desBatching, Mixin

Batching, Mixin

T ti C 

and Cod

Transpor ransporting 

Co

nology a e Tech Concret
Objectives

 Standards Batchin

g

 Mixing Transporting
ASTM C94/C94M

Standard Specification for Ready Standard Specification for Ready-Mixed 

Mixed 

 Materials specifications Ordering information Ordering information Slump tolerances Measuring tolerances Mixer/Agitator 

requirements

 D li th d Delivery methods Testing methods
ASTM C685

/C685

Standard Specification for Concrete MVolumetric Batching and Continuous 

 Materials 

s

pecifications

 Ordering 

information

 Slump tolerances Measuring 

tolerances

 Mixing mechanism Delivery methods Testing methods
ACI 304R

Guide for Measuring, Mixing, Transpoand Placing Concrete

 Control, handling, and storage of 

materials

 Measurement and batching Mixing and transporting Mixing and transporting Placing Volumetric batching Volumetric batching
Batching

 Process of m

concrete miconcrete mi

ingredients 

mass or volumass or volu

 Most specifi

Most specifi

require batcmass
Batching by Volume

 ASTM C685 Yi ld h k Yi

eld c

hec

k

s

 Proportioning checks

Tolerances for batching by volume: Cement, mass% = 0 - +4 Fi % ne aggregate, mass

% = ±

2

 Coarse aggregate, mass% = ±2 Admixtures mass or volume% = Admixtures, mass or volume%

=

±

3

 Water, mass or volume% = ±1
Batching by Mass

 ASTM C94 Batchin

g plant -

precision control discharge operation

 Plant scales -

accurate to ±0.15% total capacity or 0 4% net applied 0.4% net applied

load
Batching by Mass

Cementitious materials: Measured separately or 

combined sequentially combined sequentially

 Cement first Tolerance at 30% or greater of full s

- ±1% required mass

 Tolerance for loads smaller 30% of s

Tolerance for loads smaller 30% of s

capacity- 0-+4% required mass
Batching by Mass

Aggregate: Can be measured individually or comb Tolerances

 Individual loads - ±2% of required ma Cumulative loads Cumulative loads

30% or more of scale capacity - ±1% 

mass after each successive weighing

less than 30% of scale capacity - the 

±0.3% of scale capacity or ±3% of req
Batching by Mass

Water: Tolerance - ±1% by mass or 

volume

 Ice must be measured by 

mass

 Wash water remaining in 

truck mixer drums must be accurately measured accurately measured

 Total water tolerance - ±3% 

of the s

pecified total 

amount
Batching by Mass

Admixtures: Powdered admixtures - mass Liquid admixtures - mass or volume Tolerance - greater of: 

 ±3% of total amount required  ±100% dosage per 50kg (100lbs) of 

cement
Insp g ectin Batch Plan

ACI 311.5

 Project specification compliance Storage standards compliance Materials testing standards 

compliance

 Truck operating conditions Equipment calibration Batch ticket verification
Mixing and Transpor

Concrete  Ordering concrete

 Ready mixed concrete Mobile batcher mixed concret Remixing concrete
Ordering Concrete

ASTM C94/C685

Purchaser specifies: Sizes of coarse aggregate Slump at point of delivery Slump at point of delivery Air content at point of delivery One of three options for remai

parameters
Ordering Concrete

ASTM C94/C685

Option A—performance basPurchaser specifies: C i t th Compressive s

trength

Concrete producer selects mConcrete producer selects m

proportions.
Ordering Concrete

ASTM C94/C685

Option B—prescription basePurchaser specifies mixture 

proportions including:

 Cement content Water content Admixture type and conte
Ordering Concrete

ASTM C94/C685

Option C—mixed option:Purchaser specifies: Compressive strength Cement content Admixture type and contentConcrete producer selects mix 

proportions.
Prescription to 

Performance (P2P) Performance (P2P)

 Move away from prescrip

specifications

 Move towards performan

specifications

 Focus – final product 

performance
P2P - Advanta Advantages

 More efficient process Encourages cooperation Encourages cooperation Improved consistency Improved consistency
Ready Mixed Concre

