EVALUATE TxDOT CHIP SEAL BINDER PERFORMANCE USING PAVEMENT MANAGEMENT INFORMATION SYSTEM AND FIELD MEASUREMENT DATA SAN ANTONIO DISTRICT

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1 EVALUATE TxDOT CHIP SEAL BINDER PERFORMANCE USING PAVEMENT MANAGEMENT INFORMATION SYSTEM AND FIELD MEASUREMENT DATA SAN ANTONIO DISTRICT Interim Researc Report #3 Prepared by: Douglas D. Gransberg, P.D., P.E., C.C.E. Construction Science Division University of Oklaoma Norman, OK February 2008 OU Transportation Researc Report Sponsored by te Aspalt Emulsion Manufacturers Association 1

2 Evaluate Texas Department of Transportation Cip Seal Binder Performance Using Pavement Management Information System Data Interim Report #3 Table of Contents Executive Summary... 3 Purpose of te Researc:... 6 Literature Synopsis and Background... 6 Metodology... 6 Pavement Management Information System Data Analysis... 6 Results to Date...8 Emerging conclusions Bibliograpy

3 Evaluate Texas Department of Transportation Cip Seal Binder Performance Using Pavement Management Information System Data Interim Report #3 EXECUTIVE SUMMARY Purpose of te Researc: Tis researc as two distinct purposes. First, it seeks for te first time in te US to measure te cange in cip seal performance over time using quantitative means and comparing it wit te current metods used by te Texas Department of Transportation (TxDOT) in its Pavement Management Information System (PMIS). Secondly, it will extend te findings of te previous AEMA study regarding cip seal binder differences in te Atlanta District to te San Antonio District troug a cip seal performance study of bot ot applied and emulsion cip seals constructed during te summer of. Deliverables: Publication of researc findings in an annual report tat can be used to transfer te knowledge developed in tis project to TxDOT construction and maintenance personnel on-site at teir district offices in Texas. Additionally te researcer will seek to publis te significant findings of tis work in a national peer-reviewed journal. Finally, a cip seal performance worksops ave been and will be conducted at districts designated by te sponsor. To date, seminars ave been conducted in Austin, Brownwood, Bryan, Lufkin, Paris, Sequin, and Waco. Findings of tis study ave been presented at regional and national conferences in Nasville, TN, Wasington, DC, Austin, TX, te TxDOT Maintenance Conference and at te AEMA National meeting in Palm Springs, CA. Additionally, a peer-reviewed journal article entitled Using a New Zealand Performance Specification to Evaluate US Cip Seal Performance was publised in te American Society of Civil Engineers Journal of Transportation Engineering, in December detailing te findings of tis study. Scope of Work: Researcers initially establised test sections on 12 Farm-to-Market roads in te TxDOT San Antonio district. Premature failure of one test section and te dropping of anoter planned test section from te seal coat program forced te sample population to be reduced to 10 FM roads. Te researcers ave monitored tose sections trougout 2 ½ years (ten quarters) of service life and will continue troug te end of tird year. Engineering measurements of cip seal surface texture were made using te Transit New Zealand P17 Sand Circle test to validate tose measurements similar to te process being used by te researcer in anoter project in New Zealand. Te analysis entails processing te PMIS data for eac test section on an annual basis and using tat to do a comparative analysis of cip seal performance as measured by PMIS and in te field on te actual test sections. Metodology: Te researc was conducted in tree pases. Pase 1 is complete and consisted of data collection and reduction. Te San Antonio district furnised publicly available contract information from te test section seal coat projects completed using ot aspalt cement binder and te test section seal coat projects tat were sceduled to be completed using emulsion binder. Te data will be processed in te exact same metod as te previously cited researc project. Additionally, weigted average metrics will be calculated on a basis of unit area. Finally, cost index number teory will be applied to te problem wit specific cost index number metrics being developed for te pavement condition score. Te PMIS data for te preseal condition was correlated wit te preseal texture measurements and a qualitative windsield survey to produce a compreensive picture of te condition of te test section roads prior to te seal coat. Tis is te first time tat tis 3

