Implemented Asphalt Research

Transcription

1 Florida Department of TRANSPORTATION Implemented Asphalt Research James A. Musselman, P.E.

2 HOT MIX ASPHALT (HMA) RECYCLING Contractor, FDOT, FHWA initiative UF & FDOT Research Support First project : Rubin Construction - Palm Beach County Second project 1978: US-98 Panama City Florida Asphalt Paving Co. Third project : US-441 Marion County Okaloosa Asphalt 1980: Recycled HMA specifications developed as a standard practice

3 HOT MIX ASPHALT (HMA) RECYCLING 1980: Recycled HMA specifications developed as a standard practice Benefits: Conserves resources Allows milling without generating waste Saves money FDOT usage since 1980: 150 million tons HMA 33 million tons RAP Resource Savings from RAP usage: 31.7 million tons aggregate 1.7 million tons asphalt binder

4 Fiscal Year 12/ million tons of HMA 85% of all mixes contain RAP 940,000 tons of RAP used 893,000 tons aggregate reclaimed 47,000 tons asphalt binder reclaimed Current Materials Costs: Aggregate: $/ton Potential savings $25 million Binder: >$550/ton Potential savings $26 million

5 ASPHALT RUBBER 1988 Florida Legislature Florida Statute Directed FDOT to research and adopt specs if feasible Contract Research with NCAT & UF FDOT Laboratory research Field Test Sections: SR-120 Alachua County SR-16 Bradford County I-95 St. John s County Worker Exposure Study CR-39 Hillsborough County

6 ASPHALT RUBBER 1994: Asphalt rubber specifications developed as a standard practice ARB-5, ARB-12 & ARB-20 Used in friction courses and interlayers Benefits: Conserves resources Improves performance FDOT usage since 1994: Over 7 million tires Good cracking performance Issues with settlement With ARB Without ARB

7 ASPHALT RUBBER FDOT research on new PG binder made with Asphalt Rubber Contract research (UF) on Hybrid Binders Industry input HVS & NCAT Test Sections Effective July 2013 letting

8 SUPERPAVE Product of the Strategic Highway Research Program (SHRP) Established by Congress in Year, $150 million national research program Developed asphalt mix and binder specifications 1995: First FDOT project US-301 Hillsborough County 1996: I-75 Columbia County Used SHRP mix specifications & existing FDOT construction specifications Permeability problems!

9 SUPERPAVE In-House and contracted research: Density, permeability and conditioning Revised layer thickness and density requirements Increased lift thicknesses Eliminated nuclear density cores Higher density requirement Full Superpave implementation on all FDOT projects in 1998

10 COMPLETED SUPERPAVE RESEARCH

11 OPEN GRADED FRICTION COURSES UF Research on OGFC GDOT Experience with D Modified FDOT Experience with FC-2 Began using modified binders Higher binder contents Larger aggregate size 1/2 vs. 3/8 Increased layer thickness 3/4 vs. 1/2 Added stabilizing fibers Added hydrated lime Increased tack rate Restricted usage

12 28% Statewide 26% 24% 22% 20% Crack Ride Rut % Deficient 18% 16% 14% 12% 10% 8% 6% 4% 2% 0% Year

13 OTHER RESEARCH TO REAL LIFE PROJECTS Warm Mix Asphalt Contractor Quality Control Trackless Tack Coats Polymer Modified Asphalts Optimized Gradations

14 CURRENT IN-HOUSE RESEARCH PG (ARB) HVS NCAT Bonded Friction Course Thick tack coats Pavement Preservation Techniques Fog seal, crack seal, microsurfacing, HIPR, 4.75 mm overlay Fiber additives Binder Fracture Energy Test

15 CURRENT IN-HOUSE RESEARCH Flow Number Test Recycled Asphalt Shingles (RAS) Hydrated Lime Study Performance Test for Tack Field test section on SR 26 (Newberry): 168 psi Future project: Urban & Night Job

16 University Research: Current Validation and refinement of volumetric properties (UF) Alternative techniques to mitigate reflective cracking (UCF) Impact of RAP on FC-9.5 & FC-12.5 performance (UF) Long-term aging of recycled binders (FIU)

