1、Designation: C305 13C305 14 American 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 foll
2、owing 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 c
3、overs the mechanical mixing of hydraulic cement pastes and mortars of plastic consistency.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, as
4、sociated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C511 Specification for Mixing Rooms, Moist Cabinets, Moist
5、 Rooms, and Water Storage Tanks Used in the Testing of HydraulicCements and ConcretesC778 Specification for Sand3. Significance and Use3.1 This practice is intended for use in the mechanical mixing of pastes and mortars for the testing of hydraulic cements.4. Apparatus4.1 MixerThe mixer shall be an
6、electrically driven mechanical mixer of the epicyclic type, which imparts both a planetaryand a revolving motion to the mixer paddle. The mixer shall have a minimum of two controlled speeds. (Rheostat adjustment ofspeed is not acceptable.) The first, or slow speed shall revolve the paddle at a rate
7、of 140 6 5 r/min, with a planetary motion ofapproximately 62 r/min. The second speed shall revolve the paddle at a rate of 285 6 10 r/min, with a planetary motion ofapproximately 125 r/min. The electric motor shall be at least 124 W (16 hp). The mixer shall be equipped with either an adjustmentscrew
8、 which is an integral part of the mixer or a clearance adjustment bracket such as the one shown in Fig. 1 (Note 1) to provideclearance between the lower end of the paddle and the bottom of the bowl that is not greater than 2.5 mm but not less than 0.8mm (Note 2) when the bowl is in the mixing positi
9、on.NOTE 1When the bracket is in the proper position beneath the motor housing, 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 the sliding frame that holds the bowl. It is intended that the bracket be fastenedat the
10、 front housing connection by inserting replacement screws on an appropriate size upward through the opening in each lug and into the existingthreaded holes in the bottom of the motor housing. The original stops for the sliding frame are to be filed down if they prevent the frame from comingin contac
11、t with the adjustment screws.NOTE 2This is the approximate diameter of a grain of 20 to 30 sand as described in Specification C778.4.2 PaddleThe paddle shall be readily removable, made of stainless steel, and shall conform to the basic design shown in Fig.2. The dimensions of the paddle shall be suc
12、h that when in the mixing position the paddle outline conforms to the contour of thebowl used with the mixer, and the clearance between corresponding points on the edge of the paddle and the side of the bowl inthe position of closest approach shall be approximately 4.0 mm but not less than 0.8 mm.1
13、This practice is under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.22 on Workability.Current edition approved June 1, 2013Aug. 1, 2014. Published July 2013September 2014. Originally approved in 1953. Last previous edition approved in 20122013
14、 asC305 - 12.13. DOI: 10.1520/C0305-13.10.1520/C0305-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This
15、document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions
16、 as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*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. Un
17、ited States14.3 Mixing BowlThe removable mixing bowl shall have a nominal capacity of 4.73 L, shall be of the general shape andcomply with the limiting dimensions shown in Fig. 3, and shall be made of stainless steel. The bowl shall be so equipped that itwill be positively held in the mixing apparat
18、us in a fixed position during the mixing procedure. Provide an enclosure around themixing bowl or a lid to minimize evaporation of water during periods of rest of the mixture. The enclosure or lid shall be madeof non-absorbing material that is resistant to deterioration from the alkaline environment
19、 of cement pastes and mortars.4.4 ScraperThe scraper shall consist of a semirigid rubber blade attached to a handle about 150 mm long. The blade shall beabout 75 mm long, 50 mm wide, and tapered to a thin edge about 2 mm thick.NOTE 3A kitchen tool known as a plate and bowl scraper conforms to these
20、requirements.4.5 Supplementary ApparatusThe balances, weights, glass graduates, and any other supplementary apparatus used inmeasuring and preparing the mortar materials prior to mixing shall conform to the respective requirements for such apparatus asspecified in the method for the particular test
21、for which the mortar is being prepared.4.6 Mechanical mixing apparatus shall be inspected and checked for conformance to the requirements of this practice at leastevery 212 years.5. Temperature and Humidity5.1 The temperature and the humidity of the room and the temperature of the mixing water shall
22、 be maintained as describedin Specification C511 (Section Requirements for Cement Mixing Rooms).5.2 The dry materials shall be within the temperature range of the room.Plate and BushingsBrassScrews and NutsSteelAll Dimensions in mmFIG. 1 Clearance Adjustment BracketFIG. 2 PaddleC305 1426. Materials,
23、 Proportioning, and Consistency6.1 The materials and their proportions and quantities shall conform to the requirements contained in the particular method forwhich the paste or mortar is being prepared.7. Procedure for Mixing Pastes7.1 Place the dry paddle and the dry bowl in the mixing position in
24、the mixer. Then introduce the materials for a batch into thebowl 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 the absorption 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 St
25、op the mixer for 15 s and during this time scrape down into the batch any paste that may have collected on sides of thebowl.7.1.5 Start the mixer at medium speed (285 6 10 r/min) and mix for 60 s.8. Procedure for Mixing Mortars8.1 Place the dry paddle and the dry bowl in the mixing position in the m
26、ixer. Then introduce the materials for a batch into thebowl and mix in the following 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 and mix 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-s
27、 period, while mixing at slow speed.8.1.4 Stop the mixer, change to medium speed (285 6 10 r/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 into the batchany mortar that may have collected on the side of the
28、bowl; then for the remainder of this interval, close the mixer enclosure orcover the bowl with the lid.8.1.6 Finish by mixing for 60 s at medium speed (2856 10 r/min).8.1.7 In any case requiring a remixing interval, any mortar adhering to the side of the bowl shall be quickly scraped down intothe ba
29、tch with the scraper prior to remixing.WarningThe clearances between the paddle and the bowl specified in this practice are suitable when using mortar made withstandard sand as described in Specification C778. To permit the mixer to operate freely and to avoid serious damage to the paddleand bowl wh
30、en coarser aggregates are used, it may be necessary to set the clearance adjustment bracket to provide greaterclearances than those specified in 4.1.FIG. 3 Mixing BowlC305 143For additional useful information on details of cement test methods, reference may be made to the “Manual of CementTesting,”
31、which appears in the Annual Book of ASTM Standards, Vol 04.01.SUMMARY OF CHANGESCommittee C01 has identified the location of selected changes to this standard since the last issue(C305 12C305 13) that may impact the use of this standard. (Approved Aug. 1, 2014June 1, 2013)(1) RevisedAdded 4.14.6.AST
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