Low-carbon impervious grouting material for back filling of TBM (tunnel boring machine) tunnel lining and preparation method of low-carbon impervious grouting material

The invention relates to a solid-waste-based low-carbon impervious back grouting material and a preparation method thereof. The solid waste-based grouting material comprises the following components in parts by weight: 200-320 parts of a base material; 18.5 to 57 parts of a special densifying agent; and 140 to 200 parts of water. The base material is prepared from the following components in parts by weight: 20 to 40 parts of ordinary Portland cement, 30 to 60 parts of mineral powder, 80 to 180 parts of fly ash, 30 to 70 parts of furnace slag, 25 to 60 parts of bentonite and 20 to 30 parts of biomass ash. The special densifying agent is prepared from the following components: silica fume, nano SiO2, a defoaming agent and sunflower stalk ash. The filling compaction effect is formed by doping the superfine mineral material into the cement-based material, the material compaction degree is further improved by regulating and controlling the content of bubbles in a material system and the alkalinity of a pore solut