## 3 Test Results and Discussions
### Bond-Slip Relationship
SCGC specimens recorded an average shear connection stiffness value of 6.25 MPa, 71% lower than NC60 but 45% higher than NC40. The results indicate that increased compressive strength enhances the shear connection stiffness. However, SCGC specimens with lower compressive strength showed a higher interface connection stiffness than NC40 specimens, which was not expected. As the slip progressed, all standard concrete samples observed a sudden drop in load, indicating that the embossment's angular side was compressed within the elastic deformation zone and escaped from the indention. Afterwards, the load gradually increases with slip progress, until it approached the ultimate load. Then, the load gradually decreased until the specimen could not withstand any load. Compared to NC specimens, the different load-end slip behaviour can be attributed to the better composite interaction between SCGC and the angular side of the embossments. NC60 recorded an average ultimate load equal to 15.30 KN at an end slip equal to 3.35 mm. On the other hand, NC40 recorded a 10.26 KN average ultimate load at the relevant slip value equivalent to 2.70 mm. The results showed that NC60 specimens have 49% higher average ultimate strength than NC40. SCGC specimens have 66% higher average ultimate strength than NC40 and 11% higher average ultimate strength than NC60. The higher ultimate strength developed with SCGC specimens compared to NC specimens is due to the lower hardness associated with SCGC, allowing for better composite interaction between SCGC and the profiled steel sheet. The average ultimate load strength of the SCGC specimens was developed at 4.64 mm, which was higher than the NC specimens. The low concrete hardness associated with SCGC allowed the angular side of the embossment to \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Specimen** & **Pk** & **m** & **Pu** & **Su** & **Toughness** \\  & **(kN)** & **(MPa)** & **(kN)** & **(mm)** & **(J)** \\ \hline NC40 & 1.66 & 4.32 & 10.26 & 2.70 & 1424 \\ \hline NC60 & 1.33 & 21.50 & 15.30 & 3.35 & 2193 \\ \hline SCGC & 2.18 & 6.25 & 17.03 & 4.64 & 2564 \\ \hline \hline \end{tabular}  
* Pk is the average load at the first slip-chemical adhesion break load, m is the average interface connection stiffness, and Pu is the average ultimate load that the specimen can withstand (maximum strength). Su is the average end slip associated with Pu.  
\end{table} 
Table 7: Average results of load and end slip. crush into the concrete, causing better shear resistance at the SCGC-profiled sheet interface than the NC specimens. The composite slab toughness or ductility is the energy capacity that a composite slab can sustain without rapidly losing its strength. The integrated area under the load-slip curve is up to 80% of the ultimate load. The SCGC1 and SCGC2 specimens showed unexpected results, as they recorded 81% higher average toughness compared to NC40 and 16.5% higher average toughness compared to NC60. Compared to NC, the low concrete hardness associated with SCGC allowed for better mechanical interlock and friction between the profiled steel sheet and SCGC.