Multifunctional composite waterproof reinforcing agent of long-chain alkyl modified polymethylhydrosiloxane, hydrophobic waterproof ardealite foam concrete and preparation method of hydrophobic waterproof ardealite foam concrete

Abstract

The invention discloses a preparation method of a multifunctional composite waterproof reinforcing agent of long-chain alkyl modified polymethylhydrosiloxane, and the preparation method comprises the following steps: S1, adding polymethylhydrosiloxane and 1-octylene into isopropanol, and uniformly mixing to obtain a solution to be reacted; s2, hexachloroplatinic acid is added for a modification reaction, and long-chain alkyl modified polymethylhydrosiloxane is obtained; s3, mixing the long-chain alkyl modified polymethylhydrosiloxane with nano silicon dioxide particles and a hydrophobic aid, and uniformly dispersing at a high speed to obtain the multifunctional composite waterproof reinforcing agent of the long-chain alkyl modified polymethylhydrosiloxane. When the composite waterproof agent is applied to phosphogypsum foam concrete, a multifunctional composite waterproof system which is higher in interface reactivity, better in water resistance and higher in system stability is formed; the prepared hydrophobic waterproof ardealite foam concrete has the advantages of good interface uniformity, strong microcosmic stability, good mechanical retentivity and low water absorption.

Description

Technical Field

[0001] This invention relates to the field of building materials and functional polymer modification technology, specifically to a multifunctional composite waterproof reinforcing agent of long-chain alkyl modified polymethylhydrosiloxane, hydrophobic and waterproof phosphogypsum foam concrete and its preparation method. Background Technology

[0002] Phospholipid (PG) is a byproduct of the phosphate fertilizer industry. Due to its high impurities, potential radioactivity risks, and poor durability, its application in building materials is limited, especially in foamed concrete where water resistance is a particularly prominent issue.

[0003] Existing technologies use polymethylhydrosiloxane (PMHS) for modification, which can improve hydrophobicity to some extent, but requires high dosage, has low hydrophobic efficiency, is detrimental to mechanical properties, and lacks in-depth modification of the internal pore structure of the material. For example, CN117069944A discloses a method for preparing PMHS modified with 1-dodecene and vinyltriethoxysilane to enhance the hydrophobicity of cement mortar. Although it involves some design in terms of molecular structure modification, it does not take into account the structural characteristics of porous foam systems, nor does it provide a multi-performance enhancement strategy for phosphogypsum-based composite materials. Therefore, there is still room for improvement in terms of applicability and innovation. Summary of the Invention

[0004] To address the problems of existing technologies, this invention provides a long-chain alkyl-modified polymethylhydrosiloxane. By compounding it with functional additives such as silica sol, nano-silica, water-repellent agents, and adhesion promoters, a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane is formed. When applied to phosphogypsum foamed concrete, it forms a multifunctional composite waterproofing system with stronger interfacial reactivity, better water resistance, and higher system stability. The resulting phosphogypsum foamed concrete has the advantages of good interfacial uniformity, strong microscopic stability, good mechanical retention, and low water absorption.

[0005] The primary objective of this invention is to provide a method for preparing a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane, the method comprising the following steps:

[0006] S1. Polymethylhydrosiloxane and 1-octene are added to isopropanol and mixed evenly to obtain the reaction solution.

[0007] S2 adds hexachloroplatinic acid catalyst to the solution to be reacted to carry out the modification reaction and synthesize long-chain alkyl-modified polymethylhydrosiloxane;

[0008] S3 mixes the long-chain alkyl-modified polymethylhydrosiloxane with nano-silica particles and a hydrophobic additive, and then disperses it at high speed to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0009] Specifically, the molar ratio of polymethylhydrosiloxane and 1-octene in step S1 is 1:(1.1-1.5).

[0010] Specifically, the amount of hexachloroplatinic acid catalyst added in step S2 is 2.5-12.5 mg / L.

[0011] Specifically, the reaction temperature of the modification reaction in step S2 is 70-100℃, and the reaction time is 2-6h.

[0012] Specifically, the hydrophobic additive in step S3 is any one or more of nano-silica, methyl-terminated polysiloxane, aqueous silica sol, vinyl silane, or their mixtures.

[0013] Specifically, in step S3, the content of the nano-silica particles is 5-10 wt% of the content of long-chain alkyl-modified polymethylhydrosiloxane; the particle size of the nano-silica particles is 10-30 nm; and the high-speed dispersion time in step S3 is 20-40 min.

