Lightweight Concrete for PBES Elements Reid W. Castrodale, PhD, PE Director of Engineering The Expanded Shale, Clay and

1. Lightweight Concrete for PBES Elements Reid W. Castrodale, PhD, PEDirector of EngineeringThe Expanded Shale, Clay and Slate Institute

2. LWA is a manufactured product LWA is not a new product LWA is a lighter rock LWA meets aggregate specifications LWA has higher absorption LWA is durable LWA typically costs more than NWA LWA can be used as geotechnical fill for ABC projects Lightweight Aggregate (LWA)

3. LWA is a manufactured product • Raw material is shale, clay or slate • Expands in kiln at 1900 – 2200 deg. F • Gas bubbles form in softened material • Gas bubbles remain after cooling • Clinker is crushed and screened

4. ESCS Manufacturing Facilities 16 plants in the US See www.escsi.org for locations of member companies

5. Stephen Hayde discovered that LWA could be manufactured from shale, clay and slate Observed that some bricks bloated during burning Began developing rotary kiln process in 1908 Patent for rotary kiln process was granted in 1918 First use of LWA was for LWC to build ships in World War I Launching of the USS Selma in June 1919 LWA is not a new product

6. Soil Sand Gravel ESCS Agg. Limestone 1 lb. of each aggregate LWA is a lighter rock Rotary kiln expanded LWA • Specific gravity: 1.3 to 1.6 Normal weight aggregate • Specific gravity: 2.6 to 3.0 Twice the volume for same mass Half the mass for the same volume

7. LWA satisfies typical specifications required of NWA for structural concrete LWA conforms to AASHTO M 195 gradations and other properties Coarse gradations are shown Several gradations of fine aggregate are available ¾" ½" 3/8" 5/16" Fines 7 LWA meets aggregate specs

8. 0.73" 8 LWA has higher absorption Pores in LWA particles reduce density • Result - increased absorption • But pores are not all connected • Does not act like a sponge • Absorption range for LWA in US: 6% to 40% An expanded slate LWA particle soaked in water with fluorescent yellow dye for 180 days, then split open. Absorption at the time of testing was 8% by mass.

9. 9 LWA is durable LWA is a vitrified ceramic material • Hardness equivalent to quartz LWA meets requirements for • LA abrasion test • Freeze-thaw test for aggregate • Soundness tests

10. LWA typically costs more Reasons for increased cost of LWA High-temperature processing Shipping from the manufacturing plant

11. LWA is a high-performance low-density geotechnical fill In-place density: 45 to 60 pcf Angle of internal friction: ≥ 40 Free draining Benefits for ABC projects Reduces settlement Reduces load on walls Fast installation - like 57 stone 11 LWA as geotechnical fill

12. MSE Wall for Pentagon Secured Entrance Ramp LWA as geotechnical fill • Settlement reduced from 15” to 6” (4” actual) • Time for settlement reduced from 180 to 60 days

13. LWC is not a new product LWC is made using same process and equipment LWC weighs less than NWC LWC has enhanced durability LWC typically costs more than NWC LWC can reduce project costs DOT specifications for LWC PBES applications for LWC Lightweight Concrete (LWC)

14. LWC is not a new product Early use of LWC in a bridge project • San Francisco-Oakland Bay Bridge • Upper deck of suspension spans was built using 95 pcf all LWC in 1936 • Lower deck was reconfigured for highway traffic using LWC in 1958 • Both decks are still in service

15. When LWA is used to make LWC Can use same mix design procedures Same batch plants and mixing procedures Same admixtures Same placing and finishing methods Higher absorption of LWA requires prewetting, especially for pumping “Roll-o-meter” for measuring air content Can make self consolidating LWC, i.e., SCC 15 LWC uses same processes

16. LWC weighs less than NWC Specified Density Concrete (SDC) Density ranges shown are approximate Must add allowance for reinforcement (typ. 5 pcf)

