CN114477939A

CN114477939A - Indoor moisture-proof gypsum building material with small humidity difference response and variable humidity adjusting range and preparation method thereof

Info

Publication number: CN114477939A
Application number: CN202111659832.0A
Authority: CN
Inventors: 杨自力; 林夕; 熊茜; 姜清文; 张唯怡; 陈禹竹
Original assignee: Donghua University
Current assignee: Donghua University
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2022-05-13
Anticipated expiration: 2041-12-30
Also published as: CN114477939B

Abstract

The invention relates to an indoor moisture-proof gypsum building material with small humidity difference response and variable humidity control range and a preparation method thereof. The gypsum building material comprises the following components in parts by mass: 90-120 parts of gypsum powder, 190-210 parts of water, 1-6 parts of a strengthening absorbent and 2-8 parts of white cement. The method comprises the following steps: slowly pouring the reinforced absorbent into water, stirring, slowly adding white cement, stirring, then slowly adding gypsum powder, stirring, pouring the obtained mixed slurry into a mould, drying, cooling, demoulding and maintaining. The gypsum building material can actively and quickly respond to moisture absorption under a small humidity difference, avoid stuffy feeling caused by accumulation of air moisture in a room and reduce the mildew risk; under the condition of corresponding same target moisture absorption amount, the consumption of the required humidity-adjusting building materials is greatly reduced, and the raw materials such as gypsum and the like are effectively saved.

Description

Indoor moisture-proof gypsum building material with small humidity difference response and variable humidity adjusting range and preparation method thereof

Technical Field

The invention belongs to the field of humidity-adjusting building materials and preparation thereof, and particularly relates to a humidity-adjusting gypsum building material with small humidity difference response and variable humidity adjusting range for indoor moisture prevention and a preparation method thereof.

Background

The air humidity has a decisive influence on the comfort of the personnel and the safety of the materials. Long-term high-humidity climates (the air humidity reaches more than 80%) such as plum rainy seasons lasting for months or rainy days in the south of China, such as the middle and lower reaches of Yangtze river and the pearl triangle areas, often appear in the south of China, not only can the comfort of indoor personnel be reduced, but also the indoor propagation of mold is easily stimulated, and the health of the personnel and the safety of materials are harmed.

The humidity adjustment can be generally classified into mechanical adjustment and non-mechanical adjustment. The mechanical regulation is mainly humidity regulation through a dehumidification (humidification) machine or an air conditioner, and although the mechanical regulation has the advantages of high efficiency and the like, the mechanical regulation has huge energy consumption and is contrary to the concept of carbon neutralization. The non-mechanical regulation mainly utilizes the humidity-regulating building materials to realize the indoor air humidity regulation, does not consume energy in the regulation process, is an environment-friendly humidity control regulation method, and has higher application value.

At present, indoor commonly used humidity-adjusting building materials such as gypsum boards and the like are low in price, easy to obtain in fire resistance and high in porosity, and have the capacity of adsorbing water molecules in air. However, only depending on the limited adsorption of the pores of the material to the humid air, the moisture absorption can be effectively driven under a large humidity difference, and the adsorption pores are easily saturated, the effective adsorption time is short, the adsorption amount is small, and the indoor moisture absorption requirement under long-term high-humidity climates such as plum rain season and the like cannot be met.

For this reason, researchers often improve the moisture conditioning ability by incorporating some additives into the building materials, and there are two main categories: inorganic porous materials such as diatomite, sepiolite, zeolite, vermiculite and allophane, and artificially synthesized organic polymers represented by polyacrylate [ Pengwei, preparation and performance research of ferric silicate salt humidity-regulating material [ D ]. Wuhan science and technology university, 2016 ]. Although the porosity of the building material is further increased by the porous additive, and the adsorption capacity of the gypsum building material is increased to a certain extent, the increase of the porosity to strengthen the adsorption process is limited, and the problem of overlarge water vapor transfer resistance between the pores of the building material and the wet air is still not solved, so that the moisture absorption of the gypsum building material can be effectively started only under the condition of obviously overhigh indoor humidity. Although the addition of organic polymers such as polyacrylate can improve the moisture absorption amount and the moisture absorption speed of the existing gypsum building material to a certain extent, the volume change is large after moisture absorption, the stable shape is difficult to maintain, and the organic polymers cannot be reliably applied to actual buildings.

