Presentation on theme: "29 th Annual Airport Conference February 28 – March 2, 2006 Hershey, Pennsylvania An IPRF Project Overview of Acceptance Criteria Based on Innovative Testing."— Presentation transcript:
29 th Annual Airport Conference February 28 – March 2, 2006 Hershey, Pennsylvania An IPRF Project Overview of Acceptance Criteria Based on Innovative Testing of Concrete Pavements Soheil Nazarian, PhD, P.E. University of Texas at El Paso Wayne Seiler, PhD, P.E. All About Pavements, Inc.
Overview Contractor and Technical Panel Goals, Limitation, and Objectives Selected Technologies Lab versus Field Process Summary Research Conclusions Recommendations Products
Contractor –University of Texas at El Paso –University of Illinois Chicago –Applied Pavement Technology –US Army Engineer Research and Development Center Principal Investigator – Dr. Soheil Nazarian
Technical Panel Panel Chair: Mr. Jim LaFrenz Panel Members –Mr. Kevin MacDonald, Cemstone Products –Mr. Jeff Rapol, FAA –Mr. Robert Taylor, ACPA –Ms. Susan Winslow, Delta Airport Consultants –Dr. Wayne Seiler, All About Pavements, Inc.
Goal Evaluate New and Innovative Technologies –Basis for new P-501 acceptance criteria –Implementation by the FAA –Implementation by other agencies with PCC guide specifications
Limitations of Current Acceptance Methods and Criteria Precision of Flexural Strength Tests Time to Acceptance Lab-cured Specimens vs. Slab Coring Cost and Convenience Too Few Tests
Objectives Methods to better estimate PCC strength Use nondestructive methods to estimate thickness Develop practical protocols for lab and field testing
Operational Aspects Device Parameter Thickness Probing Maturity Seismic Initial Cost Minimal $1000-$2,500 $20,000-$30,000 Material Cost (per point) None $10-$35 None Measurement Speed 2 minutes Continuous 2 minutes Skill Level of Operator Conscientious Technician or Engineer Skill Level for Interpretation Conscientious Technician or Engineer Training Requirement Minimal One Day One day for Operation, one additional day for interpretation
Motivation Maturity ? Maturity Does not consider construction quality Seismic Seismic Can complement
Maturity: Calibration Time Temperature Datum Temperature (To) Area = TTF 1.Prepare about a dozen Specimens 2.Conduct Maturity Tests 3.Conduct Strength Tests 4.Develop Strength/Maturity Relationship
Thickness Determination Objectives Test methods are sufficiently accurate Construction-related parameters do not significantly impact the accuracy –Texture (groove pattern) of the slab. –Type of material underlying the slab. Test methods are robust, repeatable, and reproducible.
Methods Considered Probing Fresh Concrete –Not effective Impact Echo
Strength Determination Objectives 1.Laboratory relationships can be accurately developed between strength and Maturity and/or Seismic Modulus (UIC, ERDC, UTEP) 2.Changes in mixture-related parameters do not significantly impact the laboratory relationships (UIC, ERDC, UTEP) 3.Field and laboratory developed relationships are similar (ERDC, UTEP) 4.Test methods are robust, repeatable, and reproducible.
Materials UIC (Limestone): Lab Testing ERDC (Granite): Lab and Slab (Controlled Environment) UTEP (SRG): Lab and Slab (Actual Environment)
ParameterThis Study UTEPERDCUIC SlabSpecimenSlabSpecimenSlabSpecimen Cement content Three Levels As designed Greater than design Less than design Water-cement ratio Three Levels As designed Greater than design Less than design Air content Three Levels No Air-entrainer Low Air-entainer High Air-entrainer * Type of Aggregates Three Levels Siliceous River Gravel Limestone Granite % total aggregates Three Levels As Designed High Low Coarse Aggregate Fraction Three Levels As designed Greater than design Less than design Finess Modulus Three Levels As designed 5% Passing Sieve #50 25% passing Sieve #50 * a database with similar parameter is available and will be used in the final analysis Aggregates Strength-Related Activities-Material
Methodology for Calculation of PWL Find sample average X for n specimens. X = (x1 + x2 + x3 +...x n ) / n Find standard deviation S n S n = [((x1 – X) 2 + (x2 – X) 2 +...(xn – X) 2 ) /(n–1)] 0.5 For single sided specification limits (L), compute the Lower Quality Index QL : QL = (X – L ) / S n Estimate PWL from QL and the corresponding n value.
Develop regression correlations between PWL of seismic modulus and flexural strength
Research Conclusions The strengths measured on lab-cured cast cylinders and beams are different than those measured from cores and beams extracted from slabs The flexural strength of the top half of the slabs are normally less than the lower half of the slabs, especially in the early ages.
Research Conclusions For the maturity method, relationships between flexural (or compressive) strength and maturity can be established with confidence in the laboratory. The laboratory strength-maturity relationships are affected by the change in the mix proportions, especially by the cement content and water cement ratio. If the maturity method is used alone, a rigid process control is needed to ensure that the lab- developed calibration relationship can be used with confidence in the field.
Research Conclusions For the seismic method, laboratory relationships between the strength and seismic modulus can be developed with confidence. The seismic-based strength-modulus relationships are much less sensitive to the mix proportions than the maturity relationships. Again, process control during mixing is desirable.
Research Conclusions The seismic moduli measured on the slab with PSPA generally correspond well with the seismic moduli measured with the FFRC on cores and beams extracted from the same slab. The PSPA moduli are generally lower than FFRC moduli, because the PSPA is more sensitive to the properties of the top half of the slab.
Research Recommendations Do not use Impulse Echo for P-501 Thickness Acceptance Testing On a trial basis, use Maturity and Seismic Testing for Flexural Strength Acceptance Testing
IPRF Products Protocol for Laboratory and Field Testing (Regenerated from TXDOT) PSPA Training Materials Shadow P-501 specification with alternate acceptance testing methods and procedures Executive Summary report for general use