Report Implementation of concrete maturity meters

The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the New Jersey Department of Transportation or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation.

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/239572713 IMPLEMENTATION OF CONCRETE MATURITY METERS Article CITATIONS READS 219 authors, including: Allyn Luke Sun Punurai Rutgers University, Newark, NJ Independent Researcher 17 PUBLICATIONS   156 CITATIONS    PUBLICATIONS   49 CITATIONS    SEE PROFILE Some of the authors of this publication are also working on these related projects: independent research View project screws View project All content following this page was uploaded by Allyn Luke on 23 December 2014 The user has requested enhancement of the downloaded file SEE PROFILE FHWA-NJ-2002-003 IMPLEMENTATION OF CONCRETE MATURITY METERS December 2002 Submitted by Allyn Luke C.T Thomas Hsu Sun Punurai New Jersey Institute of Technology Civil & Environmental Engineering NJDOT Research Project Manager Tony Chmiel In cooperation with New Jersey Department of Transportation Division of Research and Technology and U.S Department of Transportation Federal Highway Administration DISCLAIMER STATEMENT The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein The contents not necessarily reflect the official views or policies of the New Jersey Department of Transportation or the Federal Highway Administration This report does not constitute a standard, specification, or regulation TE CH NI CA L REP O R T S TA ND AR D TI T LE PA GE Report No R ecipi ent’ s Ca tal og N o Government FHWA-NJ-2002-003 State of New Jersey Title and Subtitle R ep or t Da t e Implementation of Maturity Meters Jan 2003 Performing Organization Author(s) Allyn Luke, C.T Thomas NJIT Performing Organization Report No Hsu FHWA-NJ-2002-003 Performing Organization Name and Address 10 Work Unit No New Jersey Department of Transportation CN 600 Trenton, NJ 08625 11 Contract or Grant No 997943 13 Type of Report and Period Covered 12 Sponsoring Agency Name and Address 1/2001-1/2003 Federal Highway Administration U.S Department of Transportation Washington, D.C 14 Sponsoring Agency Code 15 Supplementary Notes 16 Abstract Practical considerations for implementing the Maturity Method to estimate the in-place strength of concrete are presented Several recommendations are made for adopting ASTM C1074 to NJDOT highway projects Confirmation of strength potential required by C1074 is achieved using early maturity testing of companion concrete samples The procedure assures applicability of the predictive equation to the specific structure Tolerance factor analysis is used to calculate the 10th percentile of strengths to determine statistical adjustment to maturity results Confidence is increased by be adding valid predictions to the data set from which the strength maturity relationship is derived and from which statistical adjustments are made A method for establishing initial strength-maturity relationships for quality assurance purposes and then refining the predictions with a data base are described Field trials in the use of the maturity method were held in all three NJDOT regions to verify the method and train personnel A draft specification for the Maturity Method is presented Also presented is a draft manual describing how the method should be applied to NJDOT projects A step-by-step example is included A second manual details instrumentation and methods for making temperature measurements A three part course to train field personnel in the use of the maturity method was developed and is described in the report 18 Distribution Statement 17 Key Words Maturity Method, Concrete Strength Prediction, General Tolerance Factor 19 Security Classification Unclassified Form DOT F 1700.7 (8-69) 20 Security Classification (of this page) Unclassified 21 No of Pages 114 22 Price Table of Contents PROJECT SUMMARY .1 SYNOPSIS DISCUSSION OF MODIFICATIONS 15 MANUAL FOR PREDICTION OF IN-PLACE CONCRETE STRENGTH USING THE MATURITY METHOD 31 TRAINING OF NJDOT PERSONNEL TO USE THE MATURITY METHOD 48 FIELD VS STANDARD CURED CYLINDERS AND STRUCTURAL STRENGTH .64 OBSERVATIONS ON TEMPERATURE EXTREMES .66 CONCLUSIONS .70 RECOMMENDATIONS 71 APPENDIX A: LITERATURE REVIEW 72 APPENDIX B: LABORATORY TESTING 83 APPENDIX C: FIELD TRIALS 95 BIBLIOGRAPHY 108 ii Table of Figures Figure Chart of Kleiger’s data, from Maltrolta, showing “cross-over effect” 10, 75 Figure Temperature and maturity curves for Falls Creek Bridge drilled shaft 13, 80 Figure Alternative cylinder predictions for Scotch Road concrete .18 Figure Alternative predictions for Scotch Road abutment two 20 Figure Strength-maturity curves for studied