17 University Research: Evaluation of FC-5 components (Rutgers) FC-5 Design using image analysis (USF) Field test method to detect polymer and/or GTR (USF) Evaluation of Florida mixes for crack resistance using Overlay Tester (FSU) Understanding mechanisms of OGFC raveling (TTI)

18 THANK YOU! Questions?

19 Florida Department of TRANSPORTATION Benefits Achieved from FDOT s Accelerated Pavement Testing Program 2014 Construction Conference James Greene Pavement Research Engineer State Materials Office

20 Overview FDOT s pavement resurfacing program APT facility and resources Benefits of selected research projects Economical Policy decision making Educations Summary and conclusions

21 Resurfacing Summary 3000 Annual statistics: 2000 lane miles resurfaced 3 million tons of HMA placed Resurfaced Lane Miles Tons of Asphalt x10 6 ) Year Arterials Interstate & Turnpike Total Tons of Asphalt 0.0

22 Deficient Lane Miles 25 Percent of Deficient SHS Lane Miles Superpave adopted in 1998 APT program began in % of the State Highway System must meet FDOT standards by Florida Statute Polymer modified binder specified in 2001 Fine graded mixtures allowed in Year

23 FDOT s APT Program Initiated in 2000 Housed at the State Materials Office Test site consists of eight 12 ft. linear tracks Originally 150 ft. long Seven tracks extended additional 300 ft. in 2011 Two additional tracks include water table control Loading performed using a Heavy Vehicle Simulator (HVS)

24 Test Tracks C A B 2 1

25 Test Pits

26 Test Track Expansion Original tracks Test Pits Extension

27 Heavy Vehicle Simulator Loading: 7 to 45 kips Dual or single tires Wheel wander from 0 to 30 inches On-board laser profiler system Heating system 10,000 loaded repetitions per day

28 Research Project Selection APT program is integrated with overall research effort Planning, development, and execution of research projects performed on an annual basis Research projects solicited from Central and District offices, FHWA, industry, and Florida Universities

29 Major Research Projects Evaluation of Superpave mixtures with and without polymer modified binders Assessment of the appropriate APT loading condition Evaluation of early strength requirement of concrete for slab replacement Evaluation of coarse and fine graded Superpave mixtures Evaluation of a thin concrete overlay of an asphalt pavement

30 Major Research Projects Development of methodologies to assess cracking potential of asphalt mixtures Evaluation of asphalt strain gauge repeatability Impact of wide-base tires on pavement damage Validation of a gradation based performance evaluation method, Dominant Aggregate Size Range (DASR) Porosity 2011 Evaluation of an ARMI to mitigate reflection cracking & resist rutting 2011 Evaluation of a PG asphalt binder

31 Current APT Projects Composite bridge deck (Testing complete) Alternative to open grid steel decks FHWA Pooled Fund Study, The Impact of Wide- Base Tires (Testing complete) Constructed and instrumented two test sections PG asphalt rubber binder (Testing 90% complete) Alternative to polymer modified binder in structural courses 4.75 mm mixture Preservation treatment or overbuild course

32 Composite Bridge Deck Cooperative effort with FDOT Structures Research Group Alternative to open grid steel decks Must have solid riding surface Weigh less than 25 psf Interested in more cooperative efforts

33 PG Asphalt Rubber Binder PG PM ARB-5 Blend of GTR and Polymer PG76-22 ARB PG76-22 ARB 1.5-inch SP inch SP inch SP inch SP inch SP inch SP inch SP inch SP inch existing SP inch existing SP inch existing SP inch existing SP inch limerock base 10.5-inch limerock base 10.5-inch limerock base 10.5-inch limerock base 12-inch granular subbase 12-inch granular subbase 12-inch granular subbase 12-inch granular subbase (two binder suppliers) (two binder suppliers)

34 4.75 mm Mixture 4.75-mm w/ PG mm mixture w/ PG inch SP-12.5 w/ PG inch SP-12.5 w/ PG mm w/ PG mm mixture w/ PG inch SP-12.5 w/ PG inch SP-12.5 w/ PG inch limerock base 10.5-inch limerock base 12-inch granular subbase 12-inch granular subbase 4.75-mm thickness ranges from ½ to 1 inch

