TWI494287B - Semi-interpenetrating polymer network structure (Semi-IPN) water-containing polyethylene glycol and its preparation method - Google Patents

Description

Semi-interpenetrating polymer network structure (Semi-IPN) water gel containing polyethylene glycol and preparation method thereof

The invention relates to a composite water-paste-PACG containing a semi-interpenetrating polymer network structure of polyethylene glycol, in particular to a concrete which can reduce the durability of the material and improve the performance by cracks caused by dry shrinkage. Self-curing agent, a composite water gel-PACG containing a polyethylene glycol-containing semi-interpenetrating polymer network structure and a preparation method thereof.

At present, concrete, especially high-performance concrete, is usually properly cured after the pouring operation is completed. Without proper curing, the moisture in the concrete will be volatilized from its surface, which will affect the hydration of the cement and the strength of the concrete. Concrete will also produce dry shrinkage cracks and reduce durability.

The traditional concrete curing methods include the stagnant water method, the continuous sprinkling method, the covering method, the delayed demoulding method, and the liquid film curing method, etc., all of which are external curing methods. These methods can be used to achieve the desired conservation goals if properly performed. The disadvantage is that these methods require periodic watering, watering, or spraying, etc., which not only saves labor and time, but also is not suitable for certain working environments or time schedules. In contrast, the addition of an internal curing agent or a self-curing agent to concrete can improve these disadvantages by increasing the water retention of the material and forming a self-curing concrete.

The composition of the internal curing agent is generally a water-soluble resin, a water-absorbent resin or a hydrogel. Some studies have pointed out that the addition of water-soluble resins such as polyethylene glycol (PEG) to cementitious materials such as cement slurries, cement mortars or concrete, due to the action of water-soluble resins and water molecules, reduces the vapor pressure of aqueous solutions, thereby reducing cement quality. The volatilization of water in the material is lost; in addition, when the water around the water-soluble resin is volatilized, the resin will precipitate and block the pores of the cementitious material. The hole, which hinders the loss of moisture, thus retains more moisture inside the material, making the cement hydrate more complete. In contrast, water-absorbing resin such as polyacrylate or polyacrylate water gel is added to the cementitious material. Because the water gel can bind moisture inside, it can play the role of a reservoir, when the water in the cement material volatilizes. When it is lost to the outside, the water inside the water gel will be released and replenished, so that the material can retain more water and higher humidity, make the cement hydrate more complete, and the material is less prone to shrinkage and cracking.

Compared with the traditional external curing methods, if the internal curing method is adopted, the self-curing agent will be added to the concrete, so that the material itself can be self-maintained, which not only saves man-hours, but also is not restricted by the working environment or time schedule; It can effectively reduce the occurrence of concrete cracks, improve the durability of concrete, reduce the maintenance of concrete structures, and ensure the service life.

Cement in concrete, mainly composed of C ₃ S (tricalcium citrate), C ₂ S (dicalcium citrate), C ₃ A (tricalcium aluminate), C ₄ AF (tetracalcium aluminate) In the composition, when the cement encounters water, it will release various ions into the water and react to form hydration products. Therefore, the pore solution in the concrete will contain Na ⁺ , K ⁺ , Ca ² within a few hours. ⁺ , OH ^- , SO ₄ ^2- and other brines of various ions. Water glue is added to the concrete as a self-supporting agent, mainly as a reservoir. When the interior of the concrete consumes moisture due to the cement hydration reaction, or the water volatilizes from the interior of the concrete to the outside, the water gel can release moisture in a timely manner to keep the interior of the concrete moist and avoid dry shrinkage cracks. Therefore, as a concrete self-curing agent, the water glue not only has a high water absorption rate in pure water, but also has a high water absorption rate in the brine, so that the function of the reservoir can be exerted. Common polyacrylate or polyacrylate glue can be used as a self-curing agent for concrete, but it has a lot of room for improvement. The reason is that although the water absorption rate of sodium polyacrylate or polyacrylate water gel in pure water is very high, water absorption per gram of water gel can be as high as several kilograms; however, the water absorption rate in salt water is very low. For example, TAISAP 283HA (polyacrylate) water gel from Formosa Plastics can absorb about 500 grams of pure water per gram of water gel, but less than 10 grams per gram of water gel can absorb 0.1M CaCl ₂ brine. Therefore, if the sodium polyacrylate or polyacrylate hydrocolloid filled with pure water is mixed into the concrete, the water contained in the sodium polyacrylate or polyacrylate water gel will be short-lived because the pore aqueous solution is brine. A large amount of the inside is released into the concrete pores outside, which cannot function as a reservoir.

