We have published post regarding measurement specifications for water in ready mixed concrete industry. Here in this post we will discuss about the measurements requirements of admixtures for concrete before entering them in to batching plant or truck mixer. There may arise a question-why measurement is so important. This is the specifications where tolerance of quantifying each constituents of concrete is provided.
Admixtures are important constituents of concrete that are used to render special properties to concrete or to change dosage of any constituents of concrete in mix to form a strong or impermeable or more durable concrete. Admixtures that are found in powdered form should be measured in mass. Those which are liquid can be used in batching by measuring either in volume or mass.
Admixtures that are not derived from mineral resources(mineral admixtures), as discussed above can be measured in either volume or mass, should have accuracy level of -
±3% of total admixture requirements or ±Dosages or amount of them required for 50 kg (100 lb) of cement
Between two conditions greater values are taken into consideration.
Now do we know what the mineral admixtures are? They are:
a. Coal flyash
b. Silica fume
c. Blast furnace slag granulated in ground
d. Or other pozzolanic admixtures
But we have missed an important information about mineral admixtures. This is-mineral admixtures are excluded in this specifications for admixture measurements. This is due to accounting mineral admixtures in measuring cement in ready mixed concrete. In the next post we will learn about cement and aggregate measuring specifications.
An Important information we can include, mechanically operated admixture dispensers are used in modern batching for ready mixed concrete industry. This dispenser can adjust variations of degree accuracy. But a simple calibration of this is recommended before use. This post is from ASTM C94-dear reader you have noticed that we providing information regarding concrete and foundation engineering from different Codes and Standards in simplified form. Here you need to switch one article to another article to gather an overall idea about any specification. We are providing all necessary definitions and specification to understand any topics except in some long explanation-there e also providing necessary link to just click to get information. Please encourage us by reading and commenting. We are doing everything to make popular this blog and to provide one stop service for our reader.