ASTM C 109 Compressive Strength of Hydraulic Cement Mortars(2)

deliver the indicated volume at20°C.The permissible variation shall be62mL.These graduates shall be subdivided to at least 5mL,except that the graduation lines may be omitted for the lowest10mL for a250-mL graduate and for the lowest25mL of a500-mL graduate.The main graduation lines shall be circles and shall be numbered.The least graduations shall extend at least one seventh of the way around,and intermediate graduations shall extend at least onefifth of the way around.

5.3Specimen Molds,for the2-in.or[50-mm]cube speci-mens shall be tightfitting.The molds shall have not more than three cube compartments and shall be separable into not more than two parts.The parts of the molds when assembled shall be positively held together.The molds shall be made of hard metal not attacked by the cement mortar.For new molds the Rockwell hardness number of the metal shall be not less than 55HRB.The sides of the molds shall be sufficiently rigid to prevent spreading or warping.The interior faces of the molds shall be plane surfaces and shall conform to the tolerances of Table1.

5.4Mixer,Bowl and Paddle,an electrically driven mechani-cal mixer of the type equipped with paddle and mixing bowl, as specified in Practice C305.

5.5Flow Table and Flow Mold,conforming to the require-ments of Specification C230.

5.6Tamper,a nonabsorptive,nonabrasive,nonbrittle mate-rial such as a rubber compound having a Shore A durometer hardness of80610or seasoned oak wood rendered nonab-sorptive by immersion for15min in paraffin at approximately 392°F or[200°C],shall have a cross section of about1⁄2by1 in.or[13by25mm]and a convenient length of about5to6 in.or[120to150mm].The tamping face shall beflat and at right angles to the length of the tamper.

5.7Trowel,having a steel blade4to6in.[100to150mm] in length,with straight edges.

5.8Moist Cabinet or Room,conforming to the require-ments of Specification C511.

5.9Testing Machine,either the hydraulic or the screw type, with sufficient opening between the upper bearing surface and the lower bearing surface of the machine to permit the use of verifying apparatus.The load applied to the test specimen shall be indicated with an accuracy of61.0%.If the load applied by the compression machine is registered on a dial,the dial shall be provided with a graduated scale that can be read to at least the nearest0.1%of the full scale load(Note2).The dial shall be readable within1%of the indicated load at any given load level within the loading range.In no case shall the loading range of a dial be considered to include loads below the value that is100times the smallest change of load that can be read on the scale.The scale shall be provided with a graduation line equal to zero and so numbered.The dial pointer shall be

of

sufficient length to reach the graduation marks;the width of the

end of the pointer shall not exceed the clear distance between

the smallest graduations.Each dial shall be equipped with a

zero adjustment that is easily accessible from the outside of the

dial case,and with a suitable device that at all times until reset,

will indicate to within1%accuracy the maximum load applied

to the specimen.

5.9.1If the testing machine load is indicated in digital form,

the numerical display must be large enough to be easily read.

The numerical increment must be equal to or less than0.10%

of the full scale load of a given loading range.In no case shall

the verified loading range include loads less than the minimum

numerical increment multiplied by100.The accuracy of the

indicated load must be within1.0%for any value displayed

within the verified loading range.Provision must be made for

adjusting to indicate true zero at zero load.There shall be

provided a maximum load indicator that at all times until reset

will indicate within1%system accuracy the maximum load

applied to the specimen.

N OTE2—As close as can be read is considered1⁄50in.or[0.5mm]

along the arc described by the end of the pointer.Also,one half of the

scale interval is about as close as can reasonably be read when the spacing

on the load indicating mechanism is between1⁄25in.or[1mm]and1⁄16in.

or[1.6mm].When the spacing is between1⁄16in.or[1.6mm]and1⁄8in.

or[3.2mm],one third of the scale interval can be read with reasonable

certainty.When the spacing is1⁄8in.or[3.2mm]or more,one fourth of

the scale interval can be read with reasonable certainty.

5.9.2The upper bearing shall be a spherically seated,

hardened metal blockfirmly attached at the center of the upper

head of the machine.The center of the sphere shall lie at the

center of the surface of the block in contact with the specimen.

The block shall be closely held in its spherical seat,but shall be

free to tilt in any direction.The diagonal or diameter(Note3)

of the bearing surface shall be only slightly greater than the

diagonal of the face of the2-in.or[50-mm]cube in order to

facilitate accurate centering of the specimen.A hardened metal

bearing block shall be used beneath the specimen to minimize

wear of the lower platen of the machine.The bearing block

surfaces intended for contact with the specimen shall have a

Rockwell hardness number not less than60HRC.These

surfaces shall not depart from plane surfaces by more than

0.0005in.or[0.013mm]when the blocks are new and shall be

maintained within a permissible variation of0.001in.or[0.025

mm].

N OTE3—A diameter of31⁄8in.or[79.4mm],is satisfactory,provided

that the lower bearing block has a diameter slightly greater than the

diagonal of the face of the2-in.or[50-mm]cube but not more than2.9in.

or[74mm],and is centered with respect to t …… 此处隐藏：4249字，全部文档内容请下载后查看。喜欢就下载吧 ……