In order to solve the above disadvantages of the prior art, one object of the present invention is to provide a semi-interpenetrating polymer network structure (Semi-IPN) composite polyethylene-PACG containing polyethylene glycol (PEG) and preparation thereof. The method can be used as an internal curing agent.

In order to solve the above disadvantages of the prior art, another object of the present invention is to provide a composite water gel-PACG containing a polyethylene-ethylene semi-interpenetrating polymer network structure and a preparation method thereof, which are Higher water retention rate.

In order to solve the above disadvantages of the prior art, another object of the present invention is to provide a composite water gel-PACG containing a polyethylene-ethylene semi-interpenetrating polymer network structure and a preparation method thereof, which can be added to a cement mortar. Among them, it can improve the degree of hydration of cement, increase the compressive strength of materials, and reduce the shrinkage of materials.

In order to achieve the above object, a composite water gel-PACG containing a polyethylene glycol-containing semi-interpenetrating polymer network structure having the following formula:

Wherein m, n, p, and q are integers of 10 to 1000, respectively.

For the above purposes, one of the present invention contains polyethylene glycol A method for preparing a composite-water-PACG of a semi-interpenetrating polymer network structure, comprising the steps of: taking Acrylamide, PCM and polyethylene glycol (PEG), and dissolving in deionized water; Placed in a four-necked reactor; slowly increase the reaction temperature, then add an appropriate amount of the initiator, dropwise, until the solution becomes a colloidal state; and purify with methanol, and soak the product in deionized water, and The water is changed periodically to remove unreacted monomers, and after several days, it is taken out and baked in an oven to obtain a solid water gel PACG.

The detailed description of the drawings and the preferred embodiments are set forth in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the IR spectrum of a composite water gel-PACG of the present invention.

2 is a schematic view showing the water absorption of the PAC water gel of the present invention in deionized water.

Fig. 3 is a schematic view showing the effect of the PACG water gel and PEG content of the present invention on the saturated water absorption in deionized water and 0.1 M CaCl ₂ aqueous solution.

4 is a schematic view showing the water retention rate of each PACG water gel of the present invention in a pore solution in a cement slurry.

FIG. 5 is a schematic view showing the effect of adding different amounts of PEG in the PACG water gel of the present invention on the weight loss of the cement mortar.

Fig. 6 is a schematic view showing the effect of adding different contents of PEG in the PACG water gel of the present invention on the compressive strength of the cement mortar sample.

FIG. 7 is a schematic view showing the effect of adding different amounts of PEG in the PACG water gel of the present invention on the dry shrinkage of the cement mortar sample.

Fig. 8 is a schematic view showing the DSC diagram of the cement slurry powder of the PACG water gel of the present invention containing different PEG ratios at 7 days.

Figure 9 is a schematic view showing the effect of the PEG ratio in the PACG water gel of the present invention on the CH content in the cement slurry.

Cement in concrete, mainly C ₃ S (tricalcium citrate), C ₂ S (dicalcium citrate), C ₃ A (tricalcium aluminate), and C ₄ AF (tetracalcium ferroate) Ingredients, when the cement encounters water, it will release various ions into the water and produce a reaction to form hydration products. Therefore, the pore aqueous solution (called the pore solution) in the concrete becomes Na ⁺ , K ⁺ in a few hours. , brine of various ions such as Ca ²⁺ , OH ^- , SO ₄ ^2- . Water glue is added to the concrete as a self-supporting agent, mainly as a reservoir. When the interior of the concrete consumes moisture due to the cement hydration reaction, or the water volatilizes from the interior of the concrete to the outside, the water gel can release moisture in a timely manner to keep the interior of the concrete moist and avoid dry shrinkage cracks. Therefore, as a concrete self-curing agent, the water glue not only has a high water absorption rate in pure water, but also has a high water absorption rate in the brine, so that the function of the reservoir can be exerted. Common sodium polyacrylate or polyacrylate water gel can be used as a self-reinforcing agent for concrete, but it has a lot of room for improvement. The reason is that although the water absorption rate of sodium polyacrylate or polyacrylate water gel in pure water is very high, water absorption per gram can reach hundreds or even thousands of grams; but the water absorption rate in brine is very low, per gram of water. The glue can absorb less than ten grams of 0.1M CaCl ₂ brine.