mixes 22 Figure Strength-maturity approximation curves 23,.37, 60 Figure Visualization of characteristic strength .27 Figure The compressive strength-maturity relation .44 Figure Strength prediction within acceptable tolerance vs maturity 45 Figure 10 Strength-maturity relation after refinement process .47 Figure 11 Scotch Road temperatures and strength prediction over time 64 Figure 12 Secaucus Rd Bridge 11-day temperature history 66 Figure 13 Route 33 temperatures and strength prediction over time .68 Figure 14 Maturity is adjusted area under temperature-time curve 73 Figure 15 Step one to determining the datum temp or Q .83 Figure 16 Datum temperature determined from K vs curing temperature .84 Figure 17 Q value from natural log of K over inverse of absolute temperature 85 Figure 18 Strength-maturity relationship for Secaucus Road mixes .87 Figure 19 Inverse of strength over inverse of age 88 Figure 20 Datum temperature for Scotch Road abutment concrete .89 Figure 21 Q for Scotch Road abutment concrete 89 Figure 22 Strength-maturity curve for Scotch Rd abutments with cylinder strengths 90 Figure 23 Step towards maturity parameters for Rt 33 concrete 91 Figure 24 Determination of datum temperature for Rt.33 concrete 91 Figure 25 Q for Rt 33 concrete 92 Figure 26 Strength-maturity relationship for Rt 33 concrete 92 Figure 27 VES maturity parameters step 93 Figure 28 VES datum temperature 6.3°C .94 Figure 29 VES Q value 94 Figure 30 Maturity and strength prediction using custom equation function 96 Figure 31 Secaucus Road Bridge test location 98 Figure 32 Secaucus Road Bridge test location 98 Figure 33 Route & VES logger temperature curves .106 Figure 34 Strength-maturity relationship for VES concrete 107 iii PROJECT SUMMARY The major intent of this study is to explain how the maturity method can be used to estimate the strength of in-place concrete for highway construction NJIT started studying the maturity method for NJDOT in 1995 to verify the strength of very early strength concrete patches Since then, several other studies on the maturity method have been conducted for NJDOT Collectively, these studies presented a convincing case for utilizing the maturity method to predict the strength of early age concrete in highway structures The purpose of this project was to move the method from an experimental to a practical setting There were five interrelated objectives for this study: To develop a procedures manual for implementing the maturity method To recommend a NJDOT specification for implementing the maturity method To evaluate field vs standard cured concrete cylinders and compare these to the in-place estimates of concrete strength To monitor the maximum temperatures inside large concrete pours To train NJDOT Materials and Construction personnel, contractors and concrete suppliers in the use of the maturity method using three ongoing projects These pilot projects also allowed further study of the temperature behavior of concrete The study began with a review of the literature on the maturity method Conversations on the maturity method were held with other State’s Departments of Transportation, contractors, equipment suppliers and other users of the maturity method were also held This information, coupled with the field experiences of the research team, led to the general conclusion that the maturity method is an effective tool to monitor concrete strength Two manuals were developed to aid field application of the maturity method by NJDOT The first is entitled, “Manual For Prediction Of In-Place Concrete Strength Using the Maturity Method,” which summarizes the overall procedure for applying the maturity method to highway construction The second manual is a how-to-do-it guide, entitled, “Detailed NJDOT Manual for the Maturity Method,” describes the instrumentation and methods for making temperature measurements, performing maturity computations and predicting concrete strength The procedures manual is based on ASTM C 1074 “Standard Practice for Estimating Concrete Strength by the Maturity Method.” Nine important modifications of ASTM C 1074 were made in order to practically implement the maturity method on NJDOT projects These modifications are incorporated into the procedures manual They are: Either the temperature-time or the equivalent age maturity methods are suitable for highway projects provided that the strength-maturity relationship has been verified The temperature-time method is preferred on account of its simplicity When implementing the temperature-time method, three possible values for the datum temperature are specified The choice is dependent on how quickly the concrete gains strength Prior laboratory testing of the design mix is