CMT MIDTERMS
311.2.10 STORAGE OF CEMENT AND
AGGREGATES

Storage buildings shall have the capacity to store
a sufficient quantity of cement to allow sampling
at least twelve (12) days before the cement is
used.
311.2.11 PROPORTIONING, CONSISTENCY, AND
STRENGTH OF CONCRETE




Design mix is based on the absolute volume
method as outlined in ACI Standard 211.1
“Recommended Practice for Selecting
Proportions for Normal and Heavyweight
Concrete.”
At least 364kg of cement per cubic meter of
concrete to meet the minimum strength
requirements.
The goal is to produce workable concrete with:
o Slump of:
 40-75mm if not vibrated
 10-40mm if vibrated
o Slump shall be determined using
AASHTO T119
The concrete must reach the minimum strength
at 14 days of
o Not less than 3.8MPa (550psi) using the
third-point flexural test (AASHTO T97)
o 4.5MPa (650psi) using the mid-point
flexural test (AASHTO T177)
o Compressive strength of 21.4MPa
(3500psi) using cores (AASHTO T24)
311.3 CONSTRUCTION REQUIREMENTS
311.3 1 QUALITY CONTROL OF CONCRETE
1. General
 Contractor is responsible for quality
control during material handling,
blending, mixing, and placement
2. Quality Control Plan
 Contractor must submit a Quality Control
Plan to the Engineer outlining:
o Procedures for production
control
o Sampling and testing
frequency
 The Engineer must have free access to:
o Production records
o Mix design, materials
certification and test reports
3. Qualification of Workmen
 Concrete Batcher: ensures accurate
material weights and moisture
measurements
 Concrete Technician: oversees concrete
quality, performs tests, adjusts mix
design, and acts as batcher when needed
4. Quality Control Testing
 Contractor performs all necessary
sampling, testing, and inspection to
ensure compliance
 Tests include aggregate gradation, slump,
air content, water-cement ratio, and
temperature

Concrete must match the approved mix
design
5. Documentation
 Maintain records of all inspections and
tests, including:
o Observations, deficiencies,
approved/rejected quantities,
and corrective actions
o Engineer may take random
independent samples for
verification
311.3.2 EQUIPMENT
1. Batching Plant and Equipment
 General
o Must include bins, hoppers,
and scales for each material
o Bulk cement needs separate
bin, hopper, and scale
o Batching plants require a nonresettable batch counter
 Bins and Hoppers
o Separate compartments for
each aggregate size
 Scales
o Must be accurate within 0.5%
o Beam or springless-dial types
only
o Must be lockable and
inspected regularly
 Automatic Weighing Device
o Required unless otherwise
specified
2. Mixers
 General
o Can be used on-site, central
plant, or truck mixers
o Must have manufacturer plate
showing capacity and mixing
speed
 Site Mixers:
o Must produce a uniform mix
within a specified time
o Requires automatic timing
device and batch counter
o If the timer fails, mixing time
defaults to 90 seconds
 Truck Mixers and Agitators
o Must comply with AASHTO
M157
 Non-agitator Trucks
o Must be mortar-tight, smooth,
and discharge concrete
without segregation
3. Paving and Finishing Equipment
o Must place, spread,
consolidate, and finish
concrete in one pass
o Requires:
 2 oscillating screeds
 Vibrators operating at
8300-9600
impulses/min, spaced
max 60 cm
4. Concrete Saw
 Must be adequate in number and power


Uses water-cooled diamond blade or
abrasive wheel
At least one standby saw and ample
blades required
5. Forms
 Made of steel and equal to pavement
thickness
 Bases wide enough for stability; braces
extend at least 2/3 form height
 Supported on compacted material and set
securely to resist vibration/impact

If any form is disturbed or the grade
becomes unstable, the form must be reset
and rechecked.
311.3.5 CONDITIONING OF SUBGRADE OR BASE
COURSE

Ensure side forms are securely set to grade.

