CN105758761A - Method for determining content of type III anhydrous gypsum in building gypsum - Google Patents
Method for determining content of type III anhydrous gypsum in building gypsum Download PDFInfo
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Abstract
The invention provides a method for determining the content of type III anhydrous gypsum in building gypsum. The method comprises the following steps: placing a building gypsum powder sample in a moist environment for moisture absorption, thereby obtaining building gypsum powder after moisture absorption; drying the building gypsum powder after moisture absorption to constant weight to obtain weight gained building gypsum powder; and finally, calculating the mass of the weight gained building gypsum powder and the mass of the building gypsum powder sample, thereby obtaining the content of the type III anhydrous gypsum in the building gypsum powder sample. According to the method, the mass fraction of the type III anhydrous gypsum in the sample can be relatively quickly detected; the detection time is short; data is accurate; the operation is simple, safe and reliable; no chemical reagent is introduced; and the detected sample can be used again and no environment pollution is generated.
Description
Technical field
The invention belongs to construction material analysis technical field, particularly relate to the assay method of type III anhydrous gypsum content in a kind of plaster of Paris.
Background technology
Along with improving constantly and urbanization of people's quality of life, the demand of building house is also day by day soaring, the demand of construction material is also increasing, accordingly that the requirement of quality is also increasingly strict, especially indoor building material, this wherein plaster of Paris be the construction material of large usage quantity.
Plaster of Paris (beta-type semi-hydrated gypsum or common gypsum powder), with β semi-hydrated gypsum CaSO4·1/2H2O is main component.It is mainly used in indoor plastering and whitewashes, preparing plasterboard, gypsum block and ornament materials etc..As plaster of Paris is added water, sand and retarder mix become gypsum mortar, for indoor plastering with whitewash.Smooth surface after plastering, exquisiteness, pure white attractive in appearance, gypsum mortar can also as the prime coat of paint etc., and can direct brushing paint or paste wall paper or wallpaper etc..Plaster of Paris adds water and retarder mix becomes gypsum slurry, is alternatively arranged as interior painting coating.By natural dihydrate gypsum, its chemical formula is CaSO4.2H2O, calcining can obtain different Gypsum Fibrosum kinds at different temperature.Plaster of Paris can be obtained as heated under the drying condition of 107～170 DEG C by natural dihydrate gypsum.
Type III anhydrous gypsum in building gypsum plaster is too much the major reason causing plastering gupsum quality problems.Type III anhydrous gypsum, also known as anhydrous gypsum III or soluble anhydrite, the consumptive use of water normal consistence that too much can cause plaster of Paris is unstable, setting time unstable, intensity reduces, the Gypsum Fibrosum simultaneously using type III anhydrous gypsum too much does plastering gupsum can cause that plastering gupsum instability setting time, cracking, intensity are low, causes accident resulting from poor quality of projects.Waiting mention at " desulphurization building gypsum three-phase separate analysis method research and application " as talked dawn green grass or young crops, type III anhydrous gypsum causes powder body consumptive use of water normal consistence to increase, intensity reduces, setting time is unstable.Thus, control type III anhydrous gypsum content in building gypsum plaster and be to ensure that the key of plastering gupsum quality.But the producer of domestic production Gypsum Fibrosum is often in order to improve production efficiency at present, make calcining heat higher, and then type III anhydrous gypsum content is more in the Gypsum Fibrosum powder obtained, and ignore the adverse effect that type III anhydrous gypsum content too much brings, the phenomenon ubiquity of Gypsum Fibrosum powder burning occurs, brings very burden to the producer using Gypsum Fibrosum powder below or operation.So, type III anhydrous gypsum content height in domestic plaster of Paris has become a key issue of plaster of Paris quality problems, the main cause of the construction market plastering gupsum quality fluctuation also building gypsum plasters being because the high type III anhydrous gypsum of use content cause more, it can cause plastering gupsum instability setting time, water requirement difference is big, backfin strength fluctuation is big, the common quality defects such as cracking, hollowing occur after upper wall.Therefore, in order to solve these quality problems, it is necessary to type III anhydrous gypsum content in strict control plastering gupsum.
