Presentation on theme: "International Compaction & Compaction Testing Update www.ticservicegroup.com.au Feb 2010 Opportunity - Increase the life of infrastructure (some experts."— Presentation transcript:
International Compaction & Compaction Testing Update Feb 2010 Opportunity - Increase the life of infrastructure (some experts say double) - Cut construction costs
2 Overview Issues with Compaction Testing The Numbers – Why is Compaction Important Compaction problem being Solved Measuring Compaction: Fundamental Changes What’s Happening in the USA & Europe Intelligent Compaction – What is It? Benefits Starting Point Case study Writing Modulus into the Specifications Questions
Issues with Compaction Testing Current practices not delivering the best quality outcome for Victoria’s road network –Quality e.g. results can be ‘massaged’ –Quantity e.g. testing capability not available when required –Knowledge & technical skills 3
4 The Numbers – USA Why is Compaction Important “I’ve studied where we spend money in the U.S. to fix our infrastructure, and a lot of the cost can be tied directly to the performance of compacted materials underneath our civil infrastructure,” –Prof David White, Iowa State University, Ames and Director of the school’s Earthworks Engineering Research Center “At the very least, improper compaction costs taxpayers $1 billion a year in wasted diesel fuel, construction labor, equipment maintenance, rework, rehabilitation, litigation and other inefficiencies” White adds. White estimates that the stiffness of soil, sand and aggregate—the building blocks of road embankments, building pads and bridge abutments—cost the public up to $100 billion a year if not built up properly. “There is something like $50 billion a year for vehicle maintenance because of poor road conditions,” he says. “Those poor road conditions are tied to what they are sitting on.”
5 Compaction problem being Solved An Intelligent Compaction (IC) roller can test the entire range of the project, and its sensors can penetrate deeper into the fill. Handheld testing devices, e.g. nuclear-density gauge, can only measure a limited amount of space at a time—covering only a small percentage of the project’s footprint. Compaction Uniformity to specification
6 Measuring Compaction: Fundamental Changes From Density to Stiffness Stiffness is the basis for calculating an even more fundamental material property, "modulus," which experts agree is the most accurate and independent means for judging deformation and, thus, a material's level of compaction. * Stiffness is loosely defined as a measure of a material's ability to resist deformation under load Density Stiffness*
7 Speaking of Intelligent Compaction (IC) “We are trying to measure and predict how [roads] will behave when a truck runs over the material. The [IC] roller is really a better simulation of how well that material will behave over the long term, over the itty- bitty, nuclear-density gauge.” –John Siekmeier, a senior research engineer for the Minnesota Dept. of Transportation.
8 Old Method New Method After Compaction is Complete Provides little or no “on the fly” feedback Compaction Control Density Verified using a compaction control device (inc DCP, GeoGauge and Light Weight Deflectometer eg Zorn ZFG2000) In-situ test methods Measurement Unit & When Nuclear Gauge Stiffness Ongoing measurement & feedback to operator Intelligent Compaction Compaction Method
Intelligent Compaction – What is It? 9
10 Intelligent Compaction – What is It? A stiffness measuring and recording system A GPS-based documentation system that is capable of producing colour- coded mapping of pertinent information during the compaction process An onboard measuring device that allows roller operators to see whether they are overcompacting (and destroying the material), undercompacting or right on target. As operators make multiple passes with the roller, a computer screen shows which areas need attention. An automatic feedback system that is capable of varying compactive effort based on measured stiffness Puts roller operators directly in charge of ground control, enabling them to inspect their own work before turning it over to the owner for verification and payment Calibrated and verified using a compaction control device measuring elastic modulus e.g. Zorn ZFG 2000 “Intelligent compaction” (IC) is the ability of a soil or asphalt roller to measure the stiffness or solidity of the underlying material and instruct the operator what to do next
11 LWD ZFG 2000 Measuring Modulus Export 2003 – 2008 –China 250 –USA 55 (mostly purchased for DOT research) –Australia 8 –Europe 680 Germany 920 Additional 1200 units from competitors Not a flash in the pan e.g.