35 Impact of APT Research Revision of pavement design and construction methods and specifications Implementation or discontinued use of researched materials and methods Informed policy decision making Furthering knowledge/education of pavement engineers

36 Examples of Benefits

37 Polymer Modified Binder Research First APT experiment evaluated SBS polymer modified binder Two layers of SBS modified PG binder One layer of SBS modified PG binder Two layers of unmodified PG binder Rate of rutting for pavement with unmodified binder approximately twice that of the pavements with modified binder Two layers of modified binder performed slightly better than one layer

38 Polymer Modified Binder Research Resurfacing ~ $125,000 per lane mile ~ 500 lane miles of Traffic Level D and E mixes placed each year Assuming 2 more years of life, the reduction in annualized cost is $1,000 per lane mile, or ~$500,000 per year

39 Polymer Modified Binder Research APT research indicated most beneficial locations to use polymer modified binder PG used for the final two structural courses in traffic level E mixtures but only the top structural course in traffic level D mixtures ~ 450,000 tons of traffic level D mix placed each year Use of modified binder for top layer only equals 50% savings on total initial cost of polymer, ~$2.1M per year

40 Fine Graded Asphalt Mixtures Based on initial Superpave guidelines, FDOT specified use of coarse graded mixtures to provide better rutting resistance A 2004 APT study showed that fine graded mixtures performed as well as coarse graded mixtures In 2005, FDOT allowed fine graded mixtures for traffic levels D and E mixtures According to industry, a cost savings of $2 to $5 per ton of asphalt mix, ~ $1.5M per year by allowing fine graded mixes

41 Other Recent Projects Impact of wide-base tires, 2010 & 2013 APT study that showed wide-base tires produced no greater pavement damage than dual tires ARMI found to be ineffective, 2012 Initiated research project to identify alternatives Implementation of High Polymer Modified Binder (PG 82-22), 2012 Pavements with history of high rutting

42 Educational Benefits Collaboration with Florida Universities Several graduate level research efforts have used APT data 2 Master 8 PhD Students work on-site and assist with APT research

43 Summary APT is a critical component of FDOT s pavement research program Key to success is the careful selection of research projects that address critical issues Technology transfer is essential

44 Thank You APT Website:

45 FLORIDA DEPARTMENT OF TRANSPORTATION Implementation of the Florida Pavement Marking Management System Charles Holzschuher, P.E. State Materials Office

46 Presentation Outline Pavement Marking Information Current Re-Striping Determinations Mobile Retroreflectivity Unit (MRU) MRU Program Background Pavement Marking Management System Implementation Plan Statewide MRU Testing Database BSSO SMO Interim Solution

47 Pavement Marking Information Driver s need for light doubles every 13 years Slower response time with age 12% of the country s drivers are over the age of 65 17% of Florida s drivers are over the age of 65 Fatalities are 3 times more likely at night 3

48 Night Time Marking Visibility How do you think these traffic signs and pavement markings perform at night?

49 Factors that Influence Retroreflectivity Climate Conditions Glass Spheres Marking Material Other Rain Dispersion Construction Roadway debris Fog Embedment depth Type Abrasion by traffic Snow Clarity Color Dirt & sand Ultraviolet light & heat Refractive Index Thickness Pavement Texture It is difficult to precisely determine when it is the best time to replace pavement markings Too late compromises safety, Too soon increases maintenance cost!

50 Current Re-Striping Determinations Visual Inspection Windshield Survey Subjective (pass/fail) Handheld Retroreflectivity Site Specific Requires M.O.T. Prescriptive Method Re-striping cycles Inefficient

51 Mobile Retroreflectivity Unit (MRU)

52 Mobile Retroreflectivity Unit (MRU) Laser Scans the Road 1 Meter Wide No Maintenance of Traffic Required Highway Speed Testing Continuous Data Collection Can be used Day or Night 1/3 rd scale of 30 meter geometry (Used in FDOT unit) 0.22 m 0.4 m Observation Angle = 1.05 Co-entrance Angle = meters

53 MRU Program Background Collaboration of FDOT and UNF (Since 2005) Mitigation Strategies to Improve MRU Test Results Collaboration with MRU Manufacturer Development of an Implementation Plan

