A method for carbon dioxide strengthening of a recycled concrete aggregate comprises the following steps: (1) crushing and sieving waste concrete; (2) placing the sieved recycled concrete aggregate in a sealed container, controlling the relative humidity of 30-90% and the CO2 concentration of 5-90%, and carrying out carbonization treatment; and (3) making the treated recycled concrete aggregate particles into recycled mortar and concrete. Compared with mortar prepared from a recycled concrete aggregate without treatment, the mortar prepared from the obtained recycled concrete aggregate after CO2 strengthening treatment enables the mortar early strength to be improved by 20.1%-22.0% and the later strength to be improved by 12.1%-13.9%; the 28 d drying shrinkage value can be reduced by 7.8%-16.7%; and the 28 d water absorption rate can be reduced by 7.7%-13.3%.

Method for carbon dioxide strengthening of recycled concrete aggregate

The invention discloses a method for reinforcing recycled concrete fine aggregate by using carbon dioxide, which comprises the following steps: (1) calcium hydroxide solution or calcium salt calcification treatment: spreading recycled fine aggregate prepared from construction waste on a tray, spraying a calcium hydroxide or calcium salt solution, and stirring uniformly; (2) CO2 curing: putting the recycled fine aggregate subjected to calcium hydroxide solution or calcium salt calcification treatment in a closed carbonization box, and carrying out carbonization curing until the surface is completely carbonized; and (3) recycled mortar preparation: preparing recycled mortar with the substitution rate of 100% by using the treated recycled fine aggregate. Compared with the unreinforced recycled aggregate, the crushing value of the recycled fine aggregate prepared by the method is lowered by nearly 45%, and the water absorptivity is lowered by nearly 53%. Compared with the recycled mortar prepared from the unreinforced recycled aggregate, the consistency of the recycled mortar prepared by the method is enhanced by 42% or so, the 7d strength of the mortar is enhanced by 15-26%, and the 28d strength can be enhanced by 17-24%.

Method for reinforcing recycled concrete fine aggregate by using carbon dioxide

The invention belongs to the technical field of building materials, and provides a method for preparing building material products through processing industrial solid waste by hydration-carbonation coupling technique. The method comprises steps of uniformly mixing the industrial waste comprising at least one of calcium oxide, calcium hydroxide, dicalcium silicate, tricalcium silicate and tobermorite with alkaline excitation material and proper amount of water so as to prepare the blank of the building material product, wherein the industrial waste comprises steel slag, mineral waste residue, furnace slag, coal ash or coal gangue, the alkaline excitation material comprises carbide slag, lime, Portland cement or waste cement; maintaining for a period through hydration, then maintaining through carbonation so as to obtain the carbonate-based building material product. The coupling technique can effectively use the industrial solid wastes such as steel slag, mineral waste residue, furnace slag, coal ash, coal gangue, carbide slag and the like, so that emission of greenhouse gases is reduced, the greenhouse effect is relieved, furthermore, the method can be used for producing the building material products with good properties, effectively uses the waste and is environmentally friendly.

Method for preparing building material products through hydration-carbonation coupling technique

The invention relates to a hollow recycled concrete component, which comprises concrete aggregate formed by fragmenting waste concrete, cement, water and a columnar substrate, wherein the cement and the water are stirred and mixed with the concrete aggregate formed by fragmenting the waste concrete to form recycled concrete; the columnar substrate accommodates the recycled concrete; and the recycled concrete is poured into the columnar substrate to form a cylindrical hollow core attached to the inner wall of the columnar substrate, and is reacted with carbon dioxide to form the hollow recycled concrete component after being formed in the columnar substrate. The recycled concrete component of the invention is formed by reacting the recycled concrete with the carbon dioxide, and the carbon dioxide and a hydration product calcium hydroxide of the cement undergo reaction to produce calcium carbonate which can improve a contact interface of the waste concrete aggregate and the cement paste, enhance the strength of the concrete and reduce holes of the concrete, so the durability of the concrete is improved.

Hollow recycled concrete component prepared by carbon dioxide and preparation method

The invention discloses a calcium-magnesium carbonate gel material and a preparation method thereof. The gel material is prepared from the following components in percentage by mass: not smaller than 60% and not greater than 100% of industrial alkaline wastes, not smaller than 0 and not greater than 20% of cement and not smaller than 0 and not greater than 20% of active magnesium oxide through CO2 carbonization. According to the calcium-magnesium carbonate gel material and the preparation method thereof disclosed by the invention, a great deal of solid wastes is utilized, so that the calcium-magnesium carbonate gel material is environmentally friendly, low in cost, excellent in breaking strength and compressive strength; and the greenhouse gas CO2 is recycled to promote the energy conservation and emission reduction in the building material industry.

Calcium-magnesium carbonate gel material and preparation method thereof

The invention relates to a recycled aggregate made by pre-adding water to carbonated curing wastes for forming balls which absorb carbon dioxide gas in industrial waste gas, which belongs to the building material technique field. The recycled aggregate is made by adopting the following processes of: utilizing steel slag or cement containing carbonization compositions as a raw material, adding water for even mixture, and implementing the granulation for spheroidizing so as to make the recycled aggregate under the curing of carbonization gas; and the carbonization compositions include one or more than one of calcium oxide, calcium hydroxide, dicalcium silicate, tricalcium silicate, hydrated calcium silicate, hydrated calcium aluminate, hydrated calcium ferrite, ettringite, magnesium hydroxide and magnesium oxide, and the carbonization compositions have a weight percentage of no less than 30 percent in materials. The recycled aggregate has the main point that: the accelerated carbonization technique is utilized to treat industrial wastes such as steel slag, sludge and waste concrete, solidify and store carbon dioxide of greenhouse gas, and make the recycled aggregate. The pollution problem of wastes such as steel slag and waste gas is released; meanwhile, the light recycled aggregate with excellent performance is prepared.

Regeneration aggregate made of carbonized maintaining castoff

The invention belongs to the technical field of building materials and relates to an enhancer for the building materials which are prepared by taking wastes (including different types of steel slag, furnace slag, smelting slag, sludge, red sludge, incineration ash and waste cement, and the like) as main materials for absorbing CO2 waste gas, in particular to the enhancer for the building materials which are prepared by the carbonation curing wastes and using steel slag and cement as the main materials for absorbing the CO2 gas. The enhancer contains more than 50 percent by weight of easily carbonized ingredients, and the easily carbonized ingredients are one or more of calcium hydroxide, calcium oxide, portland cement or waste concrete. The enhancer of the invention plays the roles of strengthening and improving the carbonation rate, improves the strength of the building materials which are prepared by carbonation and curing and the CO2 absorption rate and shortens the production cycle.

Linju Zhang

Papers

Regeneration aggregate made of carbonized maintaining castoff

Strengthening agent for construction material prepared by carbonizing curing waste