4 level of effort as been expended to quantify te condition of te underlying surface for newly sealed roads. Te PMIS results were compared wit te pysical field measurements and trends ave been identified. Pase 1 is complete. Pase 2 of te project conducted more worksops for te TxDOT district personnel. Te worksops consisted of a formal presentation to a group, a question and answer period, and a follow-on informal discussion period were interested TxDOT personnel can discuss te findings of te researcer directly wit te researcer. Additional worksops will be sceduled as requested by te sponsor. Tis pase is complete Pase 3 is ongoing and replicates Pase 1 in tat te test sections are pysically sampled once eac quarter. Teir PMIS data is collected annually and analyzed eac time tat it is updated by te district. Ten suc post-seal samples ave been taken and te results are described in detail in te body of tis interim report. At eac PMIS data update a comparative analysis is run wit te field measurements and trends are identified and documented. At tis report, sufficient data as been collected to permit te conduct of a cost index number analysis tat furnises information on te relative cost effectiveness of eac binder wit regard to te quantitative and qualitative measurements. Wen te tree-year observation period is complete, a compreensive researc report will be prepared and submitted to te sponsor. Emerging Conclusions: Te major conclusion at tis point in te researc remains tat te existing condition of te substrate significantly impacts te performance of a new seal coat. Tis is sown by te early flusing of AC road FM 427, wic ad very poor texture due to flusing and emulsion road FM 1470 wic ad a recent reseal before te new emulsion cip seal. Additionally, te AC roads tat were sot on top of flused substrate are losing teir texture dept at a rate tat is faster tan tose wose substrate was not as igly flused prior to te new seal. Wile tis is certainly not new knowledge to te members of TxDOT and te cip seal industry, tis is te first time in Texas and by te autor s knowledge in Nort America tat a quantitative measurement as been use to prove wat as been suspected for quite a long time. Tus, te metodology used in tis project is proving itself to be very valuable in developing a rationale metod using engineering measurements to objectively evaluate te post-seal performance of all types of cips seals. At tis writing, several trends are observed wit respect to te comparative performance of te two binder types. It appears tat bot binder types seem to be furnising satisfactory performance in teir early lives. Neiter te qualitative nor te quantitative measures indicate poor performance of eiter binder type. Te quantitative measures of texture dept appear to sow tat te emulsion roads are losing teir texture dept at a slower rate tan te AC roads. Tis is probably due to te increased amount of flusing tat was present on te substrate of te AC roads prior to sealing. Wen te quantitative measures of texture dept are compared to te 1-year texture dept performance criteria in use in New Zealand for new cip seals, two of te five AC roads would ave failed te test. All emulsion roads passed te criterion. Te importance of aving a detailed knowledge of te existing surface prior to te new seal coat is vital to explaining seal coat performance. Te qualitative ratings of te emulsion roads may indicate more flusing tan te AC roads because of te great contrast between te uncoated aggregate and te binder. 4

5 Terefore, bot te researc team and te reader must be careful to not attac an excessive amount of meaning to te windsield analysis. Te emulsion roads were found to be more cost effective in all five cost index number metrics tat were used in te analysis. Two of te metrics were qualitative, springing from te PMIS and windsield survey output and te oter tree were quantitative, being developed from te texture measurements taken using te TNZ T/3 sand circle tests. 5

