Fatigue behavior of high volume fly ash
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  • International Journal of Civil JOURNAL OF CIVIL(IJCIET), ISSN 0976 – 6308 INTERNATIONAL Engineering and Technology ENGINEERING AND(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME TECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 3, Issue 2, July- December (2012), pp. 404-415 IJCIET© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2012): 3.1861 (Calculated by GISI)www.jifactor.com © IAEME FATIGUE BEHAVIOR OF HIGH VOLUME FLY ASH CONCRETE UNDER CONSTANT AMPLITUDE AND COMPOUND LOADING Aravindkumar.B.Harwalkar1 and Dr.S.S.Awanti2 1 Associate Professor, Department of Civil Engineering, P.D.A.College of Engineering, Gulbarga, Karnataka State, India. e-mail: harwalkar_ab@yahoo.co.in 2 Professor and Head, Department of Civil Engineering, P.D.A.College of Engineering, Gulbarga, Karnataka State, India. e-mail: ssawanti@yahoo.co.inABSTRACT Road projects in future have to be environmental friendly and cost effective apartfrom being safe so that society at large is benefited by the huge investments made in theinfrastructure projects. To achieve this, component materials of the pavement system have tobe optimized with reference to cost effectiveness, sustainability and fatigue behavior. Thispaper presents a study on fatigue behavior of high volume fly ash concrete (HVFAC) andconventional concrete (PCC) under constant amplitude fatigue loading. Also behavior ofHVFAC was studied under compound fatigue loading. In the present investigation HVFACmix with cement replacement level of 60% with low calcium fly ash has been used. A total number of 95 prism specimens of HVFAC were tested under constantamplitude fatigue loading. Also 100 prism specimens of PCC were tested under constantamplitude fatigue loading for comparative studies. All prism specimens were of size75mm×100mm×500mm and were tested under flexural fatigue loading using haiver sinewave loading. Frequency of fatigue loading was kept at 4Hz. Lognormal model was verifiedfor probability distribution of fatigue life. Studies indicated that lognormal model wasacceptable for fatigue life distributions at all stress levels for both HVFAC and PCC. Theparameters of distribution exhibited dependency on stress levels and type of concrete.Relations between stress level and fatigue life were developed for both HVFAC and PCC.These relations were found to be dependent on type of concrete. A total number of 24 prism specimens were tested under compound fatigue loading.Based on the results of compound fatigue loading the validity of Miner’s hypothesis for highvolume fly ash concrete was verified. It was found that Miner’s hypothesis gives both unsafeand over safe predictions of failure. Miner’s sum was found to be dependent on type ofcompound loading and sequence of loading. 404
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMEKeywords: Compound fatigue loading; High volume fly ash concrete; Probabilitydistribution; lognormal.1. INTRODUCTION Fatigue strength is an important property which has to be taken into account in thedesign of various concrete structures requiring long fatigue life. Especially the understandingof the behavior of a concrete road under fatigue loading is vital for the design and theperformance prediction. Also there is a need for optimization of materials in the rigidpavement system with regard to long term fatigue resistance at lowest cost and ecologicallysound choices. Many researchers have carried out studies on developing fatigue models for plainconcrete. Majority of the researchers [1-3] have developed the fatigue model relating thestress level (S) which is defined as the ratio of maximum stress applied in cyclic loading tostatic flexural strength, to number load cycles to failure (N), termed as fatigue life. Thisrelation is commonly called as Wholer equation. The second form of fatigue model given byVesic et al [4] and Treybig et al [5] is a power equation relating S and N. Jakobsen et al [6]included the effect of ratio of minimum stress to maximum stress in cyclic