[0014] The second objective of this invention is to provide a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane prepared by the above-described preparation method.

[0015] The third objective of this invention is to provide a hydrophobic and waterproof phosphogypsum foam concrete, which comprises the following components: 26-35 wt% phosphogypsum, 17-30 wt% cement, 4-6 wt% metakaolin, 25-28 wt% water, 2.5-4 wt% water-reducing agent, 3.5-6 wt% foaming agent, and 5-20 wt% of the multifunctional composite waterproof reinforcing agent of long-chain alkyl-modified polymethylhydrosiloxane as described in claim 8.

[0016] Specifically, the water-reducing agent is a polycarboxylate water-reducing agent; the foaming agent is an animal protein foaming agent.

[0017] The fourth objective of this invention is to provide a method for preparing the above-mentioned hydrophobic and waterproof phosphogypsum foam concrete. The preparation method includes the following steps: mixing phosphogypsum, cement, metakaolin, water, water-reducing agent, and the long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent in a specific ratio, adding a foaming agent, stirring evenly, pouring into a mold and shaking to set, taking it out after 72 hours, drying it, and obtaining the hydrophobic and waterproof phosphogypsum foam concrete.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] (1) In this invention, polymethylhydrosiloxane (PMHS) is modified to obtain long-chain alkyl-modified polymethylhydrosiloxane (L-PMHS). By compounding L-PMHS with nano-silica, water-repellent functional additives, a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane is formed. The multifunctional composite waterproofing enhancer is applied to the preparation of phosphogypsum foam concrete to form hydrophobic and waterproof phosphogypsum foam concrete with stronger interfacial reactivity, better water resistance, and higher system stability. The phosphogypsum foam concrete also has the advantages of good interfacial uniformity, strong microstructure stability, good mechanical retention, and low water absorption.

[0020] (2) The L-PMHS prepared in this invention hydrolyzes in water to form Si–OH, which condenses with –OH on the PG surface to form Si–O–Ca bonds, while exposing CH3 and C8H. 17 Long-chain alkyl groups are oriented to form a hydrophobic layer; in addition, nano-silica particles fill the pores in the concrete and form a secondary network structure at the interface, which significantly improves the hydrophobic continuity, thermal stability and penetration blocking ability, and constructs a "internal + external" dual hydrophobic structure to carry out bidirectional synergistic hydrophobic modification of phosphogypsum foam concrete.

[0021] (3) In the hydrophobic and waterproof phosphogypsum foam concrete prepared by the present invention, the water absorption rate of the hydrophobic and waterproof phosphogypsum foam concrete can be reduced from 28.2% to 5.03% in 24 hours with only 10wt% of composite waterproof reinforcing agent; the compressive strength is the same as or slightly higher than that of unmodified phosphogypsum foam concrete (570–600N), showing excellent mechanical retention; the interface of phosphogypsum foam concrete has double hydrophobic bonds such as Si–O–Ca and C–C / C–H, which significantly enhances its waterproofness; the addition of nano silica enhances the uniformity and micro-stability of the material interface, which is conducive to its application in large-scale engineering. Attached Figure Description

[0022] Figure 1 The reaction equation for synthesizing long-chain alkyl-modified polymethylhydrosiloxane L-PMHS in the embodiments of the present invention is as follows;

[0023] Figure 2 (a) is the polymethylhydrosiloxane PMHS in Example 1 of the present invention. 1 H NMR spectrum;

[0024] Figure 2 (b) is the long-chain alkyl-modified polymethylhydrosiloxane L-PMHS in Example 1 of this invention. 1 H NMR spectrum;

[0025] Figure 3This is a schematic diagram illustrating the mechanism of action of the multifunctional composite waterproofing enhancer prepared in the embodiment of the present invention in hydrophobic and waterproof phosphogypsum foamed concrete.

[0026] Figure 4 Comparison of surface contact angles of hydrophobic and waterproof phosphogypsum foam concrete prepared in Examples 1-5 of this invention;

[0027] Figure 5 SEM microstructure of the hydrophobic and waterproof phosphogypsum foam concrete prepared in Example 3 of the present invention.

[0028] Figure 6 (a) XRD patterns of hydration products of hydrophobic and waterproof phosphogypsum foam concrete prepared in Examples 1 and 3 of the present invention and phosphogypsum foam concrete prepared in Comparative Example 2.

