Carbonization-based lightweight CO2 foamed cement-based material, and optimized preparation method and use thereof

An optimized preparation method of a carbonization-based lightweight CO2 foamed cement-based material, comprising the following steps:

• step S1:
• investigating existing foaming agents and foam stabilizers for lightweight cement slurries, and selecting n1 foaming agents and n1 foam stabilizers that are commonly used;
• step S2:
• using a water-based carbon dioxide foam foaming machine to conduct a pre-experiment on the n1 foaming agents and the n1 foam stabilizers in step S1, and selecting n2 foaming agents and n2 foam stabilizers according to a water-based foam stabilization time and a foaming height to prepare water-based carbon dioxide foams, wherein n2<n1;
• step S3:
• preparing a cement slurry with a predetermined initial water-to-cement ratio, and mixing a water-based carbon dioxide foam with the cement slurry in a predetermined foam-to-slurry ratio to prepare a lightweight CO2 foamed cement slurry;
• step S4:
• conducting an experimental design based on the n2 foaming agents and the n2 foam stabilizers in step S2:
• using foaming agents of different types of the n2 foaming agents and different concentrations, and foam stabilizers of different types of the n2 foam stabilizers and different concentrations to prepare lightweight CO2 foamed cement slurries according to step S3, and subjecting the prepared lightweight CO2 foamed cement slurries to slurry performance tests, wherein slurry performance comprises a specific gravity, a flowability, a consistency, a water excretion rate, a concretion volume shrinkage, a concretion density, and 7 day and 28 day uniaxial compressive strengths;
• and optimizing the type and concentration of foaming agent, and the type and concentration of foam stabilizer based on slurry performance requirements, wherein a process of the optimizing is conducted by an orthogonal experiment:
• setting a concentration range of conventional foaming agents as [w1-w2], and evenly dividing the concentration range to obtain n2 parameter points w1, A1, A2 . . . An2-2, and w2;
• setting a concentration range of foam stabilizers as [w3-w4], and evenly dividing the concentration range to obtain n2 parameter points w3, B1, B2 . . . Bn2-2, and w4;
• and in conjunction with the n2 foaming agents and the n2 foam stabilizers selected in step S2, conducting a four-factor n2 level orthogonal experiment on the type and concentration of the foaming agent, and the type and concentration of the foam stabilizer, and using a range analysis to obtain an optimization result of the experiment, the experiment mainly comprises two steps of calculation and determination, wherein the calculation is performed by:
• selecting the following four performance indexes of the lightweight CO2 foamed cement slurries for the range analysis:
• 7-day compressive strength, density, concretion rate, and foam stabilization time;
• assuming that A, B . . . represent different factors;
• r represents a number of levels of each factor;
• Ai represents an ith level of factor A, wherein i=1, 2, . . . , r;
• and Xij represents a value of an ith level of factor j, wherein i=1, 2, . . . , r, and j=A, B . . . ;
• conducting n tests under Xij to obtain n test results which are Yij, wherein calculation parameters are as follows:
• K
• ij
• =
• ∑
• k
• =
• 1
• n
• Y
• ijk
• wherein Kij represents a statistical parameter of the factor j at the ith level;
• n represents a number of tests of the factor j at the ith level;
• Yij represents an index value of the kth test result of the factor j at the ith level, wherein k=1, 2, . . . , r;
• R
• j
• =
• max
• ⁢
• {
• K
• 1
• ⁢
• j
• ,
• K
• 2
• ⁢
• j
• ,
• …
• ⁢
• K
• rj
• }
• -
• min
• ⁢
• {
• K
• 1
• ⁢
• j
• ,
• K
• 2
• ⁢
• j
• ,
• …
• ⁢
• K
• rj
• }
• m
• wherein Rj represents a range of the factor j, and m represents a number of levels of an experimental factor;
• based on comprehensive consideration of range results of the 7-day compressive strength, the density, the concretion rate, and the foam stabilization time of the slurries, determining the optimal type and concentration of the foaming agent, and the optimal type and concentration of the foam stabilizer;
• step S5:
• based on the optimal type and concentration of the foaming agent, and the optimal type and concentration of the foam stabilizer in step S4, designing different initial water-to-cement ratios and foam-to-slurry ratios to prepare slurries, subjecting the prepared slurries to slurry performance tests, and optimizing the initial water-to-cement ratio and foam-to-slurry ratio parameters based on slurry performance requirements;
• and
• step S6:
• conducting different gas-filling volume tests on the slurries obtained in step S5, subjecting the slurries to slurry performance tests, and optimizing an air-filling volume based on slurry performance requirements.