Type III anhydrous gypsum content in plaster of Paris is controlled, what we first had to do carries out quantitative test and assessment to type III anhydrous gypsum content exactly, detecting at present in the method for type III anhydrous gypsum uses ethanol method to be accepted by many people, but this method requires time for long, and alcohol in high concentration is inflammable and explosive, adding potential safety hazard, the sample after test is reunited, and is unfavorable for that sample is recycled；And use other detection method such as differential thermal analysis, the expensive equipment that halogen detection method etc. needs, although the detection time is short but general medium-sized and small enterprises are difficult to afford so expensive experimental facilities, and complicated operation is high to personnel qualifications.
Therefore, how to obtain the assay method of type III anhydrous gypsum content in a kind of plaster of Paris, quick and easy and simple to handle and easy to spread, it has also become in industry, to have producer's problem demanding prompt solution of prediction consciousness.
Summary of the invention
In view of this, the technical problem to be solved in the present invention is in that to provide the assay method of type III anhydrous gypsum content in plaster of Paris, method of testing provided by the invention compares traditional method of testing, quick, easy and simple to handle, easy to spread, and has good stability and repeatability.
The invention provides the assay method of type III anhydrous gypsum content in a kind of plaster of Paris, comprise the following steps:
A) under humid conditions, after building gypsum plaster sample is placed moisture absorption, the building gypsum plaster after moisture absorption is obtained；
B) building gypsum plaster after moisture absorption above-mentioned steps obtained is dried to constant weight, obtains the building gypsum plaster of weightening finish；
C) quality of the building gypsum plaster of weightening finish above-mentioned steps obtained and the quality of described building gypsum plaster sample are after calculating, and obtain the content of type III anhydrous gypsum in building gypsum plaster sample.
Preferably, the condition of described humidity is constant humidity.
Preferably, the humidity of the condition of described humidity is 80%～100%.
Preferably, the time of described moisture absorption is 25～120 minutes.
Preferably, the temperature of described drying is 40～55 DEG C.
Preferably, the fineness of described building gypsum plaster sample is less than or equal to 80 orders.
Preferably, described placement is specially tiling in the plane.
Preferably, the overlay thickness of described tiling is 1～5mm.
Preferably, the method for described calculating is, the quality of described building gypsum plaster sample is m1, the quality of the building gypsum plaster of described weightening finish is m2, the quality of the moisture of described building gypsum plaster sample moisture absorption is m；
Described m=m2-m1；
Described content is mass content, and in described building gypsum plaster sample, the mass content of type III anhydrous gypsum is w；
Described w=(15.11*m/m1) * 100%.
The invention provides the assay method of type III anhydrous gypsum content in a kind of plaster of Paris, comprise the following steps: first under humid conditions, after building gypsum plaster sample is placed moisture absorption, obtain the building gypsum plaster after moisture absorption；Then the building gypsum plaster after moisture absorption above-mentioned steps obtained is dried to constant weight, obtains the building gypsum plaster of weightening finish；The quality of the quality of the building gypsum plaster of the weightening finish finally above-mentioned steps obtained and described building gypsum plaster sample, after calculating, obtains the content of type III anhydrous gypsum in building gypsum plaster sample.Compared with prior art, the present invention utilizes type III anhydrous gypsum to have very strong hygroscopicity, semi-hydrated gypsum can be rapidly converted under high humidity conditions, and semi-hydrated gypsum changes into when dihydrate gypsum needs the moisture content in powder to reach certain ratio and just can occur, and response speed generates slow many of semi-hydrated gypsum than type III anhydrous gypsum, can faster detect type III anhydrous gypsum mass fraction in the sample, no matter it is produce or use the producer of Gypsum Fibrosum powder can well control the quality of building gypsum plaster, improve the quality of product, and do not quote any chemical reagent；Compare ethanol method, differential thermal analysis or halogen detection method etc., the present invention difference according to type III anhydrous gypsum and the hydration characteristics of β semi-hydrated gypsum, use high humidity environment aging method, detection the used time is short, data are accurate, simple to operate, safe and reliable, detection after sample can be continuing with, environmentally safe.Test result indicate that, the test result of assay method provided by the invention is consistent with the alcohol-pickled Oven Method test result in GB/T " plaster of Paris crystal species analysis method " standard, and the testing time shortened to from about 240 minutes less than 100 minutes, it is greatly shortened the detection time, improve work efficiency, accelerate the speed of the inspection of material, evaluation and site acceptance.
Detailed description of the invention
In order to further appreciate that the present invention, below in conjunction with embodiment, the preferred embodiments of the invention are described, but it is to be understood that these describe simply as to further illustrate the features and advantages of the present invention rather than the restriction to patent requirements of the present invention.
