Seminar & Workshop on Interlocking Concrete Pavers (ICP)

Introduction to ICP: A review

Haryati Yaacob

Overview

• History

• ICP Structure

• Concrete Paver Shapes

• Laying Pattern

• Bedding Sand

• Jointing Sand

• Edge Restraint

• Advantages of CBP

• Life Cycle Cost

3

Interlocking Concrete Paver (ICP) consists of

blocks placed over one or more layers of unbound granular

material, thin bedding sand layer, an unbound granular base (not always applied) and sand sub-base over the subgrade

History: Stone Blocks• 1st stone paving - 4000 BC in Assyria and 2000 BC

flagstones were being used to pave village streets.

• Roman roads - Appian Way, built by Roman engineers in 312 BC. 377 kilometer road was surfaced with tight-fitting paving stones.

• Romans- hexagonal-shaped flagstones as a surface course

History: Concrete Blocks• Netherlands (early 1950s) – WWII- short supply on clay

bricks. Concrete blocks were introduced.

• Betonklinderdei (BKK) concrete paving block- rectangular shape ( 200 mm x 105 mm dimension on plan).

• 1952- I shaped Block

(Van der Vlist, 1980)

1st blockmaking machine, open air

Fully mechanized and automated concrete paving block producing machine (1960s)

Production of concrete paving blocks in Netherland (1950s)

Use of Pavers Worldwide (in millions of square meters per annum).

(CMA, 2008)

Pioneer Researchers in ICP

Dr Brian Shackel

Dr John Knapton

ICP Structure

Edge

restraint

Joint

filling

sand

Concrete

paving

units

Subgrade

Subbase

Base course

Bedding sand

Concrete Paving Unit : Strength

ASTM C 939: - Blocks are manufactured from portland cement and fine sand aggregate and must meet or exceed the minimum values ASTM. The average compressive strength of block did not less than 55 MPa, with no individual unit less than 50 MPa. The average absorption of blocks is not greater than 5%, with no individual unit greater than 7%.

CCAA, T35: - compressive strength: Minimum 30 MPa

: Maximum 45 MPa

Concrete Paving Unit

BS 6717-1, 1993: The length, width and thickness of rectangular concrete blocks is 200 mm, 100 mm and 80 mm respectively with the length to width ratio is 2.

CMA, 2004: For industrial usage, the thickness of block must be at least 80 mm.

Thickness of Block for Different Type of Pavement

Block Thickness Type of Pavement

60 mm Light traffic such as pedestrians, motorcycles

80 mm Medium Traffic

100 -120 mm Heavily Trafficked

Mokaddes and Binod, 2013

Effect of Diff Thickness on ICP Deflection

Panda and Ghosh (2003)

16

PropertyRecommended

values

i. Dimensions

- aspect ratio

- width

- length

- thickness

1.5 mm – 2.3 mm

68 mm – 160 mm

200 mm – 280 mm

60 mm – 140 mm

ii. Dimension tolerances

- plan dimensions

- thickness

+ 1.6 mm - + 3 mm

+ 3 mm - + 5 mm

iii. Strength

- compression

- average

- individual

- characteristic

25 MPa – 60 MPa

20 MPa – 54 MPa

< 40 MPa

- flexural

- average

- characteristic

< 5 MPa

< 5.9 MPa

- splitting

- average

- individual

< 4 MPa – 5 MPa

< 3.2 MPa

Specification for

concrete blocks

(Shackel, 1990)

Concrete Paver Categories

Concrete Masonry Association of Australia (CMAA, 1986) – “ Specification for Concrete Segmental Paving Units (MA20).”

Classified concrete block units are manufactured in four shape type.

i. Shape type A

ii. Shape type B

iii. Shape type C

iv. Shape type X

Concrete Paver Shape Categories (Shackel,1990)

Category/Type X

Type A

Type B

Concrete Paver Shapes•dentated units that key into each other by their plan geometry.•interlock and resist the relative movement of joints parallel to both the longitudinal and transverse axes of the unit. •can be used for all loading type.

•dentated units that key into each other by their plan geometry.•Interlock and resist the relative movement of joints parallel to one axis only.

Type C

Units that do not interlock

20

ShapeSize

( mm)

Thickness

( mm)

No of blocks /

Area

(unit/m2)

Anchorlok 225 x 112.5 80 26.3

Angsana 280 x 120 60 33.3

Grasspave 337.5 x 225 80 13.2

Uni-Decor 230 x 140 60 37.8

Uni-Espave 220 x 190 60 34.7

Quadpave 200 x 100 60 and 100 44.1

Uni-Pave 225 x 112.560, 80 and

10039.5

Two major types of pattern: Herringbone & Stretcher bond.

