“THERMAL CONTROL PLAN FOR WIND TURBINE FOUNDATIONS” Mr Quoc Tuan TRINH Deputy Manager, Technical Dept FECON (+84) 904 487 486 tuantq1@fecon com vn Hanoi, 31st July 2021 VIETNAM CONCRETE ASSOCIATIO[.]
VIETNAM CONCRETE ASSOCIATION – 3rd WEBMINAR Hanoi, 31st July 2021 “THERMAL CONTROL PLAN FOR WIND TURBINE FOUNDATIONS” Mr Quoc-Tuan TRINH Deputy Manager, Technical Dept FECON (+84) 904.487.486 tuantq1@fecon.com.vn 1 Introduction Main concerns of Mass Concrete Thermal Control Plan Application to Wind Turbine Foundations Conclusions WHO WE ARE? TOWARD THE VISION 2025 FECON is striving to become a leading EPC HANOI in Infrastructure and Industrial Construction Headquarters HOCHIMINH city • Representative Office • FECON South JSC Hanoi Myanmar HOANG SA ISLANDS PHNOMPENH, CAMBODIA Cambodia HCM city • Representative Office TRUONG SA ISLANDS YANGOON, MYANMAR FROM THE START POINT Founded in 2004, FECON has become one of the most prestigious contractor in Foundation and Underground FECON.COM.VN +800 PROJECTS COMPLETED • FECON Rainbow Co., • FECON Trung Chinh JSC HUMAN RESOURCES TOTAL 1.800 EMPLOYEES FECON CORPORATION • 08 PMU • 41 PM • 81 SM • 383 engineers 15 SUBSIDIARIES 12% 38% 50% Manager Worker Engineer and back office staff FECON.COM.VN CIVIL CONSTRUCTION MAIN BUSINESS • CONSTRUCTION • INVESTMENT UNDERGROUND & INFRASTRUCTURE SOIL IMPROVEMENT & FOUNDATION CONSTRUCTION FECON.COM.VN RENEWABLE ENERGY INFRASTRUCTURE MAIN BUSINESS • CONSTRUCTION • INVESTMENT URBAN & INDUSTRIAL ZONE DEVELOPMENT TRANSPORT INFRASTRUCTURE INVESTMENT FECON.COM.VN SUPPORTING BUSINESS MACHINERY SUPPLY FECON.COM.VN MINING AND CONSTRUCTION MATERIAL SUPPLY HUMAN RESOURCE SUPPLY FECON’S EXPERIENCES IN WIND ENERGY (period 2020-2021) Onshore Wind Power Plant Near-shore Wind Power Plant FECON - B.O.P CONTRACTOR (ENGINEERING AND CONSTRUCTION) Note: BOP = Balance of Plant ONSHORE WF THAI HOA – BINH THUAN – 90 MW ONSHORE WF BT QUANG BINH – 250 MW ONSHORE WF LAC HOA & HOA DONG – SOC TRANG – 60 MW ONSHORE WF QUOC VINH – SOC TRANG – 30 MW NEARSHORE V1-3 – TRA VINH – 50 MW TOTAL OF 112 WIND TURBINE FOUNDATIONS - 480 MW Offshore Wind Power Plant (in development) WIND TURBINE FOUNDATIONS – MASS CONCRETE STRUCTURE ? • Bigger and bigger wind turbine generators (WTG) are being used • Huge overturning moment is applied to the Foundation General Information: Foundation concrete class: • Turbine: 4-5 MW • Slab: C30/37 or C35/45 (~ 700-1000 m3) • Hub-Height: > 120 (m) • Pedestal: C45/55 • Swept: > 150 (m) Mass-Concrete Classification: • Foundation: shallow or piled • Vietnam: least dimension > 2m • Shape: Conical • Japan / Korea: least dimension > 0.8-1.0 m • Bottom Diameter: 18 - 26.5 (m) • • Top Diameter: ~ 7.0 (m) • Total thickness: 3.4 - 4.0 (m) ACI: any concrete volume with dimensions large enough to require that measures to be taken … WTG Foundations must all be treated as mass concrete! Foundations are made bigger, heavier to withstand the increasing loads A typical shallow WTG Foundation Introduction Main concerns of Mass Concrete Thermal Control Plan Application to Wind Turbine Foundations Conclusions 10 Application to Wind Turbine Foundations Project Specifications Foundation dimensions Onshore or Offshore Concrete provider Water / Ice availability Project Schedule Weather Assessment of Inputs Thermal Control Plan Output Repeat if NOT OK • What is the mix design ? • Cast in one time or multiple times ? • Using pre-cooling or not ? • Using cooling pipe or not ? • What is the curing method ? • Method Statement, Working Drawings, ITP … for Mass Concrete, where Tmax and ΔT are predicted Trial & Error Output If OK Full-scale Mockup Implementation 24 Application to Wind Turbine Foundations D=26m, T = 3.6m Foundation dimensions Project Tmax < 80 ⁰C Specifications Onshore Onshore or Offshore Mix design Concrete not optimized provider Water / Ice Example No water PROJECT A availability Project Schedule Weather Hot Assessment of Inputs Not tight Thermal Control Plan Output Repeat if NOT OK Trial & Error Output If OK Full-scale Mockup Implementation 25 Application to Wind Turbine Foundations D=26m, T = 3.6m Foundation dimensions Project Tmax < 80 ⁰C Specifications Onshore Onshore or Offshore Mix design Concrete not optimized provider Water / Ice Example No water PROJECT A availability Project Schedule Weather Hot Assessment of Inputs Not tight Thermal Control Plan Try #1 Repeat if NOT OK • Mix design: OPC • Cast: one time • Pre-cooling: placing temp ≤ 30 ⁰C • Cooling pipe: No • Curing compound: Antisol type E Trial & Error Output If OK Full-scale Mockup Implementation 26 Application to Wind Turbine Foundations D=26m, T = 3.6m Foundation dimensions Project Tmax < 80 ⁰C Specifications Onshore Onshore or Offshore Mix design Concrete not optimized provider Water / Ice Example No water PROJECT A availability Project Schedule Weather Hot Assessment of Inputs Not tight Thermal Control Plan Try #1 Repeat as NOT OK • Mix design: OPC • Cast: one time • Pre-cooling: placing temp ≤ 30 ⁰C • Cooling pipe: No • Curing compound: Antisol type E Trial & Error Tmax > 80 ⁰C If OK Full-scale Mockup Implementation 27 Application to Wind Turbine Foundations D=26m, T = 3.6m Foundation dimensions Project Tmax < 80 ⁰C Specifications Onshore Onshore or Offshore Mix design Concrete not optimized provider Water / Ice Example No water PROJECT A availability Project Schedule Weather Hot Assessment of Inputs Not tight Thermal Control Plan Try #2 Repeat if NOT OK • Mix: using Fly-ash or GGBF S95 • Cast: one time • Pre-cooling: placing temp ≤ 30 ⁰ C • Cooling pipe: No • Curing compound: Antisol type E Trial & Error Output If OK Full-scale Mockup Implementation 28 Application to Wind Turbine Foundations D=26m, T = 3.6m Foundation dimensions Project Tmax < 80 ⁰C Specifications Onshore Onshore or Offshore Mix design Concrete not optimized provider Water / Ice No water PROJECT A availability Project Schedule Not tight Example Weather Hot Assessment of Inputs Thermal Control Plan Try #2 • Mix: using Fly-ash or GGBF S95 • Cast: one time • Pre-cooling: placing temp ≤ 30 ⁰ C • Cooling pipe: No • Curing compound: Antisol type E Trial & Error Semi-Mockup 1x1x1 (m) GGBF 50% replacement If OK Flyash 30% replacement Full-scale Mockup Difficult to control GGBF S95 Implementation Mix with Fly-ash performs better! 