# Effect of Aggregate Type on the Shear Behavior of Reinforced Lightweight Concrete Beams
## 4 Experimental Tests
### Test Variables  
Table 1 describes the three types of CAs used to prepare reinforced LWAC beams. Two types of lightweight CAs were used: expanded slate and expanded clay. An expanded slate aggregated commonly utilized in LWAC is produced by heating slate in a rotary kiln at approximately 1200 \({}^{\circ}\)C. It has a bulk density ranging from 720 to 880 kg/m\({}^{3}\), a particle density of 1394 kg/m\({}^{3}\), and a 24 h water absorption ratio of 5.9%. Expanded clay produced from natural clay expanded at high temperatures and features a bulk density of 400 to 800 kg/m\({}^{3}\), a particle density of 1449 kg/m\({}^{3}\), and a 24 h water absorption rate of 11.9%. A consistent type of expanded clay lightweight fine aggregate was used in casting the reinforced ALWAC specimens. Additionally, a natural CA was included for comparative analysis. Larger aggregate sizes generally enhance strength but also impact ductility and the material's ability to withstand deformation before failure. Ductility, the ability of a material to deform plastically under stress, is crucial in RC beams, as it influences their capacity to absorb energy prior to failure. Additionally, analyzing the softening branch of the load-deformation curve provides key insights into the post-peak behavior, crucial for understanding how beams may perform under sustained loads or during seismic events [40; 41]. Thus, a comprehensive understanding of these factors is essential for designing resilient and safe concrete structures. It should be noted that aggregate size was not a variable in this study; all aggregates used had similar dimensions, as shown in Table 1.  
Figure 1 illustrates the schematic diagrams of the cross-sectional and longitudinal reinforcement configurations for the beams studied. Each beam had a uniform effective depth (d) of 126 mm and an _a/d_ of 4.76 [42]. Concrete cover depths were specified at 16.0 mm for beams without stirrups and 10.0 mm for those with stirrups. All beams were longitudinally reinforced with two 16 mm diameter deformed steel bars, standardizing the reinforcement across the series. Additionally, a longitudinal reinforcement ratio of 3.2% was employed to ensure predominantly shear-based failure, supported by transition reinforcement. Four beams were prepared for each type of aggregate: two omitted shear reinforcements, while the other two included steel stirrups spaced at 90 mm intervals. The design also featured bent longitudinal bars at each beam's ends to provide necessary anchorage. To evaluate the compressive strength, three cylinders, each 100 mm in diameter and 200 mm in height, were prepared for each beam configuration. As shown in Figure 1, the stirrups in the prepared concrete beams were not placed at mid-span, assuming that mid-span stirrups might not significantly affect the test results of this study [43; 44; 45]. The nomenclature for the beams consists of three letters, each signifying specific characteristics. The first letter indicates the type of concrete used: 'L' for LWAC and 'N' for NWC. The second letter specifies the presence of steel stirrups, with 'N' denoting absence and 'S' indicating presence. The third letter identifies the type of CA used. For instance, 'LNS' refers to an LWAC beam without stirrups using expanded slate, while 'NSN' designates a shear-reinforced NWC beam containing NWA, as detailed in Table 2.  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Type of Lightweight** & **Bulk Density** & **Particle Density** & **24 h Water** & **Maximum Size** & \\
**Coarse Aggregate** & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** & **Absorption (\%)** & **(mm)** & **Shape** \\ \hline Expanded slate & 849 & 1394 & 5.9 & 12 & Angular \\ Expanded clay & 469 & 1449 & 11.9 & 10 & Spherical \\ Normal & 1563 & - & 1.13 & 13 & Angular \\ \hline \end{tabular}
\end{table}
Table 1: Coarse aggregate details.