6 Evaluate Texas Department of Transportation Cip Seal Binder Performance Using Pavement Management Information System Data Interim Report #3 PURPOSE OF THE RESEARCH: Te purpose of tis researc is to compare te performance of emulsion cip seals placed in te Texas Department of Transportation s (TxDOT) San Antonio District wit ot-applied aspalt cip seals place on similar roads in te same area. Te project builds on previous work done in te TxDOT Additionally, tis project transfers te tecnology developed in tis project via a series of worksops conducted by te researcer in approximately twelve TxDOT districts. Tis report only speaks to te binder performance comparison completed work to date. LITERATURE SYNOPSIS AND BACKGROUND Interim Report #1 detailed te significant findings from te literature review. Terefore, no additional review is necessary for tis report. A complete literature review will be included in te final report. METHODOLOGY Te metodology was described in detail in Interim Report #1. It as not canged. PAVEMENT MANAGEMENT INFORMATION SYSTEM DATA ANALYSIS Te analysis TxDOT Pavement Management Information System (PMIS) data will track te analysis done in a previous study complete under te auspices of te Aspalt Emulsion Manufacturers Association (AEMA) entitled: Comparing te Performance of Emulsion Versus Hot Aspalt Cip Seal Projects in te Texas Department of Transportation s Atlanta District. In tat study, a series of cost indices were developed to compare te performance of various roads on bot engineering and an economic basis. Te requisite information is now available to be able to conduct a similar analysis for te San Antonio roads. Tose analyses are found in te final section of tis report. Figure 1 sows te 2-year post-seal conditions of te roads in tis study along wit te cange from te pre-seal PMIS ratings over te second year of service life. Figure 2 is a istogram tat sows te cange in PMIS Pavement Condition Score and Distress Score for te two types of binders. As can be seen, on average te roads tat received a ot AC cip seal (AC roads) were in somewat better overall condition based on te PC rating one year after te new seal, but tat trend reversed itself in. Tis is a switc from te pre-seal PMIS ratings wic ad te following major differences: Te roads tat received te ot applied aspalt binder (AC roads) ad more flusing. Te EM roads ad more sligtly more distress. Te EM roads ad more sligtly rutting. 6

7 PAVEMENT MANAGEMENT INFORMATION TEXAS DEPARTMENT OF TRANSPORTATION Numerical Rating Assigned to Eac Road Condition Fiscal Year; Responsible District = 15 San Antonio Rating Rating RAV: Raveling (Selling) RD: Rut FLU: Flusing PAV CON: Pavement Condition DIS: Distress Score EM RDs County RAV FLU DIS RD PAV CON FM 117 Frio FM 140 Atacosa FM 478 Atacosa FM 1344 Wilson FM 1347 Wilson AVERAGE Cange from FY AC RDs County RAV FLU DIS RD PAV CON FM 541 W Wilson FM 541 C Wilson FM 541 E Wilson FM 427 Wilson Hwy 119 Wilson AVERAGE Cange from FY Figure 1: PMIS Data Analysis for te Post-Seal Pavement Condition After 24 monts and te Cange from te FY Condition. Cange In PMIS Scores: Preseal to Current Preseal Preseal PAVEMENT CONDITION PMIS Scores DISTRESS SCORE Figure 2: Cange in PMIS Data from Pre-Seal to Current. EM One can see tat te pavement condition difference is minor: 85.9 for AC roads versus 87.8 for EM roads. However, Figure one sows tat te drop over te second year of service in bot average pavement condition and distress scores to be greater for te AC roads tan for te EM roads. One can see in Figure 2 tat te AC roads were in poorer condition tan te AC 7