important for reliable strength prediction on strength critical applications For quality assurance means for starting a testing program without prior laboratory testing are suggested Preparation and testing of field cured cylinders is important for reliable in-place strength prediction The strength-maturity relationship should be verified in order to be sure that it is applicable to the structure In order to increase confidence in the prediction, the results of verification tests should be added to the maturity data base and the maturity predictive model for the concrete mix should be recomputed When expressing the strength-maturity relationship as an equation, the use of Excel’s logarithmic Trendline is recommended An adjustment of the prediction is required to yield the 10th percentile of strengths recommended by ACI Regular training sessions in the use of the maturity method should be given to NJDOT Materials and Construction personnel, contractors and concrete suppliers Three innovations are presented among these modifications The first is the requirement that the strength-maturity relationship be verified For strength critical applications, companion cylinders are cast and match cured along with the structure When the strength-maturity relationship is able to reasonably predict the strength of those cylinders at three different early ages, the relationship is considered validated and can be applied to the structure The second innovation is that the results of verification testing should be added to the data set from which the predictions are made and then the predictive equation is recomputed By this procedure confidence in the prediction grows as more test results become available The third innovation is a method for starting a quality assurance program with no prior laboratory testing An assumed prediction is checked and refined through the verification process A specification that places the responsibility for implementing the maturity method is presented The decision-making responsibilities will still reside with the engineer The specification requires that the contractor to submit a plan for the engineer’s approval prior to beginning the work detailing how the maturity method will be applied The specification also requires certification of persons making the maturity measurements and calculations Currently, only one commercial company provides any certification for the maturity method However, this limitation does not eliminate the need for this provision For this approach to be successful, both NJDOT and the contractor must be prepared to accept and act on the predictions When applying the maturity method for quality assurance there will still be a need for standard cured concrete test cylinders, although use of fewer cylinders than currently utilized is envisioned However, when the maturity method is used for strength critical operations, prior preparations and field cured cylinders are essential The field trials also revealed that elevated curing temperatures, approaching that of mass concrete, frequently occur in highway structures The reason is thought to be the increased use of more active cements at higher cement factors and lower watercement ratios Such behavior can occur where it is least expected, like on bridge decks, which have large surface to volume ratios that should readily dissipate heat Temperature monitoring is useful for identifying these situations and avoiding the detrimental effects of high temperatures on concrete durability To familiarize NJDOT personnel with the use of the maturity method a three part course was developed and is described in the report The first part is a general classroom session that introduces maturity concepts and methods The second part is a laboratory session that provides practice in making temperature measurements and performing maturity computations The third part is a field session where the new users actually apply method under actual field conditions on an active project Periodic offerings of this three part course are recommended During the course of this study, field trials using the maturity method were held in all three NJDOT regions These trials revealed two significant findings First, it was found that current winter concreting procedures may overheat concrete pours, creating high temperature conditions that exceed even the worst of summer concreting operations The second finding has to with the effects of a typical chloride inhibitor on the temperature behavior of concrete It was found that calcium nitrite modified the rapid temperature rise normally associated with the early strength gain of concrete Chloride inhibited mixes followed ambient temperature changes quite closely, with