Preparation method of high-performance natural polymer modified mortar based on citrus reticulata extract admixture

Abstract

The invention provides a preparation method of high-performance natural polymer modified mortar based on a wood orange extract additive, and belongs to the technical field of modified mortar. The preparation method of the high-performance natural polymer modified mortar based on the citrus reticulata extract admixture comprises the following steps: firstly, mixing the citrus reticulata extract and the natural hydraulic lime to obtain lime paste, and then mixing the lime paste with the siliceous fine aggregate to obtain a mixture in a plastic state; and finally, grinding and standing to obtain the high-performance natural polymer modified mortar of the wood orange extract additive. The prepared modified mortar can significantly improve the compressive strength, bending strength and impermeability of the mortar, has the advantages of high compressive strength, high bending strength and clear and traceable raw material carbon footprint, and has the characteristics of renewable raw materials, low energy consumption production, high performance and long service life.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of modified mortar, in particular to a preparation method of high-performance natural polymer modified mortar based on a fortifier of Fortunella margarita extract. BACKGROUND

[0002] New wall materials (such as aerated concrete blocks, light composite boards, etc.) have been widely used in modern buildings due to their light weight, energy saving and waste utilization. However, these materials generally have high water absorption and low bonding strength, which puts higher requirements on the matching mortar for masonry and plastering. Not only should the mortar have excellent water retention, bonding strength and durability, but also should meet the low-carbon and environmentally-friendly standards of green building materials.

[0003] Although traditional cement-based mortar has high strength, its high energy consumption and high carbon emission characteristics are contrary to the environmental protection intention of new wall materials. When used for new wall materials, the mortar is prone to interface cracking due to large shrinkage and poor flexibility, which seriously affects the overall performance of the wall. Although traditional lime mortar has good air permeability and good historical compatibility, its inherent defects such as slow hardening, low early strength and poor water resistance make it unable to meet the requirements of efficient construction and long-term stability of new wall materials. Especially in a humid environment, the traditional lime mortar is prone to erosion and pulverization, which leads to bonding failure between the mortar and the new wall material matrix, seriously affecting the safety and durability of the wall system.

[0004] In addition, from the perspective of life cycle assessment, the calcination energy consumption and long carbonation period of traditional lime mortar also restrict its application in new wall material systems that pursue low-carbon and fast construction.

[0005] Therefore, it is urgent to develop a green and environmentally-friendly mortar that has excellent mechanical properties and good durability, and is highly compatible with new wall materials, to solve the key technical bottlenecks of insufficient performance of matching cementitious materials and high carbon footprint in the current new wall material application system. By introducing natural polymers to modify lime mortar, it is expected to greatly reduce the material's implicit carbon while improving its mechanical strength and impermeability and frost resistance, providing a low-carbon high-performance matching mortar solution for new wall materials in the whole life cycle. SUMMARY

[0006] Therefore, the application provides a preparation method of high-performance natural polymer modified mortar based on a fortifier of Fortunella margarita extract, which has the advantages of high compressive strength, high flexural strength and clear traceable carbon footprint of raw materials, and has the characteristics of renewable raw materials, low energy consumption production and high performance and long service life.

[0007] The preparation method of the high-performance natural polymer modified mortar based on the fortifier of Fortunella margarita extract comprises the following steps:

[0008] (1) crushing and sieving the citrus trifoliata fruit pulp to obtain citrus trifoliata fruit pulp, then soaking it in an alkaline solution containing a preservative, stirring for 5-8 minutes, and then standing for 3-5 hours, and then filtering to obtain a citrus trifoliata extract;

[0009] (2) calcining clay limestone to obtain natural hydraulic lime;

[0010] (3) mixing the citrus trifoliata extract, water and natural hydraulic lime and stirring for 15-20 minutes to obtain lime paste;

[0011] (4) mixing the lime paste with siliceous fine aggregate for 5-15 minutes to obtain a mixture in a plastic state;

[0012] (5) grinding the mixture of step (4) and placing it for 20-24 hours to obtain a high-performance natural polymer modified mortar of the citrus trifoliata extract additive.

[0013] Preferably, the sieve size used in step (1) is 40-60 mesh.