 Central-mixed concrete Shrink

-mixed concrete mixed concrete

 Truck-mixed concrete
Central-mixed Conc

 Mixed completely in 

a stationary mixer a stationary mixer

 Delivered in 

 a truck agitator a truck agitator a truck mixer 

o

p g eratin

g at 

agitating speed 

 a non-agitating 

truck 
Central Central Mix Plan

Mix Plan
Stationar

y Mixers

 Stationary Mixers

 Onsite or central 

mixed concrete pmixed concrete p

 Used for complet

mixing

 Mixer Types 

― up 

 Tilting or non Tilting or non

-tilti

tilti

 Open top revolvin

paddle
Ready Mixed Concre

Shrink-mixed Concrete

 Partial mixing in stationary mixer 

completed in truck mixer

 Stationary mixing time should be 

Stationary mixing time should be 

 Performance tests same as centra

Performance tests same as centra

concrete 
Ready Mixed Concre

Truck-mixed Concrete

 Mixed comple

truck mixer

 70 to 100 mixi

revolutions, mrevolutions, m

= 6-18 rpm

 Agitating spee Discharge befo

or 300 revolut
Mixer Trucks

Used for: pavements

and buildings and buildings – dis

dis

allow discharge of within 11⁄2 hours

Advantages: centra

not needed, dischcontrolled 

Watch for: Timing of 

should suit job org

Concrete crew and Concrete crew and 

must be ready onsconcrete. Control not as good as wit

mixing.
Mixer Trucks

Rear Discharge Front Dis
Agitator Truc

Used for: Transpor

concrete for all uconcrete for all u

distances must adischarge of con

11⁄2 hours.

Advantages: Op 

er

from central mixi

Watch for: Watch for: Timing 

Timing 

should suit job oConcrete crew aequipment must equipment must 

onsite to handle 
Non-agitating T

agitating T

Used for: Transp

concrete on shconcrete on sh

over smooth ro

Advantages: Cos

agitating equiplower than that lower than that 

agitators or mix

Watch for: Slump 

limited. Possibsegregation Hsegregation. Hdischarge is ne
Mobile Batcher Mix

Concrete



Auger-t i ype m xer

 Mi i d i d b f Mi

xing rate 

determine

d

by manu

f

 Slump tolerances ~ ±40mm (1.5 in

depending on specified slump
Mobile Batcher Mix

Concrete UniformConcrete Uniform

Requirements for Within

-Batch Unifo

Range of 2 Sa

Requirements for Within

-Batch Unifo

Concrete

Air content, % 1.0Air free density 16 kg/m

3 (1.0 

Sl mp u

Avg. <100mm (4 in) 25 mm (1 in)Avg. >100mm (4 in) 40 mm (1.5 in

Coarse aggregate content, % mass 

t

6.0

concre

e

7-day strength, % of average 7.5
Mobile Batcher Mobile Batcher Mixer T

Mixer T

Used for: Intermittent 

production of concrete at jobsite or small quantities jobsite, or small quantities.

Advantages: Combined 

materials transporter and batching and mixing s

ystem. One-man 

operation.

Watch for: Watch for: Good preventive Good preventive

maintenance program. Materials must be identical to those in original mix to those in original mixdesign.
Truck Manufacturers Bu
Remixing Concrete Concrete

ASTM C94

Water may be added at jobsite provided Spec. w/c-ratio is not exceeded Measured slump less than specified Mixing time or drum revolutions not e Concrete is remixed

 min. 30 rev. at mixing speed until uniformity is within limits
Transporting Concrete

Watch out for: Delays

 Labor force management Equipment selection

 Early stiffe

 Flash/Fal

 Equipment selection

 Accelerat

 Route planning

 Accelerat
Transporting Concrete

Watch out for: Drying out

 Hot and dry weather Low W/CM Low W/CM Use of silica fume or 

admixtures that affect bleed water

 Segregation

 Cohesive mixture Placing method and rate