positive effects on the rate of strength gain and the ultimate strength coolest, and therefore the weakest, area? From Figure 12 we choose the Girder1 location This location, at the center of the bridge and in contact with the girder, is both the critical structure and the coolest location Applying the Custom Equation functions of the ACR software to the Girder1 data, Figure 30 results Figure 30 Maturity and strength prediction using custom equation function We used one TrendReader custom equation to compute the maturity, and another to estimate the strength So there are two plots shown on the graph According to the prediction, the deck concrete reached almost 5,000 psi, the expected 28-day strength, in 11 days This prediction is not that surprising, considering the temperature profile of this pour The heating of the deck kept the average curing temperature above 35° C for days This average concrete temperature is higher than those observed during summertime concreting conditions on the Region South field trial, discussed below These elevated temperatures greatly assist concrete’s development of strength Other durability properties may not be similarly enhanced, but that question will have to be the subject of another study We have a good idea of how the temperatures got and stayed so high NJ specification 501.17 B.1.requires that concrete temperatures not be lower than 16° C When asked, the consultant in charge of monitoring the temperature advised that they were maintaining the temperature at 20° C, not an unreasonable cushion They 96 measured the surface temperature every few hours with a noncontact infrared thermometer and made adjustments as necessary This measurement has no way of accounting for the high temperatures in the core of the deck It is probable that, even though the surface temperature was maintained in reasonable accordance with the specifications, the internal concrete temperature was held at uncomfortably high levels, to the probable detriment of the durability of the concrete and the bottom-line of the contractor A couple of other observations are important First and this is not unique to the observations of this study the core temperatures of common structures get remarkably high; in this case, the location at the center of the deck, only four to five inches from air, reached a temperature of 65° C (150° F) This is pretty hot, considering that NJ 501.17 B.3.puts a limit of 38° C on concrete temperatures These elevated temperatures at the heart of the structures are present in virtually all observations The implications of this fact need to be considered in further studies Finally, it is proposed that temperature monitoring can be useful by itself It is suggested that the temperature signatures from a concrete mix should be more or less the same on a day to day basis Observing the temperature curves to see how long it takes before the temperature starts to rise, the overall temperature increase, how long it takes to reach the peak temperature and how long it stays there, and to see the amount of time it takes for the mix to return to ambient conditions will form a temperature signature and will be a way of checking that the concrete one is using today is the same as the one was using yesterday We believe that differences in the temperature profiles of our observations of the first deck suggest that there was something different about the concrete placed in those two different locations Figures 31 and 32 are the temperature histories of the concrete cast for deck on November 10, 2001 97 Figure 31 Secaucus Road Bridge test location Figure 32 Secaucus Road Bridge test location Location was above the pier and was cast first around 10:00 a.m Location was at the center of the span and was not cast until about noon Both locations were covered with wet burlap and thermal blankets Because of the remote location of the 98 loggers we were not able to hook-up the equipment and start monitoring until after noon Agreement of the ambient temperatures and later thermocouple readings positively link the readings at the different locations The temperature behavior of the slabs was quite different at the two locations Location exhibits a typical temperature curve for concrete It reaches a peak temperature after about 12 hours and gradually cools off After days the heart of the deck has still not started to track the ambient temperature Compare the typical behavior of figure 31 with figure 32 The temperature at location rises only about 4°C above the ambient temperature on the first day The temperature then tracks the ambient temperature up and down after that It maintains a temperature above the ambient temperature of only 5°C or 6°C for about a day, then