[0014] Preferably, the mass of the preservative in step (1) is 4-5% of the citrus trifoliata fruit pulp.

[0015] Preferably, the preservative in step (1) is ethanol; and the mass concentration of the preservative in the alkaline solution is 2-5%.

[0016] Preferably, the alkaline solution in step (1) is a sodium hydroxide solution with a mass concentration of 8-10%.

[0017] Preferably, the specific components of the clay limestone in step (2) include, by mass percentage, 70-85% calcium carbonate and 15-30% clay minerals; the clay minerals are at least one of kaolinite, illite and montmorillonite; the calcination temperature is 900-1100°C, and the time is 2-4 hours.

[0018] Preferably, the mass ratio of the citrus trifoliata extract, water and natural hydraulic lime in step (3) is 1-2:1-2:2-4.

[0019] Preferably, the siliceous fine aggregate in step (4) is river sand or quartz sand with a particle size of 1.25-4.75 mm.

[0020] Preferably, the mass ratio of the lime paste to the siliceous fine aggregate in step (4) is 1-2:3-4.

[0021] Preferably, the particle size of the grinding in step (5) is 0.1-0.3 mm.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The application provides a preparation method of high-performance natural polymer modified mortar based on Fortunella extract additive, which comprises the following steps: DETAILED DESCRIPTION

[0024] The application provides a preparation method of high-performance natural polymer modified mortar based on Fortunella extract additive, which comprises the following steps:

[0025] (1) Fortunella pulp is obtained by crushing Fortunella pulp through a 40-mesh to 60-mesh sieve, and then the Fortunella pulp is soaked in an alkaline aqueous solution containing ethanol, stirred for 5-8 minutes, and then soaked for 3-5 hours, and then filtered to obtain Fortunella extract; the mass of the ethanol is 4-5% of the mass of the Fortunella pulp, and the mass concentration of the ethanol in the alkaline aqueous solution is 2-5%; the alkaline aqueous solution is a sodium hydroxide solution with a mass concentration of 8-10%.

[0026] (2) Natural hydraulic lime is obtained by calcining clay limestone at 900-1100 DEG C for 2-4 hours;

[0027] (3) The Fortunella extract, water and natural hydraulic lime are mixed and stirred according to a mass ratio of 1-2:1-2:2-4 to obtain lime paste;

[0028] (4) The lime paste and siliceous fine aggregate (river sand or quartz sand) with a particle size of 1.25-4.75 mm are mixed according to a mass ratio of 1-2:3-4 for 5-15 minutes until the mixture is in a plastic state with no dry powder, no clumps, and uniform color and texture, and then the mixture is obtained;

[0029] (5) The mixture in step (4) is ground to a particle size of 0.1-0.3 mm, and then placed for 20-24 hours to obtain the high-performance natural polymer modified mortar based on the Fortunella extract additive.

[0030] The application will be further described in connection with the following examples. In the specific examples of the application, the specific components of the clayey limestone include 80% of calcium carbonate and 20% of clay minerals in terms of mass percentage; the clay minerals include 4% of kaolinite, 4% of illite and 12% of montmorillonite.

[0031] Example 1

[0032] A preparation method of a high-performance natural polymer modified mortar based on a Fortunelia extract additive, comprising the following steps:

[0033] (1) Fortunelia pulp is obtained by crushing Fortunelia pulp through a 40-mesh sieve, and then the Fortunelia pulp is soaked in an alkaline aqueous solution containing ethanol, stirred for 5 minutes and then soaked for 3 hours, and then filtered to obtain a Fortunelia extract; the mass of the ethanol is 4% of the mass of the Fortunelia pulp, and the mass concentration of the ethanol in the alkaline aqueous solution is 2%; the alkaline aqueous solution is a sodium hydroxide solution with a mass concentration of 8%.