[0029] Figure 6 (b) FTIR diagrams of functional groups of the hydrophobic and waterproof phosphogypsum foam concrete prepared in Example 3 of the present invention and the phosphogypsum foam concrete prepared in Comparative Example 2.

[0030] Figure 7 (a) Comparison of the mechanical strength of phosphogypsum foamed concrete prepared in Comparative Examples 1-4;

[0031] Figure 7 (b) Comparison of mechanical strength of hydrophobic and waterproof phosphogypsum foam concrete prepared in Examples 1, 3 and 5-6;

[0032] Figure 8 (a) is the water absorption curve of the phosphogypsum foam concrete prepared in Comparative Examples 1-4.

[0033] Figure 8 (b) is a water absorption curve of the phosphogypsum foam concrete prepared in Examples 1, 3 and 5-6. Detailed Implementation Plan

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] Preparation of a multifunctional composite waterproofing enhancer using long-chain alkyl-modified polymethylhydrosiloxane:

[0037] S1 mixes 22 mL of PMHS, 24.2 mL of 1-octene and 1.5 mL of isopropanol, stirs until homogeneous, and obtains the reaction solution.

[0038] S2 added 10 mg / L hexachloroplatinic acid catalyst to the reaction solution and modified it at 80 °C for 4 h to synthesize L-PMHS;

[0039] S3 mixed 50g of L-PMHS with 3g of nano-silica particles (particle size 18nm) and 2g of aqueous silica sol, and then dispersed them at high speed for 20min to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0040] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0041] 30 wt% phosphogypsum, 26.5 wt% cement, 6 wt% metakaolin, 25 wt% water, 2.5 wt% polycarboxylate superplasticizer (Guizhou Kezhijie New Materials Co., Ltd.), and 5 wt% of the long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent prepared in Example 1 were mixed evenly, and then 5 wt% HTQ-1 type animal and plant protein composite foaming agent (Henan Huatai Building Materials Co., Ltd.) were added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 5% L-PMHS-SiO2.

[0042] Example 2

[0043] S1 mixes 22 mL of PMHS, 26.4 mL of 1-octene and 1.2 mL of isopropanol, stirs until homogeneous, and obtains the reaction solution.

[0044] S2 added 8 mg / L hexachloroplatinic acid catalyst to the reaction solution and modified it at 70 °C for 6 h to synthesize L-PMHS;

[0045] S3 mixed 50g of L-PMHS with 5g of nano-silica particles (particle size 26nm) and 2g of vinyltrimethoxysilane, and then dispersed them at high speed for 40min to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0046] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0047] 35 wt% phosphogypsum, 20 wt% cement, 4 wt% metakaolin, 25 wt% water, 3.5 wt% polycarboxylate superplasticizer, and 7.5 wt% of the long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproofing and reinforcing agent prepared in Example 1 were mixed evenly, and then 5 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 7.5% L-PMHS-SiO2.

[0048] Example 3

[0049] Preparation of a multifunctional composite waterproofing enhancer using long-chain alkyl-modified polymethylhydrosiloxane:

[0050] S1 mixes 22 mL of PMHS, 33 mL of 1-octene and 2 mL of isopropanol, and stirs until homogeneous to obtain the reaction solution;

[0051] S2 added 12.5 mg / L hexachloroplatinic acid catalyst to the reaction solution and modified it at 100 °C for 6 h to synthesize long-chain alkyl-modified polymethylhydrosiloxane;

[0052] S3 mixed 50g of L-PMHS with 2.5g of nano-silica particles (particle size 14nm) and 2g of (meth)acryloyloxymethyl-terminated polysiloxane, and then dispersed it at high speed for 20min to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0053] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0054] 34.5 wt% phosphogypsum, 17 wt% cement, 4 wt% metakaolin, 27 wt% water, 4 wt% polycarboxylate superplasticizer, and 10 wt% of the long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent prepared in Example 1 were mixed evenly, and then 3.5 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 10% L-PMHS-SiO2.

[0055] Example 4

[0056] S1 mixes 22 mL of PMHS, 25 mL of 1-octene and 1.5 mL of isopropanol, stirs until homogeneous, and obtains the reaction solution.