The present invention relates to the preparation of a composite hydrogel-PACG comprising a semi-interpenetrating polymer network structure of polyethylene glycol as an internal curing agent. The composite water gel-PACG (which contains a PEG water-soluble resin) of the present invention has a higher water retention rate in the brine than the water gel which does not contain the water-soluble resin PEG. Because PACG water gel has good water storage and water retention capacity, when it is added into cement material such as cement slurry, cement mortar or concrete, it can improve the hydration degree of cement, increase the compressive strength of the material, and reduce the shrinkage of the material. the amount. Therefore, the PACG composite water gel of the invention is a concrete self-curing agent with superior performance.

The composite water gel-PACG of the semi-interpenetrating polymer network structure (Semi-IPN) containing polyethylene glycol (PEG) of the invention can be used as a curing agent for concrete, and the water gel has the following structure:

Wherein m, n, p, q are integers from 10 to 1000, respectively. Wherein, the content of the PEG is, for example but not limited to, 0.1 to 50% by weight.

The method for synthesizing the composite water gel-PACG of the semi-interpenetrating polymer network structure containing polyethylene glycol of the present invention can be illustrated by the following examples.

Embodiment 1

65 g of aspartic acid and 49 g of phosphoric acid were weighed and placed in a four-necked reaction flask, and reacted in an oil bath at 200 ° C for 6 hours, and extracted with methanol to obtain 56 g of a yellow viscous solid PSI (Polysuccinimide). 20 g of PSI and 15 g of sodium hydroxide were dissolved in 100 ml of water, and the reaction was stirred for 2 hours in an ice bath. The pH of the solution was adjusted to 9-10 with 12N hydrochloric acid, and then extracted with methanol, and then placed in an oven. The solvent was removed at ° C for 24 hours to obtain 17 g of a yellow viscous solid polyaspartate Pasp (Sodium polyaspartate).

Take 57g of Pasp and 66g of sodium bromoacetate dissolved in 150ml of ethanol (ethanol: water = 3:7), put into a four-necked reaction flask, and adjust the pH of the solution to 9~ with sodium hydroxide. 10, the reaction was carried out at 78 ° C for 6 hours, and the reaction was stirred at room temperature for 1 day, and then extracted with acetone to obtain 97 g of poly(4-formicylmethylamino)-4-oxobutyrate) (poly(4-(carboxylato-methylamino)-4-oxobutanoate), PCM) monomer.

1. Synthesize water-free glue without PEG, that is, PAC water gel: take 10g of acrylamide and 10g of PCM, dissolve it in 200mL of deionized water, put it into a four-necked reactor, and slowly raise the reaction temperature. To 75 ° C, then add an appropriate amount of the initiator - ammonium persulfate and the cross-linking agent - N, N-methylenebisacrylamide, and continue to react for 1 hour until the solution becomes colloidal status. Purified with methanol, and the product was immersed in deionized water, water was changed once every other day to remove unreacted monomer, and after 3 days, it was taken out in an oven at 55 ° C for 24 hours to obtain 10 g of white solid water. Glue PAC.

