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普通及钢筋混凝土砌块用灰浆的预施工及施工评定方法  
 【英文标准名称】  Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry
 【原文标准名称】  普通及钢筋混凝土砌块用灰浆的预施工及施工评定方法
 【标准号】  ASTM C780-2009
 【标准状态】  Active
 【国别】  美国
 【发布日期】  2009
 【实施或试行日期】  
 【发布单位】  美国材料与试验协会(US-ASTM)
 【起草单位】  C12.02
 【标准类型】  (Test Method)
 【标准水平】  ()
 【中文主题词】  
 【英文主题词】  aggregate ratio; air content; compressive strength; concrete penetrometer; cone penetrometer; consistency; consistency retention; mortar; tensile strength; Aggregate ratio; Aggregate-to-cement ratio; Air content; Composition analysis; Compression te
 【摘要】  

During preconstruction and construction evaluations, use of these test methods establishes specific and overall performance characteristics for the mortar system.

Preconstruction testing of mortars prebatched by weight provides information for the selection of the individual mortar system best suited for the masonry to be constructed. The recommended tests and their significance are as follows:

Consistency determinations by cone penetration allow gaging the water additions for all mortars included in the preconstruction test series. Even if the mortar consistency as measured at the construction site is at a different penetration value than those measured during the preconstruction tests, the cone preparation test serves to standardize water additions for mortars being considered as alternatives before construction. Additional testing of mortar water content-consistency relationships (Annex A4) will allow relating these two factors to batch-to-batch variations at the construction site.

Consistency retention by cone penetration using disturbed or undisturbed mortar samples provides a means of establishing the early-age setting and stiffening characteristics of the mortars. Because laboratory testing is conducted under static climatic conditions, consistency retention test results reflect the relative performance of the mortar systems under test. The same general relationships are expected to hold during testing at the construction project, except as they are influenced by jobsite weather conditions.

Mortar water-content determinations (Annex A4) allow measurement of the water content of the mortar mixture. Mortars prebatched using moist masonry sand may be mathematically analyzed for mortar water content; however, this test, when used for preconstruction evaluation, establishes the effectiveness of the test method and serves as the control or base for tests performed at the construction site.

Mortar aggregate ratio testing provides a method for determining the ratio of aggregate-to-cementitious materials. The sieving operation employed during this test is incapable of separating an individual cementitious material when more than one such material is used, but can accurately establish the aggregate-to-cementitious materials ratio of the mixture.

Mortar air-content testing is useful in establishing the value of this component of the mortar. This test is of particular importance in evaluating mortars that contain air-entraining portland cement, air-entraining lime, masonry cement or any combination thereof.

Compressive strength testing of molded mortar cylinders and cubes establishes one of the characteristics of hardened mortar. Mortar compressive strength test values are not representative of the actual compressive strength of mortar in the assembly and are not appropriate for use in predicting the compressive strength that would be attained by the mortar in the masonry assembly. The measured compressive strength of a molded mortar specimen is almost always lower than the strength of the same mortar in the wall, primarily as a result of differences in mortar water content and specimen shape. Mortar compressive strength is influenced by mortar water content at the time of set. Because molded mortar specimens are not in contact with absorptive masonry units and are not subjected to other mechanisms of water loss, they have higher water contents than mortar in the wall. Higher water contents almost always result in lower strengths. Specimen size and shape also affect compressive strength. Cylinders and cubes exhibit different strengths even when made from the same mortar mix. Both of these specimen configurations yield lower strengths than what would be attained if a specimen having the same size and configuration of a typical mortar joint could be reliably tested.

Note

 【中国标准分类号】  Q13
 【国际标准分类号】  91_100_10
 【页数】  18P.;A4
 【正文语种】  英语
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