Bring subgrade or base course to proper
cross-section:
o
Trim high areas to the correct
elevation.
o
Fill and compact low areas to match
surrounding grade.
311.3.3 PREPARATION OF GRADE





After compacting the subgrade or base to
the required density, it must be trimmed
to the correct elevation using a properly
designed machine.
The trimmed and prepared area must
extend at least 60 cm beyond each edge
of the proposed concrete pavement.
If density is lost during trimming, it must
be restored through additional
compaction before placing concrete.
If traffic uses the prepared area, the
surface must be checked and corrected
right before concrete placement.
The subgrade or base must be uniformly
moist when the concrete is placed.
311.3.4 SETTING FORMS
1. Base Support

The foundation under the forms must be
hard and accurately graded to ensure firm
contact along the entire form length.

If the roadbed is below grade at the form
line, it must be filled with approved
granular material in layers not exceeding
3 cm and thoroughly compacted.


Maintain the finished grade in a smooth and
compacted condition until pavement
placement.

Subgrade or base course must be uniformly
moist when placing concrete (unless a
waterproof cover is specified).

If the subgrade becomes too dry:
o
Sprinkle it with water.
o
Avoid creating mud or pools of
water during sprinkling.
311.3.6 HANDLING, MEASURING, AND
BATCHING MATERIALS

Batch Plant Requirements:
o

Any high spots above grade must be
corrected by tamping or cutting as
needed.
Stockpiling Aggregates:
o
Build in layers not exceeding 1
meter thick.
o
Fully complete one layer before
starting the next—no coning of
material onto lower layers.
o
Do not mix aggregates from
different sources or with different
gradings in one stockpile.
2. Form Setting

Forms must be set well in advance of
concrete placement.

Once set to the correct grade, the grade at
both the inside and outside edges of the
forms must be thoroughly tamped, either
mechanically or by hand.


Handling Washed or Hydraulic
Aggregates:
o
Forms must not deviate from the true line
by more than 1 cm at any point.
3. Grade and Alignment



The contractor must check the alignment and
grade elevation of the forms immediately
before concrete placement and make
corrections as needed.
Elevation and crown can be checked using
an approved vertical template moved along
the forms.

Site, layout, equipment, and
transport provisions must ensure a
continuous material supply to the
work.
Must be stockpiled or binned for at
least 12 hours to drain before
batching.
Transporting Aggregates (when mixing
on-site):
o
Use batch boxes, vehicle bodies, or
suitable containers.
o
Containers must have effective
partitions to prevent spillage
between compartments.
Handling Bulk Cement:
o
Use approved methods (chute,
boot, etc.) from weighing hopper to
batch to avoid cement loss.
o
Cement must be fully present in
each batch as specified.
o
Cement transported in tight
compartments carrying the exact
amount for each batch.
o



If allowed, cement may be
transported between aggregates (as
per Special Provisions), but:

o
o
Must be mixed within 1.5
hours of contact with
aggregates.
Cement in original packages may
be placed on top of aggregates with
the correct number of sacks per
batch.

Mixer must be charged without
cement loss.
o
Tolerance for batching:

Cement: ±1%

Aggregates: ±2%
Water Measurement:
For site or plant mixing: 50–90 seconds,
unless tests prove shorter time is
effective.
o
Add 4 seconds if timing starts when
skip is fully raised.
o
Mixing ends when the discharge chute
opens.
o
Multiple-drum mixers: transfer time is
included in total mixing time.
o
Fully empty drum before loading next
batch.
Mixer Operation:
o
Follow manufacturer’s rated drum
speed.
o
Concrete mixed less than required
time must be discarded at Contractor’s
expense.
o
Batch volume must not exceed
mixer’s rated capacity, except up to
10% overload is allowed if no spillage
and quality is satisfactory.

Water Charging:
May be measured by volume or
weight.
o
Water must enter before cement and
aggregates.
o
Accuracy: ±1% error.
o
o
If measured by volume:
All water must be in the drum within
first 15 seconds of mixing.

Must have an auxiliary
tank equal in volume to the
measuring tank.
Auxiliary tank must have
external tap and valve for
accurate checking.