2, the synthesis of PEG-containing water gel, that is, PACG water gel: take 10g of acrylamide (Acrylamide), 10g PCM and 1g of polyethylene glycol (PEG, molecular weight of 6000), dissolved in 200 mL of deionized water, placed In the four-neck reactor, the reaction temperature is slowly raised to 75 ° C, and then an appropriate amount of the initiator - ammonium persulfate and crosslinker - N, N - methylene bis acrylamide (N, N -) is added dropwise. Methylenebisacrylamide), continued to react for 1 hour until the solution became a colloidal state. After purifying with methanol, the product was immersed in deionized water, and the water was changed once every other day to remove unreacted monomers. After 3 days, it was taken out in an oven at 55 ° C for 24 hours to obtain 11 g of white solid water. Glue PACG.

Please refer to FIG. 1 , which is a schematic diagram showing the IR spectrum of the composite water gel-PACG of the present invention. As shown, in which the wavenumber 3340.5 cm ^-1 is OH absorption peak, 2930.8 cm ^-1 absorption peak is CH, 1721.5 cm ^-1 is C = O absorption peak, 1578.4 cm ^-1 is -NH ₂ To The absorption peak, 1412.3 cm ^-1 is the absorption peak of CN, and 1164.6 cm ^-1 is the absorption peak of CO.

Take an appropriate amount of PAC (ie, 0% PEG-containing PACG) water gel, put it in a tea bag and dip it in deionized water or 0.1 M CaCl ₂ brine, etc. After soaking for a certain period of time, take out the weight to get the water gel weight absorbed. The water absorption rate of the water gel can be obtained by the difference in weight between the water gel and the water before and after water absorption.

Please refer to FIG. 2, which is a schematic diagram showing the water absorption rate of the PAC water gel of the present invention in deionized water. It can be seen from Figure 2 that the water absorption of the water gel first immersed The time increases and then gradually becomes flat. The maximum value is the saturated water absorption rate, and the saturated water absorption rate per gram of PAC water gel in deionized water is about 400 grams.

Prepare PACG water gel containing different PEG ratios, place them in tea bags and dip them in deionized water or 0.1 M CaCl ₂ brine, soak them until the water absorption of each water gel reaches the maximum value, and take out the weight to obtain water that absorbs water. The weight of the glue can be obtained from the difference in weight of the water gel before and after water absorption.

Please refer to FIG. 3, which is a schematic diagram showing the effect of the PACG water gel and PEG content (% by weight relative to PAC) of the present invention on the saturated water absorption in deionized water and 0.1 M CaCl ₂ aqueous solution. It can be seen from Fig. 3 that the water absorption rate of the water gel in the brine is lower than that in the deionized water. In addition, the saturated water absorption of PACG water gel in deionized water or 0.1 M CaCl ₂ aqueous solution will decrease with the increase of PEG content, and then tend to be a certain value. Because as the proportion of PEG increases, the number of -COO ^- functional groups in the structure on the water gel is relatively small, and the -OH functional group is relatively increased, so that the water absorption rate of the water gel is decreased. However, when the PEG content in the PACG water gel is higher than 10%, the saturated water absorption rate of the water gel gradually becomes a certain value as the PEG content increases.

A cement slurry having a water-cement ratio (W/C) of 0.485 was mixed, and a pore solution in the cement slurry was obtained by suction filtration. The cement used is from the Portland cement type I Portland cement. Then take an appropriate amount of PACG water gel containing different PEG ratios, respectively, after being saturated in deionized water, and then immersed in the pore solution of the cement slurry with a water-cement ratio of 0.485 for different time, then take out the water gel. weight. During the immersion of the water gel in the pore solution, the moisture inside the water gel is released to the outside due to the difference in ion concentration inside and outside the water gel. If the amount of water contained in the water-saturated water gel is w1, the water retention rate of the water gel is 100% at this time; after the water-absorbing saturated water gel is soaked in the pore solution for a period of time, the water gel will release Part of the water is released. At this time, the amount of water contained in the water gel is w2, and the water retention rate is (w2/w1) × 100%.