[0034] (2) Clayey limestone is calcined at 900°C for 2h to obtain natural hydraulic lime;

[0035] (3) The Fortunelia extract, water and natural hydraulic lime are mixed and stirred at a mass ratio of 1:1:2 to obtain lime paste;

[0036] (4) The lime paste and siliceous fine aggregate (quartz sand) with a particle size of 1.25 mm are mixed at a mass ratio of 1:3 for 5 minutes until the mixture is in a plastic state with no dry powder, no clumps, and uniform color and texture, to obtain a mixture in a plastic state;

[0037] (5) The mixture in the plastic state is ground to a particle size of 0.1 mm and placed for 20 hours to obtain the high-performance natural polymer modified mortar based on the Fortunelia extract additive.

[0038] Example 2

[0039] A preparation method of a high-performance natural polymer modified mortar based on a Fortunelia extract additive, comprising the following steps:

[0040] (1) Fortunelia pulp is obtained by crushing Fortunelia pulp through a 50-mesh sieve, and then the Fortunelia pulp is soaked in an alkaline aqueous solution containing ethanol, stirred for 6 minutes and then soaked for 4 hours, and then filtered to obtain a Fortunelia extract; the mass of the ethanol is 4.5% of the mass of the Fortunelia pulp, and the mass concentration of the ethanol in the alkaline aqueous solution is 3.5%; the alkaline aqueous solution is a sodium hydroxide solution with a mass concentration of 9%.

[0041] (2) Clayey limestone is calcined at 1050°C for 3h to obtain natural hydraulic lime;

[0042] (3) Mix the wood orange extract, water and natural hydraulic lime in a mass ratio of 1:1:2 and stir for 18 minutes to obtain lime paste;

[0043] (4) Mix lime paste with silica fine aggregate (quartz sand) with a particle size of 3 mm at a mass ratio of 1:2 for 10 minutes until there is no dry powder or clumping visible to the naked eye, and the color and texture are completely uniform in a plastic state, to obtain a plastic mixture.

[0044] (5) Grind the mixture from step (4) to a particle size of 0.2 mm and let it stand for 22 hours to obtain the high-performance natural polymer modified mortar with the wood orange extract additive.

[0045] Example 3

[0046] A method for preparing high-performance natural polymer-modified mortar based on Citrus reticulata extract admixture includes the following steps:

[0047] (1) Crush the pulp of the orange, pass it through a 60-mesh sieve to obtain orange pulp, then soak it in an alkaline aqueous solution containing ethanol, stir for 8 minutes and let it stand for 5 hours, then filter to obtain orange extract; the mass of the ethanol is 5% of the orange pulp, and the mass concentration of the ethanol in the alkaline aqueous solution is 5%; the alkaline aqueous solution is a sodium hydroxide solution with a mass concentration of 10%.

[0048] (2) Clay limestone is calcined at 1100℃ for 4 hours to obtain natural hydraulic lime;

[0049] (3) Mix the wood orange extract, water and natural hydraulic lime in a mass ratio of 2:1:2 and stir for 20 minutes to obtain lime paste;

[0050] (4) Mix lime paste with fine silica aggregate (river sand) with a particle size of 4.75 mm at a mass ratio of 1:3 for 15 minutes until the mixture is in a plastic state with no dry powder or clumps visible to the naked eye and with completely uniform color and texture.

[0051] (5) Grind the mixture from step (4) to a particle size of 0.3 mm and let it stand for 24 hours to obtain the high-performance natural polymer modified mortar (BEX modified mortar) with the wood orange extract additive.

[0052] Comparative Example 1

[0053] A method for preparing a reference mortar, comprising the following steps:

[0054] (1) Clay limestone was calcined at 1100℃ for 4 hours to obtain natural hydraulic lime;

[0055] (2) Mix water and natural hydrated lime at a mass ratio of 2:1 and stir for 10 minutes to obtain lime paste;

[0056] (3) Mix lime paste with fine silica aggregate (river sand) with a particle size of 4.75 mm at a mass ratio of 1:3 for 15 minutes until the mixture is in a plastic state with no dry powder or clumps visible to the naked eye and with completely uniform color and texture.

[0057] (4) Grind the mixture from step (3) to a particle size of 0.3 mm and let it stand for 24 hours to obtain a reference mortar without the addition of wood orange extract additive.

[0058] The following experiments were conducted using the mortars prepared in Example 1 and Comparative Example 1:

[0059] Experiment 1: Compressive Strength Test

[0060] Experimental group: BEX modified mortar prepared strictly according to the formula and process of Example 1.