Drum Throat Maintenance:
o

311.3.7 MIXING CONCRETE

o
o


Mixing Duration:
Batch Charging and Accuracy:
o
Contractor must provide test data
confirming mixer performance.
Keep clear of material buildup to ensure
free flow.
Transporting Mixed Concrete:
o
Use truck mixers, agitators, or nonagitating trucks (per Section 311.3.2).
o
Time limits from water addition to
placement:
Mixing Locations:
o
Concrete may be mixed on-site, in a
central-mix plant, or in truck mixers.

45 minutes: non-agitating
trucks.
o
Mixer must be of approved type and
capacity.

90 minutes: truck mixers or
agitators.

Shorter time may be required
in hot weather.
Mixing Time and Equipment:
o
o
Mixing time starts after all materials
(except water) are in the drum.
For ready-mixed concrete, follow
AASHTO M 157.

o

Minimum revolutions may be
reduced if supported by
manufacturer data.
Manufacturer’s serial plate must show
the recommended revolutions.

Volumetric Mixing for Small Projects (<75
cu.m./day):
o
Weight-to-volume conversion allowed
with moisture/bulking adjustments.
o
Follow ASTM C 685, Sections 6–9.
Mixing by Chute:
o
Allowed if weighing scales are used for
batch weight.

Retempering Rules:
o
o

Not permitted unless:

Using truck mixers,

Within 45 minutes of initial
mixing,

Water-cement ratio is not
exceeded,

Engineer approval is given.
Concrete outside specified slump limits
shall not be used.
Only permitted with Engineer’s
approval.
311.3.8 LIMITATION OF MIXING
Lighting Requirement:
o


No concrete mixing, placing, or
finishing without sufficient natural or
approved artificial light.
During hot weather, steps must be
taken to keep concrete temperature ≤
90°F (32°C).
Time Limitations:
o
Concrete must be placed within 90
minutes of charging materials into the
mixer.
o
Concrete that has set or is not placed in
time shall not be used.
No remixing of partially hardened
concrete or mortar with or without new
materials.

o
If only finishing equipment is used:
→ Adjoining lane may be paved after 3
days.
Concrete Consolidation:
o
Use vibrators to consolidate along
forms and joints.
o
Avoid vibrator contact with joint
assemblies, side forms, or grade.
o
Vibrator operation at any one location
must be ≤ 15 seconds.
Joint Areas:
o
Deposit concrete near (not on)
expansion/contraction joints.
o
Do not dump directly on joint
assemblies unless hopper is wellcentered.
o
If concrete falls on a finished slab, it
must be removed immediately.
Sampling Frequency:
o



Concrete Placement:
o
Place concrete to minimize rehandling.
o
If discharge equipment may cause
segregation, unload into an approved
spreading device and mechanically
spread to avoid segregation.
o
Continuous placement required
between transverse joints; no
intermediate bulkheads allowed.
Manual Spreading:
o
Use shovels only, not rakes.
o
Workers must not walk on fresh
concrete with dirty boots or shoes.
One set of 3 concrete beam specimens
per 330 m² of pavement (230 mm
thick) placed per day.
Specimen Size:
o
Contractor must have materials ready to
protect fresh concrete from rain until it
hardens sufficiently.
311.3.9 PLACING CONCRETE

If mechanical equipment operates on a
previously placed lane:
→ That lane must have reached 14-day
concrete strength.
Beams must be 150 mm x 150 mm x
525 mm or 900 mm.
Supervision and Materials:
o
Specimens must be made under
Engineer’s supervision.
o
Contractor must supply all materials,
concrete, and facilities and ensure
protection from damage.
Rain Protection:
o

o
311.3.10 TEST SPECIMENS
Retempering Prohibition:
o


Adjoining Lane Requirements:
Temperature Control:
o


Use of Admixtures:
o


Testing Standards:
o
Beams shall be made, cured, and tested
according to AASHTO T 23 and T 97.
o
Cylinders are not acceptable
substitutes for strength testing.
311.3.11 STRIKE-OFF OF CONCRETE AND
PLACEMENT OF REINFORCEMENT

After placing concrete, it should be leveled
(struck off) to match the planned elevation.

