Firstmix calculates the expected density of the wet concrete.
You can select either to calculate the wet concrete density by using the densities and quantities of the materials (‘best possible’ method) or by using an approximation included in the DOE Method.
If the ‘best possible’ method is used to determine the concrete density, you can either use the typical values suggested in the DOE Method for the densities of the aggregate and cement, or supply your own values for the densities. You can either specify an overall relative aggregate density or give full details for the coarse and fine aggregates in the Measurements Dialog, which may also used for specifying the cement density. The ‘best possible’ method also allows for the effect of air entrainment.
In the DOE Method approximation it appears that the cement relative density is assumed to be 3.12 and the water/cement ratio is assumed to be 0.47. You can either specify an overall relative aggregate density to be used in the DOE Method approximation or adopt the typical values suggested in the DOE Method (2.7 for crushed and 2.6 for uncrushed aggregate).
If a Trial Mix is made, the actual concrete density can be measured. A comparison of the expected and actual densities provides a valuable check of the accuracy of the data used in the mix design, in particular of the aggregate density. Also unless the concrete density predicted by Firstmix is attained in reality, the actual volume of a mix will differ from the nominal volume.
Range: 2100 - 2750 kg/m˛.