[0061] Control group: Standard mortar prepared strictly according to the formula and process of Comparative Example 1.

[0062] Test age ranges: 7 days, 28 days, 56 days, 90 days, 180 days, 270 days, 360 days.

[0063] At least six prism specimens of 40mm × 40mm × 160mm were prepared for each group at each test age. To avoid batch error, the experimental and control mortars used for all age tests were prepared in large batches on the same day using the same batch of raw materials and by the same operator, with a cement mortar mixer replacing manual mixing to ensure the homogeneity of the mortar within each group. A vibratory compaction table was used to standardize the compaction parameters. Before demolding, the specimens were left to stand in a standard curing chamber at 20℃ and relative humidity ≥95% for 48 hours; immediately after demolding, the specimens were transferred to a saturated lime water bath at 20℃ for continuous curing.

[0064] One week before reaching the designated age, all specimens in the batch were removed from the water-cured environment and immediately placed in a constant temperature and humidity laboratory at 20℃ and 65% relative humidity for 6 days to allow the specimen surface to reach a near-dry state, reducing the interference of surface moisture on the pressure test results. A 40mm×40mm×160mm prism specimen was broken in half using an electro-hydraulic servo pressure testing machine for compressive strength testing. The loading rate was strictly controlled at (2400±200) N / s, and the maximum destructive load of each specimen was recorded.

[0065] The calculation method for the compressive strength Rc of a single specimen is as shown in equation (1):

[0066] Rc=Fc / 1600 (MPa, pressure area is 1600mm²) (1)

[0067] In equation (1), Fc is the maximum failure load;

[0068] For each group, the compressive strength value at each age is taken as the arithmetic mean of three valid measurements.

[0069] At each age, the compressive strength enhancement effect (strength enhancement rate) of BEX modified mortar relative to the reference mortar is calculated according to formula (2):

[0070] (2)

[0071] In equation (2), Rc(BEX) is the compressive strength value of BEX modified mortar, and Rc(reference) is the compressive strength value of reference mortar.

[0072] After calculating the compressive strength values ​​of BEX modified mortar specimens and reference mortar specimens at each age, and substituting them into the strength increment rate formula, it was found that the compressive strength of BEX admixture modified mortar at day 90 was 23% higher than that of the reference mortar without BEX admixture, at day 180 it was 35.6% higher, and at day 360 it was 61.4% higher and then tended to stabilize.

[0073] Experiment 2: Bending Strength Test

[0074] Fill the mortar into a 40mm×40mm×160mm cube mold, vibrate for 20 seconds, and level. Prepare at least 3 prism specimens and 3 cube specimens for each group and each age, and clearly mark the group and age on the mold. Place the molded specimens in a standard curing chamber (20°C, RH≥95%), let them stand for 48 hours, then carefully demold them. Immerse all specimens in saturated lime water at 20°C and continue curing until their respective test ages.

[0075] Remove the 40mm×40mm×160mm prism specimens of the predetermined age from the curing water tank and wipe the surface dry with a damp cloth. Set the span (L) of the support rollers of the flexural strength testing machine to 100mm, place the specimen side down on the support rollers, and ensure strict alignment. Apply a uniform load at a rate of (50±10) N / s until the specimen breaks and record the maximum load Ff (N).

[0076] The flexural strength (Rf) of each specimen is calculated using formula (3):

[0077] (3)

[0078] The flexural strength enhancement rate of BEX modified mortar relative to the reference mortar is calculated using formula (4):

[0079] (4)

[0080] In formula (3), b is the side length of the specimen section (40mm); in formula (4), Rf(BEX) is the flexural strength value of BEX modified mortar; and Rf(reference) is the flexural strength value of reference mortar.

[0081] After calculating the flexural strength values ​​of BEX modified mortar specimens and reference mortar specimens at each age, and substituting them into the strength increment rate formula, it was found that the flexural strength of the BEX-modified mortar maintained a continuous increase. Compared with the reference mortar, the flexural strength of the BEX-modified mortar increased by 44.91% at 360 days and then tended to stabilize.