29 Application to Wind Turbine Foundations Project Specifications Foundation dimensions Onshore or Offshore Concrete provider Example Water / Ice availability Project Schedule PROJECT A Weather Assessment of Inputs Thermal Control Plan Output • Mix: using Fly-ash • Cast: one time • Pre-cooling: placing temp ≤ 30 ⁰ C • Cooling pipe: No • Curing compound: Antisol type E • Method Statement, Working Drawings, ITP … for Mass Concrete, where Tmax and ΔT are predicted Trial & Error Output If OK Full-scale Mockup Implementation 30 Application to Wind Turbine Foundations Flyash 30% replacement – Evolution of Core TemperatureExample PROJECT A Tmax = 78-79 ⁰C Core Concrete block Sub soil Full scale Mockup 3.6x3.6x3.6 (m) Good agreement with prediction! Little contingency (peak temp so close to Tmax) Tmax < 80 ⁰C → pass! Recommendation from OE: cast the pedestal later! 31 Application to Wind Turbine Foundations Project Specifications Foundation dimensions Onshore or Offshore Concrete provider Example Water / Ice availability Project Schedule PROJECT A Weather Assessment of Inputs Thermal Control Plan Output • Mix: using Fly-ash • Cast: Slab first, then Pedestal • Pre-cooling: placing temp ≤ 30 ⁰ C • Cooling pipe: No • Curing compound: Antisol type E • Method Statement, Working Drawings, ITP … for Mass Concrete, where Tmax and ΔT are predicted Trial & Error Output Full-scale Mockup 2nd cast (21 days after 1st cast) 1st cast Implementation 32 Application to Wind Turbine Foundations Example PROJECT A Evolution of Core Temperature of the 1st WTG Foundation Tmax = ~73 ⁰C Construction of the 1st WTG Foundation: + Max lift height: 2.95 (m) (instead of 3.6 m) + Casting time: ~ 10 (h) (~ 800 m3) + Placing temperature: ~ 29 ⁰C + Ambient temperature: ~ 27 ⁰C 33 Application to Wind Turbine Foundations Example Tougher input conditions: PROJECT B + Very tight schedule! + Max lift height: 3.4 m (pedestal included) Effectiveness of Cooling Pipes: + Concrete C35/45 MS (cement ~ 400 kg/m3) + Allowable Tmax = 70 ⁰C + Ambient temperature: ~ 33 ⁰C Thermal Control Plan must combine all available pre-cooling & post-cooling measures: w/o cooling pipe with cooling pipe + Pre-cooled concrete + layers of cooling pipes, D27 @700 + Icy circulating water, 17 litters/min Max temp < 65 ⁰C, foundations can be backfilled after days 34 Introduction Main concerns of Mass Concrete Thermal Control Plan Application to Wind Turbine Foundations Conclusions 35 Conclusions Method of controlling mass concrete temperature range from relatively simple to complex, and from inexpensive to costly: To reduce ∆T: Surface Insulation To reduce Tmax: Pre-Cooling of Concrete (spray aggregates, icy water, shelter etc ) Use lower cement content (mix with GGBF / Fly-ash) or use Low HeatGeneration Cement Placing concrete in lifts Post-Cooling of Concrete (cooling pipes) 36 Conclusions Without proper preparations and correct measures, strength & durability of the massive concrete structure shall be compromised! No unique solution for every mass-concrete project Contractors can use one or multiple measures to optimize the cost 37 Mr Quoc-Tuan TRINH Deputy Manager, Technical Dept FECON (+84) 904.487.486 tuantq1@fecon.com.vn ... Main concerns of Mass Concrete Thermal Control Plan Application to Wind Turbine Foundations Conclusions 17 Thermal Control Plan To reduce thermal stresses and control cracking, the general measures... V 1-3 – TRA VINH – 50 MW TOTAL OF 112 WIND TURBINE FOUNDATIONS - 480 MW Offshore Wind Power Plant (in development) WIND TURBINE FOUNDATIONS – MASS CONCRETE STRUCTURE ? • Bigger and bigger wind. .. Above pre-cooling measures can reduce the placing temperature by 5-1 0 ⁰C Applied in most of Fecon? ??s Wind Projects as they are relatively simple & not costly 20 Thermal Control Plan Pre-cooling