8 EM roads prior to te new seal. Tey ten ad better PMIS scores tan te EM roads. However, in tose scores ad slipped below tose of te EM roads. Te pre-seal condition of te substrate may account for tis trend reversal. Interim Report #2 on tis project sowed tat tose roads found to ave failed using te New Zealand TNZ P/17 performance specification prior to te reseal flused prematurely. Tus, tere are now two confirmed data points tat sow te importance of caracterizing te road s surface prior to deciding to reseal. Tere was a good range of pre-seal conditions amongst for types of roads. Tus, te comparison will allow te researcer to watc te trend in eac binder on roads tat were in poor conditions at te time of te seal as well as on roads tat were in excellent condition at te time of te seal. Additionally, te amount of pre-seal flusing is also across a nice range for bot binder types as eac as at least one road wit no flusing and anoter tat as a flusing rating above 2.0. Tis is particularly important to te metodology being used in tis project. Te New Zealand cip seal design metod takes great care to caracterize te road s existing surface using engineering measurements including te TNZ T/3 sand circle. Tus, aving not only a pre-seal rating for eac road but also a representative range of preseal pavement conditions will make te outcome of tis study autoritative for most conditions. RESULTS TO DATE Te reader must be careful to put te grapical results in context. For example, te texture measurements sould be viewed in a relative fasion looking at te cange from te pre-seal condition for eac binder rater tan te differences between te two binders. Te texture dept is measured in millimeters. For instance, te difference in average texture dept between te two binders two monts after te new seal is 0.55 millimeters wic is 0.02 inces, an extremely small difference. Qualitative Windsield Analysis Procedure Data collected before te placement of te new seals displayed significant flusing in every road tat was tested. Te AC roads, on average, ad a little less texture tan te EM roads. Toug te AC roads pre-conditions were inferior to te EM roads, te two post-data collections indicate tat te textures of te AC roads are sligtly better tan te EM roads. On average, bot sets of roads are considered to be satisfactory at tis juncture. Te windsield analysis results to date are synopsized in Figure 3. One can see tat te qualitative condition of te AC roads as dropped off somewat more quickly tan tat of te EM roads. Tis confirms te cange found in te PMIS survey of tese roads. It sould be noted tat te PMIS scores were collected independently from tis researc project. 8

9 Qualitative Windsield Analysis Before Seal 1st QTR 1st QTR New Seal EM RDs AC RDs Figure 3: Results of Qualitative Windsield Analysis after 1 Year Visual analysis (windsield analysis) of bot road types present unique callenges for eac cip seal type. AC roads utilize a precoated stone tat is dark in color, wile EM roads use an uncoated stone tat is very ligt. Te difference requires te analyst to calibrate is/er eyes to eac cip seal type. Some common issues tat te analyst must be aware of include: AC roads may appear to be satisfactory wen flusing or selling is actually evident te darker appearance of tis road type masks possible imperfections. EM roads may appear to be poor wen tey are actually satisfactory, because veicle tires can spread fres oil down te road giving te appearance of flusing or selling on a newly placed cip seal. Te ligt color of te road accentuates tis condition. It also makes distinguising flusing from selling difficult from a moving veicle, forcing te researcer to stop frequently to be able to differentiate between a dark spot tat is flusing and a similar dark spot tat is actually selling. Looking at Figure 3, one can see tat roads wit bot binder types were improved to nearly perfect condition. After te first progress sample (two monts), it appeared tat te EM roads and te AC roads ad eac deteriorated by te same amount (0.1 point). At te oneyear mark te AC roads ad suffered a deterioration of 1.5 points compared to a cange for te EM roads of 0.7 points over te same period as sown in Figure 3. By te tent observation, te AC roads ad lost 2.4 points compared to te EM roads loss of 1.1 points. Again, tis speaks to te poorer condition of te substrate found on te AC roads prior to te new seal. Again, tis argues for te careful caracterization of te existing surface prior to making te decision to reseal a cip sealed road tat as flusing problems. Figure 3 also furnises a great example of wat appens wen one violates te golden rule of pavement preservation: put te rigt treatment on te rigt road at te rigt time (Galeouse et al 2003). Tis leads to te use of quantitative measurements to verify te results te found in te two qualitative procedures (i.e. PMIS ratings and te windsield survey). Sand Circle Procedure Te previous interim report reported on te efficacy of using te Transit New Zealand TNZ P/17 cip seal performance specification based on te TNZ T/3 sand circle test procedure. It 9