12 IC Benefits - Minnesota DOT study Increase the Life of Infrastructure (some experts say double) –European experience, says the Minnesota DOT's research, "clearly demonstrates that greater compaction uniformity increases the useable life of pavement systems, and similar benefits occur with embankment compaction and buried-structure backfill." –Reduction in highway repair costs Increased Compaction Uniformity –Produce more uniform compaction, provided soils are within the moisture-content range necessary to achieve the target compaction –Identification of non-compactable areas –Eliminate over-compaction and under-compaction, applying additional effort only if necessary –Improved density of pavement materials –Improved depth of compaction
13 IC Benefits - Minnesota DOT study Cut Construction Costs –Maximum productivity of the compaction process –Minimising over compaction reduces costs - wasted diesel fuel, construction labor, equipment maintenance, rework etc –Reduce manual spot checks required for confirmation, since the IC roller automatically checks virtually every spot on the jobsite for compaction results (Example: 75% reduction in QA testing (Sweden) - Briaud and Seo, Texas A&M, 2004) Better Documentation & Pavement Management –Complete documentation for every lift with measurement and recording of materials stiffness values –Full documentation of compaction results may be the basis on which states potentially may award bonuses or assess penalties for compaction-work quality Construction Verification of Design Values –“Comprehensive data on the mechanistic properties of all materials compacted, permitting links between design, construction and performance. For example, the data record produced by the compactor, which covers all areas and all lifts, will be essential to the pavement- management process. Long-term performance may be correlated with the properties produced during construction.“
14 What’s Happening in the USA Objective - save billions of dollars a year in potholed roads, cracked bridges, broken dams and blown-out tires –Increase the life of infrastructure (some experts say double) –Cut construction costs The construction industry is investing millions of dollars a year to validate IC and stiffness / modulus testing as generally accepted practice. –Example - TPF-5(128), a three-year, $750,000 pooled fund between Georgia, Indiana, Kansas, Maryland, Minnesota, Mississippi, North Dakota, New York, Pennsylvania, Texas, Virginia and Wisconsin. –Visit Improved Roads –Higher density and better uniformity –Pavement service life increased –Reduced pavement distress. Reduction of Congestion –Maintenance and repair activities delayed / eliminated. –Less traffic disruption due to construction activity. Increased Safety –Pavements are smoother and safer –Less construction activity eliminates dangerous road hazards USA started from same base as Australia (Density testing using Nuclear Gauge) FHWA Strategic Plan Rationale
15 Starting Point in 2004 Federal Highway Administration (FHWA) –“Europeans have over 10 years experience with Intelligent Compaction for soils and asphalt. Once our Scan Team saw it, we knew we wanted it in the US. It was a matter of making our case to DOTs and industry…” –160-page study — "Intelligent Compaction: Strategic Plan" — which details the technology and its potential benefits, identifies research needs and presents a national implementation plan.
23 Writing Modulus into the Specifications (USA) Government agencies including Federal Highway Administration are working to write specifications so they can let contracts enabling IC. Minnesota is the only state to do so, though its specification is still under regular revision and is careful not to mandate IC due to the high up-front cost to contractors. Nationwide, “all the cards are in place” to implement IC, “I’m really impressed by this.” –Mike Adams, a geotechnical engineer in Federal Highway Administration’s McLean, Va., research office At least a dozen states are testing IC as research spans the U.S. Current/Future Standards (2005) EU Performance Related Specifications Mn/DOT DCP Specifications Aggregate and Granular ASTM DCP Test Method ASTM GeoGauge Test Method ASTM LWD Test Method (draft) FHWA GeoGauge Pooled Fund FHWA CRREL Subgrade Performance Pooled Fund NCHRP NDT QC/QA for Flexible Pavements Proposed DCP/LWD Specification Pooled Fund Proposed Intelligent Compaction Pooled Fund AASHTO M-E Pavement Design A change in specifications from density-based to stiffness-based is happening
24 Measuring Compaction: Fundamental Changes from Density to Stiffness * Stiffness is loosely defined as a measure of a material's ability to resist deformation under load Density Stiffness*
25 Thank You Can you afford to delay action further? –Longer lasting roads built at lower cost What role will stiffness / modulus acceptance criteria and quality control / quality assurance (QA / QC) procedures have within VicRoads (and other state authorities) in the future? How will it be evaluated and rolled out?