Please refer to FIG. 4 , which is a schematic diagram showing the water retention rate of each PACG water gel of the present invention in a pore solution in a cement slurry. The water retention rate of each PACG water gel in the pore solution in the cement slurry is shown in Fig. 4. It can be seen from the figure that after each PACG water gel is put into the pore solution, the water retention rate of the water gel increases with the insertion time. Gradually decreasing from 100%, when a certain value (minimum value) is reached, the water retention rate of the water gel is slowly increased. The reason for this transition is that the PACG water gel changes its functional group after a period of time in the pore solution, that is, some of the mercaptoamine groups (-CONH ₂ ) in the hydrogel structure are converted into a carboxylic acid group (-COO ^- ). The water gel is made to release water first and then absorb water. It can also be seen from Fig. 4 that the water retention rate of PACG water gel containing each proportion of PEG is higher than that of PAC water glue without PEG, and the water retention rate of PACG water gel containing 20% PEG is the highest. This result shows that PACG water gel reacts with water molecules due to the PEG contained in the structure, so that the water in the PACG water gel is released to the outside, so the PACG water-to-gel ratio PAC water gel has a high water retention rate. Therefore, PACG water gel is added to cementitious materials such as cement slurry, cement mortar or concrete, which can bind more water inside the structure and play a role as a reservoir. The addition amount of the PACG water gel is, for example, It is not limited to between 0.01 and 0.5 wt%. When the moisture in the cementitious material is lost, the water inside the water gel can be released and replenished, so that the cementitious material can retain more water and higher humidity, and the cementitious material is less likely to shrink and crack. It can reduce the moisture weight loss of the mortar and reduce the compressive strength of the mortar.

242.5g of water, 500g of cement, 1375g of sand, and an appropriate amount of PACG water-based glue and a strong plastic agent were mixed into a cement mortar with a water-cement ratio of 0.485. The cement used was from the Portland cement company's Butland type I cement. The fine sand used is Ottawa sand, the weight ratio of sand/cement is 2.75, the weight ratio of PACG water/cement is 0-0.2%, and the weight ratio of PEG/PAC in PACG water gel is 0- 50%; and adding 0.1-0.2% of the plasticizer A30 (relative to the weight percentage of cement), A30 from Qixin company, the new mortar is controlled to a certain degree of fluidity (205 ~ 215 mm). The fluidity test of the cement mortar test body is based on CNS 3655. After the mixed cement mortar is poured into the mold, it is shaken up and down 25 times in 15 seconds on the flow table, and the mortar diameter is measured in 4 times, and the average is taken. value.

The prepared cement mortar (W/C = 0.485) was prepared into a 5x5x5 cm ³ test piece. After being placed at room temperature and weighing the mortar sample at regular intervals, the weight loss of the test body relative to the initial test body (% by weight relative to the cement) can be obtained, which is the water loss in the test body. the weight of.

The test results showed that the weight loss of the test body added with 0.2% PAC water gel (ie 0% PEG PACG water gel) was 14.3 g in 28 days, which was lower than the weight loss of the test body without water gel at 28 days (15.9). g).

Please refer to FIG. 5 , which is a schematic diagram showing the effect of adding different amounts of PEG on the weight loss of cement mortar in the PACG water gel of the present invention. As shown in Fig. 5, the cement mortar contains 0.2% PACG water gel (relative to the weight of the cement), and it can be found that the moisture in the cement mortar sample reacts with the cement or volatilizes as the standing time increases. The weight of the PEG is gradually reduced, wherein the content of the PEG is, for example, but not limited to, 0.1-50 wt%; and the higher the proportion of PEG in the PACG water gel, the weight loss of the mortar sample is first decreased and then increased. The trend is that the weight loss of the mortar with 20% PEG added is the lowest, and the weight loss of the mortar sample at 12. days is 12.1g. The reason is that PEG in the water gel will retain its moisture in the water gel by using its OH group. Therefore, adding an appropriate amount of PEG to the PACG water gel can slow the release of moisture from the water gel structure, so the weight loss of the mortar is reduced; However, if PACG water gel containing 50% PEG is added, since the water gel structure contains too much PEG, the water absorption and water release space of the water gel will be reduced, and the weight loss of the mortar will increase. Therefore, the novel PACG water gel of the present invention can reduce the loss of moisture in the cement mortar if it contains an appropriate amount of PEG in its structure.