The all raw materials of the present invention, be not particularly limited its source, that commercially buy or prepare according to conventional method well known to those skilled in the art.
The all raw materials of the present invention, are not particularly limited its purity, present invention preferably employs analytical pure.
The invention provides the assay method of type III anhydrous gypsum content in a kind of plaster of Paris, comprise the following steps:
A) under humid conditions, after building gypsum plaster sample is placed moisture absorption, the building gypsum plaster after moisture absorption is obtained；
B) building gypsum plaster after moisture absorption above-mentioned steps obtained is dried to constant weight, obtains the building gypsum plaster of weightening finish；
C) quality of the building gypsum plaster of weightening finish above-mentioned steps obtained and the quality of described building gypsum plaster sample are after calculating, and obtain the content of type III anhydrous gypsum in building gypsum plaster sample.
Described building gypsum plaster sample is not particularly limited by the present invention, and with plaster of Paris well known to those skilled in the art, i.e. beta-type semi-hydrated gypsum or common gypsum powder, with β semi-hydrated gypsum CaSO4·1/2H2O is main component, by dihydrate gypsum (CaSO4·2H2O) obtain after heating under the drying condition of 107～170 DEG C.Described building gypsum plaster sample is not had other to limit especially by the present invention, those skilled in the art can be adjusted according to actually detected situation or testing requirement and select, the fineness of building gypsum plaster sample of the present invention is preferably smaller than equal to 80 orders, it is more preferably less than or equal to 85 orders, it is most preferred that 80～90 orders.Described type III anhydrous gypsum is not particularly limited by the present invention, with type III anhydrous gypsum well known to those skilled in the art, i.e. and anhydrous gypsum III or soluble anhydrite.
The present invention first under humid conditions, after building gypsum plaster sample is placed moisture absorption, obtains the building gypsum plaster after moisture absorption；The condition of described humidity is not particularly limited by the present invention, with well known to those skilled in the art for detect moist when, humidity when humidity of the present invention is preferably constant humidity, it is more preferably 80%～100%, it is more preferably 85%～99%, it is more preferably 90%～98%, it is most preferred that be 90%～97%.The condition of described humidity is not had other specifically to limit by the present invention, and those skilled in the art can be adjusted according to actually detected situation, amount of samples or testing requirement and select.
The mode of described placement is not particularly limited by the present invention, those skilled in the art can be adjusted according to actually detected situation, amount of samples or testing requirement and select, the present invention is for enabling the uniformly moisture absorption of building gypsum plaster sample, described placement is particularly preferred as tiling in the plane, more preferably it is laid on surface plate, it is most preferred that be laid on surface plate for loose；The thickness of described loose tiling is not particularly limited by the present invention, those skilled in the art can be adjusted according to actually detected situation, amount of samples or testing requirement and select, and the present invention is preferably 1～5mm, more preferably 1.5～4.5mm, it is more preferably 2～4mm, it is most preferred that be 2.5～3.5mm.The present invention time to described placement, namely the time of moisture absorption is not particularly limited, the condition of described humidity is not had other specifically to limit by the present invention, those skilled in the art can be adjusted according to actually detected situation, amount of samples or testing requirement and select, the present invention is preferably 25～120 minutes, it is more preferably 30～100 minutes, more preferably 40～80 minutes, it is most preferred that be 50～70 minutes.
The present invention to above-mentioned obtain moisture absorption after the concrete steps of building gypsum plaster do not have other to limit especially, those skilled in the art can be adjusted according to actually detected situation, amount of samples or testing requirement and select, the present invention is for ease of detection, save cost and improve practicality, being particularly preferred as:
1, take plastic seal box with cover, in box, load the deep water of about 5cm；
2, cushion block is put in water, and cushion block exceeds the water surface 2～4cm, places one piece of shelf on cushion block；
3, drimeter is put into above shelf, covers lid and seal in placement laboratory；
4, when drimeter shows more than 80%, it is possible to start experiment；
5, building gypsum plaster sample m is weighed1, then pave a thin layer by sample on surface plate, and sample, less than 5mm, is put into above the shelf of high humidity container rapidly by paving thickness together with surface plate, and seals high humidity container immediately.
6, sample seals in container at high humidity and preserves 30～120 minutes.
