Dear reader, thanks for staying with us. Now we are ready to finish the requirements for uniformity of ready mixed concrete. We have almost done all preparation for understanding this term. We will provide a table below, which provides the ranges of the terms described in previous posts and some self defining terms.
Now we will provide some tips to use this table for understanding and defining uniformity of concrete. In this table we will found some variations of some parameters between two samples taken from same batch. The differences in right side of table are derived from differences between highest and lowest values for respective test listed in left side of table.
Now the question is-where form the sample should be taken? No doubt they should be taken from the starting and ending portions of respective batches. Now the table is presented here. The next discussion will be provided after the table. Notice carefully the limits of variations provided in the table.
We have provided in the last post that in determining mass per unit volume of air free mortar, ASTM uses the reference of Bureau of Reclamation of Concrete Manual. Regarding the collection of cylinder sample, at least 3 samples are taken and result is the average of 3 cylinder samples. As 7 days average compressive strength is used in the table, after 7days a mix can be said uniform. The most important question is-should all these six limits be complied with the samples from a batch? The answer is five out of six tests limit in the table must comply to be said a concrete uniform. Now reader we are ready describe all specifications for ready mixed concrete as almost all specifications use this uniformity requirements.