Ultra Thin Continuously Reinforced Concrete -

Modelling &Testing under APT

Louw Kannemeyer (SANRAL)Bryan Perrie (C&CI)

Pieter Strauss (Consultant)Louw du Plessis (CSIR)

34 % Less Than 5 Years

Problems Ageing Network – Strengthening Requirement Environmental Legislation – Materials Availability Traffic – Increased Growth, Increased % Heavy, Increased Tire Pressures

Solutions Increased Budgets Innovative Pavement Repair Strategies

Must be able to be applied to an existing road surface with minimal preparation works required to the existing road surface or structures (in other words an Inlay or Thin Overlay);

Must be able to be constructed with road construction equipment generally available in South Africa;

Must be able to be opened to traffic within 48 hours; Must have structural life expectancy in excess of 30 years with

minimal maintenance requirements during this period; Must be able to successfully withstand increased axle loads and tyre

pressures of modern heavy vehicles; Must be able to meet all functional requirements to ensure a safe road

surface under all conditions; Must enhance utilisation of materials and labour, and Must be cost affective.

RSA Primary Network SummaryRSA Primary Network Summary

Potential Innovative Solution Potential Innovative Solution Ultra Thin Continuously Reinforced Concrete Pavement

20 to 60 mm Layer Thickness 50 x 50 mm (Ø5mm to Ø8mm) Welded Mesh

4.5% versus 0.6% Steel for Traditional CRCP

Ultra High Strength Cement (UHSC) Paste WC Ratio = 0.27- 0.30 Steel- and polypropylene fibres.

Short Term Pavement Performance (STPP) APT (HVS) Test Sections at Heidelberg TCC

Long Term Pavement Performance (LTPP) Actual Traffic on Heidelberg TCC Screener Lane

UTCRCP Testing UTCRCP Testing

UTCRCP - HVSUTCRCP - HVS Sections Layout

60 m

HVS426A5

HVS429A5

HVS427A5

HVS428A5

3.7

m

1.0mm (40 kN) Surface Deflection Before Overlay

HVS430A5

HVS431A5

3.7

m0.3mm (40 kN) 0.6mm (40 kN)

20 mm AC150 mm G7

(CBR = 15 %)

40 mm UTCRCP20 mm AC

150 mm G7

150 mm C4

40 mm UTCRCP

UTCRCP - ConstructionUTCRCP - Construction

UTCRCP - UTCRCP - Max Deflection (40kN)HVS Test Section 1.1 - Before and After FWD Deflections

0

200

400

600

800

1000

1200

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

Location on HVS Test Section

Y-M

ax

@ 4

0 k

N (

Mic

ron

)

Y-Max Before Y-Max After

Average = 854

Average = 352

UTCRCP APT - UTCRCP APT - Instrumentation

JDMD 4JDMD 5 JDMD 6

H 2

Install these at area where there are novertical anchors

MDD 1 MDD 2

H 1

1.2 m deep

JDMD 1 JDMD 2 JDMD 3 Note: TC2 depths:Top: TC top

3m deep Bottom: TC bot

TC 1 TC 2 TC 3

TC 5 TC 6

TC 4

UTCRCP - APT TestingUTCRCP - APT Testing

UTCRCP – Sections at FailureUTCRCP – Sections at Failure

UTCRCP – HVS RepetitionsUTCRCP – HVS Repetitions

Tire Pressure = 800 kPa (Truck), 1400 kPa (Aircraft)Speed = 9.0 km/h, Load Application = Canalized bi-directionalAircraft Wheel Used for wheel loads above 100kNShaded Areas = Surface Water Added Continuously

426A5 427A5 428A5 429A5 430A5 431A530 2,00040 18,000 40,000 100,000 38,000 40,160 40,00060 20,500 40,000 40,500 40,000 40,080 40,08880 26,500 197,000 59,650 177,704 122,764 120,00080 130,500

80 122,500 52,650 800,000 703,189100 23,000 21,547120 20,528125 137,000140 135,100 1,360140 103,300

Total Reps 463,400 530,000 252,800 257,704 1,046,439 903,277Total E80's

(n=4.5)92,190,469 10,470,348 2,892,170 4,306,993 25,761,052 18,915,197

Test Wheel Load (kN)

HVS Repetitions Per Test

UTCRCP – APT Test ConclusionsUTCRCP – APT Test ConclusionsCement Type: CEM I products had performance differences of up to 50 % - worst was used for the UTCRCP APT Test;Layer Placement: The use of Asphalt paver required very low slump, and with high steel mesh content - steel was not completely covered by the cement paste;Steel Fibre Type: The drawn wire steel fibres used - incorrect in terms of length and shape, and•Steel Bar Spacers: 10mm diameter steel bar spacers on top of the AC layer to support the asphalt paver, acted as crack inducers.

UTCRCP – Finite Element ModelUTCRCP – Finite Element Model FE Model developed to predict APT observations FE Model Then used to investigate:

Amount & Position of steel mesh; Thickness & Stiffness of UTCRCP layer; Bond & Impact of Void; Substructure Stiffness Load Speed

UTCRCP – Conclusions “to date” UTCRCP – Conclusions “to date” Different chemical reaction between additives and different CEMI

cements used; Do not use “spacer bars” or asphalt paver for placement; Debonding between UTCRCP and support layers a reality in

presence of water – increase in stress; Curling and presence of anchors did not have a major impact; Steel fibre length and shape do impact performance – optimum 30

mm x 0.5mm hook end fibre; UTCRCP Thickness and presence of crack/joint is critical to

performance – optimum 50 - 60 mm; Relative position of steel not crucial, closer to top better for

reducing compressive stress in crack or joint – lower spalling and water access risk;

Amount of steel not that crucial according to FE model, but lab test indicate optimum to be - Ø 5.6mm @ 50x50mm – current HVS tests in progress to verify this.

UTCRCP FutureUTCRCP Future Reconstructed APT Test Section 1

Different Steel Mesh (max Ø 5.6mm @ 50x50mm), Steel Fibre and Concrete Mix Options

Placed by Hand HVS testing currently in progress

Postulated Alternative Introduce as postulated alternative on projects – Jan 2007

New test sectionsN

othe

rn e

nd54

mS

ecS

ec4.

84.

4

0.6m

1.1m

40.5

m

4.7

4.3

27 m

4.6

4.2

13.5

m

4.5

4.1

0.7m

0.7m

0 m

Sou

th e

nd

SA

2

SA

1

Con

tec

ApS

SA

3

UTCRCP HVS testing Phase II Update First Test (Danish mix design) finished

Contec-APS binder 50 x 50 mm steel mesh, Y 5.6 mm Test lasted 1 355 657 reps at mostly 80kN (Roughly 30 mil E80s – using 4.5 power factor)

UTCRCP HVS testing Phase II Update Second Test (SA mix design # 3) just started

80kg/m3 steel fibers mix (UP designed binder) 50 x 50 mm steel mesh R 4 mm steel wire

Field mix: Compressive strengths

Cube Strength Results

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

1 Day 3 Day 7 Day 14 day 28 Day

Days after manufactoring

Str

eng

th (

MP

a)

Contec ApS Mix SA 1 SA 2 SA 3

Field mix: Flexural Beam strengths

Flexural Beam Results

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

1 Day 3 Day 7 Day 14 day 28 Day

Days after manufactoring

Bea

m S

tren

gth

(M

Pa)

Contec ApS Mix SA 1 SA 2 SA 3

Thank You