*2.1. Materials*

This study used Type I Portland cement with a specific gravity of 3.15 and fineness of 3310 cm2/g. The fine aggregate was natural river sand with saturated surface dry (SSD) specific gravity of 2.70, absorption of 1.63% and fineness modulus of 2.33. Hereafter, when used as constituent of non-cement binder, GGBS is referred to as slag (S) and CFB co-fired fly ash is referred to as fly ash (FA). FA was produced in the form of a black powder by Yong Feng Yu, Taiwan with a specific gravity of 2.73. The specific gravity of S was 2.88 and the fineness was 5860 cm2/g. The particles of FA passing through a No. 100 sieve (150 μm) are roughly 98% and the fineness was 2800 cm2/g. SEM images of the FA revealed irregular polygonal particles similar to those of S as well as rough surfaces, as shown in Figure 1. Figure 2 presents XRD patterns of FA.

**Figure 1.** SEM images: (**a**) circulating fluidized bed (CFB) co-fired fly ash and (**b**) ground-granulated blast-furnace slag (GGBS).

**Figure 2.** x-ray diffraction (XRD) pattern: (**a**) co-fired fly ash and (**b**) GGBS.

Chemical compositions of FA and S are summarized in Table 1. The chemical composition of FA was analyzed using x-ray fluorescence (XRF) as follows: SiO2 (29.47%), Al2O3 (19.27%) and CaO (35.54%). The polypropylene fibers used in the current study were 12mm in length with an aspect ratio of 375 (d = 32μm) and the fibers were produced by Poplar Co., Ltd. (Taipei, Taiwan). The specific gravity, tensile strength and Young's modulus of the fibers were 0.91, 250 and 3500 MPa, respectively.


**Table 1.** Chemical compositions of co-fired fly ash and GGBS.

#### *2.2. Mix Design and Test Methods*

The water/cementitious ratio (w/c) of the mortar specimens was maintained at a constant 0.55, whereas the cementitious materials/fine aggregate mass ratio was 1:2.75, in accordance with ASTM C109 specifications. Table 2 lists the mix design for non-cement blended materials. The specimens were numbered using two number/letters pairs indicating (1) S:F ratio and (2) the percentage of polypropylene fibers. The number after the letter S indicates the percentage of co-fired fly ash (e.g., S40 means 40% fly ash). P refers to ordinary Portland mortar. The last number indicates the percentage of polypropylene fiber (e.g., F1 means 0.1% fiber). In addition, the mixture for a preliminary test of non-cement blended composites was shown in Table 3. The S, FA, fine aggregates and fibers were mixed for about 10 min by using a low speed mixing machine to create the homogeneous mortar specimens and then cast into the metal molds. After demolding, the specimens for standard curing were placed in the standard curing room until the testing age. Table 4 presents the tests performed, the dimensions of the specimens and the standards used in this study.


**Table 2.** Mix design of the mortar specimens produced (kg/m3).

**Table 3.** Mix design of the mortar specimens for a preliminary test (kg/m3).