For 2-layer concrete:
o
Bottom layer must be compacted
enough to allow placing steel
reinforcement on it without shifting.
o

o
Steel may be placed in advance or
inserted during concrete placement.
Reinforcement steel must be clean (no dirt,
rust, oil, etc.) to bond well with concrete.
Joints control concrete movement and cracking. Types
include:
o
Use tie bars to connect lanes.
o
Tie bars must not be painted or coated.
o
Joints can be formed, sawed, or with
inserts.
o
Use preformed filler for expansion
space.
o
o
o
Made by grooving the concrete to
control cracks.
o
Avoid damaging joints during finishing
machine operation.
o
Can be non-vibratory or vibratory.
o
Must ensure smooth surface and good
compaction.
o
o
A strip

Formed in plastic concrete

Sawed after concrete hardens
slightly
Sawing must be done before cracks
appear.
4. Transverse Construction Joints
o
Needed when concreting stops for over
30 minutes.
o
Should be at least 1.5 meters away
from any other joint.
5. Load Transfer Devices (Dowel Bars)

When equipment breaks down.

For narrow or irregular areas.
Requires approved screeds and
vibrators.
o
Smooths and consolidates the surface.
o
Can be hand or mechanical.
o
Removes excess water or laitance.
6. Straight-edge Testing:
o
Use a 3-meter straight-edge to check
for dips or bumps.
o
Fix any issues immediately.
Groove can be:

Allowed only:
5. Floating:
Must be aligned, straight, and free of
concrete plugs.
3. Transverse Contraction Joints
Concrete near joints must be vibrated
and compacted.
4. Hand Finishing:
2. Transverse Expansion Joints (perpendicular to
road direction)
o
o
3. Machine Finishing:
311.3.12 JOINTS
1. Longitudinal Joints (parallel to road direction)
No water should be added on top unless
by fog spray.
2. Joint Finishing:
For 1-layer concrete:
o

Top layer must be added within 30
minutes, or the bottom layer must be
replaced.
7. Final Finish:
o
Apply broom finish (if required) once
surface water disappears.
311.3.14 SURFACE TEST

After the concrete hardens, test the surface using
a 3-meter straight-edge.

If there are bumps more than 3 mm but less
than or equal to 12 mm, grind them down.

If the bump is more than 12 mm, the concrete
must be removed and replaced at the
contractor's expense.

Removed areas must be:
o
Allow movement but keep slabs aligned.
o
At least 1.5 meters long
o
Should be coated to prevent bonding
with concrete.
o
Full width of the lane
o
Placed parallel to pavement surface and
centerline.
o
Any leftover slab portion less than 1.5
meters must also be removed.
311.3.13 FINAL STRIKE-OFF, CONSOLIDATION,
AND FINISHING
311.3.15 CURING

Curing must start immediately after finishing,
and concrete must not be left uncovered for
more than 30 minutes.

Lack of curing materials or water can suspend
the work.
1. Sequence of Finishing:
o
Strike-off → Consolidate → Float →
Straight-edge test → Final Finish

Curing must last for at least 72 hours (3 days),
using one of these methods:
1. Cotton or Burlap Mats


Soak the mats in water, then cover the
pavement completely, including the sides.
Keep the mats wet and in place for 72 hours.
2. Waterproof Paper

Cover the concrete top and sides.

Sheets should overlap by 45 cm and extend
beyond edges twice the pavement thickness.
• Seal joints after curing and before any traffic, including
contractor’s equipment.
• Clean joints of all debris and curing compounds; ensure
surfaces are dry.
• Apply sealant per plan details; stir hot-applied material
to prevent overheating.
• Avoid sealant spills on concrete; do not cover seal with
sand or similar materials.
• Install elastomeric gaskets without stretching, using
approved lubricant adhesive.

Must be weighed down to stay in contact.
• Gaskets must be compressed and set 6 mm below
pavement surface.