As can be seen, the prior modified gypsum board has too single strengthening and humidity-controlling mechanism for increasing the porosity. There are still: the air humidity control method has the important problems of incapability of responding in time along with the change of air humidity, over-high and unadjustable starting moisture absorption critical value, uncontrollable moisture absorption and release range, easiness in adsorption saturation and the like in practical application.

Disclosure of Invention

The invention aims to solve the technical problem of providing an indoor moisture-proof gypsum building material with small humidity difference response and variable humidity-regulating range and a preparation method thereof, so as to overcome the defects of slow response, limited humidity-regulating capacity and uncontrollable starting humidity of the humidity-regulating building material in the prior art.

The invention provides a gypsum building material for indoor moisture resistance with small humidity difference response and variable humidity control range, which comprises the following components in parts by mass: 90-120 parts of gypsum powder, 190-210 parts of water, 1-6 parts of a strengthening absorbent and 2-8 parts of white cement; the reinforced absorbent contains Li⁺The inorganic salt of (2).

Preferably, in the gypsum building material, the gypsum building material components include, by mass: 100 parts of gypsum powder, 200 parts of water, 1-6 parts of a strengthening absorbent and 5 parts of white cement.

Preferably, in the gypsum building material, the content of Li⁺The inorganic salt of (a) is uniformly distributed in the gypsum matrix pore walls.

Preferably, in the gypsum building material, the content of Li⁺The inorganic salt of (2) is LiCl inorganic salt.

The invention also provides a preparation method of the indoor moisture-proof gypsum building material with small humidity difference response and variable humidity control range, which comprises the following steps:

slowly pouring the enhanced absorbent into water, stirring for the first time, slowly adding white cement, stirring for the second time, then slowly adding gypsum powder, stirring for the third time, pouring the obtained mixed slurry into a mould, drying, cooling, demoulding and maintaining to obtain the gypsum building material for indoor moisture protection.

Preferably, in the above preparation method, the first stirring is performed until the enhanced absorbent is completely dissolved.

Preferably, in the above preparation method, the second stirring is carried out until no particulate matter is apparent in the solution.

Preferably, in the preparation method, the third stirring speed is 1000-2000 rpm, and the stirring is carried out for 10-20 min.

Preferably, in the above preparation method, the pouring of the obtained mixed slurry into a mold requires controlling the slurry to be flush with the height of the mold; the drying is as follows: and transferring the mixture into an oven with the temperature of 35-45 ℃ for drying for 45-55 hours.

Preferably, in the preparation method, the curing is performed in a constant temperature and humidity box with the temperature of 20-25 ℃ and the RH of 45-55% for 20-30 hours.

The invention also provides application of the indoor moisture-proof gypsum building material with small humidity difference response and variable humidity-adjusting range in humidity-adjusting building materials.

The enhanced absorbent is uniformly distributed in the pore walls of the gypsum matrix, and forms a water molecule attraction effect similar to a magnetic force under the extremely strong hydrophilic attraction, so that water molecules are attracted to actively enter the porous space in the gypsum, a synergistic enhanced absorption process is realized on the basis of adsorption, and the moisture absorption rate is greatly improved. The trace addition of the strengthening absorbent can change the starting moisture absorption response level of the gypsum building material by changing the addition proportion range, and further realize the function of flexibly adjusting the humidity adjusting range according to the humidity requirements of different users.

The addition of the strengthening absorbent greatly reduces the water vapor transfer resistance between the gypsum building material and the wet air, realizes moisture absorption response under a small humidity difference, avoids the discomfort caused by the excessive increase of the humidity of indoor personnel, ensures that the indoor humidity is always less than the critical humidity required by the growth of the mold, and has the capability of preventing the growth of the mold.

The enhanced absorbent of the invention is due to Li⁺Has affinity to water molecules, can slowly release water vapor absorbed in the building material in a dry environment, has long moisture release time, and can effectively relieve moistureThe problem of over-dry indoor air in winter and long-term.