slides below 10°C on the second night with the air By the third day, it is following the ambient temperature pretty closely What these different temperature responses mean? Both locations were cast with the same concrete delivered that day for the job, within a couple of hours, and are separated by only 50 or 60 feet, both covered by wet burlap and thermal blankets It would be expected that they would react in more or less the same way, but they don’t Why? The answer would not be found until the data from the Rt 33 Brooks Creek Overpass, cast in July 2002, was analyzed That bridge also used a concrete mix chloride inhibited with calcium nitrite The observation on that site, and later confirmed in the lab, was that the calcium nitrite seems to have an inhibiting effect on the temperature dynamics of the mix Somehow, the calcium nitrite seems to cool the initial hydration reaction to the point that under the summertime conditions of Rt 33 all the concrete on the bridge deck did was to follow the ambient temperature It exhibited no extra heat generation, as would be typically expected That is exactly what happened at location on the Secaucus bridge, the concrete essentially follows the ambient temperature The conclusion is that there was no calcium nitrite present 99 in the mix at location Samples taken from that location could confirm this conclusion Simple temperature monitoring can reveal other things as well The temperature record of the parapet from the Secaucus Bridge test 3, shown in figure 12, is an example January 25, 2002, was a windy day It would appear that, sometime around 9:00 p.m., the wind blew the blankets off the parapet It was cold, as evidenced by a drop to 5° C It warmed a little perhaps the blanket ended up partially covering the area around the sensor but around 7:00 a.m it seems that a conscientious worker replaced the blanket and the under-blanket temperature rose back in line with the rest of the structure This simple scenario explains the facts; whether it describes what actually happened is hard to say for sure, but something clearly happened, and it is generally better to know that something happened than not to know Simple temperature monitoring can tell you things Scotch Road Bridge Integral Abutments Ewing Integral abutments for the Scotch Road Bridge were cast using a Class B pump mix, NJDOT #R570449, on June and June 12, 2002 Companion cylinders were cast at the same time and kept in a standard curing box adjacent to the pours The thermal history for the abutment and cylinders, along with the strength prediction for the bottom of the abutment, in contact with the ground, are shown in figure 11 100 Scotch Rd Bridge Test Temperatures and Bottom Center Strength Prediction 4000 70 Temperture (°C) 50 40 Logger Bot Cent Bot Side Mid Cyl1 Cyl2 Str Pred 3000 2500 2000 1500 30 1000 20 10 12-Jun-02 Predicted Compressive Strength (psi) 3500 60 500 13-Jun-02 14-Jun-02 15-Jun-02 Time 16-Jun-02 17-Jun-02 18-Jun-02 Schmidt Hammer 3600 psi @ days Field Cured Cylinders 3700 psi @ days Figure 11 Scotch Road temperatures and strength prediction over time The strength is predicted to be 4000 psi in days This estimate appears reasonable, as it compares well with Schmidt hammer tests showing 3600 psi and field-cured cylinders of 3700 psi at days Most significantly, the prediction is validated by the use of field-cured cylinders, marked with red triangles on the strength-maturity curve for this mix, Figure 22, presented again here 101 Strength TTF Maturity Relationship Validated by Field Cylinders 7000 Compressive Strength (psi) 6000 5000 Excel's Logarithmic Trendline 4000 y = 1128Ln(x) - 1846.9 R2 = 0.9924 3000 This equation used to predict TTF strength on graphs 2000 1000 0 100 200 300 400 500 600 700 800 900 1000 Maturity (deg C day) Figure 22 Strength-maturity curve for Scotch Rd abutments with cylinder strengths The temperature data were emailed to NJIT in a comma delineated file format compatible with Excel After plotting the temperature history, the bottom center temperature curve was chosen for maturity analysis as it displayed the lowest temperatures in the structure Since the maturity value is but the means to estimating the strength, figure 22, showing the first days of the second abutment pour, dispenses with maturity and shows only the strength prediction for the bottom center based on the datum temperature and the strength-maturity relationship derived above Using a Texas DOT method, early age predictions at 30, 75, and 150 °C days, correspond well to cylinder tests at 1, 2, and days, Therefore, because the strength of cylinders cast of the same concrete as the structure closely match the maturity prediction, one is assured that