Accelerated Bridge Strengthening using UHP(FR)C

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Horace Boone
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1 ABC-UTC at Florida International University (FIU) Webinar : Thursday, December 14, 2017 Accelerated Bridge Strengthening using UHP(FR)C Eugen Brühwiler EPFL Swiss Federal Institute of Technology Lausanne, Switzerland and BridgIng Consultant

2 2 UHPFRC = Ultra-High Performance Fiber Reinforced Cementitious Composites UHPFRC UHPC

04 ) Fiber reinforced with steel fibers l= ½,

3 3 Performance of UHPFRC (Ultra-High Performance Fiber Reinforced Cementitious Composites) Impermeable compact matrix: powders and particles (<0.04 ) Fiber reinforced with steel fibers l= ½, l/d>65; > 3 vol.% (synthetic fibers are too soft!) Hardening (in tension) Shinkage and Creep

4 Basic concept of enhancement of bridges using UHP(FR)C UHPFRC = Ultra-High Performance Fiber Reinforced Cement-based Composites UHPFRC is not a concrete!

4 4 Basic concept of enhancement of bridges using UHP(FR)C UHPFRC = Ultra-High Performance Fiber Reinforced Cement-based Composites UHPFRC is not a concrete! use UHPFRC to enhance R-concrete Interface surface preparation by hydro jetting or sandblasting ; wetting before UHPFRC casting bond strength >> concrete tensile strength Reinforced Concrete Shortcomings: - limited durability under severe exposure: rebar corrosion, AAR, frost - high maintenance cost - heavy weight, material consuming - slow construction

5 5 Conceptual idea damage exposed reinforced concrete is not durable! often structural capacity (fatigue and ultimate resistance) of slabs and other structural elements is not sufficient!

6 6 Conceptual idea : enhance RC using UHPFRC! damage UHPFRC UHPFRC protective watertight UHPFRC layer to improve durability increase structural capacity (stiffness, ultimate resistance, fatigue resistance)

Accelerated Bridge Enhancement UHPFRC Fulfill several functions with 1 layer: 1) increase resistance

7 7 UHPFRC 2017 October 2-4 Montpellier (France) Strengthening = adding a layer of R-UHPFRC as additional reinforcement to the RC section Author(s) Title of the paper reinforced concrete ABE : Accelerated Bridge Enhancement UHPFRC Fulfill several functions with 1 layer: 1) increase resistance in bending and shear 2) increase stiffness to reduce fatigue stresses 3) act as a waterproofing layer concrete 7

8 8 Conceptual idea (1999): enhance RC using UHPFRC! UHPFRC for waterproofing t u = 1 R-UHPFRC for strengthening (t u = 1¾ to 3 ) + steel rebars Reinforced Concrete Reinforced Concrete composite behavior of (R-)UHPFRC RC elements 17 years of research and 12 PhD theses at the EPFL (Swiss Federal Institute of Technology)

analysis of R-UHPFRC RC composite members Ultimate

9 9 UHPFRC 2017 October 2-4 Montpellier (France) Author(s) Title of the paper Structural response and sectional analysis of R-UHPFRC RC composite members Ultimate bending resistance : UHPFRC Fatigue stresses and fatigue resistance :

10 10a Ultra-High Performance Fibre Reinforced Cement-based composites (UHPFRC) Publication: 1 March 2016, 44 pages in German and French, translation in English edited by a Working Group: from 02 / 2012 to 10 / 2015 Construction material, dimensioning and application

11 10b Ultra-High Performance Fibre Reinforced Cement-based composites (UHPFRC) Publication: 1 March 2016, 44 pages in German and French, translation in English edited by a Working Group: from 02 / 2012 to 10 / 2015 Construction material, dimensioning and application

12 11 UHPFRC technology is cost-effective! more than 50 applications in Switzerland since 2004: why? 1: UHPFRC fabrication cost (1 900 US dollars / yd 3 ) 2: Construction cost : several requirements are fulfilled with one UHPFRC casting/layer determinant! 3: Intervention cost = construction cost + indirect (user) costs added value for the owner 4: Life cycle cost : reduction of maintenance and environmental impact added value for owner and society

13 12 Rebar corrosion and higher traffic loads: repair strengthening - replacement

