Preserved Wood for Marine Uses Presented by Dallin Brooks, WWPI Executive Director
Western Wood Preservers Institute Represents preservative treated wood producers, chemical manufacturers and others serving the industry throughout western North America Mission Increase awareness of the proper use of treated wood products by providing information to: Homeowners Builders Architects, Specifiers Bldg. Material Dealers Code Officials Ports and Marinas 2
Remember: All materials have enemies Concrete Steel Wood Auger cast piles
Concrete issues Spalling Soil displacement Changing ph Disposal Expensive
Steel issues Corrosion Installation alignment Bending Failure Expensive
Wood issues Marine Borers Preservative Movement Failure
Wood advantages Proven Economical Long-lasting Strong, durable, resilient Availability in emergencies Domestically often locally produced Natural appearance Rugged handling On-site modification Renewable Low energy production Carbon storage Minimal on-site waste
Hurricane resistance Home in Pearlington, MS Reportedly only home to survive flooding from Hurricane Katrina Water came within inches of CCA pile girders Similarly constructed beach houses meeting wind load standards from New Jersey to Mississippi
Hurricane resistance Coastal home in Galveston, Texas Built on CCA pilings Survived Hurricane Ike, storm surge
Hurricane resistance Homes in Nags Head, NC Built on wood piles Survived tropical storms, depressions in 2009
History of wood pilings First used 6,000 years ago Neolithic tribes in Switzerland Placed logs vertically into soft soil for structural support Homes built on piles to protect against wildlife Evidence of structures still seen today
History of wood pilings Roman bridges Tiber River Bridge, built in 642 BC Span lasted more than 700 years Roman roads, aqueducts Supported on timber piles Still in good condition 1,900 years later
How strong is today s wood? Wood fiber has not changed significantly over time Little difference in old wood vs. new wood Confirmed by testing
Bending tests Horizontal force applied by cable at tip of the timber pile Results: Bending stresses could be 36% to 53% higher than currently allowed
Full-scale testing Tests on full size pieces conducted in 1999 and 2000 Intended to develop design stresses Also tested for compression strength Conducted by EDM International in Fort Collins, CO
Piling design values Normal load duration, wet use conditions Pounds per square in. 1 Property Southern Pine 2 Douglas fir 3 Compression Parallel to Grain, F c 1,200 1,250 Extreme Fiber in Bending, F b 2,400 2,450 Horizontal Shear, F v 110 115 Compression Perpendicular to Grain, F c 250 230 Modulus of Elasticity, E 1,500,000 1,500,000 Source: Values are from ANSI/AF&PA NDS-2005, National Design Specification for Wood Construction, Supplement for Timber Poles and Piles. 1 A form factor for bending members of circular cross section is incorporated in the allowable unit stresses for extreme fiber in bending listed in the table, for pile clusters. 2 Southern pine values apply to longleaf, slash, loblolly and shortleaf pine. 3 Douglas fir values apply to Pacific Coast Douglas fir.
Standing up to pressure Timber pilings well suited to withstand pressure of being driven into soil Foundation supports Marine pilings
Timber pilings - foundation Resists attack from alkaline, acidic soil Corrosion protection not required Unaffected by electrolysis from stray electrical current Takes advantage of plentiful, renewable domestic resource
Timber pilings - foundation Installs with readily available equipment Wood less noisy than other driven piling Lowest cost per ton of load carrying capacity of any deep foundation material
Piling durability FHWA Conclusion. Treated wood pilings submerged in groundwater will last indefinitely Fully embedded, treated, concrete capped foundation piles partially above the groundwater will last 100 years or longer
Load carrying basics Piles typically used with difficult conditions, weak sub-surface soils Pile transmit forces to a lower stratum that has sufficient bearing to support structures, applied loads End-bearing piles primarily transfer loads through the tip. Friction piles primarily transfer loads through tangential friction. Natural taper increases the friction reaction, recognized in design Butt Tip
Load tests Many tests conducted on load carrying capabilities Concrete block testing Results show actual capacity exceed design values with wide margin of safety Test procedure: ASTM D1143
