1、Designation: C305 11American 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 th
2、e 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 th
3、e mechanical mixing of hydrauliccement pastes and mortars of plastic consistency.1.2 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 de
4、termine 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 Us
5、e3.1 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. T
6、hemixer shall have a minimum of two speeds, controlled bydefinite mechanical means. (Rheostat adjustment of speed willnot be acceptable.) The first, or slow speed shall revolve thepaddle at a rate of 140 6 5 r/min, with a planetary motion ofapproximately 62 r/min. The second speed shall revolve thep
7、addle at a rate of 285 6 10 r/min, with a planetary motion ofapproximately 125 r/min. The electric motor shall be at least124 W (16 hp). The mixer shall be equipped with either anadjustment screw which is an integral part of the mixer or aclearance adjustment bracket such as the one shown in Fig. 1(
8、Note 1) to provide clearance between the lower end of thepaddle and the bottom of the bowl that is not greater than 2.5mm but not less than 0.8 mm (Note 2) when the bowl is in themixing position.NOTE 1When the bracket is in the proper position beneath the motorhousing, the lugs are to the front and
9、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
10、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.NOTE 2This is the approximate diameter of a grain of 20-30 sand asdescribed in Spec
11、ification 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
12、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 w
13、ith 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. There shall be provideda lid, made of a nonabsorbing material not attacked by theceme
14、nt.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 tapered to a thin edgeabout 2 mm thick.NOTE 3A kitchen tool known as a plate and bowl scraper conforms tothese requirements.4.5 Supplementary
15、 ApparatusThe balances, weights,glass graduates, and any other supplementary apparatus used inmeasuring and preparing the mortar materials prior to mixing1This practice is under the jurisdiction ofASTM Committee C01 on Cement andis the direct responsibility of Subcommittee C01.22 on Workability.Curr
16、ent edition approved April 1, 2011. Published May 2011. Originallyapproved in 1953. Last previous edition approved in 2006 as C305 06. DOI:10.1520/C0305-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AST
17、MStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.shall conform to the res
18、pective requirements for such apparatusas specified in the method for the particular test for which themortar is being prepared.5. Temperature and Humidity5.1 The temperature and the humidity of the room and thetemperature of the mixing water shall be maintained asdescribed in Specification C511 (Se
19、ction Requirements forCement Mixing Rooms).5.2 The dry materials shall be within the temperature rangeof the room.6. Materials, Proportioning, and Consistency6.1 The materials and their proportions and quantities shallconform to the requirements contained in the particular methodfor which the paste
20、or mortar is being prepared.7. Procedure for Mixing Pastes7.1 Place the dry paddle and the dry bowl in the mixingposition in the mixer. Then introduce the materials for a batchinto the bowl and mix in the following manner:7.1.1 Place all the mixing water in the bowl.7.1.2 Add the cement to the water
21、 and allow 30 s for theabsorption of the water.7.1.3 Start the mixer and mix at slow speed (140 6 5 r/min)for 30 s.7.1.4 Stop the mixer for 15 s and during this time scrapedown into the batch any paste that may have collected on sidesof the bowl.7.1.5 Start the mixer at medium speed (285 6 10 r/min)
22、 andmix for 60 s.8. Procedure for Mixing Mortars8.1 Place the dry paddle and the dry bowl in the mixingposition in the mixer. Then introduce the materials for a batchinto the bowl and mix in the following manner:8.1.1 Place all the mixing water in the bowl.Plate and BushingsBrassScrews and NutsSteel
23、All Dimensions in mmFIG. 1 Clearance Adjustment BracketFIG. 2 PaddleFIG. 3 Mixing BowlC305 1128.1.2 Add the cement to the water; then start the mixer andmix at the slow speed (140 6 5 r/min) for 30 s.8.1.3 Add the entire quantity of sand slowly over a 30-speriod, while mixing at slow speed.8.1.4 Sto
24、p the mixer, change to medium speed (285 6 10r/min), and mix for 30 s.8.1.5 Stop the mixer and let the mortar stand for 90 s.During the first 15 s of this interval, quickly scrape down intothe batch any mortar that may have collected on the side of thebowl; then for the remainder of this interval, c
25、lose the mixerenclosure or cover the bowl with the lid.8.1.6 Finish by mixing for 60 s at medium speed (2856 10r/min).8.1.7 In any case requiring a remixing interval, any mortaradhering to the side of the bowl shall be quickly scraped downinto the batch with the scraper prior to remixing.WarningThe
26、clearances between the paddle and the bowlspecified in this practice are suitable when using mortar madewith standard sand as described in Specification C778.Topermit the mixer to operate freely and to avoid serious damageto the paddle and bowl when coarser aggregates are used, itmay be necessary to
27、 set the clearance adjustment bracket toprovide greater clearances than those specified in 4.1.For additional useful information on details of cement test methods, reference may be made to the “Manual of CementTesting,” which appears in the Annual Book of ASTM Standards, Vol 04.01.SUMMARY OF CHANGES
28、Committee C01 has identified the location of selected changes to this standard since the last issue (C305 06)that may impact the use of this standard. (Approved April 1, 2011.)(1) Revised Section 5.Committee C01 has identified the location of selected changes to this practice since the last issue, C
29、305 991,that may impact the use of this practice. (Approved August 1, 2006)(1) Deleted current reference to Hobart N50A mixer becausereferences to individual manufacturers are reserved for in-stances where a single manufacturer supplies the referredequipment.(2) Revised 7.1.5.(3) Revised 8.1.5.(4) R
30、evised 8.1.6.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of suc
31、h rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for addit
32、ional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the
33、 ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C305 113