10 utilizes tis test to measure performance at te one-year mark after a new cip seal. Hence it is possible to compare te performance of te test roads in Texas to tis bencmark and use tis as anoter objective analysis of binder performance. Tis analysis is repeated in tis report because it sets te foundation against wic te current set of measurements can be compared. In oter words, it is important to identify tose roads tat are considered to ave te failed te TNZ P/17 performance specification wen looking at te long-term performance of eac binder. Cip seal contractors in New Zealand are paid on a basis of 1-year cip seal performance. rage texture dept measurements are taken after one year, and tose are compared to a 1- year texture dept calculated from an empirical deterioration model. Te entire specification is based on te assumption tat cip seals fail as a result of flusing (Transit New Zealand 2002). Te final acceptance is based on te acievement of te required texture dept, witout any significant cip loss. Te New Zealand deterioration models from wic te P17 specification is derived require te following minimum texture dept one year after te cip seal is completed, using Equation 1 below. Td 1 = 0.07 ALD log Y d (Equation 1) were Td 1 = texture dept in 1 year, Y d = design life in years, and ALD = average least dimension of te aggregate. To put tis into a life cycle perspective, Transit New Zealand defines a cip seal failure due to flusing as: Wen te cip seal s texture dept is less tan 0.7 mm in areas were te posed speed is less tan 70 kilometers per our (43.5 mp) Wen te cip seal s texture dept is less tan 0.9 mm in areas were te posed speed is greater tan 70 kilometers per our (43.5 mp) (Transit New Zealand 2002). Table 1 recapitulates te results of te one-year measurement of texture dept in te weel pat (WP) and between te weel pats (BWP) as well as te average texture dept across te test section. Te Table 1 results for te 7-year design life track well wit te comparison of pre-seal macrotexture sown in Figure 1 wit te solitary exception of FM 427. It sould be noted tat a previous study of te TxDOT cip seal program found tat TxDOT expects a service life (not a design life) of rougly seven years from new cip seals (Gransberg et al, 1999). So, discounting te subtle difference between a design and a service life, te 7-year design life performance criterion is probably te best bencmark against wic to measure cip seal performance in Texas. 10

11 Table 1: Comparison of Measured 1-Year Macrotexture to TNZ P/17 Performance Criterion Over Tree Possible Design Lives by Binder Type 5 Year Design Life minus 1-year Measurement 6 Year Design Life minus 1-year Measurement 7 Year Design Life minus 1-year Measurement Test Section WP BWP WP BWP WP BWP FM FM FM FM FM EM AVE FM 541 West FM 541 Central FM 541 East FM State AC AVE Wen one compares te results in Table 1 wit te current PMIS qualitative ratings in Figure 2, a very different picture of te new cip seals performance is found. Te PMIS results after one year sow FM 541 East s flusing score to ave improved by 2.1 out of a possible 5 points and its pavement condition to be nearly perfect wit a score of 97 out of 100. A similar picture is given for FM 427 wose pavement condition improved from 38 to 97 and wose flusing score remained uncanged. Tis sould not be read as an indictment of te TxDOT PMIS program. One must remember tat te PMIS scores sown in Table 1 are an average of te qualitative scores taken at alf-mile increment along te entire test section lengt. Tis study s texture dept measurements were taken at a single point on eac road, and a ceck of te PMIS section data for FM 427 sowed a flusing score of 2 out of 5 in te section were te sand circle test was conducted indicating tat flusing was observed by te PMIS surveyors in tat particular section. Interestingly, tat section ad a flusing score of zero indicating no flusing. Wereas, te pre-seal windsield survey by te researcers observed flusing in bot weel pats in tat section and te pre-seal measured texture dept was only 0.28 mm (0.01 inces) greater tan te TNZ P/17 failure criteria of 0.9 mm (0.035 inces). Tis discrepancy igligts te major benefit of using a quantitative metric over a qualitative one. Wit observational metods, it becomes very difficult to obtain consistent ratings between two different observers. Not witstanding te previously discussed marginal measurement accuracy problems inerent to te TNZ T/3 sand circle test, as a quantitative measure it virtually eliminates te discrepancy found wit te PMIS qualitative rating on FM 11