Keep in place for 72 hours.
• Seals must be continuous across each joint.
3. Straw Curing
311.3.18 PROTECTION OF PAVEMENT
Start with burlap or cotton mats for at least 12
hours.
• Protect pavement from all traffic until final acceptance.

Then cover with 20 cm thick wet straw or hay,
and keep it saturated for 72 hours.
• Fill test boreholes immediately after use.

On the 4th day, rewet the cover and leave it until
the required strength is reached.

4. Impervious Membrane (Curing Compound)
• Use signs, lights, barriers, and watchmen as needed.
• Repair or replace any damaged pavement at the
contractor’s expense.
311.3.19 CONCRETE PAVEMENT – SLIP FORM
METHOD

Spray white pigmented curing compound
evenly over the surface.
• Grade: Use proper machines to set elevation; compact
and correct disturbed base.

Can also be applied after removing initial mats.

Apply 4 liters for every 14 m² using mechanical
sprayers.
• Placing Concrete: Use slip-form paver for spreading,
vibrating, and finishing in one pass.

Do not apply in the rain.

If damaged, reapply immediately.

Avoid spraying inside joints—cure those areas
separately.
5. White Polyethylene Sheet

Cover the concrete top and sides with plastic
sheets, overlapping at least 45 cm.

Weigh down to keep contact with the surface.

Keep in place for 72 hours.
311.3.16 REMOVAL OF FORMS
• Maintain uniform concrete slump (≤ 40 mm); operate
paver continuously.
• Stop vibration/tamping if paver stops; do not apply
external tractive force.
• Finishing: Meet specified surface smoothness and
texture standards.
• Curing: Apply approved curing methods uniformly to
all surfaces.
• Joints: Construct as specified in Subsection 311.3.12.
• Rain Protection: Have forms and covering materials
ready; cover edges/surface during rain.
311.3.22 ACCEPTANCE OF CONCRETE

Do not remove forms for at least 24 hours
after pouring concrete.
Deficiency in Strength of
Concrete Specimens (%)
Percent (%) of Contract
Price Allowed

Use crowbars carefully to remove nails and
pins—avoid breaking edges.
Less than 5
100%
5 to <10
80%

If edges get damaged (spalled), repair with
fresh mortar (1 part cement : 2 parts sand).
10 to <15
70%

Major honeycomb areas are considered
defective and must be removed and replaced.
15 to <20
60%
20 to <25
50%
Any replaced section must cover the full width
of the lane and at least the distance between
weakened joints.
25 or more
0% (Rejected unless
cores prove adequacy)

311.3.17 SEALING JOINTS
• Rejected concrete may be verified with at least 3 cores
per area.
• Cores acceptable if average ≥ 85% of strength and
none < 75%.
• If core sampling is not possible, payment is reduced as
shown above.
311.3.23 OPENING TO TRAFFIC


Pavement opens only after strength tests confirm
minimum requirement or after 14 days if untested.
Joints must be sealed and pavement cleaned before
opening.
311.3.24 TOLERANCE AND PAVEMENT
THICKNESS
Deficiency in Average
Thickness (mm)
Percent (%) of Contract
Price per Lot
0–5
100%
6 – 10
95%
11 – 15
85%
16 – 20
70%
21 – 25
50%
>25
No payment / Must be
removed & replaced
• Each lot consists of 1000 m (1 lane) or 500 m (2 lanes)
of pavement.
• Each lot is divided into 5 segments, with 1 core per
segment (AASHTO T 24).
• Cores thicker than +5 mm above plan are capped; those
thinner by >25 mm are excluded.
• Segments with >25 mm deficiency must be removed,
replaced, or excluded from payment.
311.4 METHOD OF MEASUREMENT



Paid by square meters (m²) of accepted concrete
pavement.
Width is measured edge to edge; length is measured
along centerline.
Curb and gutter not included.
311.5 BASIS OF PAYMENT
Pay Item
Number
Description
Unit of
Measurement
311 (1)
PCC Pavement
(Plain)
Square meter
311 (2)
PCC Pavement
(Reinforced)
Square meter
• Payment includes all materials, labor, traffic
management, and incidentals.