The present invention adopts above-mentioned simple device to combine, it is provided that the environment of a stable constant humidity, and namely high humidity seals container, first in hermetic container, naturally the volatilization of water can make the humidity of closed environment arrive more than 80%, depresses the decision water content of air according to certain saturated vapor
dV=(Pb/ 760) × (1000/22.4) × (273) ÷ (273+t) × 18,
Wherein, dVFor every m during steam-laden under different temperatures3The water content (g) of gas；PbIt is temperature (DEG C) for water saturation vapour pressure (mm, Hg), t under different temperatures；
25 DEG C of saturation of the air saturated vapour pressures (mm, Hg), Pb=23.75, calculate dV=23.01 (g/m3),
If temperature is 20 DEG C～25 DEG C, during humidity change 90%～100%, the aqueous concentration of air is 0.015～0.023g/L.
And building gypsum plaster sample is when loose thin stand, gas is easy to be diffused into powder particles surface, theory of Brownian motion according to molecule, hydrone in air also can be diffused into Gypsum Fibrosum powder surface, and can this react with it, in whole process, type III anhydrous gypsum activity is high again, there is significantly high hygroscopicity, hydrone in air is easy to be adsorbed by type III anhydrous gypsum and carry out phase in version occurs, seal steam in container to be consumed, can be supplemented from the water of container again, concentration to ensure air water molecule maintains a stable value, inversion of phases is allowed to be performed continuously over, humidity can become semi-hydrated gypsum by rapid translating more than type III anhydrous gypsum under the environment of 80%, reactive chemistry equation is 2CaSO4+H2O=2CaSO4·1/2H2O, comparing traditional ethanol method, the water concentration in alcohol liquid is about 40g/L, and the water concentration in high wet method is 0.023g/L to the maximum, it is only the 0.5% of ethanol method, thus does not more have semi-hydrated gypsum and be converted into dihydrate gypsum and only have type III anhydrous gypsum can be converted into semi-hydrated gypsum.More importantly, above-mentioned steps provided by the invention, namely the Gypsum Fibrosum of high humility ageing is compared with alcohol-pickled Gypsum Fibrosum, and in Gypsum Fibrosum powder, liquid phase is lower so that follow-up drying time is shorter.
Building gypsum plaster after the moisture absorption that then above-mentioned steps is obtained by the present invention is dried to constant weight, obtains the building gypsum plaster of weightening finish.The temperature of described drying is not particularly limited by the present invention, and with drying temperature well known to those skilled in the art, the temperature of drying of the present invention is preferably 40～55 DEG C, more preferably 43～52 DEG C, more preferably 45～50 DEG C, it is most preferred that be 46～49 DEG C.The equipment of described drying is not particularly limited by the present invention, and with drying plant well known to those skilled in the art, the present invention is preferably baking oven；Other conditions of described drying are not particularly limited by the present invention, and those skilled in the art can be adjusted according to actually detected situation, amount of samples or testing requirement and select.
The quality of the quality of the building gypsum plaster of the weightening finish that above-mentioned steps is obtained by the present invention and described building gypsum plaster sample, after calculating, obtains the content of type III anhydrous gypsum in building gypsum plaster sample.
Content of the present invention is preferably mass content；Described calculation procedure is not particularly limited by the present invention, and with conventional Calculation Method well known to those skilled in the art, circular of the present invention is preferably, and the quality of described building gypsum plaster sample can set that as m1, the quality of the building gypsum plaster of described weightening finish can set that as m2, the quality of the moisture of described building gypsum plaster sample moisture absorption can set that into m, in described building gypsum plaster sample, the mass content of type III anhydrous gypsum is set as w；
Thus, described m=m2-m1,
Described w=(15.11*m/m1) * 100%, wherein 15.11 ≈ MCaSO4/0.5MH2O。
If when m≤0, it was shown that without type III anhydrous gypsum in sample, containing absorption water.
The present invention finally takes out sample and is moved into immediately drying in oven to constant weight from high humidity container, dry to constant weight, the content of type III anhydrous gypsum in plaster of Paris is obtained then through after calculating, the present invention adopts the method for high humidity promoting ageing can detect type III anhydrous gypsum content in plaster of Paris quickly and easily, this method need not buy the equipment of costliness and any test reagent, only need balance, baking oven, hermetic containers etc. just can quickly detect the content of type III anhydrous gypsum, the test result of the ethanol method in experimental result and GB " plaster of Paris crystal species analysis method " paper for approval has significantly high concordance, but the time used by experiment overall process significantly shortens than the ethanol method in GB " plaster of Paris crystal species analysis method " paper for approval.The method not only operability is also very strong, and the manufacturing enterprise of plaster of Paris raw material and plastering gupsum can be helped more simply and effectively to control product quality.The present invention adopts that equipment is simple, simple operation, and detection data are accurate, in detection process in addition to water need not other reagent, the product of detection can be recycled, and is truly realized the zero-emission to environment.