the concrete that is in the structure is the same as that for which the strength maturity relationship applies One is able now to confidently use the strength-maturity relation to predict the strength of the structure, which was done in Figure Only tests of cores taken from the structure can be 102 more definite measures of the actual structural strength It is proposed that CIPOC cylinders (cast-in-place punch-out cylinders) cast into the sidewalk areas of future tests on decks will confirm this assertion This test will be conducted at first opportunity This Texas method satisfies the third limitation listed in section 5.3 of ASTM C 1074 Namely, the method requires supplemental confirmation of the strength potential of the concrete used in the structure In this test the supplemental confirmation comes, not from a nondestructive test like the Schmidt hammer used on this project, as suggested by ACI 228-1(34), but from standard cylinder testing, differing from current procedures only in that an additional parameter, maturity, is measured and recorded at the time the compression testing is done Extra early-age testing should be undertaken to validate the strength prediction being used to estimated concrete strength for strength-critical purposes The Texas method will revolutionize use of the maturity method, regardless of whether time-temperature factor or equivalent-age computations are used, giving the user assurance that the prediction is correct Route 33 Extension Bridge Deck Freehold A concrete deck was cast for the Brooks Creek overpass, extending Route 33, on July 3, 2002, using a Class A chloride-inhibited mix, ID R307159 Due to high summertime temperature conditions, the concrete set was retarded and the deck poured in the early morning All of the luck was not good for temperature data recording In the bright sunlight it was difficult to read the computer screen while programming and retrieving the data Inevitably this eventually would lead to some kind or error Worse still, one of the loggers stopped working properly and all its data was lost In the end only results from the midspan locations were collected for the first seven days Figure 13 shows all the temperature data and the strength prediction for the center edge location 103 45 7000 40 6000 35 5000 30 4000 25 3000 20 2000 15 7/2/2002 Ambient Mid Mat 7/3/2002 7/4/2002 7/5/2002 Cpan Edge 7/6/2002 Girder Underc 7/7/2002 7/8/2002 Top mat Str Pred 7/9/2002 Compressive Strength (psi) Temperture (°C) Rt.33 Bridge Test Retarded, Chloride Inhibited Deck Concrete 1000 7/10/2002 Time Figure 13 Route 33 temperatures and strength prediction over time What is observed is that the ambient temperature experienced the most fluctuation, moving between 17°C and 43° C on July A thermocouple taped to the steel deck pan in the middle of the traffic lanes, followed the ambient temperature at night but was with the rest of the deck during the day Most of the deck stayed within 2°C to 3° C of each other throughout the day as the deck temperatures lagged the ambient temperature The only exception was the gage at the top of the steel mat It was close enough to the surface to feel the effects of the daytime sun So, its temperatures are perhaps 5°C to 6° C higher than the deck pan or the edge around mid day The data display an unusual temperature effect for concrete Concrete normally reaches its peak temperature 20 °C or 30 °C above the ambient temperature after about a day then cools off back to the ambient after a few days to a month The temperature of this Route 33 concrete closely follows the ambient temperature from the beginning The laboratory mix exhibited a similar behavior At first this effect was attributed to the retarding admixture however, lab tests showed that a mix without the 104 retarding admixture exhibited the same behavior The conclusion was that the chloride inhibitor was causing this effect This effect was also seen on the Secaucus Road Bridge deck concrete highlighted in figures 30 and 31, above Originally, it was thought there might be something wrong with the concrete at test location 2, at the center of the span because it did not behave typically, as had the temperatures at test location It also followed the ambient temperature almost right from the start It too was a chloride inhibited mix for a bridge deck, basically like that used for the Brooks Creek Bridge It seems that the proper interpretation of that data now is that the concrete at location had no inhibitor as it should have It is most interesting that this attenuation of the typical temperature effects seems to have acted beneficially on the ultimate strength gain over the first days for this Rt 33 bridge The prediction of the