54 PMM Implementation Plan Annually rate, 25,000 Line Miles of Markings per year 100% of the Center-line Markings (~ 13,000 Miles) Sampling of the Skip and Edge-lines (~ 8,000 Miles) Special Request (~ 4,000 Miles) New Construction/Overlay Projects Degradation of Pavement Markings Network Level Assessments for Pavement Marking Retroreflectivity Efficient Means to Measuring Retroreflectivity Improve Safety for Roadway Users and Field Personnel Improved Resource for Determining Maintenance Strategies

55 Florida Test Method A Florida Test Method for Measuring Retroreflectivity of Pavement Markings Using a Mobile Retrorectivity Unit has been created... FM Task Team for Proposed AASHTO Test Method

56 MRU Worksheet FDOT MRU Worksheet (Form # ) Project Specific Automatic Upload

57 Traffic Marking Certification Worksheet FDOT Traffic Marking Certification Worksheet (Form# ) Handheld Web Entry

58 Quality Assurance A Quality Assurance for Mobile Retroreflectivity Units document has been developed to ensure: The equipment and operators can adequately meet the performance requirements such as: - Equipment sensitivity - Calibration procedures - Software - Known Retro Values - Field Verification - Data Validation

59 Precision of MRU MRU Precision Repeatability (with-in unit) 8% Reproducibility (between units) 13% MRU vs. Handheld No statistical Bias Retroreflectance (mcd/m^2/lux) Retroreflectance (mcd/m^2/lux) MRUs Handhelds Segments for Sites 1-5 Segments for Sites 6-10

60 Statewide MRU Testing (Update) Contract with Beck Engineering & Company Contract Start Date: April 2013 Performed Quality Assurance Testing Statewide Testing Current Status: Network 67% Complete Special Request Projects Need District Projects Quality Assurance FDOT Sampling 30% of Statewide Data

61 BSSO Database Development Stand Alone Web-Based System System Design Phase Completed Pavement Marking Management System Construction and Testing Start Date: August 2013 Proposed Completion Date: March 2014 Features Graphs Tables Query Tools GIS Mapping Video log

62 Web-Based Filter/Query Tools Report Search Criteria Roadway ID District/County Project Certification AADT Stripe Type Roadway Type Manufacturer

63 Web-Based Filter/Query Tools

64 Graph and Table Reporting Link to SharePoint Passing Values Near End of Useful Life In Need of Re-striping

65 GIS Mapping and Video Log

66 Questions/Comments? Pavement Marking Information Current Re-Striping Determinations Mobile Retroreflectivity Unit (MRU) MRU Program Background Pavement Marking Management System Implementation Plan Statewide MRU Testing Database BSSO State Materials Office Interim Solution

67 Florida Department of TRANSPORTATION Base Approval Process and Its Implementation on the Use of New Base Materials David Horhota, Ph.D., P.E. State Geotechnical Materials Engineer State Materials Office FTBA Construction Conference February 12, 2014

68 Structural Layer Coefficient (SLC) SLCs established for flexible pavement design Subgrade Base Asphalt Structural Course Base SLCs in Standard Index 514 Optional Base Limited Use Base Units are per inch Lower Base SLC requires thicker section

69 Establish New SLC - Materials Manual 2.1 Proposed new material Recycled Geologic Formation Hybrid Review any existing data from proposed material SMO will conduct all testing for the evaluation and prepare a report Final recommendations from SMO and State Pavement Design Engineer

70 Requirements Producer supplies test results and material for SMO verification Comprehensive specification for proposed material Information provided by producer to show source will likely be approved under Aggregate Rule Sufficient quantities of material exist to provide cost effective alternative

71 Phases of Evaluation Laboratory Testing LBR must exceed 100 Other tests meet established criteria Test Pit static and cyclic plate tests (dynamic deflections & modulus) Full scale field test section with Limerock control section Initial testing during construction (Density, LBR, Field plate tests) Benchmark testing upon construction completion (Falling Weight Deflectometer, Ride, Rut, Crack) Post construction monitoring and comparison for performance

72 Reclaimed Concrete Aggregate (RCA) Base Historical Usage by the FDOT: Project-by-project basis Same requirements as Graded Aggregate Base (GAB) in Section 204 Restriction that the concrete was from a known FDOT source Typically used in non-traffic applications