17. LWC has enhanced durability Improved bond between aggregate and paste Elastic compatibility Internal curing Reduced cracking tendency Improved resistance to chloride intrusion Enhanced resistance to freezing and thawing Good wear and skid resistance Alkali-silica reactivity (ASR) resistance Increased fire resistance Results in more durable concrete 17

18. Sand LWC & All LWC did not crack during test period, but were then forced to crack Results for one type of LWA shown SLWC IC NWC ALWC Cracking Tendency of LWC Spring - 73 deg. SLWC NWC IC ALWC Summer - 95 deg. Byard & Schindler, “Cracking Tendency of Lightweight Concrete,” ESCSI, December 2010

19. LWC typically costs more • Additional cost of LWC depends on • Cost of LWA • Cost of NWA being replaced • Shipping cost for both aggregates • Familiarity of contractor and concrete supplier with LWC • LWC is commonly used for building construction in most major metropolitan areas

20. Range of cost for sand LWC bridge deck Cost / SF assumes 9 in. thick deck (average) FHWA reports that average bridge unit cost in 2010 ranged from about $55 to over $500 / SF LWC typically costs more

21. Range of cost for sand LWC bridge girders Assume $60 / CY cost premium for sand LWC Girder spacing assumed to be 10 ft LWC typically costs more

22. For precast elements, cost offset by other savings Improved structural efficiency Longer spans or fewer girders Reduced seismic loads Reduced foundation loads Reduced piece weight Handling, shipping and erection Improved safety Increased piece size Fewer pieces = faster erection Fewer truck loads in congested areas LWC can reduce project costs

23. LWC can reduce project costs Example: 3000 ft long dual bridges with 150 ft NCDOT Mod BT-74 girders • Cost premium for sand LWC girder = $1,024 • Assuming $30 / CY = $6.83 / LF • Cost reduction for sand LWC girder = $1,201 • Shipping to site (~300 mi & 3 states) = $811 • NWC girder = 69 t; LWC girder = 58 t, or 11 t less • Drop 4 strands / girder @ $0.65 / LF ea. = $390 • Net savings by using sand LWC girder $177 • For 280 girders, total savings = $49,560

24. LWC can reduce project costs Example continued: • Cost premium for all LWC deck = $400,000 • Assuming $35 / CY • Cost reduction for less girder lines = $1,080,000 • Drop 1 girder line for ea. dual @ $180 / LF • Total net savings (3.8%) $729,560 • Potential sources of savings not considered • Girder handling, bearings, substructure & foundation • Interior bent reaction reduced 773 kips (25%) • Reduced deck cracking and permeability

25. Sand LWC for Bridge Decks TennDOT Standard Specifications NCDOT, UDOT, etc., standard special provisions Other states have project special provisions All LWC NCDOT special provisions Sand LWC for Girders GDOT special provisions (10 ksi at 120 pcf) VDOT special provisions (8 ksi at 125 pcf) DOT Specifications for LWC

26. GDOT special provisions - 10 ksi sand LWC girders Maximum air-dry density is 120 pcf Size of LW coarse aggregate = ½ in. Minimum cement factor = 650 lbs/cy Maximum water-cement ratio = 0.330 Slump acceptance limits = 4½ ± 2½ in. Entrained air acceptance limit = 5 ± 1½ % Max. chloride permeability = 3,000 coulombs Same as for NW HPC, except density & aggr. size DOT Specifications for LWC

27. Internal Curing with LWA Prewetted LWA delivers curing moisture in NWC • Replace a fraction of the NW sand with the same volume of prewetted fine LWA Water absorbed in the prewetted fine LWA • Does not affect mix water or w/cm • Released over time into the concrete • Benefits of internal curing (IC) • Increased cement hydration & reaction of SCMs • Increased compressive strength & permeability • Reduced shrinkage & cracking