loading, which isknown as stress range (R), in the S-N relation for fatigue. Hsu [7] developed a more generalexpression for fatigue strength involving four variables i.e., S, N, R and period of cyclicloading (T). But the most commonly used fatigue model for design of concrete pavements isthe one given by Wholer equation. In literature [8-9] variable amplitude fatigue studies have been carried out on plainconcrete to verify the validity of Miner’s hypothesis. Miner’s hypothesis assumes thatdamage accumulates linearly with the number of cycles applied at a particular stress level. Asper Miner’s hypothesis the failure criterion is written as: ---------------- (1) Where ni = number of cycles applied at stress level i Ni = number of cycles to failure at stress level i k = number of stress levels used Studies carried out by Siemes (8) on plain concrete proved the validity of Miner’srule. But the studies carried out by Holmen (9) found variable amplitude loading to be moredamaging than that predicted by Miner’s hypothesis. As per the definition given by Mehta [10], a concrete having minimum cementreplacement level of 50% by fly ash is termed as high volume fly ash concrete (HVFAC).Limited studies [11-13] are available on fatigue behavior of HVFAC. Ramkrishnan et al [13]have developed an S-N relation for HVFAC with cement replacement level of 58% usingthird point flexural fatigue loading at a frequency of 20Hz. In the development of S-N model it has been assumed that the non dimensional term‘S’ eliminates the influence of static ultimate strength of concrete and hence eliminates theeffect of water-cement ratio, type and gradation of aggregate, type and amount of cement, ageof concrete. But there are concerns over influence of static strength of concrete on S-Nrelation due to variation in fracture toughness. There is also very limited literature availableon fatigue behavior of HVFAC under compound and variable amplitude fatigue loading. 405
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME2. RESEARCH SIGNIFICANCE AND SCOPE In the present investigation an attempt has been made to study the fatigue behavior ofHVFAC under constant amplitude and compound fatigue loading. Multistage constant amplitudeloading has been used as compound fatigue loading in the present investigation. The fatigue testresults of HVFAC were compared with that of reference concrete (PCC). To investigate the fatiguebehavior a series of prism specimens of size 75mm×100mm×500mm were tested under flexuralfatigue loading. In the present investigation HVFAC mix satisfying the criteria of pavement quality concretewas developed using a cement replacement level of 60% with low calcium fly ash. A total number of100 PCC prism specimens were tested under constant amplitude fatigue loading. For HVFAC, 95prism specimens were tested under constant amplitude fatigue loading. Probability distributions weredeveloped for experimental results of fatigue lives. S-N relations were established from regressionanalysis of fatigue data. A total number of 24 specimens of HVFAC have been tested undercompound fatigue loading to verify the validity of Miner’s hypothesis.3. LABORATORY TESTS3.1 Materials The ordinary Portland cement from single batch has been used in the present investigation.The coarse fraction consisted of equal fractions of crushed stones of maximum size 20mm and 12mm.Low calcium fly ash satisfying the criteria of fineness, lime reactivity and compressive strengthrequirements [14] has been used in the investigation. Fine aggregate used was natural sand withmaximum particle size of 4.75mm. Polycarboxylic based superplasticizer has been used as high rangewater reducing admixture (HWRA) to get the desired workability. The optimum dosage ofsuperplasticizer for each type of concrete was fixed by carrying out compaction factor test.3.2 Mixture Proportions A minimum grade of M30 which results in a minimum static flexural strength of 3.8N/mm2has been specified for pavement quality concrete by Indian Roads Congress [15]. Trial mixes weredeveloped to achieve M35 grade HVFAC at cement replacement of 