CN101503284B - Anti-erosion agent and masonry mortar material containing the same - Google Patents

Abstract

The invention discloses an anti-corrosion agent, which is composed of the following components by weight: 100 parts of fly ash, 5-20 parts of PVA resin, 0.5-2 parts of OP additive, oxalic acid or borate 1 to 10 servings. The anti-corrosion agent of the present invention can effectively resist environmental water (including corrosive ions such as SO ₄ ^2- , HCO ₃ ^- , H ⁺ , Mg ^{+ 2} , NH ₄ ⁺ and their alkali metal salts, and acidic rainwater with a pH lower than 5 ) erosion, which can effectively improve the sulfate crystallization resistance of masonry mortar with a large water-cement ratio, and meet the requirements of masonry masonry mortar against environmental water erosion. The invention also discloses a masonry mortar material for masonry masonry containing the anti-corrosion agent, which has excellent environmental water erosion resistance and can greatly improve the durability of slope protection structures against environmental water erosion.

Description

An anti-corrosion agent and masonry mortar material containing the anti-corrosion agent

technical field

The invention relates to building materials, in particular to an anti-corrosion agent against environmental water erosion and a masonry mortar material containing the anti-corrosion agent.

Background technique

In drainage (drains, side ditches) along railways and highways and slope support and protection projects (slope protection with mortar rubble), masonry structures with mortar rubble are often used, which is a kind of cement mortar masonry structure. The masonry structure of flake or block stone is used to protect the slope from the erosion of external factors, or to reinforce the slope to prevent the slope from slipping and causing disasters.

Masonry structures in slope protection engineering are generally in contact with soil, rock formations and groundwater. Due to the composition and porous structure of cement mortar used for masonry structures, when these rocks and soils contain sulfate, carbonate, water, etc. In the case of aggressive media, the masonry mortar will be eroded by these environmental media, causing changes in composition and structure and deterioration of performance, which seriously affects the service life and driving safety of masonry structures in slope protection projects. Due to the large water solubility of these aggressive media, they mainly use water as the carrier to penetrate into the porous masonry mortar, through harmful reactions with cement hydrates or unhydrated cement particles, or when exposed to the atmosphere. Surface crystallization causes changes in the composition and structure of masonry mortar. Therefore, effective measures must be taken to improve the anti-environmental water erosion performance of cement mortar used for masonry masonry structures, so as to ensure the durability and operational safety of railway and highway subgrade projects.

The substances that are corrosive to cement mortar in environmental water and rock and soil mainly include SO ₄ ^2- , HCO ₃ ^- , H ⁺ , Mg ²⁺ , NH ₄ ⁺ and other corrosive ions and their alkali metal salts. The erosion mechanism There are chemical and physical effects.

The mechanism of chemical erosion is mainly that the environmental water containing aggressive ions intrudes into the interior of the cement-based material, and chemically reacts with the ions in the pore solution or the cement hydrate on the pore wall to form soluble substances or expansive substances or non-gelling substances. The composition and structure of cement-based materials change, resulting in volume expansion or surface corrosion inside the material, causing cracking, peeling, corrosion and performance degradation on the surface of the structure. Therefore, the chemical erosion resistance of cement mortar against environmental water depends more on cement hydrates—hydroxylite and aluminate hydrates. Reducing the content of these hydrates can significantly improve the corrosion resistance of cement mortar against environmental water, thereby , to improve the durability of masonry masonry structures.