laboratory derived strength-maturity relationship was 43 percent low The average of two standard test cylinders indicated a compressive strength of 6,650 psi at days This error is due to the application of a strength-maturity relationship that was developed at 22° C to field conditions averaging 32° C The high early-age temperature had an accelerating effect on the strength Additionally, the lower differential temperatures should have been beneficial to the durability of the concrete, reducing the possibility of temperature induced cracking Perhaps a most interesting application of the calcium nitrite, the active chloride inhibiting agent, might be for controlling heat gain in mass concrete Further research should seek to discover the reasons for this effect and find ways to control it Route1 VES Trenton Highway joint repair patches were cast on August 18, 2002, using NJDOT mix # R307150, in preparation for an asphalt overlay on northbound Route1 between Market Street and Olden Avenue in Trenton, NJ Extreme summertime conditions prevailed; ambient air temperatures of over 40° C (104º F), along with concrete temperatures of 72° C (160º F), were measured Concrete beams, suspended over the pours on boards laid across the corners, were subjected to the same temperature 105 conditions as the patch and covered with wet burlap and thermal blankets The required 350-psi flexural strength needed to open the road to traffic was reached in less than six and half hours Figure 33 Route & VES logger temperature curves Figure 33 shows the temperature measurements for that day recorded using an ACR SmartReader It is of interest that these extreme temperature conditions reversed what is usually considered the critical location In previous work, it had been observed that temperatures close to the surface and in the corner, close to the forms or old slabs, usually tended to be the coolest, and that the center of the slab, away from the edges, to be the warmest In this case, due to the bright sun and very hot conditions, the normal expectation was reversed The surface had the highest temperature, and the center of the slab, insulated from the heat of the sun, the lowest The exception was the corner bottom, with heat sinks towards the underneath of the adjacent slab, this location had the coolest temperature Having the lowest temperature, this channel was selected as the critical area upon which the maturity would be computed Figure 33 also shows the resulting maturity factor 106 plotted over time with the temperatures Applying the strength-maturity relationship, shown in figure 34, the strength is predicted Strength TTF Maturity Relationship VES Concrete Compressive Strength (psi) 5000 4000 y = 1179.6Ln(x) - 3675.4 3000 2000 1000 0 100 200 300 400 500 600 700 800 900 1000 Maturity (deg C hr.) Figure 34 Strength-maturity relationship for VES concrete Applying the prediction contained in figure 34 the target flexural strength of 350 psi, reached at a maturity of 160 °Chrs., was reached in hours Testing of the beams was only conducted at six and half hours, so it was not possible to check our predictions However, based on previous experience with this VES concrete, the target strength of 350 psi is often reached when the temperature reaches its peak If that held true for this mix, the peak was reached around 1:00 p.m., which indicates that the target strength could have been achieved, in these conditions, in a bit more than four hours If the normally used critical point, the top corner, had been used (a mistake), the target strength would have been reached in just over three hours, less time than it takes for many mixes to set ! 107 BIBLIOGRAPHY Standard Practice for Estimating Concrete Strength by the Maturity Method, ASTM C 1074-93 Annual Book of ASTM Standards, Vol 4.02 Concrete and Aggregates Saul, A.G.A., Principles Underlying the Steam Curing of Concrete at Atmospheric Pressure, Magazine of Concrete Research, Vol 2(6), page 127-140, 1951 Klieger, Paul, “ Effect of Mixing and Curing Temperature on Concrete Strength”, Proceedings, American concrete Institute, Vol 55, page 1063-1081, 1958 Rastrup, Erik, “Heat of Hydration in Concrete”, Magazine of Concrete Research, Vol 6(17), page 79-92, 1954 Freisleben Hansen, P and Peterson, E.J., Vinterstobing af beton, Anvisning 125, Statens, Byggeforsknongsinstitut, Copenhegen, 1982, 96 (in Danish) McDanial, A.B., “Influence of Temperature on the Strength” University of Illinois Eng Expt Stn Bulletin 81, page 24 ,1915 Wiley, C.C., “ Effect of Temperature on the Strength of Concrete”, Engineering News Record, Vol 102 (5) , page 179-181,1929 Timms, A.G and N.H Withey , “ Temperature Effects on Compressive Strength of Concrete”, Proceddings, American