The practical significance of the present invention is in that, type III anhydrous gypsum content height in domestic plaster of Paris has become a key issue of plaster of Paris quality problems, but at present the content of semi-hydrated gypsum is only carried out requirement by plaster of Paris GB/T9776-2008 " plaster of Paris " 9776-2008, the content of type III anhydrous gypsum is not had requirement, and this is also the factor that a lot of building gypsum plaster enterprise thinks little of type III anhydrous gypsum content.Can change into β semi-hydrated gypsum in atmosphere because of type III anhydrous gypsum, people only focus on final product, and ignore the adverse effect brought in product with type III anhydrous plaster powder.Also without the quantitative analysis method being specifically designed for type III anhydrous gypsum in GB/T5484-2012 " chemical analysis of gypsum method ".Disappearance due to relevant criterion, although the type III anhydrous gypsum that a lot of enterprises both know about in plaster of Paris should control, but owing to not having method of testing and evaluation criterion, in actual production process, type III anhydrous gypsum is not controlled by building gypsum plaster manufacturing enterprise.Along with industrialized process is more and more faster, the Gypsum Fibrosum powder produced quickly can transport manufacturer by tank car, and mostly manufacturer is also equipped with storage tank, so the type III anhydrous gypsum in Gypsum Fibrosum powder be just more difficult to air contact and be transformed into semi-hydrated gypsum.Also all having better seal plus the product packaging produced, the type III anhydrous gypsum more made naturally is transformed into semi-hydrated gypsum and becomes difficulty, has increased the weight of the impact on quality of the type III anhydrous gypsum.Wuhan University of Technology Yang Xin Asia professor in 2012 organizes related scientific research institutes and Gypsum Fibrosum raw material, finished product enterprise to formulate the national standard of " plaster of Paris crystal species analysis method ", and carried out declaration the end of the year in 2014, type III anhydrous gypsum method of testing there is detailed regulation by this standard, such as ethanol method, although experimental result repeatability is better, but owing to the testing time is longer, actual production carries out quality control difficulties.
But land plaster producer is very important by the type III anhydrous gypsum content in detection Gypsum Fibrosum powder, can be adjusted according to the temperature of how many pairs of calcinings of type III anhydrous gypsum content and calcination time, make production technology more reasonable, be conducive to improving product quality, can be controlled according to how many pairs of Gypsum Fibrosum powder digestion times of type III anhydrous gypsum content simultaneously, improve product deficiency, Gypsum Fibrosum powder quality can be controlled by plastering gupsum producer by type III anhydrous gypsum content in Gypsum Fibrosum powder, and use high humidity ageing method provided by the invention can quickly detect type III anhydrous gypsum content, judge that whether the quality of Gypsum Fibrosum powder is qualified in time, more rapidly and efficiently.
Test result indicate that, the test result of assay method provided by the invention is consistent with the alcohol-pickled Oven Method test result in GB/T " plaster of Paris crystal species analysis method " standard, and the testing time shortened to from about 240 minutes less than 100 minutes, it is greatly shortened the detection time, improve work efficiency, accelerate the speed of the inspection of material, evaluation and site acceptance.
In order to be further appreciated by the present invention, below in conjunction with embodiment, the assay method of type III anhydrous gypsum content in plaster of Paris provided by the invention being illustrated, protection scope of the present invention is not limited by the following examples.
Sample source:
The plaster of Paris that this experiment is selected provides for Lucheng, Shanxi Gypsum Mine, and calcium sulphate content 60.0～65.0%, calcium carbonate 35.0～40.0%, other content are less than 1%.
Embodiment 1
First taking plastic seal box with cover, load the deep water of about 5cm in box, cushion block is put in water, cushion block exceeds the water surface 2～4cm, places one piece of shelf, drimeter is put into above shelf on cushion block, cover lid to seal in placement laboratory, obtain high humidity and seal container.When drimeter shows 80%～100%, it is possible to start experiment.