The cement mortar having the water-cement ratio (W/C) = 0.485 as described above was mixed and filled into a mold of ⁵ x ⁵ x 5 cm ³ . Wherein the weight ratio of PACG water gel/cement is 0-0.2%, the weight ratio of PEG/PAC in PACG water gel is 0-50%; and 0.1-0.2% of plasticizer A30 (weight percentage relative to cement) is added. ), so that the new mortar is controlled at a certain degree of fluidity. The test piece is made into 5x5x5 cm ³ and placed in a constant temperature and humidity chamber at 25 ° C and 60% humidity. According to CNS 1232, the compressive strength of the mortar sample at the age of 3, 7, and 28 days is tested by a compression tester. Take the average of the three test tests.

The test results showed that the compressive strength of the test piece added with 0.2% PAC water gel (ie 0% PEG PACG water gel) was 32.2 MPa at 28 days, which was higher than the compressive strength of the test body without added water gel at 28 days. (31.9MPa).

Please refer to FIG. 6 , which is a schematic diagram showing the effect of adding different amounts of PEG on the compressive strength of the cement mortar sample in the PACG water gel of the present invention. As shown in Fig. 6, this cement mortar is added with 0.2% PACG water gel (relative to the weight of cement). The results show that the compressive strength of the test body first rises first with the increase of curing time, and then gradually becomes constant. Wherein the content of the PEG is, for example but not limited to, 0.1 to 50% by weight. With the higher proportion of PEG added in PACG water gel, the compressive strength of mortar decreased first and then increased. Among them, the compressive strength of mortar with 20% PEG was the highest, and the mortar was at 28 The compressive strength of the day is 34.1 MPa. The reason is that PEG in the water gel will retain its moisture in the water gel by using its OH group. Therefore, adding an appropriate proportion of PEG to the PACG water gel can slow the release of water from the water gel structure, so the cement hydrates in the mortar. The degree of reaction increases, and the compressive strength of the test piece increases. However, if PACG water gel containing 50% PEG is added, the water retaining ability of the water gel is reduced due to the excessive PEG contained in the water gel structure, and the cement hydrates in the mortar. The degree of reaction is also reduced, and the compressive strength of the test body tends to decrease. Therefore, the novel PACG water gel of the present invention can increase the compressive strength of the cement mortar if it contains an appropriate amount of PEG in its structure.

The cement mortar having the water-cement ratio (W/C) = 0.485 as described above was mixed and filled into a mold of 32 × 2 × 1.7 cm ³ . Wherein the weight ratio of PACG water gel/cement is 0-0.2%, the weight ratio of PEG/PAC in PACG water gel is 0-50%; and 0.1-0.2% of plasticizer A30 (weight percentage relative to cement) is added. ), so that the new mortar is controlled at a certain degree of fluidity. Pour the cement mortar into the mold and tamper it with a spatula. Place it in a constant temperature and humidity chamber (temperature: 25±2°C, humidity: 90±5%) and remove the mold for 1 day to obtain 32×2. The sample of ×1.7 cm ³ was placed in a constant temperature and humidity chamber (temperature: 25 ± 2 ° C, humidity: 60 ± 5%). Based on the first day, the amount of change in the length of the next day of the mortar sample was measured, that is, the amount of dry shrinkage.

The test results showed that the test piece with 0.2% PAC water gel (ie 0% PEG PACG water gel) had a dry shrinkage of 0.193 mm in 28 days, which was lower than the dry shrinkage of the test body without added water gel at 28 days. (0.201mm).

Please refer to FIG. 7 , which is a schematic diagram showing the effect of adding different amounts of PEG in the PACG water gel of the present invention on the dry shrinkage of the cement mortar sample. As shown in Fig. 7, this cement mortar is added with 0.2% PACG water gel (relative to the weight of cement). The results show that the dry shrinkage of the test body first rises with the increase of curing time, and then gradually becomes constant. Wherein the content of the PEG is, for example but not limited to, 0.1 to 50% by weight. With the higher proportion of PEG in the addition of PACG water gel, the dry shrinkage of the mortar first decreases and then increases. Among them, the dry shrinkage of the mortar with 20% PEG is the largest, and the mortar is at 28 The dry shrinkage of the day is 0.186 mm. The reason is that PEG in the water gel will retain its moisture in the water gel by using its OH group. Therefore, adding an appropriate amount of PEG to the PACG water gel can slow the release of water from the water gel structure, so the mortar sample is dried. The shrinkage is reduced; however, if PACG water gel containing 50% PEG is added, since the water gel structure contains too much PEG, the water retention capacity of the water gel is reduced, and the dry shrinkage of the sample is increased. Therefore, the novel PACG water gel of the present invention can increase the dry shrinkage of the cement mortar if it contains an appropriate amount of PEG in its structure.