Basket weave pattern - pedestrian areas only.

Laying Pattern

21

Effect of Laying Pattern on ICP Deflection

Shackel et al. (1993).

Bedding Sand

29

To provide an even surface on which to lay the blocks.To accommodate accepted tolerances in the finished surface

level of the base.To accommodate accepted tolerances in the block thickness.To provide uniform support for the blocks and to avoid stress

concentrations as this could cause damage to the blocks.To fill the lower part of the joint spaces between adjacent

blocks in order to develop interlocking effect.To act as a barrier to upwards propagation of cracks from the

base.To contribute to the distribution of stresses resulting from

wheel loads on the pavement.

30

Bedding Sand

Compacted Thickness (mm)

References Remarks

50 Common thickness

40Knapton (1996) and Shackle (1990)

significance proportion

30 to 50Knapton (1996) and Shackle (1990)

To prevent further deformation

30Lekso (1980) & Hodgkinson (1982)

Successfullyon rural freeway -Denmark

20 to 25Beaty (1992) Underlying base to be very

smooth

20 to 40 Australia

30 to 50 Belgium

25 to 40Westcon Precast Inc. (1990) and McQueen et al., (1993)

Proper thickness

Note: compaction reduces about 20 % to 35 %

Gradation for Bedding Sand

CMAA

Sand Bedding

3333

The jointing sand is placed and filled between

blocks to provide strong pavement and interlocking

effect.

It has been recommended that the block units

should have nominal gaps of 2 mm to 4 mm

(Shackel, 1990).

Optimal block spacing is typically around 2 mm to

5 mm because as the joints get wider, the individual

blocks may show signs of rotation.

Jointing Sand

34

• T 35 (CCAA) – 2 mm to 4 mmley (1980)k

• BS 6717: part 1 - + 2 mm overall range 4 mm

• BS 6727 – Range bertween 2 mm to 8 mm

Jointing Sand

Effect of Joint Width on ICP Deflection

Joint Filling Sand

37

Jointing Sand

Coarse Sand

Gradation for Jointing Sand

CMAA

Pasir kasar sebagai pengisi sambungan

Pergerakan blok konkrit

Teknik penyusunan

yang salah

Tiada pasir pengisiBerlaku mendapan & rayapan

40

Laying CBP

41

To prevent movement either of the whole paved area or

individual blocks (Huurman, 1997).

Its should be laid at all boundaries of the block paved are

including where block paving abuts different flexible

materials, such as bituminous bound material.

Edge Restraint

The paved area must be restrained at its edges to prevent

movement, either of the whole paved area or individual

blocks.

Edge restraints resist lateral movement, prevent rotational of

the blocks under load and restrict loss of bedding sand

material at the boundaries

They should be suitable for the relevant application and

sufficiently robust to resist displacement if likely to be overrun

by vehicles.

Example of edge

restraint: PVC,

Steel, Concrete and

Aluminum

Edge Restraint

Interlocking

44

Advantages of CBP

Oil spill resistant Withstand punching load

Heavy duty application Sustain heavy load

Ecstatic value/

friction resistance

45

Advantages of CBP

Friction resistance

46

Heavy duty

application

47

Aesthetics

48

Sustain heavy load

49

Oil spill resistant

` Life Cycle Cost Comparison ( 5 million ESAL Pavement Design)

ICPI, 2008

Life Cycle Cost Analysis

Pros

• Mass production under factory conditions ensures -consistent quality and high dimensional accuracy.

• Good quality of blocks ensures durability of pavements, when constructed to specifications.

• ICP tolerates higher deflections without structural failure and will not be affected by thermal expansion or contraction.

• ICP does not require curing, and so can be opened for traffic immediately after construction.

• Construction of ICP is labor intensive and requires less sophisticated equipment.

• Provides ready access to underground utilities without damage to pavement.

• Maintenance of ICP is easy and simple and it is not affected by fuel and oil spillage.

• Use of coloured blocks facilitates permanent traffic markings.

• ICP is resistant to punching loads and horizontal shear forces caused by maneuvering of heavy vehicles

• Low maintenance cost and a high salvage value ensures low life cycle cost.

Cons

• Quality control of blocks at the factory premises is a prerequisite for durable ICP

• Any deviations of base course profile will be reflected on the ICP surface.

• High quality and gradation of coarse bedding sand and joint filling material are essential for good performance.

• ICP over unbound granular base course is susceptible to the adverse effects of poor drainage and will deteriorate faster.

• ICBP is not suited for high speed roads (speed above 60 km/h)

THANK YOU

55