Then by building gypsum plaster sample m that load weighted fineness is 80～90 orders1(5g) pave a thin layer on surface plate, paving thickness is 1～5mm, rapidly sample is put into above the shelf of high humidity container together with surface plate, and seal high humidity container immediately, sample, after high humidity seals and preserves 30 minutes in container, obtains the building gypsum plaster after moisture absorption, above-mentioned sample is taken out from high humidity container and is moved into immediately the drying in oven of 40 DEG C to constant weight, dry to constant weight, obtain the building gypsum plaster of weightening finish.
Finally after the building gypsum plaster sample increased weight is cooled to room temperature, weighing sample quality is m2, the quality of the water participating in reaction is m=m2-m1, in sample, the mass percent of type III anhydrous gypsum is w=15.11*m/m1* 100%；
Adopting above-mentioned steps, being respectively adopted humidity is 85% and 95% two kind, and paving thickness is 2mm and 4mm two kinds, obtains 1# sample and 2# sample.
30 minutes are deposited respectively at airtight high humidity environment, 60 minutes, 120 minutes, then in 40 DEG C of degree drying in oven to constant weight, contrast with the data using the test of GB/T " plaster of Paris crystal species analysis method " ethanol method, referring to table 1, table 1 is high humidity ageing method different time provided by the invention and the contrast of ethanol method.
Table 1 high humidity ageing method different time provided by the invention and the contrast of ethanol method
As shown in Table 1, method of testing provided by the invention is dried 60 minutes at 40 DEG C can reach constant weight, and ethanol method is dried and within 60 minutes, still had obvious liquid, and generally to dry 180 minutes could constant weight.And the Gypsum Fibrosum powder of ripening of the present invention has little water vapour, dry fast, the Gypsum Fibrosum that ethanol method processes has too much liquid (ethanol and water), it is necessary to the more time could dry.
By this table it can be seen that no matter be deposit 30 minutes or 60 minutes or 120 minutes under high humidity environment, its calculate anhydrous be gypsum content be all about 22%, and data are processed by the anhydrous gypsum content calculated by Ftest in Random data processing application excel, F value is the double, two tail probabilities during variance no significant difference of two groups of data, the situation a value that significance level is general is 0.05, compare time often by double, two tail probabilities F values and significance level a=0.05, when F value is be more than or equal to 0.05, significance level is low, confidence level is high, it is believed that two groups of data are with value；When F is less than 0.05, significance level is high, and confidence level is low, it is believed that two groups of data are different value.
Ftest draw deposit 30 minutes be 0.34 with the F value deposited 60 minutes, and deposit 60 minutes be 0.41 with the F value deposited 120 minutes.Therefore deposit 30 minutes and think with organizing numerical value with depositing 120 minutes.So under high humidity environment, depositing 30 minutes, the type III anhydrous gypsum in sample just can be completely converted into as semi-hydrated gypsum.And use that to deposit the F value tested for 30 minutes with ethanol method be 0.53, therefore the numerical value that two kinds of method of testings obtain is consistent.Airtight high humidity ageing method test required time was less than 100 minutes, and ethanol method needs more than 220 minutes at least.(weighing sample and sample cool time here without adding)
Simply type III anhydrous gypsum being transformed into semi-hydrated gypsum and other components do not become for checking through the phase composition of the Gypsum Fibrosum of method provided by the invention, the phase composition of raw sample and the Gypsum Fibrosum after high humidity ageing method is analyzed by we.
First by sample by high humidity ageing method ageing provided by the invention 30 minutes, then sample is taken out, the Gypsum Fibrosum of ageing method is carried out facies analysis, the Gypsum Fibrosum of raw sample (without ageing) carries out facies analysis composition test simultaneously, and test adopts the method for GB " plaster of Paris crystal species analysis method " paper for approval.Test result is referring to table 2, and table 2 is the mass percent of the dihydrate gypsum mass percent of two kinds of plaster of Paris samples and semi-hydrated gypsum mass percent and anhydrous gypsum.
The dihydrate gypsum mass percent of 2 two kinds of plaster of Paris samples of table and the mass percent of semi-hydrated gypsum mass percent and anhydrous gypsum
By the test result of table 2 it appeared that, gypsum samples after ageing method do not have anhydrous gypsum, and with the Fest of excel, the data of dihydrate gypsum are analyzed, obtaining F value is 0.77, illustrate that the type III anhydrous gypsum in sample has all been transformed into β semi-hydrated gypsum by the gypsum samples of aged 30 minutes, and type III anhydrous gypsum and β semi-hydrated gypsum do not generate dihydrate gypsum.