60%, which was the optimumreplacement percentage with water to cementitious ratio of 0.3. Water to cementitious ratio utilized inthe investigation i.e., 0.3 was the lowest value that could be used from the limitation of reduction inwater content that can be achieved using HWRA and usage of conventional means of mixing andcompaction. Corresponding conventional concrete was used as reference concrete (PCC). Mixtureproportions of the two types of concrete are shown in table 1. Table 1 Mixture Proportions of Concrete Mixture PCC HVFAC Components Cement (OPC 53 grade) in kg/m3 440 176 Class F fly ash in kg/m3 0 264 Water in kg/m3 132 132 Superplasticizer in liter/m3 15.4 3.5 3 Saturated surface dry sand in kg/m 937.6 858.2 Saturated surface dry coarse aggregate 1059 1059 in kg/m3 406
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME3.3 Test Procedure and Test Results3.3.1 Static Testing Cube specimens of size 150mm×150mm×150mm were used for determining compressivestrength. For static flexural strength, specimens of similar size to that of fatigue specimens have beenused. An effective span of 400mm has been used for both static flexural strength and fatigue strengthdetermination. All the strength properties were determined after a curing period of 28days. Staticcompressive strength and flexural strength values are shown in table 2. Table 2 Mechanical Properties of Concrete Property of concrete/ 28 day compressive strength 28 day static flexural strength Type of concrete in MPa in MPa Conventional concrete 62.3* 6.9* HVFAC60 40.8* 5.3* * Mean value of six specimens3.3.2 Fatigue Testing3.3.2.1 Constant Amplitude Fatigue Testing: Fatigue test specimens were tested under one-thirdpoint loading using frequency of loading as 4Hz. Since the present investigation was aimed atpavement application haiver sine wave form of cyclic loading was used. Typical fatigue test set upand loading pattern used are shown in figures 1 and 2 respectively. All the fatigue specimens weretested after 90 days from casting so as to give allowance for sufficient strength gain. Specimens werecured for 28 days by ponding method and then covered with polythene bags up to 90 days. Minimumstress in fatigue loading was maintained at 1% of maximum stress. Minimum stress was used mainlyto prevent any possible movement of specimens at support during testing and to simulate residualstresses in the pavement to a certain degree. Beyond the upper limits of stress levels used for differenttypes of concrete in the present investigation, the fatigue life values were insignificant to be recordedi.e., they were typically less than 10. For HVFAC at all cement replacement levels the lower limit ofstress level used was based on the criteria, when none of the test specimens failed even after ofapplication of one lakh cycles of fatigue loading. PCC was tested for eight stress levels and HVFACwas tested at seven stress levels. Constant amplitude Fatigue test results for PCC and HVFAC aretabulated in table 3 and 4 respectively. Fatigue life values have been arranged in the increasing orderso as to facilitate probability analysis. Figure 1 Flexural fatigue test setup Figure 2. Typical constsant amplitude fatigue loading 407
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME Table 3 Fatigue Life of PCC at Different Stress Levels Test S=0.85 S=0.81 S=0.76 S=0.71 S=0.65 S=0.61 S=0.57 S=0.53 specimen no. 1 22 84 158 1327 5289 16488 46582 100000* 2 43 97 284 1489 7213 20312 48270 100000* 3 69 105 312 2596 8863 22268 52164 100000* 4 78 152 382 3642 10322 34511 54416 100000* 5 82 184 411 4149 12723 39920 56005 100000* 6 94 198 474 5218 16523 46718 66012 100000* 7 102 288 578 6629 18708 51512 73676 100000* 8 110 432 694 8383 20391 61512 80520 100000* 9 122 682 916 9558 21262 77812 81891 100000* 10 138 730 1182 12009 23992 81800 100000* 100000* 11 ---- ---- ---- ---- 24771 92477 100000* 100000* 12 ---- ---- ---- ---- 27344 100000* 100000* 100000* 13 ---- ---- ---- ---- 32811 100000* 100000* 100000* 14 ---- ---- ---- ---- 40887 100000* 100000* 100000* 15 ---- ---- ---- ---- 44816 100000* 100000* 