1、Designation: C 305 06American 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 C 305; the number immediately following
2、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 (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers
3、 the 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
4、 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 778 Specification for Standard Sand3. Significance and Use3.1 This practice is intended for use in the mechanicalmixing of pastes and mortars for the testing of hydrauliccements.4. Appar
5、atus4.1 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 speeds, controlled bydefinite mechanical means. (Rheostat adjustment of speed willnot be acce
6、ptable.) 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 thepaddle 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 (
7、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(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
8、 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 facing upward and the heads of theadjustment screws are to the rear and facing downward in the path of thesliding frame that hold
9、s 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 b
10、e 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 Specification C 778.4.2 PaddleThe paddle shall be readily removable, madeof stainless steel, and shall conform to the basic design sh
11、ownin 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 shal
12、l 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 p
13、ositively 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 thecement.4.4 ScraperThe scraper shall consist of a semirigid rubberblade attached to a handle about 150 mm long. The blade shallbe abo
14、ut 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 ApparatusThe balances, weights,glass graduates, and any other supplementary apparatus used inmeasuring and preparing the mortar
15、 materials prior to mixing1This 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, 2006. Published August 2006. Originallyapproved in 1953. Last previous edition approved in 1999 as
16、C 305 99e1.2For 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.1*A Summary of Changes section appears at the end
17、of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.shall conform to the respective requirements for such apparatusas specified in the method for the particular test for which themortar is being prepared.5. Temperature an
18、d Humidity5.1 The temperature of the room shall be maintained be-tween 20 and 27.5 C (68 and 81.5 F), and the temperature ofthe dry materials, paddle, and bowl shall be within the aboverange at the time of test. The temperature of the mixing watershall not vary from 23 C (73.4 F) by more than 61.7 C
19、 (3F).5.2 The relative humidity of the laboratory shall be not lessthan 50 %.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 or mortar is being prepared.7. Proced
20、ure 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 and allow 30 s for theabsorption of
21、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) andmix for 60 s.Plate and BushingsBr
22、assScrews and NutsSteelAll Dimensions in mmFIG. 1 Clearance Adjustment BracketFIG. 2 PaddleFIG. 3 Mixing BowlC3050628. 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 follow
23、ing manner:8.1.1 Place all the mixing water in the bowl.8.1.2 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 Stop the mixer, change to medium speed (2
24、85 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, close the mixerenclosure or cover the b
25、owl 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 clearances between the paddle and the
26、bowlspecified in this practice are suitable when using mortar madewith standard sand as described in Specification C 778.Topermit the mixer to operate freely and to avoid serious damageto the paddle and bowl when coarser aggregates are used, itmay be necessary to set the clearance adjustment bracket
27、 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 CHANGESCommittee C01 has identified the loca
28、tion of selected changes to this practice since the last issue,C50399e1, 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 supplie
29、s the referredequipment.(2) Revised 7.1.5.(3) Revised 8.1.5.(4) Revised 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 valid
30、ity of any such patent rights, and the riskof infringement of such 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 comme
31、nts are invited either for revision of this standard or for additional 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 n
32、ot received a fair hearing you shouldmake your views known to the 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).C305063