The mechanism of physical erosion is mainly the damage of salt crystallization to cement mortar. One is the volume change in the process of dehydration and rehydration of salt, which causes expansion and contraction. For example, sodium sulfate can be inert under different temperature and humidity conditions. Sodium sulfate hydrate Na ₂ SO ₄ , sodium sulfate heptahydrate Na ₂ SO ₄ ·7H ₂ O, sodium sulfate decahydrate Na ₂ SO ₄ ·10H ₂ O, etc., their molar volumes are different, when these salt crystals transform into each other , a volume change will occur. The same is true for other inorganic salts; the second is the crystallization pressure on the pore wall generated by the crystallization of salt in the cement mortar inner pore solution, causing cracking and damage to the mortar. For the masonry rubble structure, since its back is in contact with rock and groundwater, and its front surface is exposed to the atmospheric environment, groundwater seeps into the masonry mortar between the rubble from the back, and then evaporates from the front surface into the atmospheric environment. In the process, the salt will crystallize on the surface layer of the mortar, causing physical erosion damage. Therefore, preventing environmental water infiltration or salt crystallization can improve the ability of masonry mortar to resist salt crystallization damage.

Therefore, cement mortar is eroded and damaged by environmental water. The internal cause is that the cement mortar contains hydrates that are easily eroded by erosive ions and the capillary channels through which environmental water can penetrate into the mortar.

Masonry mortar is generally composed of a mixture of Portland cement, sand, and water and is a building material commonly used in civil engineering. There are some patents related to this building material, but these patents mainly relate to the construction and mechanical properties of masonry mortar. For example, CN200710036822.5 patent application discloses a high-efficiency water-retaining thickening material and masonry mortar made from it. This high-efficiency water-retaining thickening material is composed of inorganic mineral materials and polymer additives. The water retention of mortar, the polymer additives involved are modified starch, lignosulfonate, polyol series and compound, higher polyol, carboxylate and its copolymer, polyoxyethylene and its derivatives, etc. . These polymer additives have a certain effect on improving the water retention of masonry mortar, but have little effect on improving the anti-environmental water erosion performance of masonry mortar, and cannot meet the durability requirements of some slope protection projects. A masonry mortar disclosed in the CN97100700.4 patent application only involves adding fibrous materials, expansion agents, air-entraining agents and plasticizers to ordinary cement to improve the seismic performance of the mortar, and does not involve masonry The anti-environmental water erosion performance of mortar. CN03116914.7 patent application discloses a special admixture for construction mortar, which is composed of naphthalenesulfonic acid formaldehyde condensate, calcium sugar, methylcellulose, sodium dodecylbenzenesulfonate, and zeolite powder, and mainly improves mortar Cohesion, consistency, water retention, stability and other construction properties. Although the admixture involved in the patent can improve the durability of the mortar by reducing the water consumption, it can also improve the anti-environmental water erosion performance of the mortar. Very limited. The cement mortar admixture disclosed in CN03118188.0 patent application is mainly composed of surfactant, cement activator and thickener, etc., such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, calcium lignosulfonate, Calcium nitrite, anhydrous sodium sulfate, carboxymethyl cellulose, etc., are also used to improve the construction performance of cement mortar.

In order to improve the corrosion resistance of cement mortar against sulfate-type environmental water, sulfate-resistant cement is generally used to prepare masonry mortar at home and abroad. The mineral composition of sulfate-resistant cement is different from that of ordinary Portland cement. C ₃ in the clinker of sulfate-resistant cement The content of A and C ₃ S is relatively low, and it needs to be prepared with a specific ratio of raw materials, so the price of this cement is relatively expensive, and it is not easy to obtain in the market.

Contents of the invention

The object of the present invention is to provide an anti-corrosion agent, which can effectively improve the sulfate crystallization resistance of masonry mortar with a large water-cement ratio, and meet the requirements of masonry masonry mortar for anti-environmental water erosion.

Another object of the present invention is to provide a masonry mortar material for masonry masonry containing the above-mentioned anti-corrosion agent, which has excellent anti-environmental water erosion performance, and can greatly improve the durability of slope protection structures against environmental water erosion. sex.

In order to realize the foregoing invention object, the technical scheme that the present invention adopts is as follows:

An anti-corrosion agent is composed of fly ash, PVA resin, OP additives, oxalic acid or borate and other components, and the weight ratio of each component is:

100 parts of fly ash, 5-20 parts of PVA resin,

0.5-2 parts of OP additives, 1-10 parts of oxalic acid or borate.

