# Application of Artificial Neural Networks to Predict Insulation Properties of Lightweight Concrete
## 2 Materials and Methods
### Methods  
The concrete mix components were mixed in a mechanical mixer with a planetary structure. The following sequence of dosing the ingredients was used: first, the cement and part of the mixing water (approx. 75%) were mixed for 2 min, and then GAA 8 mm, GEGA 4 mm and GEGA 2 mm were successively added to the cement grout in the amount according to the design given in Table 2. The mixture was mixed for another 2 min adding the remaining makeup water (20-25%) until the desired consistency (S3) was obtained in  
Figure 1: Structure of the LWA used in the tests. accordance with [26]. The consistency of concrete mixes was measured according to [27] the slump method. The consistency was in the S3 range (100-150 mm) for all mixes, with the exception of LWC 15 for which the range consistency was in the S2 (50-90 mm). The test specimens were made in accordance with [28] in the amount given in the Table 3.  
LWC tests were performed after 28 days. The LWC density was tested by the Archimedes method using three 2 \(\times\) 2 \(\times\) 2 cm samples were cut out from each LWC 1-15 variant. The first stage was to measure the mass of the dry sample (\(m_{\text{s}}\)). The samples were then saturated with a liquid of known density in a vacuum desiccator up to fill all the concrete pores. The standard liquid was deionized water (\(\rho=1\) g/cm\({}^{3}\)) and kerosene (\(\rho=0.8241\) g/cm\({}^{3}\)), depending on the composition of the tested LWC. Density \(\left(\rho_{p}\right)\) was calculated according to the pattern (1) and porosity \(\left(p_{o}\right)\) was calculated by means of the Equation (2):  
\[\rho_{p}=\frac{m_{s}}{\left(m_{n}-m_{w}\right)*d_{0}} \tag{1}\]  
\[p_{o}=\frac{m_{n}-m_{s}}{m_{n}-m_{w}}\cdot 100\% \tag{2}\]  
where \(\rho_{p}\)--volume density, (g/cm\({}^{3}\)); \(m_{w}\)--mass, saturated with the liquid, weighed in a liquid (water), (g); \(m_{n}\)--mass, saturated with the liquid, weighed in the air, (g); \(m_{s}\)--mass, weighed in the air, (g); \(d_{0}\)--liquid density in the tested temperature, (g/cm\({}^{3}\)). The compressive strength was tested with an Advantest 9 (Controls--Manufacturer, Liscate, Milan Italy) machine with a maximum pressing force of 3000 kN according to [29]. The compressive strength was determined as the arithmetic mean of the six results. Thermal conductivity tests on concrete specimens were conducted by means of a PHYWE house model (PHYWE Systeme GmbH and Co., Gottingen, Germany). It consists of removable side walls and its purpose is to determine thermal conductivity of the speci  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**LWC**} & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **11** & **12** & **13** & **14** & **15** \\ \hline \multirow{2}{*}{GEGA 2 mm} & (\%) & 0 & 25 & 50 & 75 & 0 & 0 & 25 & 25 & 25 & 50 & 50 & 0 & 0 & 75 & 100 \\ \cline{2-13}  & (kg/m\({}^{3}\)) & 0 & 65 & 130 & 195 & 0 & 0 & 65 & 65 & 65 & 130 & 130 & 0 & 0 & 195 & 260 \\ \hline \multirow{2}{*}{GEGA 4 mm} & (\%) & 0 & 0 & 0 & 0 & 100 & 75 & 50 & 25 & 75 & 50 & 25 & 50 & 25 & 25 & 0 \\ \cline{2-13}  & (kg/m\({}^{3}\)) & 0 & 0 & 0 & 0 & 240 & 180 & 120 & 60 & 180 & 120 & 60 & 120 & 60 & 60 & 0 \\ \hline \multirow{2}{*}{GAA 8 mm} & (\%) & 100 & 75 & 50 & 25 & 0 & 25 & 25 & 50 & 0 & 0 & 25 & 50 & 75 & 0 & 0 \\ \cline{2-13}  & (kg/m\({}^{3}\)) & 580 & 435 & 290 & 145 & 0 & 145 & 145 & 290 & 0 & 0 & 145 & 290 & 435 & 0 & 0 \\ \hline \multicolumn{2}{c}{CEM 14 2.5R} & (kg/m\({}^{3}\)) & \multicolumn{11}{c}{} & \multic  
mens, made of different materials. Figure 2a,b shows the construction of the house model. The chamber consists of thermally insulated base with a removable cover, measurement walls, inner insulation, heater. The floor of the base is insulated by means of the polystyrene plate, about 5 cm thick. Side walls with square holes 210 \(\times\) 210 mm are put inside and fixed with two screws at each side of the hole gasket.