Batching, Mixing, Transporting,
and Handling Concrete
Ordering Ready Mixed Concrete
ASTM C 94
Specify:
 Coarse aggregate size
 Slump
 Air content
 Basis for proportioning,
select Options A ,B, or C.
Batching, Mixing,
Transporting, and
Handling Concrete
Ordering Ready Mixed Concrete
ASTM C 94
Option A—performance based:
Purchaser specifies:
 Compressive strength
Concrete producer selects mix
proportions.
Batching, Mixing,
Transporting, and
Handling Concrete
Ordering Ready Mixed Concrete
ASTM C 94
Option B—prescription based:
Batching, Mixing,
Transporting, and
Handling Concrete
Purchaser specifies mixture
proportions including:
 Cement content
 Water content
 Admixture type and content
Ordering Ready Mixed Concrete
ASTM C 94
Option C—mixed option:
Purchaser specifies:
 Compressive strength
 Cement content
 Admixture type and content
Batching, Mixing,
Transporting, and
Handling Concrete
Concrete producer selects mix
proportions.
Batching
Batching, Mixing,
Transporting, and
Handling Concrete
Stationary Mixing

Stationary Mixers




Batching, Mixing,
Transporting, and
Handling Concrete
Onsite or Central Mix R/M plant
Used for complete or shrink
mixing
Mixer Types ― up to 9m3
 Tilting or non-tilting drum
 Open top revolving blade or
paddle
Typical complete mixing times
 Minimum of 1 min. for up to 1
yd3 or less mixer capacity plus
15 sec. for each additional yd3
or fraction thereof
Ready Mixed Concrete

Shrink-mixed concrete


Truck-mixed concrete

Batching, Mixing,
Transporting, and
Handling Concrete
mixed partially in a
stationary mixer and
completed in a truck mixer
mixed completely in a
truck mixer
Ready Mixed Concrete

Central-mixed concrete
mixed completely in a
stationary mixer
 delivered in




Batching, Mixing,
Transporting, and
Handling Concrete
a truck agitator
a truck mixer operating
at agitating speed
a nonagitating truck
Ready
Mix Plant
Batching, Mixing,
Transporting, and
Handling Concrete
Truck Mixed Concrete
ASTM C 94
Batching, Mixing,
Transporting, and
Handling Concrete

70 to 100 revolutions required for mixing,
mixing speed = 6 to 18 rpm

After mixing, drum revolves at agitating
speed, 2 to 6 rpm

Discharge before exceeding 300 drum
revolutions

Discharge before 1½ hours
Mobile Batcher Mixer
Batching, Mixing,
Transporting, and
Handling Concrete

Used for: Intermittent
production of concrete at
jobsite, or small quantities.

Advantages: Combined
materials transporter and
batching and mixing system.
One-man operation.

Watch for: Good preventive
maintenance program.
Materials must be identical to
those in original mix design.
Nonagitating Truck
Batching, Mixing,
Transporting, and
Handling Concrete

Used for: Transport concrete
on short hauls over smooth
roadways.

Advantages: Cost of
nonagitating equipment is
lower than that of truck
agitators or mixers.

Watch for: Slump should be
limited. Possibility of
segregation. Height upon
discharge is needed.
Agitator Trucks
Batching, Mixing,
Transporting, and
Handling Concrete

Used for: Transporting concrete for all
uses. Haul distances must allow
discharge of concrete within 1½ hours.

Advantages: Operate usually from
central mixing plants.

Watch for: Timing of deliveries should
suit job organization. Concrete crew and
equipment must be ready onsite to
handle concrete.
Remixing Concrete
(1)
ASTM C 94 (AASHTO M 157)
Water may be added at jobsite
provided:
 Spec. w/c-ratio is not exceeded
 Measured slump less than specified
 Allowable mixing and agitating time
(or drum revolutions) are not
exceeded
 Concrete is remixed
Batching, Mixing,
Transporting, and
Handling Concrete
min. 30 rev. at mixing speed
 until uniformity is within limits

Transporting and
Handling
Wheelbarrows and Buggies
Batching, Mixing,
Transporting, and
Handling Concrete

Used for: Short flat hauls on
all types of onsite concrete
construction.

Advantages: Versatile—ideal
inside and on jobsites with
changing placing conditions.

Watch for: Slow and labor
intensive.
Transporting and Handling
Belt conveyor



Batching, Mixing,
Transporting, and
Handling Concrete
Used for: Conveying concrete
horizontally or higher/lower
level.
Advantages: Adjustable
reach, traveling diverter,
variable speed.
Watch for: End-discharge
arrangements needed to
prevent segregation and
mortar on return belt. Belt
cover needed in hot and windy
weather.
Transporting and Handling
Truck mounted conveyors



Batching, Mixing,
Transporting, and
Handling Concrete
Used for: Conveying concrete
horizontally or higher/lower
level.
Advantages: Conveyer arrives
with concrete. Adjustable reach
and variable speed.
Watch for: End-discharge
arrangements needed to
prevent segregation and
mortar on return belt. Belt
cover needed in hot and windy
weather.
Transporting and
Handling
Buckets



Batching, Mixing,
Transporting, and
Handling Concrete
Used with: Cranes,
cableways, and helicopters.
Advantages: Enables full
versatility of cranes,
cableways, and helicopters to
be exploited. Clean discharge.
Watch for: Select bucket
capacity to conform to size of
the concrete batch and
capacity of placing equipment.
Transporting and Handling
Batching, Mixing,
Transporting, and
Handling
Concrete
Rear
Discharge
Front Discharge
Transporting and Handling
Cranes and Buckets



Batching, Mixing,
Transporting, and
Handling Concrete
Used for: Work above ground
level.
Advantages: Can handle
concrete, reinforcing steel,
formwork, and sundry items.
Watch for: Has only one hook.
Careful scheduling between
trades and operations is
needed to keep crane busy
Transporting and Handling
Pumps
Batching, Mixing,
Transporting, and
Handling Concrete

Used for: Conveying concrete from
central discharge point to formwork.

Advantages: Pipelines take up little
space and can be readily extended.
Delivers concrete in continuous
stream. Pump can move.

Watch for: Constant supply of
freshly-mixed concrete is needed
without any tendency to segregate.
Transporting and Handling
Flexible Hose at End of Pump’s Rigid Pipeline
Batching, Mixing,
Transporting, and
Handling Concrete
Transporting and Handling
Screw Spreaders



Batching, Mixing,
Transporting, and
Handling Concrete
Used for: Spreading concrete
over large flat areas.
Advantages: Concrete can be
quickly spread over a wide
area to a uniform depth.
Watch for: They are normally
used as part of a paving train.
They should be used for
spreading before vibration is
applied.
Transporting and Handling
Batching, Mixing,
Transporting, and
Handling Concrete
Work Above Ground Level
Videos 1/3
Batching
Batching, Mixing,
Transporting, and
Handling Concrete
Stationary Mixers
Videos 2/3
Truck Mixer Types
Batching, Mixing,
Transporting, and
Handling Concrete
Nonagitating Mixers
Videos 3/3
Agitators
Batching, Mixing,
Transporting, and
Handling Concrete