Advantageous effects

(1) Compared with the traditional gypsum building material taking the porosity as a strengthening means, the building material has the advantages that the LiCl with strong hydrophilicity can form a water molecule attraction effect similar to a magnetic force effect, water molecules in wet air are actively pulled to enter gypsum pores, the water vapor transfer resistance between the gypsum building material and the wet air is greatly reduced, the building material can actively and quickly respond to moisture absorption even under a small humidity difference (3%) when the indoor air humidity (such as 58%) is just higher than the human comfortable humidity (55%), the stuffiness caused by the accumulation of the air humidity in a room is avoided, and the mildew risk is reduced.

(2) The invention adjusts the moisture absorption rate of the gypsum building material by changing the proportion of the lithium chloride which is added in a trace amount, realizes the adjustment of the moisture absorption capacity of the gypsum building material according to different user humidity requirements, has quick response when the indoor air humidity changes, can start to absorb or release moisture in time, and realizes accurate moisture control.

(3) Compared with the conventional paper gypsum or the existing modified gypsum board, the moisture-adjusting building material consumption is greatly reduced under the condition of corresponding same target moisture absorption amount, the raw materials such as gypsum and the like are effectively saved, the estimated saving rate can reach 91%, and the moisture absorption process of the invention does not need to consume any energy and has excellent economy.

(4) The humidity regulation performance of the gypsum building material can be greatly improved, the problem of uneven humidity regulation in a large space can be solved by paving the gypsum building material, automatic uniform humidity regulation is realized, the indoor air humidity is stabilized in a human body comfort range of 40-55%, the problems of overlarge indoor humidity, mildewing and the like in long-term high-humidity climates such as plum rainy season, return to south and the like in south of China can be effectively solved, and the gypsum building material has great application value.

Drawings

In FIG. 1, A is a preparation method of the gypsum building material of the present invention, B is a microstructure of internal pores of the gypsum building material of the present invention (left) and a mechanism for enhancing moisture absorption and desorption properties (taking a moisture absorption process as an example, moisture desorption is reversed) (right), and C is a characteristic diagram of the gypsum building material of the present invention for indoor humidity adjustment, which is shown in the following drawingsWherein 1 is water; 2 is LiCl inorganic salt; 3 is gypsum powder; 4 is white cement; 5 is a gypsum matrix; 6 is a gypsum board pore structure; 7 is LiCl crystal; 8 is a water molecule; 9 is Cl^-Ions; 10 is Li⁺Ions; 11 is a hydrogen atom; 12 is an oxygen atom; 13 is a modified gypsum building material.

FIG. 2 is a graph of the moisture absorption at 58% ambient relative humidity for modified gypsum board with 1% addition in example 1, modified gypsum board with 6% addition in example 2, and pure gypsum board in example 3.

FIG. 3 is a graph showing the saturated moisture absorption curves of 1% addition of the modified gypsum board of example 1, 6% addition of the modified gypsum board of example 2, and pure gypsum board of example 3 at different ambient humidities.

FIG. 4 is a graph showing the performance of the modified gypsum board of example 2 with an amount of 6% added and the pure gypsum board of example 3 at an ambient relative humidity of 85. + -. 5% for an actual humidity control over 24 hours, wherein the gray areas are within the range of relative humidity for human comfort.

FIG. 5 is a diagram showing the moisture absorption rate and moisture absorption capacity of example 3 of the present invention at different ratios of lithium chloride added in a trace amount.

Fig. 6 is a partial enlarged view of the moisture absorption and desorption pattern (a) and the moisture absorption process (B) and the moisture desorption process (C) of the gypsum board of example 2 of the present invention with rapid response under the change of the humid air (75%) and the dry air (33%).

FIG. 7 is an SEM image of a pure gypsum board of example 3 of the invention (left) and a 6% modified gypsum board of example 2 (right).

FIG. 8 is a physical representation of a 1% lithium chloride modified gypsum board of example 1 of the present invention and a 8% lithium chloride modified gypsum board of comparative example 1.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The gypsum powder, white cement and lithium chloride required by the invention are all purchased from the market.