[0082] Experiment 3: Permeability Test

[0083] Experimental group: BEX modified mortar prepared in Example 1

[0084] Control group: Standard mortar without BEX added prepared in Comparative Example 1

[0085] The mixed mortar was poured into two layers into a frustum-shaped impermeability test mold coated with a release agent. After each layer, a vibrator was used to tamp the mortar 20 times around the perimeter of the mold and 10 times in the center to prevent voids. The surface was then smoothed. At least six specimens were formed per group. The specimens were placed in a standard curing chamber (20°C, RH≥95%) for 24 hours while still in the mold. The specimens were carefully demolded, and the cement slurry film on both ends was scraped clean with a wire brush. The specimens were then immediately placed in 20°C saturated lime water and cured for 28 days before testing.

[0086] At 28 days of age, remove the specimens from the curing water and wipe the surface dry. Use a screw pressurizer to press the specimens into the preheated impermeability mold, creating a sealed cavity for pressure bearing between the specimen and the mold base. Ensure the pressurized surface of the specimen is exposed. Install the mold with the specimens in place onto the permeameter, open the permeameter valve to allow water to enter the cavity from the bottom, expelling air from the cavity. When water overflows from the top of the mold, it indicates that the air has been expelled; tighten the plug. Set the initial water pressure to 0.1 MPa, and increase the water pressure by 0.1 MPa every 8 hours, continuously observing for water seepage on the specimen surfaces. Stop the test when the water pressure reaches 1.2 MPa and no water seepage is observed on the surfaces of all six specimens within 8 hours.

[0087] Immediately after the test, the specimen was removed from the permeameter and split in half longitudinally on a press. The split specimen was placed on a trapezoidal glass plate, and the seepage height at 10 equally spaced points (measured from the bottom pressurized surface) was measured with a ruler, accurate to 1 mm. For a single specimen, the arithmetic mean of the seepage height at the 10 measuring points was calculated, and then the total average seepage height of the 6 specimens in the same group was calculated.

[0088] Comparing the water seepage point heights of modified mortar with added BEX admixture and reference mortar without added BEX admixture, it was found that the water resistance of modified mortar with added BEX admixture exceeded that of reference mortar without added BEX admixture by 23%.

[0089] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing high-performance natural polymer-modified mortar based on Citrus reticulata extract admixture, characterized in that, Includes the following steps: (1) After crushing and sieving the pulp of the citrus fruit to obtain citrus pulp, soak it in an alkaline aqueous solution containing preservatives, stir for 5-8 minutes, let it stand and soak for 3-5 hours, and then filter to obtain citrus extract. (2) Calcining clay limestone yields natural hydraulic lime; (3) Mix the wood orange extract, water and natural hydraulic lime and stir for 15-20 minutes to obtain lime paste; (4) Mix lime paste with siliceous fine aggregate for 5-15 minutes to obtain a mixture in a plastic state; (5) Grind the mixture from step (4) and let it stand for 20-24 hours to obtain the high-performance natural polymer modified mortar with the wood orange extract additive.

2. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The sieve size used in step (1) is 40-60 mesh.

3. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The preservative in step (1) is 4-5% of the pulp of the citrus fruit.

4. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The preservative in step (1) is ethanol; the mass concentration of the preservative in the alkaline aqueous solution is 2-5%.

5. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The alkaline aqueous solution in step (1) is a sodium hydroxide solution with a mass concentration of 8-10%.

6. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The specific composition of the clay limestone in step (2) by mass percentage includes 70-85% calcium carbonate and 15-30% clay minerals; the clay minerals are at least one of kaolinite, illite, and montmorillonite; the calcination temperature is 900℃-1100℃ and the time is 2-4 hours.

7. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The mass ratio of the wood orange extract, water and natural water-hard lime in step (3) is 1-2:1-2:2-4.

8. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The siliceous fine aggregate in step (4) is river sand or quartz sand with a particle size of 1.25mm-4.75mm.

9. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The mass ratio of lime paste to siliceous fine aggregate in step (4) is 1-2:3-4.

10. The method for preparing high-performance natural polymer-modified mortar based on *Citrus reticulata* extract admixture according to claim 1, characterized in that, The particle size of the grinding in step (5) is 0.1mm-0.3mm.