Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

3. Section-1500
1504: INTERLOCKING CONCRETE BLOCK PAVEMENT
A. Methodology
1. Concrete Paving Blocks shall conform to the relevant IS Standard.
2. Ensure a trial length of 30 m is laid for demonstrating the procedure and equipment for laying the
main pavement.
3. Prepare the sub-grade to the specified grades and cross-sections and uniformly compact to the
design strength. Sub-grade shall have a camber of 3% and of soaked CBR not less than 4 %.
4. Lay a minimum 100 mm thick granular/ stabilized base course conforming to sub-section 402.
The base course shall be extended at least 300 mm beyond the edge restraints.
5. Lay interlocking concrete block pavement over a 100 mm thick granular sub-base layer conforming
to sub-section 401 or over a 100 mm thick WBM Gr. 1 conforming to sub-section 405.
6. Lay 25 mm thick (compacted) bedding sand conforming to grading requirements indicated in
Table No. 1503.1 uniformly over the base course. The bedding sand shall have about 6% moisture
content to facilitate its spreading and compaction. Compact with a hand rammer; preferably plate
compactor and readjust the level using a screed.
7. The pattern for paving blocks shall be herringbone or stretcher. The joints between stretcher bond
shall be staggered by about half the length of stretcher.
8. The minimum thickness of paving blocks shall be 80 mm for projected traffic upto 100 vehicles
per day and 100 mm for projected traffic from 100 to 250 vehicles per day. The dimensions and
tolerances for paving blocks shall meet the requirements of Table 1504.1.
9. The average 28 days compressive strength of 8 blocks shall not be less than 30 MPa and strength
of individual block shall not be less than 26 MPa. The edge blocks shall have equivalent cube
compressive strength not less than 30 MPa.
1. Compression testing machine of adequate capacity shall be used for testing the blocks. The blocks
shall be stored for 24 + 4 hours in water maintained at a temperature of 20 + 5 O C before testing.
The load shall be applied without shock and increased continuously @ 15 + 3N/mm 2 /minute and
the maximum load that can be applied to a specimen shall be noted. Apparent compressive strength
shall be calculated by dividing the maximum load by the plan area. This shall then be multiplied
with a correction factor, as indicated in Table 1504.2 to obtain the corrective compressive strength.
2. The width of joint shall be between 2 mm and 4 mm. On curves non-uniform joint width may
have to be resorted to. When space does not permit the use of cut piece of blocks, the use of
premixed or dry packed concrete is recommended. After a section has been paved, compaction
with a vibratory plate compactor shall be done in the following sequence of operations.
(i) The blocks shall be vibrated with three passes of a standard vibrating plate compactor of
adequate capacity.
(ii) A thin layer of joint filling sand as per clause 1503.2.6 shall be spread on the top of paved
blocks and swept into joints using suitable brooms.
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