Concrete Institute, Vol 30 , page 159-180, 1934 Price, W.H., “Factors Influencing Concrete Strength” Proceedings, American Concrete Institute, Vol.47 , page 417-432, 1951 10 McIntosh, J.D , Electrical Curing of Concrete”, Magazine of Concrete Research, Vol 1(1), page 21 , 1949 11 Nurse, R.W., “Stem Curing of Concrete”, Magazine of Concrete Research, Vol 1(2), page 79-88, 1949 12 Bergstrom, Sven C., “Curing Temperature, Age and Strength of Concrete”, Magazine of Concrete Research, Vol 4(14), page 61-66, 1953 13 Plowman, J.M.,”Maturity and the Strength of Concrete”, Magazine of Concrete Research, Vol 8(22), page 13-22, 1956 14 Nykanen, A., “ Hardening of Concrete at Different Temperatures, Especially Below the Freezing Point, Proceeding, RILEM Symposium on Winter Concreteing (Copenhagen 1956), Danish Institute for Building Research Copenhagen, Session BII 108 15 Carino, N.J “Temperature Effects on Strength-maturity Relations of Mortar”, NBSIR 81-2244, U.S National Bureau of Standard, March 1981 16 Marshall ,”Discussion of Refference 11, Magazine of Concrete Research, Vol 8(24), page 169-183, 1956 17 MacIntosh, J D., “The Effects of Low-temperature Curing on the Compressive Strength of Concrete”, Proceeding, RILEM Symposium on Winter Concreteing (Copenhagen 1956), Danish Institute for Building Research Copenhagen, Session BII 18 Maltrolta,V.M., “Maturity concept and the Estimation of Concrete Strength, Information Circular IC 277, Department of Energy Mine resources (Canada), November 1971 19 Verbeck, G.J and C.W Foster, “Long Time-Study of Cement in Concrete Chapter 6, The Heats of Hydration of Cements” Proceedings, American Society for Materials” ,1950 20 Carino, N J., “The Maturity Method: Theory and Application” , ASTM Journal of Cement, Concrete and Aggregate, Vol.6(2), Winter, page 61-73, 1984 21 Carino, N J., Lew, H.S, “Temperature Effects on Strength-Maturity Relations of Mortar”, Vol.80(3) , May-June, page 177-182, 1983 22 Bernhardt, C.J., ”Hardening of Concrete at Different Temperatures, Proceedings, RILEM Symposium on Winter Concreteing (Copenhagen 1956), Danish Institute for Building Research Copenhagen, Session BII 23 Chin, F.K., Relation Between Strength and Maturity of Concrete, Journal of American Concrete Institute, Vol 68(3) page 196, 1971 24 Carino, N J., “Closure to discussion of Carino, N J., Lew, H.S., and Volz, C.K., Early Age Temperature Effects on Concrete Strength Prediction by the Maturity Method“, Journal of American Concrete Institute, Vol 81(1) page 98, 1984 25 Ansari, F and Luke, A “High Early Strength Concrete for Fast-track Construction and Repair,” Report to NJDOT, March 29, 1996 26 Ansari, Luke, Vitillo, Blank, Turhan, “Developing Fast Track Concrete for Pavement Repair,” Concrete International Vol 19 (5), pages 24-29, May 1997 27 Ansari, F , Luke, A and Dong, “Development of Maturity Protocol for Construction of NJDOT Concrete Structure,” Report to NJDOT, July 27, 1999 109 28 Dong, Luke, Vitillo and Ansari, “Use of the Maturity Method During Highway Construction,” Concrete International Vol 24 (2), pages , Feb 2002 29 Carino, N.J., “ The Maturity Method” HandBook on Nondestructive Testing of Concrete,eds V.M.Malhotra and N.J Carino, Boca Raton, Fl:CRC Press,1991 30 Carino, N.J and Tank, R.C., “Maturity Functions for Concretes Made With Various Cements and Admixtures,” ACI Materials Journal, V.89, No.2, pages 188196, March 1992 31 Angelo, W., “Embedded Devices Speed Job,” ENR, Aug 19, 2002 32 “Maturity Meters: A Concrete Success,” FHWA Focus, page 1, October 2002 33 “In-place Methods to Estimate Concrete Strength,” ACI Manual of Concrete Practice 1999, Part 2, Report of ACI Committee 228 35 Rens, K.L., Lacome, Matthew, Hoang, Trieu “Concrete Maturity: New Approaches in Developing Maturity-Strength Relations for use in Fast-Track Pavement Applications” Presentation given at 2001 ACI Convention 34 Tikalski, P.J., Scheetz, B.E., Tepke, D.G “Using the Concrete Maturity Meter for QA/QC,” Report 2002-20, Pennsylvania Department of Transportation, 2001 35 Texas Manual of Testing Procedures, Sec 27, Tex-426-A 110 View publication stats ... that the maturity method developed out of work on electrical and steam curing of concrete by Nurse and Saul Saul coining the term maturity and stated the Maturity Law as: Concrete of the same... Estimating Concrete Strength by the Maturity Method”(1) The basic premises of the maturity method are: (1) concrete derives strength from the hydration of cement; (2) the hydration of cement produces... Concrete Strength by the Maturity Method.” (1) This standard defines maturity as “the extent of cement hydration in a concrete. ” Maturity is evaluated from the recorded temperature history of