CN-119569391-B - Design method of carbonization 3D printing concrete mixing ratio and carbonization 3D printing concrete

CN119569391BCN 119569391 BCN119569391 BCN 119569391BCN-119569391-B

Abstract

The invention relates to a design method of a carbonization 3D printing concrete mixing ratio and carbonization 3D printing concrete. According to the invention, carbon dioxide is introduced into the cement-based printing slurry, the amount of magnesium chloride is calculated according to the content of CaCO 3 which is a carbonization reaction product and the proportion of calcite to aragonite in the required concrete mixture, and the magnesium chloride and the carbon dioxide are simultaneously added into the cement-based printing slurry for full reaction, so that the 3D printing concrete material is finally prepared. According to the invention, through the addition of magnesium chloride, the generation of aragonite type calcium carbonate improves the thixotropic behavior of the material, the cement slurry has stronger constructability, and meanwhile, the orientation of the nano aragonite fibers is arranged according to the printing direction, so that the nano aragonite type calcium carbonate has excellent reinforcing and toughening effects, and the anti-bending, anti-bending and anti-compression strength are all improved.

Inventors

ZHANG HONGZHI
JIAO ZHILIN
GE ZHI
SONG SHUAI
XUE XINGJIE
JIANG NENGDONG
FENG YUJIE

Assignees

山东大学

Dates

Publication Date: 20260505
Application Date: 20241118

Claims (6)

1. A design method of a carbonized 3D printed concrete mix, the design method comprising the steps of: 1) Weighing silicate cement clinker, adding deionized water to dissolve out calcium ions, adding an additive, adjusting pH, and fully reacting to obtain cement-based printing slurry; 2) Introducing carbonate source material into the cement-based printing slurry, controlling the introducing amount of the carbonate source material, enabling minerals in the cement-based printing slurry and the carbonate source material to carry out carbonization reaction to generate carbonate, simultaneously, calculating the using amount of magnesium chloride solution according to the content of CaCO 3 which is a carbonization reaction product and the proportion of calcite and aragonite in the required concrete mixture when introducing the carbonate source material into the cement-based printing slurry, and simultaneously adding the magnesium chloride solution and the carbonate source material into the cement-based printing slurry for full reaction; the method for calculating the dosage of the magnesium chloride solution according to the content of CaCO 3 as a carbonization reaction product and the proportion of calcite to aragonite in the required concrete mixture comprises the following steps: (1) Determination of calcium content According to the ratio of calcium element in silicate cement clinker, determining the generation amount of calcium carbonate after carbon dioxide is introduced, and the calculation method comprises the following steps: ; wherein: The method comprises the steps of taking the ratio of calcium element in silicate cement clinker, x is the mass of C 3 S、C 2 S in the silicate cement clinker, k represents the proportion of calcium element in C 3 S、C 2 S in the silicate cement clinker, M is the total weight of all materials of the silicate cement clinker, N is the ratio of calcium element in mineral admixture, N is the mass of the mineral admixture, M Ca is the total amount of calcium element in a product, and z is the reaction efficiency, namely the calcium carbonate generation rate; is the calcium carbonate production amount; (2) Determination of magnesium content Determining the reasonable length-diameter ratio of the calcium carbonate sample through the aragonite needle-shaped calcium carbonate fiber orientation index; the morphological characteristics of the nano-scale fibers have a remarkable influence on the fiber orientation, the fiber orientation index is used for representing the orientation of aragonite needle-shaped calcium carbonate in a cement-based material, and the higher the numerical value is, the more parallel the fibers are arranged with the printing direction; the orientation index obeys the following formula (4): ; In the formula, Is fiber orientation index #) ); N is the total number of fibers; The ratio of the added amount of the magnesium chloride solution to the generated amount of the calcium carbonate is determined by the analysis of the length-diameter ratio of the aragonite phase calcium carbonate, (3) Aragonite phase ratio determination and magnesium chloride solution concentration determination The thixotropic behaviour of 3D printed concrete is quantified by a thixotropic index, defined as the ratio of static to dynamic yield stress: ; In the formula, Is thixotropic index; And Static and dynamic yield stress (Pa) at a given shear rate and shear time, respectively; the evolution of static and dynamic yield stress over time at different aragonite phase calcium carbonate ratios is typically fitted with a linear regression model: ; Wherein, the Is a dynamic yield stress; Is static yield stress; the ratio of the aragonite phase calcium carbonate is calculated; For the structure accumulation rate (Pa/s), the CaCO 3 crystal form was determined by X-ray diffraction (XRD), and the content of aragonite phase calcium carbonate whiskers in the product was calculated by the following formula (9): ; wherein y is the content percentage of the aragonite phase, ia and Ic are the integral intensities of the strongest characteristic peaks of the aragonite phase and calcite phase in the XRD spectrum respectively, and the diffraction surfaces are (221) and (104) respectively; determining an influence index according to dynamic yield stress and static yield stress under different aragonite phase calcium carbonate ratios; Determining an optimal duty cycle of aragonite phase calcium carbonate based on the impact index; determining the concentration of the magnesium chloride solution based on a formula of the change of the proportion of the aragonite phase calcium carbonate with the concentration of the magnesium chloride solution; The change of the aragonite phase calcium carbonate ratio with the concentration of the magnesium chloride solution under different temperature conditions obeys the following formula: ; Wherein q is the temperature, p is the magnesium ion concentration, r is the duty ratio of aragonite phase calcium carbonate; The value of (2) is changed along with the proportion of aragonite phase calcium carbonate and is compliant with the formula (11); 3) And then adding the mineral admixture, and fully stirring to obtain the 3D printing concrete material.
2. The method according to claim 1, wherein the main mineral components of the portland cement clinker are tricalcium silicate, dicalcium silicate, tricalcium aluminate and tetracalcium aluminoferrite, the weight content of the tricalcium silicate and dicalcium silicate is 70% -85%, the total volume of the fully hydrated solution is 65% -75% of C-S-H gel, the total volume of the fully hydrated solution is 15% -25% of calcium hydroxide, and the hydration characteristics of the portland cement clinker are very similar to those of portland cement.
3. The method according to claim 1, wherein the carbonate source material is air or carbonized gas containing carbon dioxide, the molar concentration of the magnesium chloride solution is 0.1125mol/L to 0.1375mol/L, and the ionic strength of the magnesium chloride is 3.0.
4. The method according to claim 1, wherein the mineral admixture is selected from one or more of fly ash, granulated blast furnace slag, silica fume, lime powder, steel slag powder industrial solid waste, and the additive is selected from one or more of water reducing agent, retarder, air entraining agent, pumping agent and rust inhibitor.
5. A carbonized 3D printed concrete produced by the method of any one of claims 1-4.
6. Use of the carbonized 3D printed concrete of claim 5 in 3D printed construction.