The moisture absorption dynamics curve of the gypsum board obtained by the test of the invention in figures 2 and 5 has the following specific experimental steps: 1) pretreatment: drying the gypsum board to constant weight at the temperature of 50-60 ℃, continuously weighing the gypsum board for 3 times at intervals of 24 hours, wherein the change of the mass difference is less than 0.1 percent, and determining that the sample reaches a completely dried state; 2) moisture absorption process: and (3) putting the pretreated composite gypsum board into constant-temperature and constant-humidity environments with the temperature of 23 ℃, 58 percent and the temperature of 23 ℃ and 85 percent respectively for absorbing moisture, recording the mass change rate of the sample every half hour, and continuously testing for 24 hours, wherein the test results are shown in fig. 2 and fig. 5. The obtained result can reflect the dynamic change rule of the moisture absorption capacity of the gypsum board of the invention in a wet environment along with the time, namely a moisture absorption dynamic curve.

The standard adopted by the test of the figure 3 of the invention is a static adsorption method recommended by ISO 12571-2013 for testing an isothermal moisture absorption curve (Section 7.2.3). The test procedure was as follows: the completely dried samples were placed in sequence under isothermal conditions (23 ℃) for wet exchange in a series of environments with increasing relative humidity (11%, 33%, 44%, 58%, 75%, 85%, 95%) and the sample mass was recorded every 24h until the point of moisture absorption equilibrium was reached (the difference in mass was less than 0.1% for 3 consecutive 24h measurements, i.e. the samples were considered to be in wet equilibrium).

The test of FIG. 6 (wet buffered MBV value of gypsum board) according to the invention was carried out using the International standardized dynamic test method proposed by NORDTEST (ISSN 1601-2917, Nordisk Innovationcenter, Denmark university of science). The test procedure was as follows: and (3) taking 24h as a test period, placing the composite gypsum board in a constant temperature and humidity box with indoor relative humidity step-cycle change, recording the mass change of the sample by an electronic balance every 30min, and measuring the wet migration volume of the sample on a unit contact area. The relative humidity of the high-humidity environment and the low-humidity environment is respectively set to be 75% and 33%, the duration time is respectively 8h and 16h, the sample absorbs moisture in the high-humidity environment, the low-humidity environment releases moisture, the test is continued for 7 periods, and the wet buffer value of the gypsum board, of which the mass change reflects the moisture absorption/moisture release response process, is obtained through weighing by a precision balance.

The test method of the invention shown in the figure 4 is that a common 2-3-person office volume 3.8 x 2.3 x 2.5(m) is taken as a prototype, and two simulation experiment rooms are built by reducing the ratio by 10 times, wherein the numbers are 1 and 2. The example 2 of integrally laying the top of the No. 1 simulation room is a suspended ceiling, the example 2 of integrally laying a pure gypsum board (the gypsum board without adding lithium chloride in the example 3) on the top of the No. 2 simulation room is a suspended ceiling of the room, the parameters of other installation materials, sealing means, the laying area of the gypsum board and the like of the two rooms are completely the same, and the gypsum board reaches a wet balance state in a low-humidity artificial climate room (the No. 1 climate room, air conditions before the beginning of a simulated plum rainy season, hereinafter called a low-humidity environment) with RH50 +/-5% and 27 +/-2 ℃ before laying; after the air humiture in the room to be simulated is stable in the low-humidity environment after being laid, the two rooms balanced in the low-humidity environment are quickly moved to an RH85 +/-5% high-humidity artificial climate chamber (a No. 2 climate chamber, temporary air conditions from simulated plum rain season are called high-humidity environment hereinafter) at 27 +/-2 ℃, the humiture in the room to be simulated is monitored in real time through a humiture sensor, the time when the 2 rooms to be simulated enter the high-humidity environment is taken as a starting point, a counting point is taken every 30 minutes for continuous detection for 24 hours, and the humidity conditioning capacity and the indoor air humidity change condition of the gypsum board (the gypsum board without lithium chloride in the embodiment 3) laid in the room in the practical high-humidity climate such as the plum rain season are evaluated.

Example 1

The embodiment provides a gypsum building material for indoor moisture protection, which comprises the following components in parts by mass: 100 parts of gypsum powder, 200 parts of water, 1 part of lithium chloride and 5 parts of white cement.

