZATION REQUIREMENTS FOR CEMENT STABILIZATION
IS Sieve Designation Percent passing
26.5 mm 100
5.6 mm 80
4. Cement should be properly stored to avoid prolonged exposure to the atmosphere.
5. The compacted thickness of any layer to be treated should not be less than 100 mm and not be
greater than 200 mm provided the plant is accepted by the Engineer.