[0057] S2 added 8 mg / L hexachloroplatinic acid catalyst to the reaction solution and modified it at 80 °C for 6 h to synthesize L-PMHS;

[0058] S3 mixed 50g of L-PMHS with 5g of nano-silica particles (particle size 29nm) and 2g of vinyltris(2-methoxyethoxy)silane, and dispersed them at high speed for 20min to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0059] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0060] 30 wt% phosphogypsum, 18 wt% cement, 5 wt% metakaolin, 28 wt% water, 2.5 wt% polycarboxylate superplasticizer, and 12.5 wt% long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent prepared in Example 1 were mixed evenly, and then 4% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 12.5% ​​L-PMHS-SiO2.

[0061] Example 5

[0062] S1 mixes 22 mL of PMHS, 28.6 mL of 1-octene and 1.2 mL of isopropanol, stirs until homogeneous, and obtains the reaction solution.

[0063] S2 added 5 mg / L hexachloroplatinic acid catalyst to the reaction solution and modified it at 100 °C for 2 h to synthesize L-PMHS;

[0064] S3 mixed 50g of L-PMHS polymethylhydrosiloxane with 7.5g of nano-silica particles (particle size 22nm) and 2g of vinylsilane, and then dispersed them at high speed for 30min to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0065] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0066] 26 wt% phosphogypsum, 22 wt% cement, 4.5 wt% metakaolin, 25 wt% water, 4 wt% polycarboxylate superplasticizer, and 15 wt% of the long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent prepared in Example 1 were mixed evenly, and then 3.5 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 15% L-PMHS-SiO2.

[0067] Example 6

[0068] S1 mixes 22 mL of PMHS, 28.6 mL of 1-octene and 1.5 mL of isopropanol, stirs until homogeneous, and obtains the reaction solution.

[0069] S2 added 5 mg / L hexachloroplatinic acid catalyst to the reaction solution and modified it at 100 °C for 2 h to synthesize L-PMHS;

[0070] S3 mixed 50g of L-PMHS polymethylhydrosiloxane with 7.5g of nano-silica particles (particle size 22nm) and 2g of vinylsilane, and then dispersed them at high speed for 30min to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0071] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0072] 26 wt% phosphogypsum, 17 wt% cement, 4 wt% metakaolin, 25 wt% water, 4 wt% polycarboxylate superplasticizer, and 20 wt% long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent prepared in Example 1 were mixed evenly, and then 4 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 20% L-PMHS-SiO2.

[0073] Example 7

[0074] S1 mixes 22 mL of PMHS, 24.2 mL of 1-octene and 1.5 mL of isopropanol, stirs until homogeneous, and obtains the reaction solution.

[0075] S2 added 5 mg / L hexachloroplatinic acid catalyst to the solution to be reacted, and modified the reaction at 80 °C for 4 h to synthesize L-PMHS with pH 6-7 and viscosity 270 mPa·s.

[0076] S3 mixed 50g of L-PMHS polymethylhydrosiloxane with 3g of nano-silica particles (particle size 22nm) and 2g of silica sol, and then dispersed it at high speed for 30min to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

[0077] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0078] 200g (32wt%) of phosphogypsum, 190g (30wt%) of cement, 35g (5wt%) of metakaolin, 120mL (20wt%) of water, 20g (3wt%) of polycarboxylate superplasticizer, and 36mL (6wt%) of the long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent prepared in Example 7 were mixed evenly. Then, 20mL (4wt%) of HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was removed and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 6% L-PMHS-SiO2, with a finished product density of 450kg / m³. 3 .

[0079] Comparative Example 1

[0080] The difference from Example 1 is that the polymethylhydrosiloxane is not modified.

[0081] Preparation of waterproofing enhancers using polymethylhydrosiloxane:

[0082] 50g of PMHS was mixed with 3g of nano-silica particles (particle size 18nm) and 2g of aqueous silica sol, and then dispersed at high speed for 20min to obtain a waterproof reinforcing agent of polymethylhydrosiloxane.

[0083] Preparation of phosphogypsum foamed concrete:

[0084] 30 wt% phosphogypsum, 26.5 wt% cement, 6 wt% metakaolin, 25 wt% water, 2.5 wt% polycarboxylate superplasticizer, and 5 wt% polymethylhydrosiloxane waterproofing reinforcing agent prepared in Comparative Example 1 were mixed evenly, and then 5 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain phosphogypsum foam concrete, denoted as 5% PMHS-SiO2.

