Update: Internal Curing Implementation in the U.S. Jeff Speck, P.E., FACI Trinity Lightweight

Transcription

1 Update: Internal Curing Implementation in the U.S. Jeff Speck, P.E., FACI Trinity Lightweight

2 Update: Internal Curing Implementation in the U.S. What is Internal Curing? History of Internal Curing Current Status of Internal Curing Implementation

3 What is Internal Curing? Internal curing - process by which the hydration of cement occurs when internal reservoirs provide additional water that is not part of the mixing water Allows curing to be well distributed Allows curing as needed

4 What is Internal Curing? Internal curing reservoirs are usually prewetted fine lightweight aggregate Expanded Shale Clay or Slate (most common) SAPs

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7 How Does Internal Curing Work? Porous lightweight aggregate is prewetted before mixing Water moves from the pores in LWA to the paste when it is needed This movement is due to fact that smaller pores want to remain water filled Conceptual Model of Pores In Concrete Conventional Concrete Internally Cured Concrete

8 How Does Internal Curing Work? Desorption Properties of ESCS Conceptual Model of Pores In Concrete

9 History of Internal Curing Klieger 1957: LWA absorb considerable water during mixing which apparently can transfer to the paste during hydration. Philleo 1991: a way must be found to get curing water into the interior

10 History of Internal Curing UPRR Intermodal Facility (TX), 2005: 250,000 CY of IC low slump pavement

11 History of Internal Curing Hwy 121 (TX), miles of CRCP 21 cracks at 10 mo. V. 52

12 History of Internal Curing Interstate 81 Southbound Bridge, 2008, Whitney Point, NY

13 By Fall, 2010 NYSDOT had 16 IC decks built or under construction History of Internal Curing Syracuse, NY: Court St. Bridge over I-81, 2009 Comparison with Spencer St. Bridge Cicero, NY: Bartell Road Bridge over I-81, 2010 IC HPC span comparison with non-ic HPC span

14 History of Internal Curing Indiana DOT Test Bridges 2010 Comparison to non-ic decks Reduced cracking

15 History of Internal Curing Denver Water 10 MG Water Tank CY monolithic slab pour Contractor requested to use IC everywhere

16 History of Internal Curing Denver Water Lone Tree 10 MG Water Tank 2011

17 History of Internal Curing Illinois Tollway 15 yr, $12B pgm Bridges beginning Year Design Life Stainless Steel Re-bar Jointless Load Limit Increased 80,000 lbs to 120,000 lbs

18 History of Internal Curing Illinois Tollway Bridges 2013 Performance Based Concrete Spec Limits on shrinkage Includes options: IC, SRA or both

19 History of Internal Curing LA DOTD US 80 Bridge, Ada, LA First LA DOTD bridge using Internal Curing in deck Two of seven spans use IC First span used 300 lb of pre-wetted lightweight fine aggregate Placed July 1, 2015 Second span used 150 lb of prewetted lightweight fine aggregate - Placed July 24, 2015

20 History of Internal Curing LTRC Report US 80 Bridge, Ada, LA

21 Implementation of Internal Curing

22 Implementation of Internal Curing New York State More than 50 bridge decks constructed to date using IC New 2018 bridge specifications require IC in all bridge deck concrete Specifies a fixed amount of presoaked fine LWA 30% sand replacement by volume

23 Implementation of Internal Curing Indiana 6 bridge decks constructed using IC in comparison test program As a result, INDOT now requires IC in all bridge deck concrete

24 Implementation of Internal Curing Illinois Tollway Between 2013 and 2015, ITA has built 77 bridge decks using the ITA Performance Spec limiting shrinkage (among other req ts) Allows SRAs, IC with LWAs, or both 49 Mainline Bridges 28 Secondary Bridges over the mainline 4 developed widespread shrinkage cracks in the first 3 years 3 developed isolated shrinkage cracks

25 Implementation of Internal Curing Illinois Tollway Of the 77 ITA Bridge Decks: 44 Used SRAs only 21 Used LWAs only 12 Used both SRAs and LWAs 8 of the 21 using LWAs only developed any cracks. Investigation showed cracking decks contained insufficient volume of (non- ESCS) LWA for effective IC ITA continues to use IC for decks and is testing IC for pavements

26 Implementation of Internal Curing Ohio DOT 3 bridge decks complete Specifying IC for decks currently in development Specifying intermediate grading to optimize combined aggregate grading (reducing gap-grading)

27 Implementation of Internal Curing States in Early Stages of Implementation Illinois 2 decks in 2017 Missouri several decks prior to 2017 Budget woes Oregon statewide road show to prepare industry Florida moving slowly toward implementation Wisconsin RFP for IC study

28 Implementation of Internal Curing Virginia A different approach to IC VDOT has used Lightweight Concrete in bridge decks for more than 30 years VDOT attributes excellent performance to: Low crack potential Lower modulus of elasticity Lower coefficient of thermal expansion Internal Curing

29 Implementation of Internal Curing Local Jurisdictions St. Louis County, MO replacing up to 5 decks per year, requiring IC Lafayette Consolidated Gov t., LA 3 bridges completed to date; the 4 th bridge scheduled this year. Both of these require IC in all Decks Concrete approach pavement Bridge approach slabs Safety barriers Sidewalks on structure

30 Implementation of Internal Curing Other applications of IC (non-bridge) Water Tanks Denver Industrial pavements Industrial floor slabs Concrete pavement patches

31 Implementation of Internal Curing Industrial Pavements 2013

32 Implementation of Internal Curing Industrial Floor Slabs 2014

33 Implementation of Internal Curing Early opening pavement patches Problem: insufficient curing Solution: Internal Curing

34 Implementation of Internal Curing Early opening pavement patches Problem: insufficient curing Solution: Internal Curing Eliminates premature cracking Reduces curling and warping Improves hydration of cement at opening Quick conversion of mix design 60 minutes from start to in the truck

35 Implementation of Internal Curing Water Tanks - Denver Water Lone Tree 10 MG tank 2011 Highlands 8 MG tank IC in all concrete Ashland Two 10 MG tanks IC in floor and roof slabs only Hillcrest Three 15 MG tanks IC in all concrete

36 Implementation of Internal Curing Summary At least 13 State, Regional and Local Highway Departments are using IC for bridge decks Several are using IC in all concrete above the structure In addition, IC is being used in non-bridge projects like water tanks, industrial pavements and floor slabs IC is being used to lower the first cost of CRCP IC is being used in early-opening patches

37 I d like to close with a few words from Dr. Jason Weiss On Internal Curing

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43 What s next? Concrete Pavements 100 year pavements? Better structural performance, longer life Reduced thickness, lower cost It can be concluded that although replacing a portion of the fine aggregate with LWFA for internal curing may increase the initial investment by 2.7%, the strength and durability properties of such mixtures are improved, and pavement constructed using these mixtures will last longer.

44 But what about supply? If IC really takes off, say, in concrete pavements, can the industry handle the demand? A few statistics: ACPA reports 50,000,000 square yards of concrete paving per year (2016) Assuming an average thickness of 8 inches, and Assuming 30% replacement of sand with prewetted fine LWA LWA demand for concrete paving is 1.5 million CY At 100% market penetration!!! ESCSI reports excess capacity in 2017 of more than 2 million CY. You do the math Not to mention

45 Questions?

46 For More Information TrinityLightweight.com ESCSI.org