73 Previous Research Use of Recycled Concrete Made with Florida Limestone Aggregate for a Base Course in Flexible Pavement, Kuo & Chini, 2001: Evaluated numerous RCA sources using concrete from unknown source RCA can be used effectively as a base course when appropriate QC techniques are utilized Average gradation of most samples met requirements in the GAB Specification Average LBR = 181 (Range: 67 to 266)

74 Result of Research Test Pit Program Proposed Test Section Added a sub-section for Reclaimed Concrete to Special Provision Section 204 Year implemented: 2007 FHWA approval restricted the use of this SP to only non-federal Aid projects

75 Special Provision Section 204 LBR Requirement of 120 Gradation slightly increased existing Section 204 limits Deleterious Material Restrictions on brick, wood, steel, heavy metals Address Environmental Issues Shall meet all FDEP requirements for solid waste FDEP definition of clean debris includes uncontaminated concrete Shall be free of asbestos and hazardous materials

76 Implementation of SP204 Not widely used because: Contractual reasons since only on non-federal Aid projects Lack of approved sources of RCA in high demand economy; RCA supply was being used on private projects Limited interest by sources to get FDOT approval

77 Recent Events When economic conditions changed, resulting in a down-turn of private projects, more sources have been approved for FDOT use As of 2013, total of 9 FDOT approved sources statewide Test Section on US-301 (Manatee County) constructed in 2010 to evaluate SLC of RCA base

78 Materials/Construction Bulletin March 2013 The current restriction of using of RCA on projects with Federal Aid is removed with the following conditions: RCA base shall not be used in interstate roadway pavements FDOT needs to continue monitoring the long term performance of RCA base pavements. If FDOT finds any premature failure or pavement performance concerns, the usage of RCA in Federal-aid projects will be reevaluated Until/unless the Department can furnish adequate data to support an increase, the SLC of 0.15 for RCA base material must be used For existing Federal-aid projects, cost saving analysis must be included in the approval process for switching to RCA base Scheduled for Standard Specifications Workbook in January 2015

79 Reclaimed Asphalt Pavement (RAP) Base Section 283: Use of RAP base only on paved shoulder, bike paths or other non-traffic applications Test pit program: based on plate tests total deflections, did not meet criteria for approved optional base materials Low LBR values Creep deformations

80 Previous Research Investigating the Statewide Variability and Long Term Strength Deformation Characteristics of RAP and RAP-Soil Mixtures, Cosentino, 2008: Sampled RAP from 50 plants across Florida (gradation, asphalt content, unit weight, proctor density, and LBR) Wide variability for milled RAP: AC from 4.9% to 8.5% and LBR from 5 to 44 RAP-soil blends with AC < 3.5% produced test results with lower creep deformations

81 Previous Research (cont.) Improving the Properties of Reclaimed Asphalt Pavement for Roadway Base Applications, Cosentino, 2012: RAP blends with 75% Limerock, Cemented Coquina and possibly Reclaimed Concrete Aggregate (3 base materials used for the research) may be acceptable for use as base materials 50/50 RAP Blends with Limerock would be acceptable if stabilized with cement and possibly asphalt emulsions

82 Implementation Test Pit program on blends to evaluate the following effects: Varying proportions Different sources of RAP and base Assess performance based on plate test modulus and deflections under varying moisture conditions (optimum, drained, and soaked) Based on results, determine appropriate applications and develop preliminary SLC

83 Florida Department of TRANSPORTATION Questions

84 Florida Department of TRANSPORTATION Internal Curing of Structural Concrete Dale DeFord Structural Materials Research Specialist State Materials Office Presented at the 2014 FTBA Construction Conference February 11 12, 2014

85 Presentation Outline This Presentation Addresses the Following Topics About Internal Curing of High Performance Concrete (HPC): What is Internal Curing of Concrete (ICC)? Why is ICC needed? What are the beneficial aspects of ICC? How does ICC work?

