Study On The Preparation Of Ecological Pervious Concrete With Carbon-activated Steel Slag

At present,the annual emission of steel slag in China is large,but the utilization rate of resources is not high,only about 30%.Poor wearability and poor stability of steel slag is the bottleneck of its comprehensive utilization.Using CO₂ to react with active CaO and other components in steel slag to form a stable carbonate cementing material provides a new way for comprehensive utilization of steel slag.Not only can a large number of steel slag be utilized as a resource,but also can a large number of solidified and permanent storage of CO₂,which is a new technology of energy saving and emission reduction.In this paper,the carbonation and consolidation of steel slag are explored,and the synergistic effect of steel slag hydration and carbonization on the performance of steel slag products.The steel slag powder is used as cementitious material,and make full use of the high-strength wear characteristics of steel slag aggregates to form a porous skeleton,and this paper use the high concentration CO₂ in industrial waste gas and the active CaO in the steel slag to quickly react to form a carbon-excited steel slag porous concrete material with CaCO₃ as the main body,and obtain the following research results:1.Study on carbonation and consolidation of steel slagThe particle fineness and carbonization time of steel slag are the important factors that affect the carbonization effect of steel slag.With the increase of its specific surface area,the strength of the prepared slurry specimen after carbonization increases.The XRD diagram of the slurry specimen of the steel slag powder can clearly see the diffraction peak of Calcite（CaCO₃）.With the increase of specific surface area,the strength of the diffraction peak of the steel slag sample carbonized CaCO₃ is enhanced,the better the carbonization effect is.The carbonization effect of steel slag is different under different molding modes.Under the conditions of water mixing and molding,when the water ratio W/C=0.27,the pure slurry strength of steel slag powder reaches a maximum of 41.4 MPa.Under the condition of pressed molding,the optimum molding pressure of steel slag powder pressing and molding is 30KN,the optimum water content is 10%and the maximum strength of steel slag powder is 72.4MPa.2.Effect of activator on carbonation and consolidation of steel slagWhen adding phosphogypsum,Na₂CO₃ and Na₂SO₄ respectively into the steel slag powder,the strength of the steel slag test piece increases gradually and then decreases.When the content of phosphogypsum is 2.5%,the carbonation rate of steel slag can be increased,and the strength of the steel slag powder carbide solid structure specimen is the maximum.The steel slag mixtures with a content of 2.5%phosphogypsum per 1kg can be carbonized and stored 155g CO₂ after carbonization,and the amount of CaCO₃ produced during carbonization is about 352.3g.When the content of Na₂CO₃ is 1%,the net pulp sample of its slag powder reaches the maximum strength of 65.7MPa after carbonization and its strength is increased by58.7%.When the amount of Na₂SO₄ was 1%,the strength of the specimen was60.3MPa,and its strength increased by 45.7%.3.Preparation of pervious concrete with carbon-excited steel slagWith the fineness of steel slag powder,the specific surface area increases,the strength of steel slag porous concrete increases.With the increase of steel slag powder dosage,the strength of steel slag porous concrete increases.When the amount of steel slag powder is 300³30 kg/m³,the 28d strength of the carbon-excited steel slag pervious concrete can exceed 8MPa,and the porosity is over 20%.The strength of steel slag through concrete can be improved by adding phosphogypsum and sodium carbonate.When the content of Phosphogypsum is 5%,the strength of steel slag permeable concrete is up to 9.4MPa,and 30.5%higher than control group.When the Na₂CO₃ admixture is w=1%,the strength of the steel slag pervious concrete is up to9.1MPa.