28. With internal curing Without internal curing One day after placement Internal Curing with LWA Test pour for 10 M gallon water tank base slab • Internal Curing vs. No Internal Curing • Highlands Ranch, CO – 92F ambient, 20% RH • No conventional curing

29. Internal Curing with LWA Indiana DOT Test Slabs - 2010 • IC slab: no cracks after 1 yr • Slab without IC cracked after a few months +75% +20% +25% Resistivity Compressive Strength

30. Actual and potential applications Precast foundation elements Precast pile & pier caps Precast columns Precast full-depth deck slabs Cored slabs & Box beams NEXT beams & Deck girders Full-span bridge replacement units with precast deck Bridges installed with SPMTs PBES Applications for LWC

31. PBES Applications for LWC • Sand LWC & Specified Density Concrete • Use for any precast or prestressed conc. elements • All LWC • Use for any precast concrete elements • No tests available for prestressed conc. elements These are fresh densities for concrete up to about 6 ksi Add 5 pcf allowance for reinforcement

32. Edison Bridges, FL Project did not use LWC Precast columns • Max wt = 45 tons @ 150 pcf • Max wt = 37 tons @ 125 pcf • Using 128 pcf SDC could have eliminated pedestal for tall columns Precast caps • Max wt = 78 tons @ 150 pcf • Max wt = 65 tons @ 125 pcf

33. Woodrow Wilson Br, VA/DC/MD Deck replacement with full-depth precast deck panels in 1983 Sand LWC was used for panels • Allowed thicker deck • Lower shipping cost & erection loads • Allowed roadway widening with no super- or substructure strengthening • Reduced project cost and duration Sand LWC deck performed well until bridge was recently replaced to improve traffic capacity

34. NEXT D Beams 16% 8 ft 10 ft 12 ft 8 ft 10 ft 12 ft • Compare section weights for NEXT 36 D • 12 ft width not used to limit weight of NWC section • Max. span charts are provided for sandLWC • 16% reduction in weight for same width sections • 12 ftLWC is lighter than 10 ft NWC NEXT 36 D

35. Deck Girders, NY • Precast deck girder • Project did not use LWC • 41” deep deck girders with 5 ft top flange • 87.4 ft long girders NWC density was obtained from girder fabricator Specified concrete compressive strength = 10,000 psi

36. I-95 in Richmond, VA Prefabricated full-span units • First project completed in 2002 • Steel girders and sand LWC deck Max. precast unit weight for current project Deck densities do not include reinforcement allowance

37. Scott Rd / Montour Run, PA Prefabricated full-span bridge • Designed as 2 pieces with NWC filled grid deck • Redesigned by contractor with sand LWCin grid deck • Allowed contractor build & lift bridge as 1 piece • Eliminated closure pour by using LWC

38. Ben Sawyer Bridge, SC Replace swing span and approaches • Swing span constructed off-site and floated in • Approach spans constructed off-line and slid in • Swing span and approaches have sand LWCdecks

39. Graves Ave. over I-4, FL Complete span replaced using SPMTs • Project did not use LWC Comparison of weight for NWC and sand LWC • Appendix C in FHWA “Manual on Use of SPMTs …” Comparison with all LWC deck is not in Manual

40. Rte 33 Bridges, West Pt, VA Bridges across Mattaponi and Pumunkey Rivers were completed in 2006 and 2007 Each bridge has two 200'-240'-240'-200' spliced units with haunched pier segments Sand LWC girders and decks reduced foundation loads on poor soils

41. Benicia-Martinez Bridge, CA I-680 over the Carquinez Strait near San Francisco Cast-in-place box girder • 82-ft wide deck • 658 ft maximum spans Sand LWC was used for the box girder section • Full length of 6,500 ft long bridge except for pier segments • Reduced seismic forces, foundations & cost

42. LWC can be used to achieve both accelerated construction and longer-life structures For more information on LWA and LWC • Contact Reid Castrodale: rcastrodale@escsi.org • Or visit: www.escsi.org