## 2 Experimental Study
### Testing Procedure  
All the composite slabs were tested with 640 days of age, and moisture was measured using a non-destructive concrete moisture meter CM 1700, with a content ranging from 6 to 10%. The fire tests were conducted in the furnace of the University of Oviedo [12]. The horizontal dimensions of the furnace are 1.20 m wide and 2.60 m long. The furnace was heated with three burners, which are fueled by light oil and operate with two-stage operation. The furnace temperature was measured with four K-type plate thermocouples placed inside the furnace. The readings of the thermocouples were used to adjust the temperature in the furnace to the ISO-834 standard fire curve [30]. The ambient temperature was close to 20 \({}^{\circ}\)C at the beginning of the fire resistance tests. More details of the static scheme and boundary conditions of the experimental procedure can be found in [12]. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Elastic Modulus (MPa)**} & \multicolumn{1}{c}{**Young’s Modulus (GPa)**} & \multicolumn{1}{c}{**Poisson Coefficient**} \\ \hline Average value & 271 & 208 & 0.31 \\ Standard Deviation & 3.51 & 2 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Properties of steel decking. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Mixing Compositions**} & \multicolumn{5}{c}{**Constituents**} \\ \cline{2-5}  & **ECF (\%)** & **ECC (\%)** & **Siliceous Aggregate 0/2 (\%)** & **Cement 42.5R (\%)** & **Water (\%)** \\ \hline LWC-1 & 5.85 & 6.05 & 40.42 & 32.14 & 15.54 \\ LWC-2 & 5.89 & 4.11 & 44.68 & 30.55 & 14.77 \\ LWC-3 & 3.91 & 4.50 & 44.44 & 31.79 & 15.36 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mixing proportions of lightweight concretes in mass fractions. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Type**} & **Bulk Density** & \begin{tabular}{c} **Compression** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} & \begin{tabular}{c} **Strength Class** \\ **(\(f_{ck}\), MPa)** \\ \end{tabular} & \begin{tabular}{c} **Young’s Modulus** \\ **(GPa)** \\ \end{tabular} & \
\begin{tabular}{c} **Thermal** \\ **(GPa)** \\ \end{tabular} &
\begin{tabular}{c} **Specific Heat** \\ **(\(k_{20^{\circ}\)C, W/m\(\cdot\)K)** \\ \end{tabular} \\ \hline LWC-1 & 1740 & 25.60 & LC 25/28 & 207 & 1.65 & 950 \\ LWC-2 & 1819 & 28.59 & LC 25/28 & 216 & 1.73 & 840 \\ LWC-3 & 1906 & 30.22 & LC 30/33 & 272 & 1.51 & 850 \\ NC & 2350 & 36.97 & C 30/37 & 457 & 2.52 & 900 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Material properties of concrete. Before the fire exposure, the slabs were subjected to a designed 3-point bending test (see Figure 2c) for 15 min following EN 13381-5. Designed testing load was set corresponding to 60% of the maximum ambient bending strength. Previous experimental studies for this specific type of composite slab at ambient temperature were conducted to provide reference load carrying capacity [12]. Afterward, the furnace fire was ignited and controlled following the ISO-834 curve until the failure of composite slabs. The temperature distribution in each slab was measured using sixteen K-type thermocouples (see Figure 2). Four of the thermocouples (1A-2B-3A-4B) were used to monitor the non-exposed surface temperature (see Figure 2). These thermocouples were used to verify the insulation criterion specified in Eurocode 4. The other twelve thermocouples, placed in groups of three (C: 7-10-14; D: 6-11-15; E: 8-9-13; F: 5-12-16), measured the temperature within the slab at different depths. Thermocouples in zone C at a depth of 160 mm were placed in contact with the steel decking (see Figure 2). Likewise, thermocouples in zone D were placed in contact with the steel decking at the thinner part of the slab, at a depth of 100 mm (see Figure 2). Zone E and zone F measured the evolution of temperature within the concrete at a depth of  
Figure 2: Details of the fire tests: (**a**) Top view of the slab and arrangement of thermocouples (units: mm). (**b**) Cross section of the slab (units: mm).