ASTM C 109 Compressive Strength of Hydraulic Cement Mortars

Designation:C109/C109M–02

Standard Test Method for

Compressive Strength of Hydraulic Cement Mortars

(Using2-in.or[50-mm]Cube Specimens)1

This standard is issued under the?xed designation C109/C109M;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.

A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.

This standard has been approved for use by agencies of the Department of Defense.

1.Scope*

1.1This test method covers determination of the compres-sive strength of hydraulic cement mortars,using2-in.or [50-mm]cube specimens.

N OTE1—Test Method C349provides an alternative procedure for this determination(not to be used for acceptance tests).

1.2This test method covers the application of the test using either inch-pound or SI units.The values stated in either system shall be regarded separately as standard.Within the text,the SI units are shown in brackets.The values stated in each system are not exact equivalents;therefore,each system shall be used independently of the bining values from the two systems may result in nonconformance with the speci?cation.

1.3Values in SI units shall be obtained by measurement in SI units or by appropriate conversion,using the Rules for Conversion and Rounding given in Standard IEEE/ASTM SI 10,of measurements made in other units.

1.4This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility 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.(Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.2)

2.Referenced Documents

2.1ASTM Standards:

C230Speci?cation for Flow Table for Use in Tests of Hydraulic Cement3

C305Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency3

C349Test Method for Compressive Strength of Hydraulic Cement Mortars(Using Portions of Prisms Broken in Flexure)3

C511Speci?cation for Moist Cabinets,Moist Rooms and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes3

C670Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials4

C778Speci?cation for Standard Sand3

C1005Speci?cation for Reference Masses and Devices for Determining Mass and V olume3

C1437Test Method for Flow of Hydraulic Cement Mor-tar3

IEEE/ASTM SI10Standard for Use of the International System of Units(SI):The Modern Metric System5

3.Summary of Test Method

3.1The mortar used consists of1part cement and2.75parts of sand proportioned by mass.Portland or air-entraining portland cements are mixed at speci?ed water/cement ratios. Water content for other cements is that sufficient to obtain a ?ow of11065in25drops of the?ow table.Two-inch or [50-mm]test cubes are compacted by tamping in two layers. The cubes are cured one day in the molds and stripped and immersed in lime water until tested.

4.Signi?cance and Use

4.1This test method provides a means of determining the compressive strength of hydraulic cement and other mortars and results may be used to determine compliance with speci-?cations.Further,this test method is referenced by numerous other speci?cations and test methods.Caution must be exer-cised in using the results of this test method to predict the strength of concretes.

5.Apparatus

5.1Weights and Weighing Devices,shall conform to the requirements of Speci?cation C1005.The weighing device shall be evaluated for precision and bias at a total load of2000 g.

5.2Glass Graduates,of suitable capacities(preferably large enough to measure the mixing water in a single operation)to

1This test method is under the jurisdiction of ASTM Committee C01on Cement and is the direct responsibility of Subcommittee C01.27on Strength.

Current edition approved June10,2002.Published August2002.Originally published as C109–st previous edition C109/C109M–01.

2See the section on Safety,Manual of Cement Testing,Annual Book of ASTM

Standards,V ol04.01.

3Annual Book of ASTM Standards,V ol04.01.

4Annual Book of ASTM Standards,V ol04.02.

5Annual Book of ASTM Standards,V ol14.04. 1

*A Summary of Changes section appears at the end of this standard. Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.

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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 one?fth of the way around.

5.3Specimen Molds,for the2-in.or[50-mm]cube speci-mens shall be tight?tting.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 speci?ed in Practice C305.

5.5Flow Table and Flow Mold,conforming to the require-ments of Speci?cation 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 be?at 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 Speci?cation 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 veri?ed 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 veri?ed 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 block?rmly 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 the upper bearing block and

TABLE1Permissible Variations of Specimen Molds

2-in.Cube Molds[50-mm]Cube Molds Parameter New In Use New In Use

Planeness of sides<0.001in.<0.002in.[<0.025mm][<0.05mm]

Distance between opposite sides2in.60.0052in.60.02[50mm60.13mm][50mm60.50mm] Height of each compartment2in.+0.01in.2in.+0.01in.[50mm+0.25mm[50mm+0.25mm

to?0.005in.to?0.015in.to?0.13mm]to?0.38mm] Angle between adjacent faces A9060.5°9060.5°9060.5°9060.5°

A Measured at points slightly removed from the intersection.Measured separately for each compartment between all the interior faces and the adjacent face and between interior faces and top and bottom planes of the mold.

held in position by suitable means.