The proportioning by weight of above-mentioned each component can preferably be:

100 parts of fly ash, 10-15 parts of PVA resin,

1-2 parts of OP additives, 5-10 parts of oxalic acid or borate.

Among the above components:

Fly ash is dry fly ash discharged from thermal power plants, which can be Class I or Class II low-calcium fly ash, and Class I low-calcium fly ash is the best. Fly ash can not only dilute the content of C ₃ A minerals in Portland cement that are sensitive to environmental water erosion, but also react with volcanic calcium stone Ca(OH) ₂ formed by cement hydration, reducing the impact on environmental water. Increase the content of hydroxycalcite, which is more sensitive to erosion, and increase the content of calcium silicate hydrate CSH, which is relatively stable under environmental water erosion and has a smaller calcium-silicon ratio C/S, thereby significantly improving the environmental water erosion resistance of masonry mortar .

PVA resin refers to polyvinyl alcohol resin, which contains many hydroxyl groups OH ^- in its macromolecular chain, and this macromolecular compound has multiple functions. First, they have the function of adsorbing sulfate ion SO ₄ ^2- , as shown in Figure 1 . When the ambient water containing sulfate ions penetrates into the masonry mortar, they adsorb sulfate ions, which can effectively inhibit the chemical and physical erosion of sulfate ions on the masonry mortar; second, they can improve the masonry mortar and flakes The bonding properties of the surface can increase the bonding strength between the masonry mortar and the chip stone; thirdly, they can improve the construction performance of the masonry mortar such as water retention and fluidity. Thus, the physical mechanics and environmental water erosion resistance performance of the masonry mortar are improved.

OP additives are a kind of alkylphenol and ethylene oxide condensation product surfactant (octylphenol polyoxyethylene ether), commonly used in printing and dyeing and textile industries, they can reduce the surface tension of water, therefore, they are compatible with PVA resin Combined, it can introduce closed air pores with small pore size in the masonry mortar mixture, which can not only improve the construction performance of the masonry mortar, but also significantly improve the impermeability and frost resistance of the masonry mortar; OP-10 can be preferred (octylphenol ethoxylate (10) ether).

Oxalic acid or borate is a coagulation regulator for some Portland cement; oxalic acid has a coagulation-accelerating effect, and borates such as sodium borate and potassium borate have a retarding effect; therefore, they can adjust the setting and hardening time of masonry mortar. At the same time, they can also form complexes with hydroxycalcite, PVA resin, etc., which can effectively improve the environmental water erosion resistance of masonry mortar.

The above-mentioned anti-corrosion agent can be prepared by the following method: firstly, the PVA resin is mechanically powdered into a fine powder, and then the fly ash, PVA resin, OP additives, oxalic acid or borate, etc. are mixed uniformly in a mixer to obtain Anti-corrosion agent according to the present invention.

The anti-corrosion agent mentioned above can be used to prepare various masonry mortars or other cement mortars.

The masonry mortar containing the above-mentioned anti-corrosion agent is composed of the following components by weight:

60-90 parts of Portland cement, 10-40 parts of anti-corrosion agent, 200-400 parts of sand, the amount of water to meet the requirements of construction performance and strength of masonry mortar, the optimal value is 40-60 parts .

The proportioning by weight of above-mentioned each component can preferably be:

70-88 parts of Portland cement, 12-30 parts of anti-corrosion agent, 200-300 parts of sand,

The consumption of water is 40～60 parts.

Portland cement in the above components can be selected from PI Portland cement, PII Portland cement, ordinary Portland cement, and slag Portland cement; ordinary Portland cement without limestone powder can be preferably used .

The above-mentioned masonry mortar can be prepared by the following method: use an ordinary mortar mixer as the mortar mixing equipment, first add sand, water and anti-corrosion agent into the mixer, stir for 5 to 10 minutes, then add cement and continue stirring until a uniform mortar is formed. mortar.