86 What is Internal Curing? Provision of Internal Water Needed to Prevent Self-Desiccation Internal curing - supplying water within a cementitious mixture using pre-wetted lightweight aggregate, or other materials that readily release water from within the particles, thereby mitigating self-desiccation and sustaining hydration. (ASTM C1761 Definition) Internal curing provides an additional source of water to sustain hydration and substantially reduce the earlyage autogenous shrinkage and self-desiccation that can be significant contributors to early-age cracking. Prewetted Fine LWA act as water reservoirs and continually supply extra water needed for hydration

87 Why is ICC Needed? Reduce Shrinkage and Associated Early-Age Cracking For concretes with lower water-to-cementitious material (w/cm), there is not enough internal water to satisfy the needs of hydration. As curing progresses, hydration product is deposited in the interconnected pore network, progressively reducing the permeability. As the permeability is reduced, transport of external curing water to the interior is insufficient to meet the needs of hydration and self-desiccation occurs.

88 Reduce Shrinkage with Coarser Cement Significant improvement can be made by reducing cement fineness Cement fineness has steadily increased for the past 60 years (top figure on right) An increase in cement fineness substantially increases the shrinkage (bottom figure on right) Cement fineness values for samples in bottom figure) Fine 380 m 2 /kg Coarse 311 m 2 /kg Source: Bentz, et al. (2008) Early-Age Properties of Cement-Based Materials. I - Influence of Cement Fineness

89 Early-Age Cracking Problem Areas Bridge Deck Cracking and Associated Corrosion In a 2003 FHWA national survey of high performance concrete (lower w/cm), the most common categories for distresses were: Early-age deck cracking (56.6 % were a 4 or 5, 5=often) Corrosion, which is intimately linked to cracking (42.3%) Cracking of girders, etc. (31.4 %) Others (sulfate attack, ASR, F/T, overload, poor construction quality were all below 25 % level) 2005 NRC/Canada report stated that over 100,000 bridges in the U.S. have developed transverse cracking of their deck shortly after construction Source: Adapted from Bentz ACI Webinar

90 Causes of Early-Age Cracking - 1 Early-Age Cracking Typically Caused by Thermal Stresses and Shrinkage Stresses Any time the tensile stress in a region of concrete exceeds the tensile strength of the concrete, the concrete will crack Tensile stresses arise from Differential temperature Not mitigated by IC Chemical shrinkage Autogenous shrinkage Differential drying shrinkage Can be mitigated by IC

91 Causes of Early-Age Cracking - 2 Chemical Shrinkage The volume of hydration reaction products is less than that of the reactants. Chemical shrinkage is the total shrinkage. Total Shrinkage Sum of the volumes of the external bulk shrinkage plus the volume of porosity created due to the volume differential between the reactants and products. Autogenous Shrinkage Internal drying shrinkage Capillary water loss from hydration of cementitious particles induces capillary forces that act to consolidate surrounding particles. Autogenous shrinkage is the total external shrinkage that occurs in a sealed environment after final set.

92 Causes of Early-Age Cracking - 3 Differential Drying Shrinkage Evaporation of water from a cementitious body starts at the surface and works toward the center of the body in a somewhat planar profile. This moisture gradient, from the surface inward, causes a stress gradient, due to capillary forces, with the highest stresses at the surfaces. The central area, where little or no evaporation has occurred, acts to resist the shrinkage of the outer surfaces. This puts the surface area in tension. The steeper the moisture gradient, the higher the stress differential, and the higher the tendency to crack.

93 Shrinkage Definitions ASTM C1761 Chemical shrinkage - the reduction in volume of cementitious paste that occurs during hydration because the hydration products occupy less volume than the volume occupied originally by the water and unhydrated cementitious materials. Autogenous shrinkage - reduction in volume due to chemical shrinkage of a sealed cementitious mixture, not subjected to external forces and under constant temperature, measured from the time of final setting. Self-desiccation - reduction in the internal relative humidity of a sealed cementitious mixture as a result of chemical shrinkage.

