The present invention belongs to the technical field of metallurgical solid waste resource utilization, and particularly relates to acidification and carbonization coupling modified steel slag as well as a preparation process and an application thereof. The process specifically includes the following steps of adopting acetic acid, tributyl phosphate, ethanolamine and a NaOH and Ca(OH).sub.2 emulsion as reaction reinforcing agents, and modifying the steel slag together with CO.sub.2-rich lime kiln flue gas. The process for modifying the steel slag through acidification and carbonization coupling provided in the present invention has the advantages of simple reaction conditions and no need of high-pressure CO.sub.2, additionally, the carbonation reaction rate can be greatly increased, and f-CaO and f-MgO in the steel slag can be effectively eliminated.

Methods of preparing engineered cementitious composite precursors include carbonating a fly ash comprising >about 25% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the fly ash to a first gas stream comprising carbon dioxide to form a carbonated fly ash. A steel slag is also carbonated that comprises >about 40% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the steel slag to a second gas stream comprising carbon dioxide to form a carbonated steel slag. The carbonated fly ash and the carbonated steel slag are suitable for use as engineered cementitious composite precursors in a bendable engineered cementitious composite composition that further comprises Portland cement, a polymeric fiber, and a superplasticizer.

Methods of preparing engineered cementitious composite precursors include carbonating a fly ash comprising >about 25% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the fly ash to a first gas stream comprising carbon dioxide to form a carbonated fly ash. A steel slag is also carbonated that comprises >about 40% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the steel slag to a second gas stream comprising carbon dioxide to form a carbonated steel slag. The carbonated fly ash and the carbonated steel slag are suitable for use as engineered cementitious composite precursors in a bendable engineered cementitious composite composition that further comprises Portland cement, a polymeric fiber, and a superplasticizer.

This invention discloses a double-liquid grouting slurry, its technology and application for super large diameter underwater shield engineering under high water pressure condition. The materials of slurry I are: 35-45 parts of cement clinker; 15-25 parts of slag; 24-35 parts of fly ash; 15-25 parts of steel slag; 5-15 parts of bentonite; 4-10 parts of limestone tailing; 0.3-2.0 parts of water reducing agent; 0.5-2.5 parts of cellulose. The materials of slurry II are: 0.2-3.8 parts of short-cut fiber; 96-99 parts of sodium silicate solution; 0.8-4.8 parts of viscous polymers. This invention generates the double-liquid slurry preparation process including crushing-screening-milling-group mixing-grouped mixing at different speeds, the volume ratio of slurry I and II is 1:1-10:1 during grouting, and the slurry is injected into the shield void through the six-point position technology at the shield tail and 3+2+1 segment splicing synchronous grouting techniques.

An anti-corrosive concrete grouting material for coastal structure connection and a method for preparing the same, belonging to the technical field of anti-corrosion of coastal assembled structure connectors. The grouting material includes the following components: expansible compound cement, slag sand, fly ash (FA), polyvinyl alcohol (PVA) (containing an oxidant and a catalyst), graphene oxide (GO), a water reducer, an adjusting admixture, a defoaming agent, a mineral admixture and water. A shrinkage-free effect of the grouting material is realized through internal curing of GO-PVA hydrogel, micro-expansion of the compound cement and shrinkage reduction effect of the FA; an energy storage effect of a GO-PVA hydrogel micro-capacitor is exerted to avoid formation of a reinforcement corrosion micro-battery in a grouting material sleeve, a reinforcement corrosion self-immune effect is achieved, seawater corrosion resistance of the grouting material is improved by the slag sand, and it has huge economic and environmental protection benefits.

An anti-corrosive concrete grouting material for coastal structure connection and a method for preparing the same, belonging to the technical field of anti-corrosion of coastal assembled structure connectors. The grouting material includes the following components: expansible compound cement, slag sand, fly ash (FA), polyvinyl alcohol (PVA) (containing an oxidant and a catalyst), graphene oxide (GO), a water reducer, an adjusting admixture, a defoaming agent, a mineral admixture and water. A shrinkage-free effect of the grouting material is realized through internal curing of GO-PVA hydrogel, micro-expansion of the compound cement and shrinkage reduction effect of the FA; an energy storage effect of a GO-PVA hydrogel micro-capacitor is exerted to avoid formation of a reinforcement corrosion micro-battery in a grouting material sleeve, a reinforcement corrosion self-immune effect is achieved, seawater corrosion resistance of the grouting material is improved by the slag sand, and it has huge economic and environmental protection benefits.

A vegetal concrete masonry unit is provided which comprises cooked crop residues, binder and pulverized fuel ash in a mass ratio of 1:1:1.5 to 1:1.5:3.

A vegetal concrete masonry unit is provided which comprises cooked crop residues, binder and pulverized fuel ash in a mass ratio of 1:1:1.5 to 1:1.5:3.

The method for producing a carbonate bonded, compacted article, which method comprises the steps of providing a particulate, carbonatable material; compacting the particulate material to form a compact; and carbonating said compact. The carbonation of the compact is started and subsequently continued for at least 1 hour with a low partial carbon dioxide pressure in the carbonation gas which is lower than 0.5 bars, after which carbonation of the compact is continued for at least 8 hours with a high partial carbon dioxide pressure in the carbonation gas which is higher than 0.5 bars. By carbonating in two phases with a low and a high partial carbon dioxide pressure, a higher compressive strength of the carbonated compacts can be achieved within a predetermined carbonation time, in particular within a carbonation time of about 24 hours so that every day new compacts can be carbonated.

The method for producing a carbonate bonded, compacted article, which method comprises the steps of providing a particulate, carbonatable material; compacting the particulate material to form a compact; and carbonating said compact. The carbonation of the compact is started and subsequently continued for at least 1 hour with a low partial carbon dioxide pressure in the carbonation gas which is lower than 0.5 bars, after which carbonation of the compact is continued for at least 8 hours with a high partial carbon dioxide pressure in the carbonation gas which is higher than 0.5 bars. By carbonating in two phases with a low and a high partial carbon dioxide pressure, a higher compressive strength of the carbonated compacts can be achieved within a predetermined carbonation time, in particular within a carbonation time of about 24 hours so that every day new compacts can be carbonated.