Grameen Sampark Final April 0... - pmgsy

Block Pavement at Typical Locations
Essentially, there are three important aspects in
detailing. These are: (i) Curves (ii) Intrusions, and (iii)
Changes in alignment
Curves: It is necessary to cut the paving units to fit the
edge restraints. Rectangular blocks of similar or
contrasting colour as an edging have been used to
minimize the visual effects of small errors in block
cutting. To avoid unsightly and potentially weak joints,
it is often preferred to change the laying pattern at the
curves. The curve itself can be installed in Herringbone
bond and yet the pavement can revert to stretcher bond
on the approaches [4 & 5].
Intrusions:
On some pavements, like in city streets,
there could be several intrusions, like, manholes,
drainage gulleys, etc. where coping with these
intrusions with the pavement is desirable. Around
intrusions, it is good practice to lay blocks along both
sides of the intrusion simultaneously so that closure is
made away from the starting workface, rather than
carrying the pavement around the intrusion to return to
the original laying face to avoid accumulation of closing
error [7].
Compaction
For compaction of sand bedding and paving blocks laid
over it, the vibratory plate compactors are used over the
laid paving blocks; at least two passes of the vibratory
plate compactors are needed. Such vibratory
compaction should be continued until the top of each
paving block is in level with the adjacent blocks. It is not
a good practice to leave compaction till the end of the
day, as some blocks may move under construction
traffic, resulting in the widening of joints and corner
contact of blocks, which may cause spalling or cracking
of the blocks. There should not be any delay in the
compaction after paving blocks have been laid. This is
necessary to achieve uniformity of compaction and
retention of the pattern of laying. During compaction of
the blocks laid, some amount of bedding sand may get
filled up into the joints between them; the extent of sand
Pradhan Mantri Gram Sadak Yojana
getting filled up into the joints will depend on the degree
of compaction of sand, i.e. the force applied by the
compactor. Standard compactors may have a weight of
about 90 kg with plate area of about 0.3 m2 and apply a
centrifugal force of about 15 kN. On the other hand,
heavy duty compactors may weigh 300-600 kg, with
plate area of about 0.5-0.6 m2 and apply a centrifugal
force of 30-65 kN. Where the bedding sand is required
to be compacted for heavily trafficed pavements, heavyduty
compactors should be used. After compaction by
vibratory plate compactors, some 2 to 6 passes of
vibratory roller (with rubber coated drums or those of
static weight less than 4 tonne and nominal amplitude of
not more than 0.6 mm) will further help in compaction
of bedding sand and joint filling [7].
Laying and Surface Tolerances
While constructing the block pavement, the surface
toleranes of individual layers may be observed, as
indicated in IRC:SP:63-2004.
Conclusion
ICBP technology is gaining importance and is
becoming more popular day-by-day because it is
user friendly and requires less infrastructure in
terms of construction equipment / machineries, as
compared to the conventional flexible and rigid
pavements.
ICBP technology can provide durable and
sustainable road infrastructure where construction
and maintenance of conventional pavements are
not cost effective.
ICBP is much cheaper than the rigid (concrete)
pavement, designed for identical operating
conditions. Compared to the bituminous
pavement for low traffic volume roads and high
strength subgrade, the initial construction cost of
ICBP is likely to be equal to or marginally higher.
For high traffic volume roads and low strength
subgrade, ICBP will be cheaper than the flexible
pavement.
Grameen Sampark 13