100000**specimen did not fail after the application of given number of cycles of loading-- data not available Table 4 Fatigue Life of HVFAC at Different Stress Levels Test S=0.80 S=0.75 S=0.70 S=0.65 S=0.60 S=0.54 S=0.50 specimen no. 1 44 78 312 4159 5324 18785 100000* 2 48 102 422 5802 6852 19084 100000* 3 52 146 584 6802 7102 21039 100000* 4 65 182 886 7759 8404 22259 100000* 5 72 212 1092 8759 12723 29384 100000* 6 88 292 1109 9259 14785 32911 100000* 7 92 344 1243 10014 15680 45512 100000* 8 99 459 1422 12008 22348 62214 100000* 9 112 582 1586 14620 28109 68743 100000* 10 120 889 1704 14882 36891 76544 100000* 11 ---- ---- 1959 16822 45841 82477 100000* 12 ---- ---- 2390 16822 49869 86792 100000* 13 ---- ---- 3532 18826 52113 100000* 100000* 14 ---- ---- 4426 23426 59641 100000* 100000* 15 ---- ---- 3962 28110 65869 100000* 100000* * specimen did not fail after the application of given number of cycles of loading -- data not available 408
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME3.3.2.2. Compound Fatigue Testing: Compound fatigue testing was carried out on HVFACspecimens only. Two stage, three stage and four stage constant amplitude fatigue loadings have beenused as compound fatigue loading. In two stage loading test specimen was subjected to a fixednumber of load cycles at a particular stress level in the first stage and after the first stage amplitudewas changed corresponding to second stress level and maintained constant up to failure. In three stagefatigue loading three stress levels have been applied to the test specimen. Fixed numbers of loadcycles were applied for two stress levels and testing was continued up to failure at the third stresslevel. In four stage loading fixed numbers of load cycles were applied for three stress levels and atfourth stress level specimen was tested up to failure. Minimum stress was maintained at 1% of thecorresponding maximum stress for all the specimens. Test results of compound fatigue loading wereused to check the validity of Miners hypothesis for HVFAC.4. PROBABILITY ANALYSIS OF CONSTANT APLITUDE FATIGUE TEST RESULTS Since the fatigue lives for both types of concrete showed larger scatter, an attempt todetermine the probabilistic distributions was made. Few researchers [16-17] have developed Weibulldistribution models for fatigue lives at different stress levels in case of conventional concrete. In thepresent study lognormal distribution models were developed and verified for different stress levels.Conservatively for few specimens which did not fail after the application of one lakh cycles ofloading at some of the stress levels fatigue life value has been taken as one lakh cycles in theprobability analysis.4.1 Determination of Lognormal Distribution Model The probability density function of lognormal distribution model is given by equation (2).The parameters of lognormal distributions are µ and σ which are mean and standard deviation ofobserved ln (N) values. In the equation (2), ‘X’ represents ln(N) values. ………… (2) The values lognormal distribution parameters for all the types of concretes and at differentstress levels are shown in table 5. It can be seen that the parameters of lognormal distribution aredependent on type of concrete and the stress level. Table 5 Lognormal Distribution Parameters for Fatigue Lives at Different Stress Levels Type of concrete Stress level Parameters of log normal distribution µ σ PCC 0.85 4.3450 0.5501 0.81 5.4036 0.7867 0.76 6.1377 0.5925 0.71 8.3841 0.7565 0.65 9.7882 0.6293 0.61 10.8915 0.6321 0.57 11.2150 0.3007 HVFAC 0.80 4.3158 0.3599 0.75 5.5329 0.7742 0.70 7.2237 0.7795 0.65 9.3603 0.5369 0.60 9.9538 0.8700 0.54 10.7820 0.6580 409