14 13 Conventional repair and retrofit is not sufficient! Reinforced concrete needs to be enhanced! UHPFRC ABE : Accelerated Bridge Enhancement Fulfill several functions: restoration of elements; waterproofing protection against water and chloride ions; increase in structural capacity (bending, shear, fatigue); drivable surface; simplify construction process and reduce intervention time. cost effective

resistance increase in stiffness and strength in the longitudinal direction waterproofing of slab no increase in dead

15 14 UHPFRC 2017 October 2-4 Montpellier (France) Author(s) Title of the paper Enhancement of the Chillon Viaducts 2014/15 Functions of R-UHPFRC: strengthening of deck slab in the transverse direction: bending, shear and fatigue resistance increase in stiffness and strength in the longitudinal direction waterproofing of slab no increase in dead load short duration of intervention R-UHPFRC : thickness: 2 (50mm) 12 joint detailed design by: Monod-Piguet + Associés IC / GVH

Photo: July 4, 2014 July/August 2014 and June 2015: Casting of 1 600 yd 3 UHPFRC on each 1.

16 15 UHPFRC 2017 October 2-4 Montpellier (France) Author(s) Title of the paper Enhancement of the Chillon Viaducts 2014/15 Owner: Swiss Federal Roads Office ABE : Accelerated Bridge Enhancement Photo: July 4, 2014 July/August 2014 and June 2015: Casting of yd 3 UHPFRC on each 1.30 miles long viaduct Intervention cost : 22 US dollars / ft 2 deck surface Contractor: WALO Bertschinger SA

17 16 UHPFRC ready mix plant on site

18 17

19 18

20 19 maximum slope: 7% working joint detail curing

Temperature dependent strength evolution of UHPFRC Holcim 710 UHFB Owner: Canton of

21 20 Enhancement of the Cudrex Viaduct (2016) Concept: accelerated intervention in 8 work phases of 36 hours Saturday 5pm Monday 5am ABE : Accelerated Bridge Enhancement Temperature dependent strength evolution of UHPFRC Holcim 710 UHFB Owner: Canton of Vaud Total length: 500yd (450m) Compressive strength MPa 10ksi hours Project: Ing. D.Willi, Montreux

22 21 curb coated with UHPFRC pea gravel for roughness

22 Enhancement of the Cudrex Viaduct (2016) Concept: accelerated intervention: bridge in service during the week Rehabilitation of curb using UHPFRC Curb coated with

23 22 Enhancement of the Cudrex Viaduct (2016) Concept: accelerated intervention: bridge in service during the week Rehabilitation of curb using UHPFRC Curb coated with UHPFRC Costs : UHPFRC works 28 US dollars per ft 2 bridge deck surface + further works (piers, bearings, dilation joints) = about 20% of hypothetical replacement project

resistance: h U = 4, φ su = 0.8 @ 4, 2 layers asphalte pavement: 3 h c =7.

24 23 UHPFRC 2017 October 2-4 Montpellier (France) Author(s) Title of the paper Enhancement of 3 highway viaducts (2017/18) Cross section at support: 2: new curbs 1 : increasing ultimate bending resistance: h U = 4, φ su = 4, 2 layers asphalte pavement: 3 h c =7.5 c =2400 ft Owner: Swiss Federal Roads Office 3: rehabilitation of corrosion damaged zones using UHPFRC 4 total length: 1 100yd

25 24 UHPFRC 2017 October 2-4 Montpellier (France) Author(s) Title of the paper Principle of structural strengthening using R-UHPFRC tension chord rebars longitudinal transverse hogging sagging hogging sagging hogging increase hogging moment capacity by adding R-UHPFRC tension chord transverse rebars for load distribution and increase in transverse stiffness check at ULS: plastic sagging moment + plastic hogging moment > overall acting moment ultimate shear resistance > acting shear force concrete compressive stress < concrete strength check at SLS: maximum UHPFRC tensile strain < 1 %o check at FLS: fatigue stress in rebars < fatigue endurance limit 25

26 25 UHPFRC 2017 October 2-4 Montpellier (France) Author(s) Title of the paper Rehabilitation of corrosion damaged zones using UHPFRC : 2017 Photos: 13 September 2017

26 Traditional: Repair of steel rebar corrosion damage using repair mortar Principle: front view : section : steel rebar corrosion repair mortar Invasive concrete removal up to 4 depth =>

