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217 <br /> <br /> Passing a ten (10) mesh sieve and retained on a Per cent. <br /> <br />forth (40) mesh sieve ............................. 15 to 50 <br />Passing a forty (40) mesh sieve and retained on a <br />eighty (80) mesh sieve ............................ 25 to g5 <br />Passing an eighty (80) mesh sieve and retained on <br />a two hundred (200) mesh sieve .................... V to 40 <br />Passing a two hundred (200 mesh sieve ............. 0 to 8 <br /> <br />SECTION 4. ~IEING. <br /> <br /> (a) TT~e asphalt cement shall be bested in kettles <br />or tanks designed to secure uniform hea*ing of tke entire con- <br />tents and shall be brought to a temperature of not less than <br />250' Fahrenheit to not more than 550' Fahrenheit. <br /> <br /> (b) The oo~rse and fine aggregate for the asphaltic <br />concrete wearing surface misture shall be dried and heated at <br />the paving plant in suitably designed revolvin~ driers. The <br />misture shall be heated to a temperature of not less th~mtwo <br />hundred fifty (250') degrees Fahrenbelt to not more tkan three <br />hundred fifty (Z50'~ degrees F~hrenhett as determined on the <br />mixing platform. The temperature shall be taken in the blnS~ <br /> <br />· he aggregates may be simultaneously fed into tbs same drier, <br /> t~ey shall, Im-edlately after heatldg, b~ <br /> least four (4) different sizes and stored in <br /> <br />but in that case <br />s~reened into at <br />separate bins. <br /> <br /> (c) <br /> <br />follows: <br /> <br /> The <br />least four (4) <br />rarely weighed <br /> <br />Each batch shall be combined and mixed <br /> <br />coarse and fine aggregates consisting of at <br /> diTferent sizes shall be separately and accu- <br /> by means of multiple beam or dial scales of <br /> sufficient capacity to weigh the entire batch to be mixed. <br /> The required a~o~nt of asphalt cement for each batch shall be <br /> measured by actual wei~hlng wlt? tbs s~ales attached to the <br /> asphalt cement bucket. <br /> <br /> The mixture shall be m~de in an approved twin plug <br />mixer, having at least forty-eight (48) paddles which shhll <br />rotate not less than seventy (V0) nor more than ninety (90) <br />revolutions per minute. The hot coarse aggregate and sand, <br />and the cold stone dust sha~l be placed in the mixer and tho- <br /> <br />roughly mixed for not less than fifteen (15) seconds, after <br />which tho hot asphalt cement shall be added and the whole <br /> <br />mixed for at least one (1) minute or longer if necessary to <br />produce a homogeneous mixture, in which all particles of the <br />mineral aggregate ~re uniformly coated. <br /> <br /> Time shall be allowed for c?~ging the mixer, but <br />no case shall bhe time be less than ten (10) s~conds, An ac- <br />curate time piece shell be provided at the mixer. <br /> <br /> ~Ixer cuddles s?a~l be replaced when worn to such <br /> <br /> <br />