The embodiment also provides a preparation method of the indoor moisture-proof gypsum building material, which comprises the following steps:

(1) weighing water and LiCl inorganic salt according to the mass parts, slowly adding lithium chloride into a beaker filled with water, and stirring by using a glass rod until LiCl is completely dissolved in the water;

(2) weighing the white cement according to the mass parts, slowly adding the white cement into a beaker containing LiCl solution, and stirring by using a glass rod until no obvious granular substances exist in the solution;

(3) pouring the obtained mixed solution into a mixing container, uniformly stirring, weighing gypsum powder according to the mass parts, slowly adding the gypsum powder into the mixing container, pouring while stirring until the gypsum powder is uniformly mixed to obtain mixed slurry, starting a stirrer, setting the rotating speed to be 1500r/min, and stirring for 15min to obtain uniformly mixed slurry;

(4) injecting the obtained slurry into a mold, controlling the height of the slurry to be flush with the height of the mold, transferring the slurry into a drying oven with the temperature of 40 ℃ for drying for 48 hours, cooling and demolding to obtain a dried gypsum building material prototype; and then placing the materials into a constant temperature and humidity environment with the temperature of 23 ℃ and the RH of 50 percent for curing for 24 hours to obtain the gypsum building material for indoor moisture protection.

The concrete method for applying the gypsum building material for indoor moisture prevention in the embodiment comprises the following steps:

(1) after measuring the room area, selecting the modified gypsum board with the thickness of 10mm obtained in the embodiment according to the room area;

(2) fixing the gypsum board on the ceiling keel by using air gun nails and wood screws, and then performing batch ashing treatment;

(3) and after the surface layer putty powder is dried, coating latex paint.

As shown in FIG. 2, the moisture absorption rate of the present example was 0.911 (h) within 12 hours at an ambient humidity of 58%^-1) And the gypsum board is improved by 900 percent compared with a pure gypsum board (the gypsum board without adding lithium chloride in example 3). As shown in figure 3, under the environment of small humidity difference (which is compared with 40% -55% of human body comfort interval), the saturated moisture absorption amount per unit mass of the suspended ceiling structure is increased by 820% compared with that of a pure gypsum board, and is 0.0123 (kg/kg). Under the condition that the moisture absorption amount is 1g, the required mass of the gypsum board is 81 g, the pure gypsum board needs 622g, the raw material saving rate is up to 87.7%, the indoor laying amount of the gypsum building material can be reduced, and the consumption of materials such as gypsum, lime and the like is greatly reduced.

Example 2

The difference from example 1 was that the amount of lithium chloride was changed to 6 parts by mass, and the remainder was the same as in example 1, thereby obtaining a gypsum building material for indoor moisture resistance. The obtained gypsum board has good structure.

Detected as shown in FIG. 2, in the ringAt an ambient humidity of 58%, the moisture absorption rate of the present example was 1.624 (h) in 12 hours^-1) And the lifting force is 17 times higher than that of the conventional gypsum board. As shown in figure 3, under the condition of small humidity difference, the saturated moisture absorption capacity per unit mass of the suspended ceiling structure is increased 49 times than that of pure gypsum board, and is 0.0735 (kg/kg). Under the condition that the moisture absorption amount is 1g, the mass required by the embodiment is 13.61g, the pure gypsum board (the gypsum board without adding lithium chloride in the embodiment 3) needs 662g, and the raw material saving rate is as high as 97.9%. As shown in fig. 4, the practical application effect of this example is that the present embodiment can maintain the indoor humidity within a comfortable range (RH40 to 55%) under the high humidity outdoor environment.