Compared with prior art, the beneficial effect of the present invention is:

The anti-corrosion agent of the present invention can effectively resist environmental water (including corrosive ions such as SO ₄ ^2- , HCO ₃ ^- , H ⁺ , Mg ^{+ 2} , NH ₄ ⁺ and their alkali metal salts, and acidic rainwater with a pH lower than 5 ) erosion, which can effectively improve the sulfate crystallization resistance of masonry mortar with a large water-cement ratio, and meet the requirements of masonry masonry mortar against environmental water erosion. Therefore, the masonry mortar material for masonry masonry masonry containing the above-mentioned anti-erosion agent has excellent environmental water erosion resistance, and can greatly improve the durability of slope protection structures against environmental water erosion.

Description of drawings

Fig. 1 is the infrared spectrogram of PVA resin (a) and its adsorption SO ₄ ^2- (b);

Fig. 2 is that the expansion rate of the masonry mortar of embodiment 1～4 is soaked in the sulfate solution varies with soaking time curve;

Fig. 3 is a graph showing the change of the corrosion resistance coefficient of the masonry mortar half-soaked in the sulfate solution with the immersion time in Examples 5-7.

In Fig. 3, S0 is the mortar test piece of Example 5, S1.2 is the mortar test piece of Example 6, and S2 is the mortar test piece of Example 7.

Detailed ways

The present invention will be further described in detail below in combination with specific embodiments.

However, it should not be construed that the scope of the above-mentioned subject matter of the present invention is limited to the following examples.

Embodiment 1-4

The composition and ratio of the anti-corrosion agent are: 100 parts of Class II low-calcium fly ash, 5 parts of PVA resin, 1 part of OP-10, 5 parts of oxalic acid, and these substances are stirred into a mixture.

Ordinary Portland cement (OPC) with a clinker mineral composition of 57.7% C ₃ S, 19.6% C ₂ S, 10.6% C ₃ A and 5.8% C ₄ AF, the anti-erosion agent of the above composition and sand are used to make masonry Build mortar. The masonry mortar proportions of Examples 1-4 are shown in Table 1, wherein Example 1 is a comparative example.

The masonry mortar proportioning of table 1 embodiment 1～4

cement anti-corrosion agent water sand Example 1 100 0 50 275 Example 2 90 10 50 275 Example 3 80 20 50 275 Example 4 70 30 50 275

First add sand and anti-corrosion agent into water and stir for 5-10 minutes, then add ordinary Portland cement in sequence, and then stir evenly at a high speed of 120 rpm to obtain fresh mortar. Form the freshly mixed mortar into a prism of 25×25×285mm ³ and a cube of 50×50×50mm ³ , and demould after 24 hours. When the compressive strength of the cube specimen reaches 20.0MPa, soak it in the In 5% Na ₂ SO ₄ solution, measure the linear length expansion rate of prism specimens when immersed for 1, 2, 3, 4, 8, 12, 16, 24, 36, 52, 65, 78, 91 and 104 weeks , and the result is shown in Figure 2.

As can be seen from Fig. 2, the linear length expansion rate _of the prismatic mortar specimen of embodiment 1 (not containing anti-corrosion agent) increases sharply with 5%Na _SO The immersion time prolongs in the solution, and when immersing to 35 weeks, Its linear expansion rate reaches 0.6%, and the mortar specimen has already cracked and failed at this time. And containing anti-corrosion agent (embodiment 2～4) the linear length expansion rate of the prismatic mortar specimen with 5% _{Na SO} The change of soaking time in the solution is related to the content of anti-corrosion agent, when the content of anti-corrosion agent When it was 20 (embodiment 3), when soaked to 110 weeks, the linear length expansion rate of the prism mortar specimen was only 0.05%, showing excellent corrosion resistance to sulfate-containing environmental water.

