*2.1. Materials*

Ordinary Portland cement with a 28 d strength grade of 42.5 MPa was employed in this experiment. Ordinary mortar with a standard 28 d strength grade of 10 MPa was used as the binder. The fine NA with a grain size of 0–5 mm were river sand. RCA was provided by Shaanxi Jianxin Technology Environmental Protection Co., Ltd. The RCA with a grain size of 5–10 mm (Figure 1) were crushed, cleaned, sieved, and separated from waste concrete. The fine NA and coarse NA were replaced by 0% recycled fine aggregates, and 100% RCA, respectively, and the mixture proportion of recycled aggregate concrete (RAC) is shown in Table 1. The grading of aggregates and properties of aggregates are shown in Figure 2 and Table 2, respectively. Based on the Chinese standard GB/T 41,112,013 [31] and the GB/T 8239-2014 [32], RCHB, prepared by RAC, with a compressive strength of 10 MPa were used for the fabrication of masonry walls, and the dimension of RCHB is 390 mm × 240 mm × 190 mm (Figure 3). A hot-rolled ribbed (HRB335) steel bar with a yielding strength of 335 MPa was used as longitudinal rebars. A hot-rolled plain (HPB235) steel bar with yielding strength of 235 MPa was selected as stirrups.

**Figure 1.** Aggregate components.



**Figure 2.** Fuller grading curves.


**Table 2.** Properties of aggregates.

**Figure 3.** The dimension of recycled concrete hollow block.

#### *2.2. Design of Specimens*

Figure 4 shows the masonry procedure of all the specimens, including masonry the bottom beams, infill walls, structural columns, and ring beams. It is important to mention that ordinary mortar with a strength of 10 MPa was selected to masonry the mortar joints of the infill walls, and the fullness degree of mortar joints should be up to 80% to ensure the propagation of shear forces according to the seismic design requirements. In addition, the horizontal joint width was required to range from 8 to 12 mm.

**Figure 4.** Process of the construction of masonry wall specimens.

The experimental parameters used to determine the seismic performance of specimens were the compressive stress, aspect ratios, and the materials of the structural columns. The test specimens were divided into two groups. The first group consisted of three walls W1, W2, and W3, and the cyclic loading tests of them were conducted to analyze the influence of different compressive stress and aspect ratio on the seismic capacity. The second group contained two specimens, W4 and W5, which were constrained by structural columns, and the tests of them were conducted to analyze the influence of structural columns of different materials on the seismic capacity. The other components of all specimens, such as bottom beams and ring beams, were consistent in the test. Additionally, the value of the compressive stress was 0.6 MPa and 0.9 MPa, respectively, corresponding to the compressive stress of the upper weight on the middle floor and the bottom floor of an ordinary 9-storey residential building, respectively. Properties and dimensions of the five masonry walls are shown in Table 3 and Figure 5.

**No. W1 W2 W3 W4 W5 Unit** Width 2000 2000 1200 2240 2240 mm Height 1400 1400 2000 1350 1350 mm Aspect ratio 0.700 0.700 1.667 0.603 0.603 — Vertical load 288 432 259 323 323 kN Vertical Axial stress 0.6 0.9 0.9 0.6 0.6 MPa Materials of Structural columns — — — NA RCA —

**Table 3.** Design of recycled concrete hollow block (RCHB) masonry walls.

.H\ EDUVRI03D
