clsm or flowable fill

7/30/2019 CLSM or Flowable Fill

1/30

Flowable Fill aka

Controlled Low-Strength Material

Charles Pierce

Civil & Environmental Engineering

University of South Carolina

4thAnnual South Carolina

Count on Concrete Conference

October 4, 2006

What isControlled Low-Strength Material?

Cement

+

Fly Ash

+

Fine Aggregate

+

Water+

[Admixtures]

=

CLSM


2/30

ACI 229

Organized in 1984

Published 229R-94

Revised 229R-99

Reapproved in 2005

ACI Committee Reports

intended for guidance in

planning, designing, executing,

and inspecting construction.

ASTM

C09 Concrete and Concrete Aggregates

NOT THIS COMMITTEE

D18 Soil and Rock

D18.15 Stabilization with Admixtures

WHY?


3/30

ASTM Standard Tests

Standard Practice for Sampling Freshly Mixed CLSM[D5971-01]

Unit Weight, Yield, Cement Content, and Air Content(Gravimetric) of CLSM [D6023-02]

Flow Consistency of CLSM [D6103-97]

Ball Drop on CLSM to Determine Suitability for LoadApplication [D6024-02]

Preparation and Testing of CLSM Test Cylinders[D4832-02]

Controlled Low-Strength Material

Is not concrete but is produced like concrete using the same materials.

Is not soil but, in many applications, has hardened properties

similar to compacted or stabilized earthen fill {hence

ASTM D18.15}.

Is somewhere in between CLSM is a self-compacted, cementitious material used

primarily as a [flowable] backfill as an alternative to

compacted fill [ACI 229R-99].


4/30

Comparison

Mechanicalcompaction

Self-leveling, noequipment needed

Placement

1600-2000 kg/m3

[ 100-125 pcf ]

1840-2320 kg/m3

[ 115-145 pcf ]Density

< 0.3 MPa

[ < 50 psi ]

< 2.1 MPa

[ < 300 psi ] *

28-Day

Compressive

Strength

Compacted

Earth Fill

Typical

CLSMProperties

* By definition, must be less than 1,200 psi [ACI 229R-99].

CLSM has an Image Problem

Several terms are currently used to describe this

material, including flowable fill, unshrinkable fill,

controlled density fill, flowable mortar, plastic

soil-cement, soil-cement slurry, and other

various names [ACI 229R-99].


5/30

State DOT Terms for CLSM

0 2 4 6 8 10 12 14 16 18

Flowable Fill

CLSM

Flowable Backfill

Controlled Density Fill

Flowable Mortar

Cement Mortar Flowable Backfill

Controlled Low Strength Backfill

Controlled Low Strength Flowable Fill

Flowable Concrete Fill

Flowable Select Material

Lean Mix Backfill

Low Strength Mortar Backfill

Slurry Cement Backfill

Structure Backfill (Flow-Fill)

Number of States

Advantages

Easy to place

Versatile

Fast return to

traffic

Will not settle

Can be excavated


6/30

Applications

Backfills (e.g. pavement patches)

Structural fills

Pavement bases

Conduit bedding

Erosion control

Void filling

CLSM Placement

Bridge Approach

Orangeburg SC


7/30

Cincinnati OHCourtesy of Rick Roth

Cincinnati OH

Courtesy of Rick Roth


8/30


Cincinnati OH

Courtesy of Rick Roth


9/30


Sumter SC


10/30

Sumter SC

Sumter SC


11/30

BackfillCourtesy of Tom Fox

Structural FillCourtesy of Tom Fox


12/30

Void FillCourtesy of Tom Fox

Example Mixture Proportions (PCY)

41530008050-100WY

5002673None185AL

458 or 541250060050SC

200-5002800-300015-25020-50OK

WaterSSD FAFly AshCementState DOT


13/30


14/30


15/30

Setting and Hardening

Setting time is the time when the CLSM

transitions from fluid-state to hardened-

state [< 24 hours]

Hardening time is when CLSM has sufficient

bearing capacity to support construction

loads [up to 2-3 weeks]

Hardening [ASTM D6024]

< 3 in. Diameter

Based on person

stomping on

surface [50 ft-lb]

Shortcomings Indentation diameter of 5.5 in.after 24 hrs.


