Ultra Thin Continuously Reinforced Concrete - Modelling &Testing under APT
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Transcript of Ultra Thin Continuously Reinforced Concrete - Modelling &Testing under APT
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
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Location on HVS Test Section
Y-M
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@ 4
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N (
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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
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1.1m
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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
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Days after manufactoring
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Contec ApS Mix SA 1 SA 2 SA 3
Field mix: Flexural Beam strengths
Flexural Beam Results
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Days after manufactoring
Bea
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Contec ApS Mix SA 1 SA 2 SA 3
Thank You