Soaked in 5% Na ₂ SO ₄ solution, the time and strength loss rate of the cubic mortar specimen cracking are shown in Table 2. It can be seen that when soaked for 8 months, the mortar specimen of embodiment 1 cracked, and its compression and flexural strength retention rates were only 73.7% and 30.3% respectively, and the mortar specimen of embodiment 3 was soaked for 2 years After a long time, the compression and flexural strength retention rates are both greater than 80%, 84.7% and 153% respectively, showing good corrosion resistance to sulfate-containing environmental water.

Table 2 Cracking time and strength retention rate of masonry mortar specimens soaked in sulfate solution

Table 3 Mass loss rate of masonry mortar soaked in sulfuric acid solution

After immersing in 0.1N (normal concentration unit) and 1N sulfuric acid solutions for 4 days, the test results of the mass loss rate of the cube mortar specimens are shown in Table 3. It can be seen that the mass loss rates of the mortar specimens in Example 1 were 1.15% and 6.24%, respectively. However, the mass loss rate of the mortar specimens of Examples 2 to 4 decreases with the increase of the anti-corrosion agent content in the mortar. Among them, its mass loss rate is only 0.42% and 5.18%, compared with the test piece of embodiment 1, reduces respectively 63.5% and 17%. Therefore, the anti-erosion agent significantly improves the anti-acid environmental water erosion performance of masonry mortar.

The carbonization test was carried out on the mortar specimen in a standard carbonization test chamber to simulate the performance of masonry mortar against carbonated water and CO ₂ gas in the atmosphere. After the mortar specimen was exposed for different times, it was split to measure the The carbonization depth, the results are shown in Table 4. The results show that, compared with Example 1, the masonry mortars of Examples 2-4 containing anti-corrosion agents have better corrosion resistance to carbonated water and CO ₂ gas.

Table 4 Carbon dioxide erosion resistance of masonry mortar containing anti-corrosion agent

The above test results show that the anti-corrosion agent can effectively improve the anti-environmental water erosion performance of the masonry mortar, and the masonry mortar prepared with the anti-corrosion agent can significantly improve the performance of the masonry masonry structure in the subgrade protection project in the environment containing erosive ions. Durability in water.

Embodiment 5-7

The composition and ratio of the anti-corrosion agent are: 100 parts of Class II low-calcium fly ash, 10 parts of PVA resin, 2 parts of OP-10, 10 parts of sodium borate, and stir these substances into a mixture.

Ordinary Portland cement (OPC) with a clinker mineral composition of 57.7% C ₃ S, 19.6% C ₂ S, 10.6% C ₃ A and 5.8% C ₄ AF, the anti-erosion agent of the above composition and sand are used to make masonry Build mortar. The masonry mortar proportions of Examples 5-7 are shown in Table 5, wherein Example 5 is a comparative example.

First add sand and anti-corrosion agent into water and stir for 5-10 minutes, then add ordinary Portland cement in sequence, and then stir evenly at a high speed of 120 rpm to obtain fresh mortar. The freshly mixed mortar was formed into cylindrical specimens of φ25×150mm ³ , demolded after 24 hours, and placed under standard conditions for 28 days of curing. The half-immersion test is used to simulate the physical erosion of salt crystals during use, that is, half of the specimen is immersed in 5% Na ₂ SO ₄ solution at 23°C, and the half is exposed to indoor air at 23°C. For the flexural strength at 1, 2, 3, 4 and 6 months, the ratio of the initial flexural strength of the specimen to the flexural strength of the specimen after half-immersion in 5% Na ₂ SO ₄ solution for different times was used to calculate the corrosion resistance coefficients, and the results are shown in Figure 3.

The masonry mortar proportioning of table 5 embodiment 5～7

cement anti-corrosion agent water sand Example 5 100 0 80 275 Example 6 88 12 80 275 Example 7 70 30 80 275

As can be seen from Fig. 3, after half immersion in 5% Na SO ₄ solution for 6 months, the corrosion resistance coefficient of the mortar specimen of Example 5 of _the comparative example is only 0.62, which does not meet the requirements for use, and contains anti-corrosion agent The anti-corrosion coefficient of the mortar specimens of Example 6 and Example 7 reached 0.9, indicating that the anti-corrosion agent can effectively improve the sulfate crystallization resistance of the large water-cement ratio masonry mortar, and meet the requirements of the masonry masonry mortar against environmental water erosion .

