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solutionforHW_3

solutionforHW_3 - ‘ Dr Marwa Hassan [email protected] CM3400...

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Unformatted text preview: ‘ Dr. Marwa Hassan . \ [email protected] CM3400: Assignment No. 3 Due Date: 10/10l07 A hot-mix asphalt surface course (38mm thick) is to be designed to carry 15 x 106 ESALs during the life of the pavement. A 9.5mm nominal size aggregate is required. Based on environmental information, a PG 64-22 is used as the binder. For this problem, it is assumed that the binder'to be used meet the SuperPave requirements. [ fl 0 If the binder viscosity was determined at two temperatures (at 135C: 0.575 Pa-s ' and at 175C: 0.142 Pa-s), determine the ranges of mixing and compaction temperatures from the temperature-viscosity plot. @l a Four aggregate sources are available for use. Results of tests conducted to (1/ determine whether these aggregates meet the specifications are presented in the table below. Determine whether these aggregates can be used in HMA according to the SuperPave specifications shown below. Su erPave_Specifications for Agggggte Properties Merty Srflification Coarse Agggegfiflgulafly 95/90 minimum Fine A_ggregaiAngula‘rity 45 minimum Flat & Elongated 10 maximum Fine A_gg_regate Sand Eflvalent 45 minimum : Test Results 1 _Agg£gate 1 Aggregate 2 Agfigate 3 figregate 4 Coarse Aggregate 100/100 100/ 100 — - An ularit Fine Aggregate 48 47 An ularity Flat & Elo_ngated 3 5 - Fine Aggregate ‘ Sand E uivalent 51;) Aggregate 1: passes coarse aggregate angularity Passes flat & elongated Aggregate 2: passes coarse aggregate angularity Passes fine aggregate angularity Passes flat & elongated Aggregate 3: passes fine aggregate angularity Passes fine aggregate sand equivalent Aggregate 4: ms fine aggregate angularity Passes fine aggregate sand equivalent ott¢mzl§i¥+¥%+;!v 1:va \ w u M W l _ f17;3m1: zy/szxtyiéwfii! « ISCOSI V Xix’wffifwaz, w W Go EMU 33.92359 0 Dr. Marwa Hassan [email protected] %Gmm at Nmax = 97.4 (passes) VMA: fl VFA: passes Blend 3: %Gmm at Ni = 86.8 (passes) %Gmm at Nmax = 97.4 (passes) VMA: passes VFA: passes n Blends 1 and 3 satisfy the specifications but blend 3 is preferred since blend 1 barely meets the Ni and Nm requirements. - A designer decides to select Blend No. 3 to use and now needs to determine the asphalt content that will achieve 4% air voids while satisfying the other volumetric mixture requirements. He prepares eight samples at four different asphalt contents. Results of these measurements are presented in the table below. Create plots showing the relation between: 0 Asphalt content (%) vs. Air Voids (%) o Asphalt content (%) vs. Percent of Gmm at N o Asphalt content (%) vs. VMA o Asphalt content (%) vs. VFA o Asphalt content (%) vs. Percent of Gmm at Nm 0 Based on these plots, determine the asphalt content to achieve 4% air voids and use the other graphs to check that the produced mixture will satisfy the Mixture SuperPave requirements discussed in class. Asphalt Voids at Nd Gmm A Content %Gmm at N %Gmm at Nm W mum 86-2 87-1 88-0 84.4 95.5 97.3 A . 98.7 Solution: See attached figures. To satisfy 4% air voids, an asphalt content of 5.2% should be used. Using this asphalt content in the other graphs, we can see that this blend satisfy all the other requirements. Dr. Marwa Hassan [email protected] - Three trial blends of the aggregates available for this project were prepared and their volumetric properties at the estimated optimum asphalt content were measured. Results of these blends are shown in the table below. Determine which blends meet the SuperPave requirements discussed in the lecture. Solution: Assume N ini is 9 Log Nini = 0.45 Log Ndes Log Nmax = 1.10 Log Ndes Ndes 132 Nmax 215 Min. VMA: 15 — Range of VFA: 65 to 75 %Gmm at Nini < 89% %G..nmat Nmax < 98% Blend 1: %Gmm at Ni = 88.9 (barely passes) %Gmm at Nmax = 97.9 (barely passes) VMA: passes VFA: passes Blend 2: %Gmm at Ni = 86.5 (passes) Air Voids, % M K mm.» Pan—5: moan...” AX; a .w . 9 >293»: 9:33 GS 3;; M W w 8? . mm .....,..LM.. mm:w m m0. +013 6,3 m ”E w a L”: L M ‘ W M W v/ a A L w 8 4w :4: 1 a 3 m 3 m 3 r WW >253» 958:» 1% mum All! melI.’ . x 9:, 9+ 77.. A “Wot. no.3 .m mom a m mm: m m o % mm mmb ..Ta‘ mam f. ‘ “ m# [4’ ~ 1m \ m 1:611; .526: 9383 A5 % of Gmm at Nm Pan—gm: noanman G3 ...
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