A1.2 Significance and Use

A1.2.1 These tests and requirements are used to evaluate loading and operating procedures; verify the accuracy of proportioning and indicating systems; and determine if mixing uniformity has been degraded by excessive wear or by accumulations of hardened concrete, or both (Note A1.1).

Note A1.1: The method of loading the batching-mixing unit, proper maintenance, and other factors may have an effect on the ability of the unit to produce uniformly mixed concrete. For this reason, the use of this test method not only measures the efficiency of the mixer, but also the combined effect of the method of loading and operating the unit.

A1.2.2 This annex provides additional procedures and cautions that are necessary in the application of existing test methods and practices when used to determine the uniformity of freshly mixed concrete.

This specification covers concrete made by volumetric batching and continuous mixing. Requirements for quality of concrete shall be either as hereinafter specified or as specified by the purchaser. When the requirements of the purchaser differ from this specification, the purchaser's specification shall govern. This specification does not cover the placement, consolidation, finishing, curing, or protection of the concrete after delivery to the purchaser. Tests and criteria for batching accuracy and mixing efficiency are specified herein. Materials such as cement, aggregates, water, ground granulated blast-furnace slag, air-entraining admixtures, and chemical admixtures shall conform to the requirements covered in this specification. The material shall be subjected to the following test methods: compression test specimens; compression tests; yield; unit weight; air content; slump; and temperature.