A proper mix design optimizes the environmental impact and the cost effectiveness of a concrete. A minimum cement paste content is desirable without deteriorate the concrete properties. Thus, cement paste content is dependent on the packing properties of the aggregates. Three different methods to optimize the aggregate composition have been evaluated by concrete tests: one curve fitting method and two particle packing methods. Crushed and natural aggregates have been tested at two different w/c ratios. The results show that the methods suggest very different aggregate compositions and they can´t handle fine crushed aggregates that consume a lot of mixing water.

A proper mix design optimizes the environmental impact and the cost effectiveness of a concrete. A minimum cement paste content is desirable without deteriorate the concrete properties. The cement paste content is dependent on the packing properties of the aggregates and it of interest to estimate the packing correctly. Three methods to optimize the aggregate distribution have been evaluated by concrete tests for crushed and natural aggregates: one curve fitting method and two particle packing methods. It is shown that the methods suggest very different aggregate distributions for an optimum concrete mix and they can´t handle fine crushed aggregate that consumeings a lot of mixing water.

An optimized aggregate particle packing density used as a base for concrete mix design provides economic, environmental and technical advantages. The particle packing density can be determined by many methods and predicted by different models. This paper reviews common packing and procedures and compares predictions of three common packing models to each other. It was found that the models tend to show different packing densities and percentage of ingredients for the same mixture. A test setup is proposed to determine the accuracy of each model’s prediction.