[0085] Comparative Example 2

[0086] The difference from Example 3 is that the polymethylhydrosiloxane is not modified.

[0087] Preparation of waterproofing enhancers using polymethylhydrosiloxane:

[0088] 50g of PMHS was mixed with 2.5g of nano silica particles (particle size 14nm) and 2g of (meth)acryloyloxymethyl-terminated polysiloxane, and then dispersed at high speed for 20min to obtain a waterproofing enhancer of polymethylhydrosiloxane.

[0089] Preparation of phosphogypsum foamed concrete:

[0090] 34.5 wt% phosphogypsum, 17 wt% cement, 4 wt% metakaolin, 27 wt% water, 4 wt% polycarboxylate superplasticizer, and 10 wt% polymethylhydrosiloxane waterproofing reinforcing agent prepared in Comparative Example 2 were mixed evenly, and then 3.5 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain phosphogypsum foam concrete, denoted as 10% PMHS-SiO2.

[0091] Comparative Example 3

[0092] The difference from Example 5 is that the polymethylhydrosiloxane is not modified.

[0093] Preparation of waterproofing enhancers using polymethylhydrosiloxane:

[0094] 50g of PMHS polymethylhydrosiloxane was mixed with 7.5g of nano silica particles (particle size 22nm) and 2g of vinylsilane, and then dispersed at high speed for 30min to obtain a waterproofing enhancer of polymethylhydrosiloxane.

[0095] Preparation of phosphogypsum foamed concrete:

[0096] 26 wt% phosphogypsum, 22 wt% cement, 4.5 wt% metakaolin, 25 wt% water, 4 wt% polycarboxylate superplasticizer, and 15 wt% polymethylhydrosiloxane waterproofing reinforcing agent prepared in Comparative Example 3 were mixed evenly, and then 3.5 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain phosphogypsum foam concrete, denoted as 15% PMHS-SiO2.

[0097] Comparative Example 4

[0098] The difference from Example 6 is that the polymethylhydrosiloxane is not modified.

[0099] Preparation of waterproofing enhancers using polymethylhydrosiloxane:

[0100] 50g of PMHS polymethylhydrosiloxane was mixed with 7.5g of nano silica particles (particle size 22nm) and 2g of vinylsilane, and then dispersed at high speed for 30min to obtain a waterproofing enhancer of polymethylhydrosiloxane.

[0101] Preparation of phosphogypsum foamed concrete:

[0102] 26 wt% phosphogypsum, 17 wt% cement, 4 wt% metakaolin, 25 wt% water, 4 wt% polycarboxylate superplasticizer, and 20 wt% polymethylhydrosiloxane waterproofing reinforcing agent prepared in Comparative Example 4 were mixed evenly, and then 4 wt% HTQ-1 type animal and plant protein composite foaming agent was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was taken out and dried to obtain phosphogypsum foam concrete, denoted as 20% PMHS-SiO2.

[0103] Comparative Example 5

[0104] Preparation of a waterproofing enhancer for long-chain alkyl-modified polymethylhydrosiloxanes without hydrophobic additives:

[0105] S1 mixes 22 mL of PMHS, 24.2 mL of 1-octene and 1.5 mL of isopropanol, stirs until homogeneous, and obtains the reaction solution.

[0106] S2 added 10 mg / L hexachloroplatinic acid catalyst to the reaction solution and modified it at 80 °C for 4 h to synthesize L-PMHS;

[0107] S3 dispersed 50g of L-PMHS and 5g of nano-silica particles (particle size 26nm) at high speed for 40min to obtain a waterproof reinforcing agent of long-chain alkyl-modified polymethylhydrosiloxane.

[0108] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0109] 30 wt% phosphogypsum, 26.5 wt% cement, 6 wt% metakaolin, 25 wt% water, 2.5 wt% polycarboxylate superplasticizer (Guizhou Kezhijie New Materials Co., Ltd.), and 5 wt% of the long-chain alkyl-modified polymethylhydrosiloxane waterproofing reinforcing agent prepared in Comparative Example 5 were mixed evenly, and then 5 wt% HTQ-1 type animal and plant protein composite foaming agent (Henan Huatai Building Materials Co., Ltd.) was added. After stirring evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was removed and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 5% L-PMHS, with a finished product density of 455 kg / m³. 3 .

[0110] Comparative Example 6

[0111] Compared to Example 7, no modification treatment was performed on the polymethylhydrosiloxane.