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME4.2 Model Verification Probabilistic models developed in the present investigation were tested usingKolmogorov-Smirnov test. For conducting this test, the test statistic D2 was calculated usingequation (3) in which FO (Nj) is the observed distribution of N and FN (Nj) is the hypothesizeddistribution of N and m is the total number of specimens. …………….. (3) The D2 values were compared with critical D2 for the given sample size andsignificance level of 5%. If calculated value is less than critical D2, model is accepted. Thebasic calculations for verification of lognormal model for PCC at stress level of 0.85 areshown in table 6. The D2 values and verification of lognormal distributions for both types ofconcretes at different stress levels are shown in table 7. It can be seen that lognormal modelwas accepted for both types of concretes at all stress levels.Table 6 Kolmogorov-Smirnov Test for Lognormal Distribution for PCC at Stress Level of 0.85Nj j FO(Nj) FN(Nj) D2 for Maximum D2 for 5% Inference = j/m from lognormal D2 from significanc lognormal distribution= lognormal e level and distribution | FO (Nj)- distribution m=10 FN(Nj)| 22 1 0.1 0.0113 0.0887 43 2 0.2 0.1443 0.0557 69 3 0.3 0.4201 0.1201 Lognormal 78 4 0.4 0.5085 0.1085 model for 82 5 0.5 0.5447 0.0447 0.1449 0.41 fatigue life 94 6 0.6 0.6408 0.0408 distribution is 102 7 0.7 0.6946 0.0054 accepted 110 8 0.8 0.7409 0.0591 122 9 0.9 0.7980 0.1020 138 10 1 0.8551 0.1449 Table 7 Kolmogorov-Smirnov Test for Lognormal Distribution at Different Stress Levels Type of Stress level Maximum D2 D2 for 5% Inference concrete from lognormal significance distribution level PCC 0.81 0.1583 0.41 0.76 0.0781 0.41 Lognormal 0.71 0.1230 0.41 models for 0.65 0.0739 0.34 fatigue life 0.61 0.1628 0.34 distributions 0.57 0.1609 0.34 are accepted HVFAC 0.80 0.1445 0.41 in all the 0.75 0.0901 0.41 cases 0.70 0.0868 0.34 0.65 0.0757 0.34 0.60 0.1208 0.34 0.54 0.1462 0.34 410
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME5. DETERMINATION OF S-N RELATION S-N relations were developed by carrying out regression analysis on fatigue test dataof constant amplitude loading. The S-N curves determined for the two types of concretes areshown in figure 3. S-N relations for PCC and HVFAC are shown in equations (4) and (5)respectively along with R2 values where R is the coefficient of correlation. It can be seen thatS-N relations are dependent on type of concrete i.e., on the strength of concrete. In thepresent investigation existence of upper limits of stress levels for fatigue loading, dependenton type of concrete, was observed. The 95% confidence limits using constant variance weredetermined for both PCC and HVFAC. Upper and lower confidence limits along with S-Ncurve for PCC and HVFAC are shown in figures 4 and 5 respectively. Lower confidencelimits are important in design of structures. S = -0.0358Ln(N) + 0.9948 (R2=0.9332) --------------- (4) S = -0.0338Ln(N) + 0.9389 (R2=0.8759) --------------- (5) S-N Curve for PCC and HVFAC 1 y = -0.0358Ln(x) + 0.9948 0.9 R2 = 0.9332 -- Eqn for PCC y = -0.0338Ln(x) + 0.9389 0.8 R2 = 0.8759 -- Eqn for HVFAC Stress Level (S) 0.7 S-N Curve for PCC 0.6 S-N Curve 0.5 for HVFAC 0.4 Log. (S-N Curve for PCC) 0.3 0 20000 40000 60000 80000 100000 120000 Log. (S-N Curve for Fatigue Life in No. of Cycles of Loading HVFAC) Figure 3. S-N Curves for PCC and HVFAC S-N Curve S-N Curve and 95% Confidence Limits for PCC 1 Upper 95% 0.9 y = -0.0358x + 0.9948 confidence 2 limit R = 0.9332 -- S-N curve 0.8 Lower 95% confidence Stress Level (S) limit 0.7 Linear (S-N y = -0.0358x + 1.0439 Curve) 0.6 -- Upper 95% confidence limit eqn 0.5 Linear y = -0.0358x + 0.9457 (Upper 95% -- Lower 95% confidence limit eqn confidence 0.4 limit) Linear (Lower 95% 0.3 confidence 0 2 4 6 Ln(N) 8 10 12 14 limit) Figure 4. S-N Curve and 95% confidence limits for PCC 411