Test data vs. design loads Southern Pine Piles PILE SIZE TEST DESIGN LOAD NO. OF LOAD LOCATION Length Butt Tips (tons) TESTS (tons) Donaldsonville, LA 80 and up Class B 140 & 150 1 60 Mobile, AL 60 14 9.5 140 65 Virginia Beach, VA 76 Class A 100 50 Charleston, SC 75.8 14 8.25 118 1 50 South Pierce, FL 70 14 7 100 50 Port Arthur, TX 65 14-15 8-9 150 5 75 Chicago, IL 43.7-44.3 Class B 80 & 150 2 40 Chicago, IL 43.5-48.2 Class A 100 & 142 2 40 Portsmouth, VA 86 Class A 100 1 4 50 Virginia Beach, VA 40 100 1 1 50 Scotland, LA 53 15 8 100 12 40 1 Not to failure Source: AWPI Data
Foundation piling typical sizes Specified Tip Circumferences with Corresponding Minimum Butt Circumferences A (from ASTM D25 -- Table X1.5) (Approximate Diameters in Brackets) Required Minimum Tip Circumference, In 16(5) 19(6) 22(7) 25(8) 28(9) 31(10) 35(11) 38(12) Length (ft) Minimum Circumferences 3 ft from Butt, in. 20 19(6.0) 22(7.0) 25(8.0) 28(8.9) 31(9.9) 34(10.8) 38(12.1) 41(13.0) 25 20(6.4) 23(7.3) 26(8.3) 29(9.2) 32(10.2) 35(11.1) 39(12.4) 42(13.4) 30 21(6.7) 24(7.6) 27(8.6) 30(9.5) 33(10.5) 36(11.4) 40(12.7) 43(13.7) 35 22(7.0) 25(8.0) 28(8.9) 31(9.9) 34(10.8) 37(11.8) 41(13.0) 44(14.0) 40 26(8.3) 29(9.2) 32(10.2) 35(11.1) 38(12.1) 42(13.4) 45(14.3) 45 27(8.6) 30(9.5) 33(10.5) 36(11.1) 39(12.4) 43(13.7) 46(14.6) 50 31(9.9) 34(10.8) 37(11.8) 40(12.7) 44(14.0) 47(15.0) 55 32(10.2) 35(11.1) 38(12.1) 41(13.0) 45(14.3) 48(15.3) 60 33(10.5) 36(11.4) 39(12.4) 42(13.4) 46(14.6) 49(15.6) 65 34(10.8) 37(11.8) 40(12.7) 43(13.7) 47(15.0) 50(15.9) 70 35(11.1) 38(12.1) 41(13.6) 44(14.0) 48(15.3) 51(16.2) 75 36(11.4) 39(12.4) 42(13.4) 45(14.3) 49(15.6) 52(16.6) 80 37(11.8) 40(12.7) 43(13.7) 46(14.6) 50(15.9) 53(16.9) 85 38(12.1) 41(13.0) 44(14.0) 47(15.0) 51(16.2) 54(17.2) 90 39(12.4) 42(13.4) 45(14.3) 48(15.3) 52(16.6) 55(17.5) A Piles purchased as 8-in. and natural taper have a required minimum tip circumference of 25 in. and are available in lengths of 20 to 45 ft.
Wood treating yesterday, today Modern wood preserving began in England in 1832 The first U.S. treating plant built in 1848 Today s plants have latest in environmental protection features Drip pads protected from leakage with liners below the concrete Drippage is recaptured and recycled.
Purpose of treating Protection against Decay Marine organisms Mollusks Shipworms Boring Clams Crustaceans Limnoria (gribbles) Sphaeroma Chelura
Treatment goal Piling cannot be 100% penetrated, usually because of heartwood content Inject preservative shell around wood, providing protective envelope of treatment Penetration and retention requirements must be met Sapwood Heartwood
Treating standards American Wood Protection Assn. (AWPA) American Society for Testing and Materials (ASTM)
AWPA Marine (Salt Water) Use Categories
Treating requirements AWPA Use Category AWPA T1-13 Section E AWPA T1-13 Section G Marine AWPA Reference Type Penetration Assay Zone(s) Retention CCA Pcf. Retention ACZA Pcf. Retention Creosote Pcf. UC4C Foundation SYP 2.5 Dfir 0.75 0.0-2.0 0.80 0.80 12.0-17.0 UC4C Land & Freshwater SYP 3.0 Dfir 0.75 0.0-3.0 0.80 0.80 12.0-17.0 UC5A Marine - Long Island, NY, & North SYP 4.0 Dfir 1.0 0.0-0.5 0.5-2.0 1.5 0.9 1.5 0.9 25.0 UC5B & 5C Marine - Long Island, NY, & South SYP 4.0 Dfir 1.0 0.0-0.5 0.5-2.0 2.5 1.5 2.5 1.5 25.0 UC5B & 5C Dual treatment CCA SYP 4.0 Dfir 1.0 0.0-1.0 1.0 1.0 25.0 UC5B & 5C Dual Treatment Creo SYP 4.0 Dfir 1.0 0.0-1.0 20 20 25.0
Assuring quality preservation AWPA U1 Treatment per Label T1-13 Section E T1-13 Section G Marine A2, A9 Analysis A3 Penetration Customer requirements Treating company BMPs are available for foundation and marine applications
Environmental protection BMPs Risk assessment model Wraps, Polyurea coatings
CCA Piling Human Health Risk Assessment Examined risks to workers, children Conducted by Gradient Corp. No documented cases of adverse health effects Potential health effects within EPA s risk limits
CCA Piling Human Health Risk Assessment Arsenic complex present on surface and in soil; arsenic in piling bonded with wood Studies of carpenters, treating plant workers show no increased risk. Amount of arsenic complex potentially taken into body is at least 14 times less than that amount from food and drinking water
Piling Life Cycle Assessment Review of environmental impacts of treated wood, concrete, galvanized steel and plastic pilings Conducted under ISO 14044 standards
Piling Life Cycle Assessment Treated wood showed lower impacts in all six categories assessed
Thank you Dallin Brooks Executive Director dallin@wwpinstitute.org 360-693-9958