[0112] S3 mixed 50g of PMHS polymethylhydrosiloxane with 3g of nano silica particles (particle size 22nm) and 2g of vinylsilane, and then dispersed them at high speed for 30min to obtain a waterproofing enhancer of methylhydrosiloxane.

[0113] Preparation of hydrophobic and waterproof phosphogypsum foam concrete:

[0114] 200g (32wt%) of phosphogypsum, 190g (30wt%) of cement, 35g (5wt%) of metakaolin, 120mL (20wt%) of water, 20g (3wt%) of polycarboxylate superplasticizer, and 36mL (6wt%) of the polymethylhydrosiloxane waterproofing reinforcing agent prepared in Comparative Example 6 were mixed evenly. Then, 20mL (4wt%) of HTQ-1 type animal and plant protein composite foaming agent was added. After mixing evenly, the mixture was poured into a mold and shaken to set. After 72 hours, it was removed and dried to obtain hydrophobic and waterproof phosphogypsum foam concrete, denoted as 6% PMHS-SiO2, with a finished product density of 475kg / m³. 3 .

[0115] Structural characterization

[0116] Please see Figure 1 , Figure 1 The reaction equation for the synthesis of long-chain alkyl-modified polymethylhydrosiloxane L-PMHS in Example 1 of this invention is shown below; where R is a carbon chain (CH2CH2 CH2CH2CH2CH3); Figure 2 (a) is PMHS in Embodiment 1 of the present invention. 1 H NMR spectrum; Figure 2 (b) is the L-PMHS in Embodiment 1 of the present invention. 1 H NMR spectrum; in Figure 2 In (a), peak "a" (δ≈4.7ppm) represents the Si-H proton signal, and peak "b" (δ≈0.1ppm) represents the Si-CH3 proton signal; Figure 2 In (b), the modified L-PMHS shows a significant decrease in peak "a", indicating that Si-H participated in the reaction. Simultaneously, new peaks "c" (δ≈1.3ppm) and "d" (δ≈0.9ppm) appear, attributed to the -CH2- and -CH3 proton signals of the grafted 1-octene chain, respectively. These results demonstrate that the long-chain alkyl group has been successfully introduced into the PMHS backbone, forming long-chain alkyl-modified polymethylhydrosiloxane L-PMHS.

[0117] Figure 3 This is a schematic diagram illustrating the mechanism of action of the multifunctional composite waterproofing enhancer prepared in this embodiment of the invention in hydrophobic and waterproof phosphogypsum foamed concrete; as shown. Figure 3 As shown, the long-chain alkyl-modified polymethylhydrosiloxane L-PMHS in the multifunctional composite waterproofing reinforcing agent hydrolyzes in water to form Si-OH, which condenses with the -OH on the surface of phosphogypsum (PG) to form Si-O-Ca bonds, while exposing CH3 and C8H. 17 Long-chain alkyl groups are oriented to form a hydrophobic layer; while nano-silica particles fill the pores and form a secondary network structure at the interface, which significantly improves the hydrophobic continuity, thermal stability and penetration blocking ability, achieving synergistic waterproofing of the exterior and interior.

[0118] Figure 4 The images show a comparison of the surface contact angles of the hydrophobic and waterproof phosphogypsum foam concrete prepared in Examples 1-5 of this invention; the surface contact angle CA of the pure phosphogypsum blank sample is 0°, exhibiting superhydrophilicity. Figure 4 As shown, with the increase of the amount of multifunctional composite waterproofing enhancer, its coverage on the concrete surface will gradually increase. When the doping amount is 15wt%, the water contact angle is as high as 118.73°, realizing the transformation from hydrophilic to hydrophobic. Figure 5 The image shows the SEM microstructure of the hydrophobic and waterproof phosphogypsum foam concrete prepared in Example 3 of this invention. When the amount of functional composite waterproof reinforcing agent is 10 wt%, the phosphogypsum foam concrete exhibits a densely interwoven elongated structure, forming a three-dimensional network. The hydration products are few, reflecting that the hydration reaction is inhibited and the internal hydrophobicity of the material is significantly enhanced. Moreover, there are no visible cracks at the interface, indicating that the microstructure is dense and uniform, the micro-stability is improved, and the hydrophobicity is enhanced.