Description

Design method of carbonization 3D printing concrete mixing ratio and carbonization 3D printing concrete Technical Field The invention belongs to the field of 3D concrete printing, and relates to a design method of a carbonization 3D printed concrete mixing ratio and carbonized 3D printed concrete by regulating thixotropic behavior of a material through carbonization. Background In the building field, the research 3D printing technology is combined with the industry, and is the forefront research direction for realizing digital and intelligent building in the industry. The 3D concrete printing technology is a novel non-mould concrete forming technology because the 3D concrete printing technology has higher plasticity in the actual construction printing process and does not need to be supported in the forming process. In the field of 3D printing concrete, a large amount of additive is needed to be added into cement-based slurry to meet the thixotropic requirement, and the cost is high. Materials are the core of building 3D printing, while 3D printed building materials currently still use cement-based materials, cement being the main source of carbon emissions. In the process of producing the 3D printing concrete material, the carbon emission is reduced, the carbon fixation is realized, the solid waste utilization rate and the material printing performance are improved, and the rheology of the calcium carbonate is regulated by regulating and controlling the crystal form of the calcium carbonate, so that the calcium carbonate becomes a research hot spot in the field of engineering materials. Disclosure of Invention Based on the above, the invention provides a design method of the mix proportion of carbonized 3D printing concrete and carbonized 3D printing concrete, so as to solve the technical problems of high cost, increased carbon emission, constructability and incompatibility of rheology, which are caused by the requirement of adding a large amount of additives to meet the thixotropic requirement in the prior art. The invention utilizes magnesium ions to regulate and control the crystal form of calcium carbonate so as to improve the rheological behavior of the material, establishes a relational expression of the proportion of aragonite phase calcium carbonate to the concentration and the temperature of magnesium ions, and provides the fiber orientation index of aragonite needle-shaped calcium carbonate fibers for quantitatively improving the mechanical property of the printed material. In order to achieve the above purpose, the invention adopts the following technical scheme: A design method of a carbonization 3D printing concrete mixing ratio comprises the following steps: 1) Weighing the component A, adding deionized water to dissolve out calcium ions, adding an additive, adjusting pH, and fully reacting to obtain cement-based printing slurry; 2) Introducing a component B into the cement-based printing paste, controlling the introducing amount of the component B, enabling minerals in the cement-based printing paste and the component B to carry out carbonization reaction to generate carbonate, simultaneously, calculating the using amount of a component C according to the content of CaCO 3 which is a carbonization reaction product and the proportion of calcite and aragonite in the required concrete mixture when introducing the component B into the cement-based printing paste, and simultaneously adding the component C and the component B into the cement-based printing paste for full reaction; 3) And then adding the component D, and fully stirring to obtain the 3D printing concrete material. The preferred raw materials of the invention are: according to a preferred embodiment of the invention, component A is Portland cement clinker. According to the invention, the main mineral components of silicate cement clinker, namely tricalcium silicate, dicalcium silicate, tricalcium aluminate and tetracalcium aluminoferrite, account for 70% -85% by weight, C-S-H gel accounts for 65% -75% of the total volume of the fully hydrated solution, and calcium hydroxide accounts for 15% -25%. Portland cement clinker hydration characteristics are very similar to portland cement hydration characteristics. Known as strength minerals. According to a preferred embodiment of the invention, component B is a carbonate source, which is air or a carbon dioxide-containing carbonization gas. The main chemical composition of component B is carbon dioxide, and the treated concrete mixture shows an increase in compressive strength. For the OPC mixture, the compressive strength benefit of the concrete sample with the carbon dioxide content of 0.10% is as high as 30%, and the addition of carbon dioxide during the stirring process obviously influences the durability of the concrete and has no influence on the pH value of the concrete. According to the invention, the component C is preferably magnesium chloride solution, the molar concentration of