27 26 Traditional: Repair of steel rebar corrosion damage using repair mortar Principle: front view : section : steel rebar corrosion repair mortar Invasive concrete removal up to 4 depth => criterion remaining chloride content => important reduction of cross section:=> temporary support => possibly additional rebars / surface protection conventional method = not efficient! 1 ¾ 3 4

27 Rehabilitation of local steel rebar corrosion damage using UHPFRC Principle: front view : section : steel rebar UHPFRC corrosion 2 minimal concrete removal behind rebar

28 27 Rehabilitation of local steel rebar corrosion damage using UHPFRC Principle: front view : section : steel rebar UHPFRC corrosion 2 minimal concrete removal behind rebar re-profiling using UHPFRC waterproof layer around the damaged rebar no chloride migration to the rebar UHPFRC tensile resistance to compensate section loss due to corrosion

29 28 UHPFRC mixing plant Photo: 13 September 2017

29 General concept of UHPFRC intervention PABBS

Objectives: 1 UHPFRC layer for: - waterproofing

surface - structural strengthening - simplified

30 29 General concept of UHPFRC intervention PABBS Pre-stressed Adjacent Box Beam Superstructures Objectives: 1 UHPFRC layer for: - waterproofing protection - repair of local damage - drivable surface - structural strengthening - simplified execution - reduce time for construction works

31 30 General concept of UHPFRC intervention to enhance bridge performance (deck surface = ft 2 ) UHPFRC ABE : Accelerated Bridge Enhancement Approach slab with UHPFRC span pier span pier h U* = min 1.5" L = 43ft-4.5" h U = min 2.5" L = 34 ft h U = min 1.5" L = 45ft-2" h U = min 2.5" L = 34 ft span h U = min 1.5" L = 32ft-4" Approach slab with UHPFRC * h U = thickness op UHPFRC layer

32 31 UHPFRC intervention: General cross-section at mid-span (Phase II) 2 in 2 in detail 2 Main benefits: Detail 2: Deck slab reinforcement Drivable surface with required skid resistance Existing connectors (steel rebars) 1) HPW jetting removal of 1 to 1.5 inches of concrete (depending of condition) 2) Deck surface: New UHPFRC layer (thickness min. 1.5 inches) including transversal rebars Above joints between precast box girders: Removal of unsound concrete + filling with UHPFRC (existing rebars kept in place) Structural strengthening: 1) Transversal stiffness + resistance ( ) Reducing relative vert. displacement of box-girders (= eliminating source of longitudinal cracking in deck slab) Enhanced durability: 1) Waterproofing (entire cross section) 2) Local repair of concrete damage Protection of underlying pre-cast box girders subjected to water infiltrations from top (cracked deck slab) + chloride induced corrosion of steel rebars and prestressing

33 32 UHPFRC intervention: Phase III (parapet & barrier) detail 3 detail 3 Detail 3: Restoring parapet Detail 3: Restoring concrete barrier min 4.0" h U = min 1.0" h U = min 1.0" HPW jetting removal of min. 1 inch of concrete min 4.0" NEW UHPFRC waterproofing layer (thickness min. 1 inch) 2 in 2 in

33 Removal of armored joints on abutments and creating a UHPFRC «sealing» UHPFRC detail 6 detail 6 Detail 6: UHPFRC «sealing» Continuous UHPFRC layer over existing

34 33 Removal of armored joints on abutments and creating a UHPFRC «sealing» UHPFRC detail 6 detail 6 Detail 6: UHPFRC «sealing» Continuous UHPFRC layer over existing approach slab UHPFRC «sealing» Integral bridge (removal of armored joints + continuous UHPFRC layer removal of last «weak detail» to enhance durability and reduce maintenance)

35 34 Thank you! UHPFRC Technology to enhance bridge performance ABE = Accelerated Bridge Enhancement validated by many applications cost effectiveness proven from to

Strengthening & waterproofing of concrete structures with Ductal UHPFRC

Strengthening & waterproofing of concrete structures with Ductal UHPFRC Laurent Boiron 1, Kerstin Wassmann 2, Eugen Brühwiler 3 1 Ductal - Holcim, Zurich, Switzerland 2 TEC - Holcim, Siggenthal, Switzerland