[0119] Figure 6 (a) XRD patterns of hydration products of the hydrophobic and waterproof phosphogypsum foam concrete prepared in Examples 1 and 3 of this invention and the phosphogypsum foam concrete prepared in Comparative Example 2; Figure 6 As shown in (a), as the addition amount of L-PMHS-SiO2 multifunctional composite waterproofing enhancer increased from 5% to 10%, the diffraction peak intensity of CaSO4·0.5H2O (2θ≈11.6°, 20.7°) increased, indicating that the hydration reaction weakened. The addition of L-PMHS-SiO2 multifunctional composite waterproofing enhancer formed a more effective hydrophobic barrier in the phosphogypsum foamed concrete, inhibiting phosphogypsum hydration, reducing the formation of dihydrate gypsum, and improving waterproofing. The mineral composition of the phosphogypsum foamed concrete prepared with the unmodified waterproofing enhancer in Comparative Example 2 was not significantly different. Figure 6 (b) FTIR spectra of functional groups in the hydrophobic and waterproof phosphogypsum foam concrete prepared in Example 3 and the phosphogypsum foam concrete prepared in Comparative Example 2; both the phosphogypsum foam concrete prepared in Example 3 and Comparative Example 2 exhibit C–H (2960 cm⁻¹) functional group analysis. -1 ) and Si–O–Si (1080cm) -1 The characteristic absorption peaks indicate that the prepared waterproofing enhancers all underwent similar chemical reactions with the matrix.

[0120] Performance testing

[0121] To analyze the influence of long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproofing enhancer on the physical properties of phosphogypsum foam concrete, the mechanical properties and water absorption properties of the hydrophobic and waterproof phosphogypsum foam concrete prepared in the examples were tested.

[0122] Mechanical performance testing: The compressive strength performance of the phosphogypsum foamed concrete in the examples and comparative examples was tested in accordance with the provisions of "Determination of Mechanical Properties of Building Gypsum". Figure 7 (a) Comparison of the mechanical strength of phosphogypsum foamed concrete prepared in Comparative Examples 1-4; Figure 7 As shown in (a), the compressive strength decreases with increasing doping amount of unmodified PMHS-SiO2. The compressive strength is 1253.49 N when the doping amount is 5 wt%, and 502.71 N when the doping amount is 20 wt%. Figure 7 (b) Comparison of the mechanical strength of the hydrophobic and waterproof phosphogypsum foam concrete prepared in Examples 1, 3, and 5-6; Figure 7 As shown in (b), the compressive strength decreases with increasing L-PMHS-SiO2 doping amount. When the doping amount is 10wt%, the compressive strength is 857.17N, while when the doping amount is 20wt%, the compressive strength is 570.5N, which is slightly improved compared with Comparative Examples 1-4. This indicates that the multifunctional composite waterproof reinforcing agent can improve the hydrophobicity of phosphogypsum foam concrete while maintaining its excellent mechanical properties.

[0123] Water absorption test: Prepare the phosphogypsum foamed concrete and weigh it G0. Put the phosphogypsum foamed concrete into a suitable container, add water to completely submerge the phosphogypsum foamed concrete, leave it at room temperature for 24 hours, take it out, wipe it dry with a cloth and weigh it G1. Calculate the water absorption rate of the phosphogypsum foamed concrete according to the following formula: W=(G1-G0) / G0×100%. Figure 8 (a) is the water absorption curve of the phosphogypsum foam concrete prepared in Comparative Examples 1-4. Figure 8 (b) shows the water absorption curves of the phosphogypsum foamed concrete prepared in Examples 1, 3, and 5-6. Figure 8As shown in (ab), the phosphogypsum foamed concrete prepared by adding 20% ​​unmodified PMHS-SiO2 waterproofing agent in Comparative Example 4 only reduced the water absorption rate to 11.80%, while the phosphogypsum foamed concrete prepared by adding only 5% L-PMHS-SiO2 modified multifunctional composite waterproofing reinforcing agent achieved an even lower water absorption rate of 6.56%. This indicates that the addition of the long-chain alkyl-modified L-PMHS-SiO2 multifunctional composite waterproofing reinforcing agent gives the phosphogypsum foamed concrete more efficient hydrophobic properties. This performance improvement is attributed to the long-chain alkyl groups in its molecular structure, which not only enhances the compatibility with the matrix but also improves the interfacial bonding force, thereby forming a more stable and continuous hydrophobic barrier. Compared with traditional PMHS-SiO2 waterproofing agents, the modified L-PMHS-SiO2 multifunctional composite waterproofing reinforcing agent can significantly improve the waterproofing of phosphogypsum foamed concrete at a lower addition amount. Furthermore, the 24-hour water absorption rate and mechanical properties of the phosphogypsum foam concrete prepared by L-PMHS-SiO2 doping in Example 7 were tested, and the results were: water absorption rate 5.03% and compressive strength 857.17 N. In Comparative Example 5, the phosphogypsum foam concrete prepared by doping with L-PHMS without water-reducing agent (silica sol) under the same preparation conditions had a water absorption rate of 12.97% and a compressive strength of 893.25 N. In Comparative Example 6, the phosphogypsum foam concrete prepared by doping with unmodified PHMS under the same preparation conditions as in Example 7 had a 24-hour water absorption rate of 18.21% and a compressive strength of 959.57 N. It can be seen that the phosphogypsum foam concrete prepared by the modified multifunctional composite waterproofing reinforcing agent can significantly reduce water absorption while still maintaining good mechanical properties.

