Composite Properties of Non-Cement Blended Fiber Composites without Alkali Activator

Abstract

The vigorous promotion of reuse and recycling activities in Taiwan has solved a number of problems associated with the treatment of industrial waste. Considerable advances have been made in the conversion of waste materials into usable resources, thereby reducing the space required for waste storage and helping to conserve natural resources. This study examined the use of non-alkali activators to create bonded materials. Our aims were to evaluate the feasibility of using ground-granulated blast-furnace slag (S) and circulating fluidized bed co-fired fly ash (F) as non-cement binding materials and determine the optimal mix proportions (including embedded fibers) with the aim of achieving high dimensional stability and good mechanical properties. Under a fixed water/binder ratio of 0.55, we combined S and F to replace 100% of the cement at S:F ratios of 4:6, 5:5, 6:4. Polypropylene fibers (L/d = 375) were also included in the mix at 0.1%, 0.2% and 0.5% of the volume of all bonded materials. Samples were characterized in terms of flowability, compressive strength, tensile strength, water absorption, shrinkage, x-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. Specimens made with an S:F ratio of 6:4 achieved compressive strength of roughly 30 MPa (at 28 days), which is the 80% the strength of conventional cement-based materials (control specimens). The inclusion of 0.2% fibers in the mix further increased compressive strength to 35 MPa and enhanced composite properties.

Engineering Properties of Ternary Cementless Blended Materials

“…The SEM images also revealed needle-like C-S-H particles stacked irregularly on the surface of the gypsum, slag, and co-fired fly ash particles. These results are consistent with those reported in previous studies [23,26,31,37], in which the main hydration products were C-S-H and C-A-S-H gels with high strength development in later curing stages (56 to 91 days). It has previously been demonstrated that cementless materials containing ggbs are capable of self-hydration when combined with industrial by-products even in the absence of an alkali activator.…”

“…The compressive strength of specimens with 3% desulfurized gypsum exceeded that of the other samples at 7, 14, 28, and 56 days. Note that the G50D3 sample achieved compressive strength of 47.4 MPa at 56 days, which far exceeds the typical target strength of conventional Portland (35 MPa) [24,[31][32][33].…”

Novel Bioderived Composites from Wastes

“…The paper authored by Wei-Ting Lin and coworkers [15] showed the feasibility of using ground-granulated blast-furnace slag (S) and circulating fluidized bed co-fired fly ash (FA) as non-cement binding materials. In fact, they determined the optimal mix proportions (100% cement replacement, S:FA ratios of 4:6, 5:5, 6:4, water/binder ratio of 0.55) in order to achieve high dimensional stability and good mechanical properties with inclusion in the resulting composite of polypropylene fibers.…”

“…For that purpose, six papers were related to the preparation of innovative composite materials. Specifically, five papers reported the reuse of end-of-life tire rubber, porous glass, expanded polystyrene, slags, fly ashes and sheep's wool fibers for the preparation of cement conglomerates [12][13][14][15][16], while the last one reported the reuse of amorphous silica nanoparticles for the preparation of composites with natural rubber [17]. Moreover, five papers were related to the treatment of wastes for environmental applications.…”