12 427 for no oter reason tan te test mandates tat te test taker stop and make te measurement rater tan derive a qualitative judgment from a moving veicle. Tese tecniques also serve to reinforce te primary tenet of pavement preservation tat public agencies must place te rigt treatment, on te rigt road, at te rigt time (Galeouse et al 2003). Looking at te pre-seal conditions of te roads in tis study, only FM 541 Central and FM 541 East would ave been considered as failed due to flusing using te TNZ P/17 performance specification before te new seal was applied. Table 5 sows te cange in texture dept for tese two test sections. It can be seen tat FM 541 Central was only failed in te weel pats, wereas, FM 541 East was failed across te entire section. On FM 541 East, te weel pats gained better tan a full millimeter of texture wit te new seal, but at te next measurement two monts later, te weel pats are already nearing te failure level of 0.9 mm (0.035 inces). Tis may be due to traffic embedding te aggregate into te existing soft flused substrate, or it is also possible tat tere was rutting in te weel pats tat cause tem to be flooded wit binder during construction of te new seal creating excessive binder in te weel pats tat led to premature flusing. In eiter case, it is obvious tat placing a new cip seal on FM 541 East was not te rigt treatment as te road ad become too eavily flused to permit te new cip seal to restore its surface texture for more tan a sort period of time, in tis case less tan two monts. Tis is confirmed by te 1-year measurement in te weel pats being less tan te TNZ P/17 ultimate failure criterion. Tus, using tese two roads as an example, one would ave to conclude tat quantitatively caracterizing te pre-seal macrotexture not only aids te engineer on evaluating cip seal performance, but also furnises a rational metodology for determining te proper pavement preservation treatment to use based on objective measurements rater tan qualitative observational condition ratings. Table 2 Cange in Measured on Two Roads Tat Were Failed Due to Flusing Prior to te New Seal (Note: bold values are less tan te TNZ P/17 Ultimate Failure Criterion). Before Seal New Seal 2 Monts After 1 Year After Rd FM 541 C FM 541 E Total WP BWP Total WP BWP Total New Seal WP BWP Total New Seal WP BWP Given te above discussion, te project as now progressed for 2 ½ years and as a result as a large data set for te ten test roads. Figures 4, 5, and 6 sow te average cange in surface texture over time for bot te AC and te EM roads taken as sown in te above tables. Tese figures allow te direct comparison of te two binder types wit regard to one anoter in maintaining macrotexture as measured by te TNZ t/3 sand circle test. 12

13 Cange in rage versus Time 3.50 rage st QTR 1st QTR Preseal New Seal Observation Emulsion Figure 4: Cange in rage Over Time Hot AC Cange in rage Weelpat versus Time rage Weelpat st QTR 1st QTR Preseal New Seal Observation Emulsion Hot AC Figure 5: Cange in rage Weelpat Over Time 13

14 Cange in rage Between Weelpat versus Time 4.50 rage st QTR 1st QTR Preseal New Seal Observation Emulsion Hot AC Figure 6: Cange in rage Between Weelpat Over Time One can see tat in all tree cases te EM roads ave lost teir surface texture at a slower rate tan te AC roads. Te difference is most pronounced in te weel pats were macrotexture is critical to skid resistance. Tere is no seemingly logical pysical explanation regarding te differences in te binders for tis. It is probably due to te fact tat te AC roads substrate was more igly flused before te new seal as can be seen in eac figure. However, te comparison on tis quantitative basis certainly supports te conclusion tat te EM roads are performing as well if not better tan te AC roads. Cost Index Number Analysis Te final category of comparative metrics comes from a variant of Utility Teory called Cost Index Number Teory (West and Riggs, 1986). As PMIS is itself is based on Utility Teory (TxDOT, 2001), using Cost Index Number Teory is a logical coice for tis type of analysis. Te metod seeks to combine cost and engineering measurements into a single index tat can permit te direct comparison of two or more alternatives simultaneously and tus provide a measure of cost effectiveness on an engineering property basis. Tis teory allows te researc team to compare a more expensive tecnology wit a less expensive tecnology to determine if te incremental cost difference between te two alternatives is offset by enanced engineering performance. Te actual contract prices for te seal coat contract were used for eac of te test roads. Te actual quantities were multiplied by te contract unit prices to obtain te total cost for te aggregate and binder for eac road. Te EM roads ad an average unit cost of $0.82 per square yard and te AC roads ad an average unit cost of $0.92 per square yard. Te general formula developed for eac of te five cost indices was derived by dividing te cost per square yard by a pysical parameter as follows: CI = (CSY/PP) x 10 X (equation 2) 14