Mixing cement slurry with water-cement ratio (W/C)=0.3, the cement used is from Portland cement company's Butland type I cement, PACG water gel/cement weight ratio is fixed at 0.2%, PACG water gel The weight ratio of PEG/PAC in the range is 0-50%. Put the cement slurry into a constant temperature and humidity chamber (temperature: 25±2°C, humidity: 60±5%), take it out at 3, 7 and 28 days, put it in methanol solution to stop the hydration reaction, then dry and grind it. Cement slurry powder. An appropriate amount of cement slurry powder was placed in an aluminum crucible, and its DSC pattern was obtained by a thermal differential scanning card gauge (DSC, METTLER TOLEDO DSC822e, Switzerland). The conditions for sample determination were as follows: temperature rise rate of 10 ° C / min, temperature range of 50 ~ 500 ° C, while nitrogen gas was introduced at a flow rate of 80 cc / min.

Cement mainly containing C ₃ S (tricalcium silicate), C ₂ S (dicalcium silicate), C ₃ A (tricalcium aluminate), C ₄ AF (tetracalcium calcium ferric) composed of four kinds of mineral components, wherein The C ₃ S and C ₂ S contents together account for more than 70% of the total composition. When the cement is exposed to moisture, both C ₃ S and C ₂ S react with water to produce CH (calcium hydroxide). Generally, the higher the CH content in the cement slurry, the cement mortar sample, or the concrete sample, the higher the degree of hydration of the cement therein.

Please refer to FIG. 8 , which is a schematic diagram showing the DSC of the cement slurry powder of the PACG water gel of the present invention containing different PEG ratios at 7 days. As shown in Fig. 8, the endothermic peak at 400-500 °C in the figure represents the thermal decomposition of calcium hydroxide. The larger the endothermic peak area, the higher the calcium hydroxide content in the test sample, and the higher the degree of cement hydration. It can be seen from the figure that the cement slurry of PACG water gel containing 10% or 20% PEG contains a higher amount of CH than the cement of PACG water gel containing 0% PEG. According to the endothermic peak of 400-500 ° C in the DSC chart, the heat absorption (J/g), that is, the CH content, can be estimated for each gram of each cement slurry powder at different ages.

Please refer to FIG. 9 , which is a schematic diagram showing the effect of the PEG ratio in the PACG water gel of the present invention on the CH content in the cement slurry. As shown in Figure 9. The higher the heat absorption, the more the amount of CH contained in the cement slurry, and the higher the degree of cement hydration. Figure 9 shows that the amount of CH in the cement slurry first rises as the curing time increases, and then gradually becomes constant. With the higher proportion of PEG in the addition of PACG water gel, the amount of CH in the cement slurry increased first and then decreased, and the amount of CH in the cement slurry with 20% PEG added water gel was the largest. The reason is that PEG in the water gel will retain its moisture in the water gel by using its OH group. Therefore, adding an appropriate amount of PEG to the PACG water gel can slow the release of water from the water gel structure, and the water retention capacity of the water gel increases. Therefore, the amount of CH in the cement slurry increases, and the degree of cement hydration also increases. However, if PACG water gel containing 50% PEG is added to the cement slurry, the water retention capacity of the water gel will be reduced due to the excessive PEG content in the water gel structure, and the degree of cement hydration in the cement slurry will be reduced. Therefore, the novel PACG water gel of the present invention can increase the degree of cement hydration in the cement slurry if it contains an appropriate amount of PEG in its structure.