Embodiment 8～11

The composition and ratio of the anti-corrosion agent are: 100 parts of Class I low-calcium fly ash, 20 parts of PVA resin, 2 parts of OP-10, 10 parts of sodium borate, and these substances are stirred into a mixture.

The masonry mortar proportioning of embodiment 8～11: in the embodiment 8 and 9 that adopt P·I type portland cement, sand consumption is 400 parts; Adopt fly ash portland cement (P·F) embodiment In 10 and 11, the amount of sand used is 300 parts. The amount of mixing water is determined by the working degree of the masonry mortar, so as to facilitate the masonry construction operation. The amount of cement and anti-corrosion agent is shown in Table 6.

First add sand and anti-corrosion agent into water and stir for 5 to 10 minutes, then add P·I type Portland cement or P·F Portland cement, and then stir evenly at a high speed of 120 rpm to obtain freshly mixed mortar. Form the freshly mixed mortar into cylinders of φ25× ^150mm3 , demould after 24 hours, and after curing for 28 days, soak the cylinder specimens in 5% Na ₂ SO ₄ solution at 23°C, and measure the specimens after soaking for 1, For the flexural strength at 3 and 6, calculate the ratio of the flexural strength of the specimen after soaking for a certain period of time to the initial flexural strength—corrosion resistance coefficient. The results are shown in Table 6.

Table 6 Sulfate attack resistance of masonry mortars containing anti-corrosion agents

From the above examples, it can be seen that the anti-corrosion agent can significantly improve the sulfate erosion resistance of cement mortar. When using pure Portland cement, the parameter of the anti-corrosion agent can take a larger value. When using fly ash silicic acid When salt cement is used, the parameter of the anti-corrosion agent can take a small value, which can meet the engineering requirements of the anti-corrosion coefficient greater than 0.8.

The content (%) of the anti-corrosion agent described in each of the above-mentioned embodiments is calculated by taking the total amount of cement and the anti-corrosion agent as 100%.

Claims (10)

1. An anti-corrosion agent is characterized in that: it is made up of the component of following weight portion proportioning: 100 parts of fly ash, 5-20 parts of PVA resin, 0.5-2 parts of OP additives, 1-10 parts of oxalic acid or borate. 2. The anti-corrosion agent according to claim 1, characterized in that: the weight ratio of each component is: 100 parts of fly ash, 10-15 parts of PVA resin, 1-2 parts of OP additives, 5-10 parts of oxalic acid or borate. 3. The anti-corrosion agent according to claim 1 or 2, characterized in that: said fly ash is Class I low-calcium fly ash or Class II low-calcium fly ash. 4. The anti-corrosion agent according to claim 3, characterized in that: said fly ash is Class I low-calcium fly ash. 5. The anti-corrosion agent according to claim 1 or 2, characterized in that: the OP additive is OP-10. 6. The anti-corrosion agent according to claim 1 or 2, characterized in that: the borate is selected from sodium borate and potassium borate. 7. the masonry mortar material containing the anti-corrosion agent described in claim 1 or 2, is made up of the component of following weight portion proportioning: Portland cement 60-90 parts, anti-corrosion agent 10-40 parts, sand 200-400 parts; The amount of water is selected to meet the requirements of the construction performance and strength of the masonry mortar. 8. The masonry mortar material according to claim 7, characterized in that: the weight ratio of each component is: 70-88 parts of Portland cement, 12-30 parts of anti-corrosion agent, 200-300 parts of sand, The consumption of water is 40～60 parts. 9. The masonry mortar material according to claim 7, characterized in that: said Portland cement is selected from P·I Portland cement, P·II Portland cement, ordinary Portland cement, Slag portland cement. 10. The masonry mortar material according to claim 7, characterized in that: the Portland cement is ordinary Portland cement without limestone powder. the

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