Concrete Mixed Design

Introduction Concrete mixed design is define as a process of selecting the suitable ingredients determining their relative proportions with the objective of producing concrete of having certain workability, strength and durability as economically as possible (Suryakanta, 2014). Which it is means that the content in concrete should be calculated and limited carefully so that the cost will not exceed the budget. But at the same time, the quality of the concrete should not been affected so that it can achieve the supervision exercised at the site. In this case, the concrete mixed design is very important in affecting the quality control (QC) of the concrete.

The quality control (QC) of a concrete is refer to the initial instance of the supervision

To form the concrete which can achieved the grade given, 30 N/mm2, some calculation is needed to get the exacted volume of the aggregates, cement, and also the water. The reading of the standard deviation is taken from a table depend on the number of the reading needed and also the characteristic strength.

Figure 3 the table which show the relationship between the characteristic strength and the standard deviation.

Since the reading that we needed in our experiment is less than 20 and the characteristic strength for our experiment is 30 N/mm2 , the standard deviation for our experiment is 8 N/mm2. After the standard deviation is founded, the target mean strength can be found by using the formula, f target mean strength = f characteristic strength + margin ( standard deviation )

= 30 N/mm2 + 1.64 (8 N/mm2)

=43 N/mm 2

The purpose of the target mean strength is to increases the possibility of the concrete achieve the compressive strength which it is needed. The cement type and the aggregates’ type that had been chosen in this experiment is the ordinary portland cement, and also the crushed fine and course aggregates. The water per cement ratio is found through the

For our experiment, the characteristic strength for our concrete is 30 N/mm2 . There are 7 cubes and 2 beams which is needed for the sample in our experiment. The total volume of the concrete that we needed in the experiment is 0.04035 m3. So the mass of the aggregates, cement, and also important to ensure that the concrete is produced in good quality. So, the mass of the course aggregate, fine aggregate, cement, and also the water content are 49.63 kg, 19.37kg, 17.15kg, and 9.08 kg