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME S-N Curve and 95% Confidence Limits for HVFAC 1 S-N Curve y = -0.0338x + 0.9389 0.9 R2 = 0.8759 -- S-N curve Upper 95% confidence 0.8 limit Stress Level (S) Lower 95% 0.7 confidence limit 0.6 Linear (S-N Curve) y = -0.0338x + 0.9977 0.5 -- Upper 95% confidence limit eqn Linear (Upper y = -0.0338x + 0.8801 95% 0.4 confidence -- Lower 95% confidence limit eqn limit) Linear (Lower 0.3 95% 0.000 2.000 4.000 6.000 8.000 10.000 12.000 14.000 confidence Ln(N) limit) Figure 5. S-N Curve and 95% confidence limits for HVFAC6. ANALYSIS OF TEST RESULTS OF COMPOUND FATIGUE LOADING Test results of compound fatigue testing along with calculation of cumulative damagefactor for HVFAC are shown in tables 8 to 11. Stress levels shown in the tables 8 to 11 aregiven in the order in which they have been applied to the specimens during testing. Fatiguelives at different stress levels in tables 8 to 11 have been calculated from equation (5).Cumulative damage factor i.e., Miner’s sum varied between 0.824 and 2.103. Miner’s sumshowed dependency on type of compound fatigue loading and also on the sequence ofloading. Table 8. Cumulative Damage Factors for HVFAC for Two Stage Compound Fatigue Loading No. of load cycles applied at Fatigue Life at Cumulative damage Specimen Stress level Stress Level factor no. S=0.55 S=0.6 S=0.55 S=0.6 (n1) (n2) N1 N2 M=(n1/N1)+(n2/N2) 1 20000 20672 99302 22621 1.115 2 20000 21453 99302 22621 1.150 3 20000 24550 99302 22621 1.287 4 40000 27683 99302 22621 1.627 5 40000 25894 99302 22621 1.548 6 40000 19527 99302 22621 1.266Table 9. Cumulative Damage Factors for HVFAC for Two Stage Compound Fatigue Loading No. of load cycles Fatigue Life at Cumulative damage Specimen applied at Stress Stress Level factor no. level S=0.65 S=0.6 S=0.65 S=0.6 M=(n1/N1)+(n2/N2) (n1) (n2) (N1) (N2) 1 2000 9861 5153 22621 0.824 2 2000 15683 5153 22621 1.081 3 2000 13187 5153 22621 0.971 4 1000 17122 5153 22621 0.951 5 1000 15566 5153 22621 0.882 6 1000 19891 5153 22621 1.073 412
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMETable 10. Cumulative Damage Factors for HVFAC for Three Stage Compound Fatigue Loading Fatigue Life at Stress Cumulative Specimen No. of load cycles applied Level damage factor no. at Stress level M=(n1/N1)+(n2/N2) S=0.55 S=0.6 S=0.65 S=0.55 S=0.6 S=0.65 +(n3/N3) (n1) (n2) (n3) (N1) (N2) (N3) 1 40000 6000 2838 99302 22621 5153 1.219 2 40000 6000 3836 99302 22621 5153 1.412 3 40000 6000 4126 99302 22621 5153 1.469 4 20000 10000 3645 99302 22621 5153 1.351 5 20000 10000 3358 99302 22621 5153 1.295 6 20000 10000 5372 99302 22621 5153 1.686Table 11. Cumulative Damage Factors for HVFAC for Four Stage Compound Fatigue LoadingSpecimen No. of load cycles applied at Fatigue Life at Stress Level Cumulativeno. Stress level damage factor S=0.55 S=0.6 S=0.65 S=0.7 S=0.55 S=0.6 S=0.65 S=0.7 M=(n1/N1)+ (n2/N2)+(n3/N3) (n1) (n2) (n3) (n4) (N1) (N2) (N3) (N4) +(n4/N4) 1 40000 5000 1000 911 99302 22621 5153 1174 1.594 2 40000 5000 1000 811 99302 22621 5153 1174 1.509 3 40000 5000 1000 1025 99302 22621 5153 1174 1.691 4 20000 10000 2000 1258 99302 22621 5153 1174 2.103 5 20000 10000 2000 852 99302 22621 5153 1174 1.757 6 20000 10000 2000 1042 99302 22621 5153 1174 1.9197. CONCLUSIONSBased on experimental investigations following conclusions were made. • For probability distribution of fatigue life lognormal distribution model was found to be satisfactory for both PCC and HVFAC at all stress levels. • Parameters of lognormal model were found to be dependent on type of concrete and the stress level. • There is an upper limit for stress level in fatigue loading which is dependent on type of concrete, beyond which fatigue life value was insignificant. • S-N relations obtained from regression analysis were found to be dependent on type of concrete i.e., mainly on the static strength of concrete. Following are the S-N relations for PCC and HVFAC S = -0.0358Ln(N) + 0.9948 -------- for PCC S = -0.0338Ln(N) + 0.9389 -------- for HVFAC • Miner’s sum varied between 0.824 and 2.103. Hence Miner’s hypothesis gives both unsafe and over safe predictions for failure of HVFAC under compound fatigue loading. • Miner’s sum shows dependency on type of compound fatigue loading and also on sequence of loading. 413
