1 Mar 98
h. Forms and stringline (para. x in xxxxx). The stringline, used to control the surface
alignment of each lane, is crucial to a successful job. The stringline should be used by the
Contractor to check the grade prior to each lane placement. A large portion of one airfield apron
was recently removed due to inadequate thickness when these checks weren't made.
i. Batching and mixing of concrete (para. x in xxxxx). Because of the high concrete
production necessary for this project, and the low slump concrete required, an on-site central mix
concrete plant is required. No transit mixers may be used. The recorder data should be checked
daily to assure that the Contractor is batching materials properly. Improper batch weights is a
common problem that has led to inadequate pavement strengths. The Contractor must perform
periodic mixer efficiency tests. Inspectors should become very familiar with the plant, how it is
operated and how each part should function. Plant calibration should be monitored closely,
particularly if load cells are used instead of visible weigh scales.
j. Placing (para. x in xxxxx). A few early cores for thickness can be used to insure that the
paver is properly consolidating the concrete by observing the cores for voids or segregation.
k. Finishing (para. x in xxxxx). A concrete pavement does not require much finishing. If the
paver is working well finishers should hardly have to touch the pavement surface. Finishing with
cutting straightedges should be almost all that is required. Do not permit finishers to add water to
the surface! Also do not let finishers build up edges that have slumped by adding mortar or
concrete. While the concrete is still plastic, a straightedge should be laid longitudinally and
transversely in the lane to assure surface smoothness of the hardened concrete will be acceptable.
l. Curing (para. x in xxxxx). Adequate concrete curing is essential for strength gain and for a
durable pavement surface. White pigmented membrane curing compound must be applied as soon
as the texturing is completed. Application rate should be checked each shift by placing 1 foot
square pieces of cardboard on the pavement surface, and removing them after the curing machine
has passed by. By weighing the cardboard before and after application, the amount put down can
be calculated. This can be checked by determining the total quantity sprayed during each shift.
Properly applied curing compound will appear as a continuous white film with no concrete
m. Surface tests (para. x in xxxxx). For slipform construction, particular attention should be
paid to lane edges where edge slump can occur. Straightedge testing must be completed no later
than 36 hours after placement. For assistance with Profileograph measurement issues, contact the
design office or the TSMCX.
n. Pavement thickness tolerance (para. x in xxxxx). Pavement load capacity is heavily