Therefore, the composite water gel-PACG of the present invention is applied to cement mortar In addition, the degree of hydration of the cement in the cement slurry can be increased; in addition, the addition of the PACG water gel of the present invention to the cementitious material such as cement slurry, cement mortar or concrete can reduce the material lifting due to the shrinkage. Durability; in addition, when the moisture in the cementitious material is lost, compared to the conventional "in-type" curing agent or self-curing agent such as TAISAP 283HA (polyacrylate) water gel (from Formosa Plastics Co., Ltd.), compound There is more water inside the water gel-PACG which can be released and replenished, so that the material can retain more water and higher humidity, and the material is less prone to dry cracks.

In addition, the present invention also discloses a method for preparing a composite water gel-PACG containing a semi-interpenetrating polymer network structure of polyethylene glycol, which comprises the following steps: taking Acrylamide, PCM and polyethylene. Alcohol (PEG), dissolved in deionized water, placed in a four-neck reactor (step 1); the reaction temperature is slowly increased, then an appropriate amount of the initiator is added dropwise, and the reaction is continued until the solution becomes a colloidal state ( Step 2); and purified by methanol, and the product is immersed in deionized water, and the water is changed periodically to remove unreacted monomers, and after several days, it is taken out and baked in an oven to obtain a solid water gel. PACG (step 3).

In the step 1, acrylamide, PCM and polyethylene glycol (PEG) are dissolved in deionized water and placed in a four-neck reactor; wherein the weight of the acrylamide is, for example, not Limited to 10 g, the weight of the PCM is, for example but not limited to, 10 g, the weight of the polyethylene glycol is, for example but not limited to, 1 g, and the molecular weight thereof is, for example but not limited to, 6000, and the amount of the deionization is, for example but not limited to, 200 mL.

In the step 2, the reaction temperature is gradually increased, and then an appropriate amount of the initiator is added dropwise, and the reaction is continued until the solution becomes a colloidal state; wherein the reaction temperature is, for example but not limited to, 75 ° C, the initiator is, for example, However, it is not limited to being ammonium persulfate and a crosslinking agent, N,N-methylenebisacrylamide, and the reaction time is, for example but not limited to, 1 hour.

In this step 3, it is purified by methanol, and the product is immersed in deionized water, and water is changed periodically to remove unreacted monomers, and taken after several days. After being baked in an oven, the solid water gel PACG can be obtained; wherein the water exchange time is, for example but not limited to, changing the water once every other day, and the take-out time is, for example, but not limited to, 3 days, and the temperature of the oven is, for example, Not limited to 55 ° C, the baking time is, for example but not limited to, 24 hours.

The disclosure of the present invention is a preferred embodiment. Any change or modification of the present invention originating from the technical idea of the present invention and being easily inferred by those skilled in the art will not deviate from the scope of patent rights of the present invention.

In summary, this case, regardless of its purpose, means and efficacy, is showing its technical characteristics that are different from the conventional ones, and its first invention is practical and practical, and it is also in compliance with the patent requirements of the invention. I will be granted a patent at an early date.

Claims (6)

A composite water gel-PACG containing a semi-interpenetrating polymer network structure of polyethylene glycol, which has the following formula: Wherein m, n, p, and q are integers of 10 to 1000, respectively. The composite water gel-PACG according to claim 1, wherein the PACG water gel is placed in the pore water solution of the cement slurry after absorbing the saturated water amount, and exhibits a phenomenon of first releasing water and then absorbing water. The composite water gel-PACG according to claim 1, wherein the PEG content is 0.1-50% by weight. The composite water gel-PACG according to claim 1, wherein the water weight loss of the mortar is reduced when the PACG water gel is added to the cement mortar, wherein the PACG water gel is added in an amount of 0.2 wt%. The composite water gel-PACG according to claim 1, wherein the compressive strength of the mortar is reduced when the PACG water gel is added to the cement mortar, wherein the PACG water gel is added in an amount of 0.2 wt%. The composite water gel-PACG according to claim 1, wherein the dry shrinkage of the mortar is reduced when the PACG water gel is added to the cement mortar, wherein the PACG water gel is added in an amount of 0.2 wt%.