FIG. 1 shows that: the invention adds a trace amount of LiCl powder in the initial preparation of the gypsum board, so that the LiCl powder is well and uniformly embedded and wrapped in the gypsum matrix in the subsequent hydration and hardening processes of the gypsum board to become a dense and inseparable organic part of the gypsum body, LiCl cells and CaSO in the gypsum board₄The structures are organically embedded, a new coupling effect structure is formed (please see microcosmic photographs shot by a scanning electron microscope in fig. 1 and fig. 7), so that under the condition of micro addition, the similar magnetic attraction effect is formed on the inner core of the gypsum matrix, the affinity of the gypsum board body to water vapor is improved, and the effective humidity conditioning capability of the gypsum board body is strengthened. This is simply not possible by mechanically bonding LiCl to the gypsum board. In addition, the simple substance LiCl is very soluble in water, and if LiCl is mechanically combined with gypsum (such as direct surface action), a trace amount of LiCl can be quickly dissolved and lost, the reinforcing significance is lost, and a new pore form cannot be formed at the same time. These are all technical difficulties effectively overcome by the present invention. In the invention, the trace LiCl and the gypsum are organically combined into a new coupling effect structure, the moisture absorption capacity of the gypsum matrix is enhanced by enabling the gypsum matrix to generate a similar magnetic absorption effect, and the LiCl is not used for directly absorbing moisture; more importantly, LiCl which is embedded and fused into a gypsum matrix to form a structure is not contacted with humid air, and the process is completely different from the process of preparing a high-concentration (32-40%) LiCl aqueous solution in the existing solution dehumidifying air-conditioning system and directly contacting the humid air after spraying. Is a brand newA new mechanism for strengthening the humidity-adjusting capability of the gypsum building material.

In fig. 1, C shows that, in humid air, the gypsum building material starts a moisture absorption mode, and the moisture absorption mode is characterized in that: starting with small humidity difference; actively and quickly responding; lasting moisture absorption, strong moisture absorption force and adjustable balance humidity; the gypsum building material starts a dehumidification mode under dry air, and the dehumidification mode is characterized in that: firstly, moisture is released for a long time; ② uniform humidity adjustment in large space.

FIG. 6 shows that: the modified gypsum board has quick response of moisture absorption and moisture release when the conditions such as humid air (75%), dry air (33%) and the like change; the gypsum board of the present invention absorbs moisture (desorbs moisture) in a rapid response from high (low) to low (high) in about 1 minute; the method specifically comprises the following steps: when the indoor humidity is increased from low humidity of 33 percent to high humidity of 75 percent, the gypsum board of the invention almost instantaneously responds to moisture absorption; likewise, within about 1 minute of room air becoming dry (33%) from wet (75%), the gypsum board of the present invention begins to respond by dewing to alleviate the air drying problem. Meanwhile, the quick response moisture absorption/desorption circulation process also enables the gypsum building material to regenerate stronger moisture absorption/desorption capacity. In conclusion, when the air humidity is increased, the gypsum board provided by the invention almost has no delayed response to absorb moisture, and the mass is increased; when the air humidity is reduced, the gypsum board of the invention has rapid moisture release response and reduced mass.

FIG. 7 shows that: the pure gypsum board without the lithium chloride has a random, messy and compact structure, while the gypsum board modified by 6% of lithium chloride in the embodiment has an organic fusion and forms a new regular and ordered layered microstructure.

The invention is particularly suitable for areas with bright long-term high-humidity climatic features, such as the triangular area of the Yangtze river with a plum rainy season or the triangular area of the pearl with a backsouth day:

in humid hot climates, the main energy consumption of the air conditioning system is used to handle the humid load. According to the invention, the LiCl inorganic salt with strong hydrophilicity is added in a trace amount, so that the integral attraction of the microporous structure of the gypsum building material to water molecules is strengthened, the humidity-adjusting response under a small humidity difference is realized, the humidity-adjusting capacity of the traditional gypsum building material is improved, the humidity-adjusting target range is controllable, the indoor humidity load is greatly reduced, and the energy consumption of an air-conditioning system is effectively reduced.

When the humid and hot climate changes into a partially dry climate along with the change of seasons, under the condition of large humidity difference formed between the interior and the exterior of the gypsum building material, the pressure difference of water vapor between the indoor dry air and the developed gypsum building material is larger than the affinity of LiCl inorganic salt to water molecules, and the invention can orderly release the water molecules stored in the pore structure and relieve the problem of over-dry indoor air in the dry season (as shown in figure 6). Meanwhile, with the release of water molecules, the water stored in the internal pores is reduced, so that the potential can be provided for moisture absorption in the next rainy season, and the effect of regeneration and recycling is realized.

In conclusion, by implementing the invention, the purposes of improving indoor wet comfort, preventing mildew and saving building energy can be realized in the regions with longer high-humidity climates such as plum rainy season, south China and the like, and the invention has great popularization and application values.

