Effects of Different Silicon Sources on the Properties of Geopolymer Planting Concrete Mixed with Red Mud

Abstract

In order to reduce the carbon emission of planting concrete in the process of preparation, and to realize the application of large amounts of red mud in the geopolymer, in this study, high silicon source materials and blast furnace slag are added to a large content of red mud base geopolymer planting concrete, which can remove the dependence of planting concrete on ordinary Portland cement and provide a new direction for the comprehensive utilization of red mud. In the paper, the effects of different A (Alkali solid content)/P (Powder dosage) and high silica sources (silica fume and diatomite) on the microstructure and fluidity of the geopolymer, as well as the compressive strength, pore characteristics, and alkalinity of the planting concrete, are comparatively evaluated. The corresponding results showed that when A/P was 0.25, the planting performance of the planting concrete would be reduced due to its high alkalinity; when A/P was 0.15, the planting concrete would have its sedimentation and the compressive strength decreased. On the other hand, the pozzolanic reaction among the silica fume, diatomite, and Ca(OH)2 significantly weakened the alkali pan phenomenon in the later stage of planting concrete formation. The addition of an appropriate amount of silica fume and diatomite also made the structure of the geopolymer more compact with better fluidity, which yielded superior pore characteristics and planting performance for the planting concrete. For good planting concrete pore characteristics, the test results showed that the fluidity of the mortar should be 112–128 mm. Overall, the best planting concrete performance was achieved at an A/P ratio of 0.2, with the contents of silica fume and diatomite being 10% and 5%, respectively. Furthermore, the slope finite element analysis showed that planting concrete made with red mud geopolymer had better slope protection potential than ordinary Portland cement.

Enhancing the Mechanical Properties and Water Permeability of Pervious Planting Concrete: A Study on Additives and Plant Growth

“…When PVAP was 0.6%, compressive strength was slightly lower than that of 0.8%. In addition, the mechanical properties were all higher than the previous scholars' research results or national standards [11,29].…”

“…When PVAP was 0.6%, compressive strength was slightly lower than that of 0.8%. In addition, the mechanical properties were all higher than the previous scholars' research results or national standards [11,29]. The effect of PVAP on the internal pore structure of PPC and the coating of the aggregate by cement slurry is shown in Figure 6 (See Figure 11).…”

“…Scholars have studied some properties of PPC. Chen Wei et al studied the effect of silica fume and diatomite on the mechanical properties of PPC prepared with high-content red mud [11]. It was found that an appropriate content of silica fume and diatomite could make its structure denser and provide excellent pore characteristics for PPC.…”

Research and Application Progress of Vegetation Porous Concrete

“…Furthermore, the use of mineral admixtures such as fly ash [37,41,42], mineral powder [38,43,44], and silica fume [38,45], as shown in Figure 3, or waste like steel slag [46] and charcoal powder [47] as supplementary cementitious materials (SCMs) in lieu of traditional cement not only reduces costs but also benefits the environment [20]. Ganapathy [42] investigated the influence of fly ash and silica fume on the planting characteristics of vegetation porous concrete, confirming that both fly ash and silica fume could enhance plant growth by improving alkalinity.…”

“…This method allows for the control of the distribution and size of pores within the concrete [62]. However, when using the volume method for the mix design of vegetated ecological concrete, discrepancies between the measured porosity and the target porosity can arise as the slurry volume increases [45].…”