# Properties of Foamed Lightweight High-Performance Phosphogypsum-Based Ternary System Binder
## 3 Results and Discussion
### Properties of Foamed Ternary System Binder
#### 3.2.2 Physical and Mechanical Properties  
The physical properties of ternary system binder foams are given in Table 5. Due to larger pores, the bulk density of GCP-BG foams is lower comparing to GCP-PG foams. The lightweight material with density 368 and 486 kg/m\({}^{3}\) was obtained depending on the amount of paste mixed with foams. GCP-PG foams density increased to 634 and 697 kg/m\({}^{3}\), respectively, which is associated with the smaller pores formed in the production process. The total porosity was higher for GCP-BG, which explains the lower bulk density. The total porosity was 84 and 79 vol.% for GCP-BG and 72 and 70 wt.% for GCP-PG. Important finding was that open porosity was formed for GCP-BG foams, while for GCP-PG more pores were closed. This is also evidenced by the fact that during the water absorption test the GCP-PG foams remained flowing after total immersion in water (total test time was 72 h). The water absorption was 105 and 91 wt.% for GCP-PG foams, while for GCP-PG it was 46 and 39 wt.%, respectively. Density for water-saturated samples increased and was in range from 758-901 kg/m\({}^{3}\).  
The lowest thermal conductivity of produced specimens was for GCP-BG-1. With the lowest bulk density, the thermal conductivity was as low as 0.086 W/m\(\cdot\)K. The increase of bulk density for GCP-BG  
Figure 8: The micrographs of ternary system binder foam observed with SEM. (**a**) GCP-BG-1, (**b**) GCP-PG-1.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Composition** & **\(\rho\)\_kg/m\({}^{3}\)** & **\(\rho\)\_wet, kg/m\({}^{3}\)** & **Water** & **Open Porosity,** & **Closed Porosity,** & **Total Porosity,** & **Thermal Conductivity,** \\  & & & **Absorption, wt.\%** & **vol.\%** & **vol.\%** & **vol.\%** & **vol.\%** & **\(\lambda\), W/m\(\cdot\)K** \\ \hline GCP-BG-1 & 368 & 758 & 105 & 39 & 45 & 84 & 0.086 \\ GCP-BG-2 & 486 & 901 & 91 & 43 & 36 & 79 & 0.123 \\ GCP-PG-1 & 634 & 876 & 46 & 28 & 45 & 72 & 0.111 \\ GCP-PG-2 & 697 & 901 & 39 & 25 & 44 & 70 & 0.153 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Physical properties of foamed ternary system binder.  
increased the thermal conductivity to 0.123 W/m-K. Furthermore, GCP-PG-1 had higher bulk density, and due to finer pore size distribution, the thermal conductivity was lower comparing to GCP-BG-2 and it was 0.111. The GCP-PG-2 had thermal conductivity of 0.153 W/m-K.  
The compressive strength results of prepared ternary system binder foams are given in Figure 9. The compressive strength of GCP-BG-1 was 0.33 MPa and increased to 1.0 for GCP-BG-2. The increase of compressive strength was observed for GCP-PG. For GCP-PG-1, it was 2.4 MPa and increased to 5.4 MPa for GCP-PG-2. The strength increase is associated with the increase of foam bulk density and with the size of macropores formed during production. For samples made with PG, pores were smaller. Foam samples after water absorption tests were tested for compression to determine softening coefficient of the foams. Since gypsum is not watertight material and in proposed binder it is a major part of the binders' component (50 wt.%), concerns regarding water tightness were analyzed (Table 6). It was detected that water softening coefficient was from 0.50-0.64. Similar trends were observed with concrete foams before--the compressive strength decreases with the increase of volumetric moisture content for every density ranging from 300-800 kg/m\({}^{3}\), but the softening rate was lower--the compressive strength in the immersed saturation state is about 0.86-0.89 times of that in the standard curing state [21].