6.Materials

6.1Graded Standard Sand:

6.1.1The sand(Note4)used for making test specimens shall be natural silica sand conforming to the requirements for graded standard sand in Speci?cation C778.

N OTE4—Segregation of Graded Sand—The graded standard sand should be handled in such a manner as to prevent segregation,since variations in the grading of the sand cause variations in the consistency of the mortar.In emptying bins or sacks,care should be exercised to prevent the formation of mounds of sand or craters in the sand,down the slopes of which the coarser particles will roll.Bins should be of sufficient size to permit these precautions.Devices for drawing the sand from bins by gravity should not be used.

7.Temperature and Humidity

7.1Temperature—The temperature of the air in the vicinity of the mixing slab,the dry materials,molds,base plates,and mixing bowl,shall be maintained between73.565.5°F or [23.063.0°C].The temperature of the mixing water,moist closet or moist room,and water in the storage tank shall be set at73.563.5°F or[2362°C].

7.2Humidity—The relative humidity of the laboratory shall be not less than50%.The moist closet or moist room shall conform to the requirements of Speci?cation C511.

8.Test Specimens

8.1Make two or three specimens from a batch of mortar for each period of test or test age.

9.Preparation of Specimen Molds

9.1Apply a thin coating of release agent to the interior faces of the mold and non-absorptive base plates.Apply oils and greases using an impregnated cloth or other suitable means. Wipe the mold faces and the base plate with a cloth as necessary to remove any excess release agent and to achieve a thin,even coating on the interior surfaces.When using an aerosol lubricant,spray the release agent directly onto the mold faces and base plate from a distance of6to8in.or[150to200 mm]to achieve complete coverage.After spraying,wipe the surface with a cloth as necessary to remove any excess aerosol lubricant.The residue coating should be just sufficient to allow a distinct?nger print to remain following light?nger pressure (Note5).

9.2Seal the surfaces where the halves of the mold join by applying a coating of light cup grease such as petrolatum.The amount should be sufficient to extrude slightly when the two halves are tightened together.Remove any excess grease with

a cloth.

9.3After placing the mold on its base plate(and attaching, if clamp-type)carefully remove with a dry cloth any excess oil or grease from the surface of the mold and the base plate to which watertight sealant is to be applied.As a sealant,use paraffin,microcrystalline wax,or a mixture of three parts paraffin to?ve parts rosin by mass.Liquify the sealant by heating between230and248°F or[110and120°C].Effect a watertight seal by applying the lique?ed sealant at the outside contact lines between the mold and its base plate.

N OTE5—Because aerosol lubricants evaporate,molds should be checked for a sufficient coating of lubricant immediately prior to use.

If an extended period of time has elapsed since treatment,retreatment may be necessary.

N OTE6—Watertight Molds—The mixture of paraffin and rosin speci?ed for sealing the joints between molds and base plates may be found difficult to remove when molds are being e of straight paraffin is permissible if a watertight joint is secured,but due to the low strength of paraffin it should be used only when the mold is not held to the base plate by the paraffin alone.A watertight joint may be secured with paraffin alone by slightly warming the mold and base plate before brushing the joint. Molds so treated should be allowed to return to the speci?ed temperature before use.

10.Procedure

10.1Composition of Mortars:

10.1.1The proportions of materials for the standard mortar shall be one part of cement to2.75parts of graded standard sand by e a water-cement ratio of0.485for all portland cements and0.460for all air-entraining portland cements.The amount of mixing water for other than portland and air-entraining portland cements shall be such as to produce a?ow of11065as determined in accordance with10.3and shall be expressed as weight percent of cement.

10.1.2The quantities of materials to be mixed at one time in the batch of mortar for making six and nine test specimens shall be as follows:

Number of Specimens

69

Cement,g Sand,g Water,mL

500

1375

740

2035

Portland(0.485)

Air-entraining portland(0.460)242

230

359

340

Other(to?ow of11065)...... 10.2Preparation of Mortar:

10.2.1Mechanically mix in accordance with the procedure given in Practice C305.

