ASTM_C_305_-_14.pdf

Designation:C30514American Association StateHighway and Transportation Officials StandardAASHTO No.:T162Standard Practice forMechanical Mixing of Hydraulic Cement Pastes and Mortarsof Plastic Consistency1This standard is issued under the fixed designation C305;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This practice covers the mechanical mixing of hydrauliccement pastes and mortars of plastic consistency.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C511 Specification for Mixing Rooms,Moist Cabinets,Moist Rooms,and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC778 Specification for Sand3.Significance and Use3.1 This practice is intended for use in the mechanicalmixing of pastes and mortars for the testing of hydrauliccements.4.Apparatus4.1 MixerThe mixer shall be an electrically driven me-chanical mixer of the epicyclic type,which imparts both aplanetary and a revolving motion to the mixer paddle.Themixer shall have a minimum of two controlled speeds.(Rheo-stat adjustment of speed is not acceptable.)The first,or slowspeed shall revolve the paddle at a rate of 140 6 5 r/min,witha planetary motion of approximately 62 r/min.The secondspeed shall revolve the paddle at a rate of 285 6 10 r/min,witha planetary motion of approximately 125 r/min.The electricmotor shall be at least 124 W(16hp).The mixer shall beequipped with either an adjustment screw which is an integralpart of the mixer or a clearance adjustment bracket such as theone shown in Fig.1(Note 1)to provide clearance between thelower end of the paddle and the bottom of the bowl that is notgreater than 2.5 mm but not less than 0.8 mm(Note 2)whenthe bowl is in the mixing position.NOTE1When the bracket is in the proper position beneath the motorhousing,the lugs are to the front and facing upward and the heads of theadjustment screws are to the rear and facing downward in the path of thesliding frame that holds the bowl.It is intended that the bracket befastened at the front housing connection by inserting replacement screwson an appropriate size upward through the opening in each lug and into theexisting threaded holes in the bottom of the motor housing.The originalstops for the sliding frame are to be filed down if they prevent the framefrom coming in contact with the adjustment screws.NOTE2This is the approximate diameter of a grain of 20 to 30 sandas described in Specification C778.4.2 PaddleThe paddle shall be readily removable,madeof stainless steel,and shall conform to the basic design shownin Fig.2.The dimensions of the paddle shall be such that whenin the mixing position the paddle outline conforms to thecontour of the bowl used with the mixer,and the clearancebetween corresponding points on the edge of the paddle and theside of the bowl in the position of closest approach shall beapproximately 4.0 mm but not less than 0.8 mm.4.3 Mixing BowlThe removable mixing bowl shall have anominal capacity of 4.73 L,shall be of the general shape andcomply with the limiting dimensions shown in Fig.3,and shallbe made of stainless steel.The bowl shall be so equipped thatit will be positively held in the mixing apparatus in a fixedposition during the mixing procedure.Provide an enclosurearound the mixing bowl or a lid to minimize evaporation ofwater during periods of rest of the mixture.The enclosure or lidshall be made of non-absorbing material that is resistant todeterioration from the alkaline environment of cement pastesand mortars.1This practice is under the jurisdiction ofASTM Committee C01 on Cement andis the direct responsibility of Subcommittee C01.22 on Workability.Current edition approved Aug.1,2014.Published September 2014.Originallyapproved in 1953.Last previous edition approved in 2013 as C305-13.DOI:10.1520/C0305-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.4 ScraperThe scraper shall consist of a semirigid rubberblade attached to a handle about 150 mm long.The blade shallbe about 75 mm long,50 mm wide,and taper