16/30


17/30

Penetration Resistance : Time

0

200

400

600

800

1000

1200

2 4 6 8 10 12 14

Elapsed Time (hrs. )

MortarPenetrationResistance(psi)

0

1000

2000

3000

4000

5000

6000

7000

8000

MortarPenetrationResistance(kPa)

Accelguard Standard (calcium c hloride)

Accelguard NCA (non-chloride)

Pocket

Penetrometer

(1.0 kg/cm2)

Pocket

Penetrometer

(> 4.5 kg/cm2)

Kelly Ball < 76 mm

Setting Time

Hardening Time

Effect of Accelerating Admixtures

50

60

70

80

90

100

110

0 10 20 30 40 50 60 70 80

Time (hrs.)

KellyBallI

ndentationDiameterAt5Dro

(mm)

Accelguard Standard (Calcium Chloride)

Accelguard NCA (Non-Chloride)

Control


18/30

Strength : w/cm Ratio and Time

0

100

200

300

400

500

600

700

800

900

0 20 40 60 80 100

Time (days)

U

nconfinedCompressiveStrength(kPa)

w/b = 0.69

w/b = 0.82

w/b = 0.97

w/b = 1.00

w/b = 1.05

w/b = 1.14

Effect of Accelerating Admixtures

0

50

100

150

200

0 10 20 30 40 50 60

Time (days)

AverageUCS(psi)

0

200

400

600

800

1000

1200

1400

AverageUCS(kPa)

Accelguard Standard (calcium ch loride)

Accelguard NCA (non-chloride)

Control

Manual Excavation

Mechanical Excavation


19/30


20/302

Questions?

For More Information

[email protected]

Conclusions (1)

State DOT Specifications Vary Widely

Prescriptive

Performance

Hybrid

Cement and Fly Ash Contents More Variable

than Fine Aggregate and Water Contents

Limited and Variable Field Testing of Flowability

and Setting and Hardening Time

ASTM Standard Test Methods for CLSM not often

s ecified


21/302

Conclusions (2)

Wide Range of 28-Day Strengths

Some exceed CLSM limit

Minimum and maximum strength specifications needed

for excavatable and non-excavatable mixtures

Specifications Likely to Evolve as DOTs Gain

Experience

Slump Test

Slump

Requirements (in.)

0-5 or 6-8

3-10

7 min. 8 min.

9-11

10-12

Slump (in.)Flowability

> 8High

6-8Normal

< 6Low

ACI 229R-99


22/302

Penetration Resistance Tests

(2) DCP

IL: 1.5 in. per blow at 3 days

Rebar Test

NM: 6 < blows < 25 to drive #6 rebar 12 in.

using 15 lb. fence driver at 24 hrs.

NV: #4 rebar does not penetrate surface

Pocket Penetrometer

MT: 2.5 tsf minimum at 24 hrs.

Setting and Hardening

Requirements

0

5

10

15

20

25

30

35

Not Specified Time Tested Engineer

Setting and Hardening Acceptance

N

umberofStates


23/302

Strength Measurements

0

5

10

15

20

25

30

35

40

Not Specified 3 Day 7 Day 14 Day 28 Day 56 Day 90 Day 180 Day

Test Age

NumberofStates

20-1500 psi

Strength Measurements

ASTM D4832

6 states

ASTM C39 or AASHTO T23

7 states

Cylinder Size 4 x 8 in. (2)

3 x 6 in. (1)


24/30


25/30


26/302

Temperature Restrictions

Ambient Temperature: 7 States

30-40F minimum

Mixture Temperature: 4 States

40F min. (3) or

50F min. (1)

Ground Temperature: 2 States Not on frozen ground

Freezing Protection

None, 9

24 Hours, 2

36 Hours, 10


27/302

Flowability Requirements

Observed: Self-leveling / Self-compacting /

Not Specified, 15

Observed, 12

Measured, 20

How Flowability is Measured

0

2

4

6

8

10

12

14

Slump Spread Flow: CRD-C611-80

Test Method

NumberofStates

MA AllowsSlump or Spread


28/302


29/302


30/30

clsm or flowable fill

Documents