10.3Determination of Flow:

10.3.1Determine?ow in accordance with procedure given in Test Method C1437.

10.3.2For portland and air-entraining portland cements, merely record the?ow.

10.3.3In the case of cements other than portland or air-entraining portland cements,make trial mortars with varying percentages of water until the speci?ed?ow is obtained.Make each trial with fresh mortar.

10.4Molding Test Specimens:

10.4.1Immediately following completion of the?ow test, return the mortar from the?ow table to the mixing bowl. Quickly scrape the bowl sides and transfer into the batch the mortar that may have collected on the side of the bowl and then remix the entire batch15s at medium speed.Upon completion of mixing,the mixing paddle shall be shaken to remove excess mortar into the mixing bowl.

10.4.2When a duplicate batch is to be made immediately for additional specimens,the?ow test may be omitted and the mortar allowed to stand in the mixing bowl90s without covering.During the last15s of this interval,quickly scrape the bowl sides and transfer into the batch the mortar that may have collected on the side of the bowl.Then remix for15s at medium speed.

10.4.3Start molding the specimens within a total elapsed time of not more than 2min and 30s after completion of the original mixing of the mortar batch.Place a layer of mortar about 1in.or [25mm](approximately one half of the depth of the mold)in all of the cube compartments.Tamp the mortar in each cube compartment 32times in about 10s in 4rounds,each round to be at right angles to the other and consisting of eight adjoining strokes over the surface of the specimen,as illustrated in Fig. 1.The tamping pressure shall be just sufficient to ensure uniform ?lling of the molds.The 4rounds of tamping (32strokes)of the mortar shall be completed in one cube before going to the next.When the tamping of the ?rst layer in all of the cube compartments is completed,?ll the compartments with the remaining mortar and then tamp as speci?ed for the ?rst layer.During tamping of the second layer,bring in the mortar forced out onto the tops of the molds after each round of tamping by means of the gloved ?ngers and the tamper upon completion of each round and before starting the next round of tamping.On completion of the tamping,the tops of all cubes should extend slightly above the tops of the molds.Bring in the mortar that has been forced out onto the tops of the molds with a trowel and smooth off the cubes by drawing the ?at side of the trowel (with the leading edge slightly raised)once across the top of each cube at right angles to the length of the mold.Then,for the purpose of leveling the mortar and making the mortar that protrudes above the top of the mold of more uniform thickness,draw the ?at side of the trowel (with the leading edge slightly raised)lightly once along the length of the mold.Cut off the mortar to a plane surface ?ush with the top of the mold by drawing the straight edge of the trowel (held nearly perpendicular to the mold)with a sawing motion over the length of the mold.

10.5Storage of Test Specimens —Immediately upon completion of molding,place the test specimens in the moist closet or moist room.Keep all test specimens,immediately after molding,in the molds on the base plates in the moist closet or moist room from 20to 72h with their upper surfaces exposed to the moist air but protected from dripping water.If the specimens are removed from the molds before 24h,keep them on the shelves of the moist closet or moist room until they are 24-h old,and then immerse the specimens,except those for the 24-h test,in saturated lime water in storage tanks con-structed of noncorroding materials.Keep the storage water clean by changing as required.

10.6Determination of Compressive Strength :

10.6.1Test the specimens immediately after their removal from the moist closet in the case of 24-h specimens,and from storage water in the case of all other specimens.All test