94 Chemical and Autogenous Shrinkage Chemical Shrinkage Volume: Bulk Shrinkage + Porosity Created by Chemical Shrinkage Autogenous Shrinkage Volume: External Bulk Shrinkage Chemical and Autogenous Shrinkage versus Time Cement Paste, w/c=0.30, 23 C Source: Adapted from Henkensiefken, Sant, Nantung, and Weiss (2008)

95 Benefits Attributed to Internal Curing Durability (Reduced Cracking and Permeability) Reduced cracking due to reduced plastic shrinkage and autogenous shrinkage (early-age shrinkage) Improved hydration no self-desiccation, denser interfacial transition zone Reduced permeability less ingress of chlorides, etc. Reduced slab curling and warping Structural Endurance (Reduced Cracking & Fatigue) Small reduction in weight Lower elastic modulus Lower coefficient of thermal expansion Small increase in strength

96 Literature Data Showing IC Benefits - 1 Comparison of Internally-Cured with Normally-Cured HPC Property Normally-Cured HPC (w/c=0.35) Internally-Cured HPC (w/c=0.35) Amount of IC Water, w/c ic (kg/kg) Improvement Made by Internal Curing C-S-H Content at 28d (%) % Compressive Strength at 7d (MPa) % Compressive Strength at 28d (MPa) % Water Permeability (m/s) 2.1 x x % Chloride Permeability (Coulomb) % Freeze-Thaw Resistance, mass loss (%) Salt Scaling Resistance, mass loss (%) Source: Cusson and Margeson (2010)

97 Literature Data Showing IC Benefits - 2 Cost, Service Life, and Life-Cycle Predictions Property Normally-Cured Normal Concrete (w/c=0.40) Normally-Cured HPC-SCM (w/c=0.35) Internally-Cured HPC-SCM (w/c=0.35) Concrete Costs $450/m 3 $600/m 3 $624/m 3* Service Life Predictions 22 years 40 years 63 years Life-Cycle Cost Predictions (60-yr Analysis) $783/m 2 $470/m 2 $292/m 2 Approximate Cost Above Normal Concrete 0% 33% 39% Increase in Service Life Above Normal Concrete 0% 82 % 186% Decrease in Life-Cycle Cost Above Normal Concrete 0% 40% 63% Compared to normally-cured HPC, internally-cured HPC Costs about $24/m 3 more (4%) Increases service life by 23 years (58%) Reduces life-cycle costs by $178/m 2 (38%) Source: Adapted from Cusson, Lounis, and Daigle (2010)

98 How Does ICC Work? The internal sources of water can minimize stresses by greatly reducing the moisture gradients that result from loss of free water due to evaporation and hydration reactions Typically, a portion of the fine aggregate is replaced by LWA in a prewetted condition Prewetted Aggregate- wetting of the aggregate so that it contains the prescribed water content available for cement hydration. [ACI ( )R-13] The prescribed water content is calculated with the objective to add about 7 lb of water per 100 lb cement. This is the typical dosing to provide all the water needed for hydration (maintain saturation) Since the IC water is contained in the LWA until needed, it is not included in the w/cm

99 Available Water from LWA ASTM C1761 Absorption, A 72 - of lightweight aggregate, the increase in mass of a specimen of oven-dry lightweight aggregate due to water penetrating into the permeable pores of the particles after being submerged for 72 h, expressed as percentage of oven-dry mass. Desorption (LWA Water Available for Hydration) - the decrease in mass of lightweight aggregate, originally containing absorbed water, due to water leaving the permeable pores as the aggregate attains moisture equilibrium with the surrounding environment maintained at constant temperature and a relative humidity less than 100 %.

100 Distribution of LWA To be effective at enabling a high degree of hydration, the LWA needs to be very well dispersed, since the overall mobility of water decreases as the capillaries providing transport become increasingly restricted The use of fine LWA is the most efficient way to thoroughly distribute the internal reservoirs Estimated Distance Traveled by Water from Internal Reservoirs (Bentz et al. 2007) Hydration Age days Estimated Distance in (mm) Less than (20) 1 to (5) 3 to (1) More than (0.25)

101 Summary When properly sized, proportioned, and mixed in HPC (low w/cm), prewetted LWA provides welldispersed reservoirs that continually supply water for hydration, maintaining a saturated condition, and preventing self-desiccation, thereby reducing shrinkage strains that can cause early-age cracking in such structures as bridge decks For no more than a modest increase in placement cost (4% or less), internal curing can increase the predicted service life of HPC by over 50% and reduce predicted life-cycle costs by almost 40%

102 Florida Department of TRANSPORTATION Questions?