15 Were: CI CSY PP X = Cost index number = Cost per square yard ($/SY) = Pysical parameter = A power of ten tat allows te resultant number to be rougly a wole number between 1 and 120 Te pysical parameters were defined as follows: PC = rage PMIS pavement condition score for eac class of road WR = rage windsield rating score for eac class of road AT = rage texture dept for eac class of road WP = rage weelpat texture dept for eac class of road BWP = rage between weelpat texture dept for eac class of road Terefore te PCCI is te pavement condition cost index and is essentially te cost per square yard to attain one point of PMIS pavement condition score. Because te purpose of tis analysis is to compare te two binders, te CI numbers for bot groups will be reported as dimensionless to reduce confusion and allow te focus on relative rater tan absolute values. Table 3 contains te resultant values of te pysical parameters used for eac road and te average for te two groups in eac parameter. One can see tat te EM roads ave a sligtly better PMIS pavement condition score and windsield rating score as a group tan te AC roads. As previously reported, tey also ave a retained an average deeper texture in all tree measurements. Table 3: Pysical Parameters Used in te Cost Index Number Analysis for Eac Road EM RDs Avg Avg WP Avg BWP Pavement Condition Score Windsield Rating Score FM FM FM FM FM AVERAGE Avg Avg WP Avg BWP AC RDs Pavement Condition Score Windsield Rating Score FM 541 W FM 541 C FM 541 E FM Hwy AVERAGE Table 4 is te result of applying te cost index number analysis to eac of te roads and ten taking an average value for comparison between te two different types of binders. Te average index values are lower for te EM tan te AC roads in all five categories. Tus, tis clearly demonstrates tat te EM binder is more cost effective tan te AC binder. Tis 15

16 approac demonstrates tat te lower cost option actually produces a result tat is at least as good if not measurably better in eac of te five metrics cosen for tis study. Table 4: Cost Index Numbers for Eac Road. EM RDs PCCI WRCI ATCI WPCI BWPCI FM FM FM FM FM AVERAGE AC RDs PCCI WRCI ATCI WPCI BWPCI FM 541 W FM 541 C FM 541 E FM Hwy AVERAGE EMERGING CONCLUSIONS At tis writing, te researc is tird year into a tree year project tat will compare te performance of te two binder types wic sould ideally perform witin te specified criterion for a minimum of 5 years. Te use of te TNZ performance specification allowed te researc team to create a bencmark based on a well-establised and long-standing practice against wic to compare te two binders during teir first year of life. A potential trend seems to be emerging in te comparative analysis. Based on te qualitative windsield survey and te PMIS data, bot binder types seem to be furnising satisfactory performance in teir 2 ½ years of service. Neiter te qualitative nor te quantitative measures indicate poor performance of eiter binder type. Tus, at tis point it appears tat bot binders are performing satisfactorily wen te preseal conditions of te substrate are taken into account. Next, te previous interim report found tat quantitative measures of texture dept appear to sow tat te emulsion roads are losing teir texture dept at a slower rate tan te AC roads. Tis trend continues wit te measurements taken for tis report. Tis is probably due to te increased amount of flusing tat was present on te substrate of te AC roads prior to sealing. Once again te importance of aving a detailed knowledge of te existing surface prior to te new seal coat is vital to explaining seal coat performance. Using te TNZ P17 performance criterion as a bencmark against wic to measure te oneyear texture dept performance, it was found tat all te EM roads and tree of five AC roads exceeded te performance bencmark based on weelpat texture dept for bot 5 and 6-year design lives. If te 7-year criterion is used, all EM and only two AC roads would pass te test. If a design life is back-calculated using te same equation, te EM roads ave an average design life based on averaged measured texture dept and average measured weelpat texture dept tat is double tat observed for te AC roads. Tis second trend sould be viewed as indicative rater tan predictive as a design life is fundamentally different tan a service life, and te TNZ P17 1-year performance criterion equation was not developed to predict service life. 16