specimens for a given test age shall be broken within

the permissible tolerance prescribed as follows:Test Age Permissible Tolerance 24h 61?2h 3days 61h 7days 63h 28days 612h If more than one specimen at a time is removed from the moist closet for the 24-h tests,keep these specimens covered with a damp cloth until time of testing.If more than one specimen at a time is removed from the storage water for testing,keep these specimens in water at a temperature of 73.56 3.5°F or [2362°C]and of sufficient depth to completely immerse each specimen until time of testing.10.6.2Wipe each specimen to a surface-dry condition,and remove any loose sand grains or incrustations from the faces that will be in contact with the bearing blocks of the testing machine.Check these faces by applying a straightedge (Note 7).If there is appreciable curvature,grind the face or faces to plane surfaces or discard the specimen.A periodic check of the cross-sectional area of the specimens should be made.N OTE 7—Specimen Faces—Results much lower than the true strength will be obtained by loading faces of the cube specimen that are not truly plane surfaces.Therefore,it is essential that specimen molds be kept scrupulously clean,as otherwise,large irregularities in the surfaces will occur.Instruments for cleaning molds should always be softer than the metal in the molds to prevent wear.In case grinding specimen faces is necessary,it can be accomplished best by rubbing the specimen on a sheet of ?ne emery paper or cloth glued to a plane surface,using only a moderate pressure.Such grinding is tedious for more than a few thousandths of an inch (hundredths of a millimetre);where more than this is found necessary,it is recommended that the specimen be discarded.10.6.3Apply the load to specimen faces that were in contact with the true plane surfaces of the mold.Carefully place the specimen in the testing machine below the center of the upper bearing block.Prior to the testing of each cube,it shall be ascertained that the spherically seated block is free to e no cushioning or bedding materials.Bring the spherically seated block into uniform contact with the surface of the specimen.Apply the load rate at a relative rate of movement between the upper and lower platens corresponding to a loading on the specimen with the range of 200to 400lbs/s [900to 1800N/s].Obtain this designated rate of movement of the platen during the ?rst half of the anticipated maximum load and make no adjustment in the rate of movement of the platen in the latter half of the loading especially while the cube is yielding before failure.N OTE 8—It is advisable to apply only a very light coating of a good quality,light mineral oil to the spherical seat of the upper platen.11.Calculation 11.1Record the total maximum load indicated by the testing machine,and calculate the compressive strength as follows:fm 5P /A (1)where:fm =compressive strength in psi or [MPa],FIG.1Order of Tamping in Molding of Test Specimens

P =total maximum load in lbf or [N],and A

=area of loaded surface in 2or [mm 2].

Either 2-in.or [50-mm]cube specimens may be used for the determination of compressive strength,whether inch-pound or SI units are used.However,consistent units for load and area must be used to calculate strength in the units selected.If the cross-sectional area of a specimen varies more than 1.5%from the nominal,use the actual area for the calculation of the compressive strength.The compressive strength of all accept-able test specimens (see Section 12)made from the same sample and tested at the same period shall be averaged and reported to the nearest 10psi [0.1MPa].12.Report

12.1Report the ?ow to the nearest 1%and the water used to the nearest 0.1%.Average compressive strength of all specimens from the same sample shall be reported to the nearest 10psi [0.1MPa].

13.Faulty Specimens and Retests

13.1In determining the compressive strength,do not con-sider specimens that are manifestly faulty.

13.2The maximum permissible range between specimens from the same mortar batch,at the same test age is 8.7%of the average when three cubes represent a test age and 7.6%when two cubes represent a test age (Note 9).

N OTE 9—The probability of exceeding these ranges is 1in 100when the within-batch coefficient of variation is 2.1%.The 2.1%is an average for laboratories participating in the portland cement and masonry cement reference sample programs of the Cement and Concrete Reference Laboratory.

13.3If the range of three specimens exceeds the maximum in 13.2,discard the result which differs most from the average and check the range of the remaining two specimens.Make a retest of the sample if less than two specimens remain after disgarding faulty specimens or disgarding tests that fail to comply with the maximum permissible range of two speci-mens.

N OTE 10—Reliable strength results depend upon careful observance of all of the speci?ed requirements and procedures.Erratic results at a given test period indicate that some of the requirements and procedures have not been carefully observed;for example,those covering the testing of the specimens as prescribed in 10.6.2and 10.6.3.Improper centering of specimens resulting in oblique fractures or lateral movement of one of the heads of the testing machine during loading will cause lower strength results.

A

These numbers represent,respectively,the (1s %)and (d2s %)limits as described in Practice C 670.

SUMMARY OF CHANGES

This section identi?es the location of changes to this test method that have been incorporated since the last

issue,C109/C109M–01.

(1)Temperatures were revised in7.1.(2)A warning statement was added to1.4,with accompanying

footnote.

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