[0124] In summary, the multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane prepared by this invention, when applied to phosphogypsum foam concrete, can form a multifunctional composite waterproof body with stronger interfacial reactivity, better water resistance, and higher system stability in the phosphogypsum foam concrete structure. With a dosage of 10%, the resulting hydrophobic and waterproof phosphogypsum foam concrete has a water absorption rate of less than 6% after 24 hours and a compressive strength of more than 850N. It has the advantages of good interfacial uniformity, strong microscopic stability, good mechanical retention, and low water absorption.

[0125] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane, characterized in that, The preparation method includes the following steps: S1. Polymethylhydrosiloxane and 1-octene are added to isopropanol and mixed evenly to obtain the reaction solution. S2 adds hexachloroplatinic acid catalyst to the solution to be reacted to carry out the modification reaction and synthesize long-chain alkyl-modified polymethylhydrosiloxane; S3 mixes the long-chain alkyl-modified polymethylhydrosiloxane with nano-silica particles and a hydrophobic additive, and then disperses it at high speed to obtain a multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane.

2. The preparation method according to claim 1, characterized in that, The molar ratio of polymethylhydrosiloxane and 1-octene in step S1 is 1:(1.1-1.5).

3. The preparation method according to claim 1, characterized in that, The amount of hexachloroplatinic acid catalyst added in step S2 is 2.5-12.5 mg / L.

4. The preparation method according to claim 1, characterized in that, The reaction temperature of the modification reaction in step S2 is 70-100℃, and the reaction time is 2-6h.

5. The preparation method according to claim 1, characterized in that, The hydrophobic additive mentioned in step S3 is any one or more of nano-silica, methyl-terminated polysiloxane, aqueous silica sol, vinyl silane, or their mixtures.

6. The preparation method according to claim 1, characterized in that, In step S3, the content of the nano-silica particles is 5-10 wt% of the content of long-chain alkyl-modified polymethylhydrosiloxane; the particle size of the nano-silica particles is 10-30 nm; and the high-speed dispersion time is 20-40 min.

7. A multifunctional composite waterproofing enhancer of long-chain alkyl-modified polymethylhydrosiloxane prepared by the preparation method described in claims 1-6.

8. A hydrophobic and waterproof phosphogypsum foamed concrete, characterized in that, The hydrophobic and waterproof phosphogypsum foam concrete comprises the following components: 26-35 wt% phosphogypsum, 17-30 wt% cement, 4-6 wt% metakaolin, 25-28 wt% water, 2.5-4 wt% water-reducing agent, 3.5-6 wt% foaming agent, and 5-20 wt% of the multifunctional composite waterproof reinforcing agent of long-chain alkyl-modified polymethylhydrosiloxane as described in claim 8.

9. The phosphogypsum foamed concrete according to claim 8, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent; the foaming agent is an animal protein foaming agent.

10. A method for preparing hydrophobic and waterproof phosphogypsum foamed concrete as described in claim 8, characterized in that, The preparation method includes the following steps: mixing phosphogypsum, cement, metakaolin, water, water-reducing agent and the long-chain alkyl-modified polymethylhydrosiloxane multifunctional composite waterproof reinforcing agent in a specific ratio, adding foaming agent, stirring evenly, pouring into a mold and shaking to set, taking it out after 72 hours, drying it to obtain hydrophobic and waterproof phosphogypsum foam concrete.

Images