*2.4. Test Contents and Methods*

## 2.4.1. Dry Density

In order to save the engineering cost, foamed concrete needs to be of good expansibility, and dry density was chosen as the evaluation index of the expansibility, which is convenient for measurement. The standard cylindrical samples of 50 mm × 100 mm were selected, put into a constant temperature vacuum drying oven (see Figure 2), adjusted to 80 ± 5 ◦C for 24 h, and then the temperature adjusted to 120 ◦C until gaining the constant weight *M*. The diameter and height of the sample were measured, and its volume was calculated *V*. Then the dry density ρ of the concrete material can be obtained by the formula:

$$
\rho = \frac{M}{V} \times 1000\tag{1}
$$

where, ρ is the dry density of the sample, kg/m3; *M* is the mass of the sample after drying, g; *V* is the volume of the sample, cm3.

**Figure 2.** Constant temperature vacuum drying oven.
