Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

3. Section-400
6. The cement stabilized soil subbase/base should be constructed by mix-in-place method of
construction . Manual mixing can be permitted only where the width of laying is not adequate for
mechanical operations, as in small-sized jobs.
7. The equipment used for mix-in-place construction should be a tractor-towed Rotavator or similar
approved equipment capable of pulverizing and mixing the soil with additive and water to specified
degree to the full thickness of the layer being processed and of achieving the desired degree of
mixing and uniformity of the stabilized material.
8. The mixer should be equipped with an appropriate device for controlling the depth of processing
and the mixing blades should be maintained or reset periodically so that the correct depth of
mixing is obtained at all times.
9. Appropriate tractor-towed equipment, approved by the Engineer, are suitable for performing
various operations in the construction process, like pulverization of soil clods by tractor-towed
disc harrows and mixing of soil with stabilizer by tractor-towed Rotavator.
10. The surface to receive the stabilized soil layer should be prepared to the lines, grade and camber.
11. Immediately after spreading, grading and levelling of the mixed material, compaction shall be
carried out. The moisture content of soil-cement mix at compaction should be within(±) 2% of
optimum moisture content (as per IS-2720 Part 7). During rolling, the surface shall be checked for
grade and camber. A density of at least 100% of the maximum dry density of the material, as
determined in accordance with IS:2720 Part 7 should be achieved.
12. Compaction of cement stabilized material shall be completed within two hours of its mixing.
13. The compacted soil-cement mix should be cured by moist curing with water for a period of 7 days
after which subsequent pavement courses should be laid to prevent the surface from drying out
and becoming friable.
B. Quality Control Requirements
1. Materials
(i) Materials to be stabilized: The material for cement treatment includes sand, gravel, laterite
kankar, brick aggregate, crushed rock, slag or flyash or combination of these. Material for
subbase/base should conform to the grading given in Table 404.1
TABLE 404.1: GRADING LIMITS OF MATERIALS FOR STABILIZATION WITH CEMENT
IS Sieve Per cent by Weight Passing IS Sieve
Sub-base Finer Than Base wihtin the Range
53.0 mm 100 100
37.5 mm 95 95-100
19.0 mm 45 45-100
9.5 mm 35 35-100
4.75 mm 25 25-100
600 micron 8 8-65
300 micron 5 5-40
75 micron 0 0-10
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