17 Te cost index number analysis permitted te researcer to do a bang for te buck comparison. Te EM roads were found to be te more cost effective in every single metric. Tey were particularly cost effective in teir ability to retain surface texture, te set of metrics based on pysical measurements rater tan qualitative ratings. Te qualitative metrics also tracked togeter wit te study-specific windsield survey conducted by tis researc team giving te same outcome as te PMIS pavement condition score tat was conducted by te San Antonio District s PMIS surveyors. At tis point, te researc metodology as proven itself to furnis useful output data. It as autoritatively proven te ypotesis tat poor substrate condition will adversely impact te performance of a new seal coat. Tis is sown by te early flusing of AC road FM 541 East and EM road FM Tis is furter confirmed by te fact tat te AC roads tat were sot on top of flused substrate are losing teir texture dept at a rate tat is faster tan tose wose substrate was not as igly flused prior to te new seal. Wile tis is certainly not new knowledge to te members of TxDOT and te cip seal industry, tis is te first time in Texas and by te autor s knowledge in Nort America tat a quantitative measurement as been use to prove wat as been suspected for quite a long time. Tus, te metodology used in tis project is proving itself to be very valuable in developing a rational metod using engineering measurements to objectively evaluate te post-seal performance of cips seals. 17

18 BIBLIOGRAPHY Galeouse, L., J.S. Moultrop, and R.G. Hicks. (2003). Principles for Pavement Preservation: Definitions, Benefits, Issues and Barriers, TR News, September/October 2003, pp.4-9. Gransberg, D.D. and M. Zaman, Analysis of Emulsion and Hot Aspalt Cement Cip Seal Performance, Journal of Transportation Engineering, ASCE, Vol.131 (3), Marc,, pp Gransberg, D.D., Using a New Zealand Performance Specification to Evaluate US Cip Seal Performance, Journal of Transportation Engineering, ASCE, Vol. 133 (12), December, pp Gransberg, D.D., S. Senadeera, and I. Karaca. (1998). Analysis of Statewide Seal Coat Constructability Review, Texas Department of Transportation, Researc Report TX-98/ R, Texas Tec University, Lubbock, Texas. Texas Department of Transportation (2003). Seal Coat and Surface Treatment Manual, Texas Department of Transportation, Austin, Texas. Transit New Zealand, (1981). Standard Test Procedure for Measurement of by te Sand Circle Metods, TNZ T/3, Wellington, New Zealand. Transit New Zealand, (1993). Bituminous Sealing Manual. 2 nd Zealand. Edition. Wellington, New Transit New Zealand, (2002). Notes for te Specification for Bituminous Reseals, TNZ P17, Wellington, New Zealand. Transit New Zealand, (). Cipsealing in New Zealand, Transit New Zealand, Road Controlling Autorities, and Roading new Zealand, Wellington, New Zealand. West, T.M. and Riggs, J.L, (1986). Engineering Economics, Tird Edition, McGraw-Hill Inc. New York, New York, pp