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME8. ACKNOWLEDEGEMENT The financial support under Research Promotion Scheme from All India Council forTechnical Education, New Delhi, India, is gratefully acknowledged.REFERENCES 1. Hilsdorf, H.K., and C.E.Kesler. Fatigue Strength of Concrete under VaryingFlexural Stresses. ACI Journal Proceedings, Vol. 63, No. 10, 1966, pp. 1059-1076. 2. Ballinger, C.A. Cumulative Fatigue Damage Characteristics of Plain Concrete.Highway Research Record, No. 370, 1972, pp. 48-60. 3. Tepfers, R., and T.Kutti. Fatigue Strength of Plain, Ordinary, and LightweightConcrete. ACI Journal Proceeding, Vol. 1979, pp. 635-652. 4. Vesic, A.S., and S.K.Saxena. Analysis of Structural Behavior of Road Test RigidPavements. Highway Research record, No.291, 1969, pp. 156-158. 5. Treybig, H.J., McCullough, B.F., Smith, P., and H.Von Quintus. Overlay Designand Reflection Cracking Analysis for Rigid Pavements. Development of New DesignCriteria. FHWA Report No. FHWA-RD-77-76, Vol.1, 1977. 6. Aas-Jakobsen, K. Fatigue of Concrete Beams and Columns. NTH Institute ofBetonkonstruksjoner, Trondheim, Bulletin No. 70-1, Norway, 1970, 148 pp. 7. Hsu, T.T.C. Fatigue of Plain Concrete. ACI Journal Proceeding, Vol. 78, No. 4,1981, pp. 292-305. 8. A.J.M.Siemes. Miner’s Rule with Respect to Plain Concrete Variable AmplitudeTests. ACI Special Publication, No. SP-75, 1987, pp. 343-371. 9. Jan Ove Holmen. Fatigue of Concrete by Constant and Variable AmplitudeLoading. ACI Special Publication, No. SP-75, 1987, pp. 71-109. 10. P.K.Mehta. High Performance, High Volume Fly Ash Concrete for SustainableDevelopment. Proceedings of International Workshop on Sustainable Development andConcrete Technology, Ottawa, Canada, 2002, pp. 3-14 11. Tse, E.W., Lee, D.Y., and F.W.Klaiber. Fatigue behavior of Concrete ContainingFly ash. ACI Special Publication, No. SP-91, 1986, pp. 273-289. 12. Naik, T.R., and S.S.Singh. Fatigue Property of Concrete with and without mineraladmixtures. ACI Special Publication, No. SP-144, 1994, pp. 269-288 13. Ramakrishnan, V., Malhotra, V.M., and W.S.Langley. Comparative Evaluation ofFlexural Fatigue Behavior of High Volume Fly Ash and Plain Concrete. ACI SpecialPublication, No. SP-229, 2005, pp. 351-368. 14. IS 3812 (Part 1): 2003, Pulverized Fuel ash-Specification for use as Pozzolana inCement, Cement mortar and Concrete. Bureau of Indian Standards, New Delhi, India. 15. IRC: SP:62-2004, Guidelines for the design and Construction of Cement ConcretePavements for Rural Roads. 16. Byung Hwan Oh. Fatigue-Life Distributions of Concrete for Various StressLevels. ACI Materials Journal, Vol.88. No. 2, 1991, pp. 122-128. 17. Shi, X.P., Fwa, T.F., and S.A.Tan. Flexural Fatigue Strength of Plain Concrete.ACI Materials Journal, Vol. 90, No. 5, 1993, pp. 435-440. 18. Dr. Shanthappa B. C., Dr. Prahallada. M. C. and Dr. Prakash. K. B., “Effect OfAddition Of Combination Of Admixtures On The Properties Of Self Compacting ConcreteSub-Jected To Alternate Wetting And Drying” International Journal of Civil Engineering &Technology (IJCIET), Volume 2, Issue 1, 2011, pp. 17-24, Published by IAEME 414
  • International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME 19. A.S Jeyabharathy, Dr.S.Robert Ravi and Dr.G.Prince Arulraj “Finite ElementModeling Of Reinforced Concrete Beam Column Joints Retrofitted With Gfrp Wrapping”International Journal of Civil Engineering & Technology (IJCIET), Volume 2, Issue 1, 2011,pp. 35-39, Published by IAEME. 20. M.N.Bajad, C.D.Modhera and A.K.Desai, “Influence Of A Fine Glass Powder OnStrength Of Concrete Subjected To Chloride Attack” International Journal of CivilEngineering & Technology (IJCIET), Volume 2, Issue 2, 2011, pp. 01-12, Published byIAEME. 21. H.Taibi Zinai, A. Plumier and D. Kerdal, “Computation Of Buckling Strength OfReinforced Concrete Columns By The Transfer-Matrix Method” International Journal ofCivil Engineering & Technology (IJCIET), Volume 3, Issue 1, 2012, pp. 111 - 127, Publishedby IAEME. 22. P.A. Ganeshwaran, Suji and S. Deepashri, “Evaluation Of Mechanical PropertiesOf Self Compacting Concrete With Manufactured Sand And Fly Ash” International Journalof Civil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 60 - 69,Published by IAEME. 23. K. Sasiekalaa and R. Malathy, “Flexural Performance Of Ferrocement LaminatesContaining Silicafume And Fly Ash Reinforced With Chicken Mesh” International Journal ofCivil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 130 - 143, Publishedby IAEME. 415