Example 3

The gypsum building material additive component lithium chloride in parts by mass was 0, 1 part, 2 parts, 4 parts and 6 parts, and the remainder was the same as in example 1, to obtain a gypsum building material. The obtained gypsum board (1 percent of lithium chloride is modified, 2 percent of lithium chloride is modified, 4 percent of lithium chloride is modified, and 6 percent of lithium chloride is modified) has a good structure. The application method of the gypsum building material was the same as in example 1.

FIG. 5 shows that: the moisture absorption capacity (speed) of the gypsum board is changed remarkably under different micro-adding proportions, the moisture absorption capacity is very sensitive to the adding amount of lithium chloride, the moisture absorption capacity is remarkably increased along with the increase of the adding amount, therefore, the moisture absorption speed of the gypsum building material is adjusted by changing the proportion of the micro-added lithium chloride, the moisture absorption capacity of the gypsum building material can be adjusted according to different user humidity requirements, the response is rapid when the indoor air humidity changes, moisture absorption or moisture release can be started in time, and accurate moisture control is realized. It was determined that pure gypsum board (gypsum board of example 3 without lithium chloride) had a moisture absorption rate of 0.097 (h) within 12 hours at an ambient humidity of 58% (h) as shown in FIG. 2^-1). The required mass of the pure gypsum board is 662g under the condition that the moisture absorption amount is 1 g. As shown in FIG. 3, the humidity at the above-mentioned ambient humidity of 58% and the comfort requirement humidityAnd under the environment with small humidity difference of 55%, the saturated moisture absorption capacity per unit mass of the suspended ceiling structure is 0.00151 (kg/kg). The practical application effect of the pure gypsum board is shown in fig. 4, and the pure gypsum board breaks through the upper limit of human body humidity comfort (RH 60%) within 8 hours under the condition of outdoor environment high humidity.

Comparative example 1

The difference from example 1 is that a gypsum building material for indoor moisture resistance was obtained in the same manner as in example 1 except that the amount of lithium chloride was changed to 8 parts by mass.

FIG. 8 shows that: the large amount of lithium chloride can not maintain the pore structure, which is mainly because when the amount of lithium chloride is too large, the lithium chloride is easily exposed on the surface of the pore structure of the plate body directly, the water absorption amount is larger than the pore volume of the pores, and the solution seepage phenomenon occurs, so that the pore structure and the form of the gypsum plate are damaged, the plate structure is unstable or even damaged, and therefore, the amount of lithium chloride added is less than 8%.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. The gypsum building material for indoor moisture protection with small humidity difference response and variable humidity control range is characterized by comprising the following components in parts by mass: 90-120 parts of gypsum powder, 190-210 parts of water, 1-6 parts of a strengthening absorbent and 2-8 parts of white cement; the reinforced absorbent contains Li⁺The inorganic salt of (1).

2. The gypsum building material of claim 1, wherein the gypsum building material components comprise, in parts by mass: 100 parts of gypsum powder, 200 parts of water, 1-6 parts of a strengthening absorbent and 5 parts of white cement.

3. The gypsum building material according to claim 1 or 2, wherein the Li-containing material⁺The inorganic salt of (a) is uniformly distributed in the gypsum matrix pore walls.

4. The gypsum building material according to claim 1 or 2, wherein the Li-containing material⁺The inorganic salt of (2) is LiCl inorganic salt.

5. A process for preparing the gypsum building material of claim 1 or 2, comprising the steps of:

6. The preparation method according to claim 5, wherein the third stirring speed is 1000-2000 rpm, and the stirring is performed for 10-20 min.

7. The method for preparing a composite material according to claim 5, wherein the pouring of the resulting mixed slurry into a mold requires controlling the slurry to be flush with the height of the mold; the drying is as follows: and transferring the mixture into an oven with the temperature of 35-45 ℃ for drying for 45-55 hours.

8. The method according to claim 5, wherein the curing is performed in a constant temperature and humidity chamber at 20 to 25 ℃ and 45 to 55% RH for 20 to 30 hours.

9. Use of a gypsum building material according to claim 1 or 2 for conditioning a building material.