Simply the type III anhydrous gypsum in sample is transformed into β semi-hydrated gypsum for verifying further in the sample of airtight high humidity ageing method provided by the invention, and β semi-hydrated gypsum and type III anhydrous gypsum are not converted to dihydrate gypsum, separately take a batch sample and test.The method of this employing is to carry out follow-on test with a Sample Gypsum, high humidity ageing method and ethanol method is first used to carry out type III anhydrous gypsum test, then according to the method for GB " plaster of Paris crystal species analysis method " paper for approval, the sample that high humidity ageing method and ethanol method test is carried out the test of semi-hydrated gypsum and dihydrate gypsum content, test result is referring to table 3, and table 3 is the semi-hydrated gypsum in sample and dihydrate gypsum Comparative result after method of testing provided by the invention is tested anhydrous gypsum content with ethanol method and tested.
Semi-hydrated gypsum in sample and dihydrate gypsum Comparative result after table 3 method of testing provided by the invention and ethanol method test anhydrous gypsum content and test
Use Ftest formula in excel that data are analyzed, calculating the F value of type III anhydrous gypsum in the sample of different detection method test is 0.47, the F value of β semi-hydrated gypsum is 0.70, the F value of dihydrate gypsum is 0.07, calculating it can be seen that use different detection methods by F value, in the Gypsum Fibrosum calculated, the mass percent of each component is identical.
Thus adopt the assay method of type III anhydrous gypsum content in plaster of Paris provided by the invention, namely high humility ageing method may be employed to quickly detection plaster of Paris in type III anhydrous gypsum weight/mass percentage composition.
The anhydrous gypsum percentage composition that two kinds of diverse ways detect is essentially identical, and the sample through two kinds of processing methods is carried out again facies analysis, the semi-hydrated gypsum tested out and dihydrate gypsum all difference are very micro-, double; two tail probabilities F-test during by the variance no significant difference of data calculate, we draw the result no significant difference adopting two kinds of method tests, this absolutely proves that it is identical for adopting the result that in high humidity environment ageing method test architecture Gypsum Fibrosum, type III anhydrous gypsum content and ethanol method test type III anhydrous gypsum, and high wet method takes short, operate simpler.
Above the assay method of type III anhydrous gypsum content in a kind of plaster of Paris provided by the present invention is described in detail.Principles of the invention and embodiment are set forth by individual example specifically used herein, and the explanation of above example is only intended to help to understand method and the core concept thereof of the present invention.It should be pointed out that, for those skilled in the art, under the premise without departing from the principles of the invention, it is also possible to the present invention carries out some improvement and modification, these improve and modify in the protection domain also falling into the claims in the present invention.
Claims (9)
1. the assay method of type III anhydrous gypsum content in a plaster of Paris, it is characterised in that comprise the following steps:
A) under humid conditions, after building gypsum plaster sample is placed moisture absorption, the building gypsum plaster after moisture absorption is obtained；
B) building gypsum plaster after moisture absorption above-mentioned steps obtained is dried to constant weight, obtains the building gypsum plaster of weightening finish；
C) quality of the building gypsum plaster of weightening finish above-mentioned steps obtained and the quality of described building gypsum plaster sample are after calculating, and obtain the content of type III anhydrous gypsum in building gypsum plaster sample.
2. assay method according to claim 1, it is characterised in that the condition of described humidity is constant humidity.
3. assay method according to claim 1, it is characterised in that the humidity of the condition of described humidity is 80%～100%.
4. assay method according to claim 1, it is characterised in that the time of described moisture absorption is 25～120 minutes.
5. assay method according to claim 1, it is characterised in that the temperature of described drying is 40～55 DEG C.
6. assay method according to claim 1, it is characterised in that the fineness of described building gypsum plaster sample is less than or equal to 80 orders.
7. assay method according to claim 1, it is characterised in that described placement is specially tiling in the plane.
8. assay method according to claim 7, it is characterised in that the overlay thickness of described tiling is 1～5mm.
9. assay method according to claim 1, it is characterised in that the method for described calculating is, the quality of described building gypsum plaster sample is m1, the quality of the building gypsum plaster of described weightening finish is m2, the quality of the moisture of described building gypsum plaster sample moisture absorption is m；
Described m=m2-m1；
Described content is mass content, and in described building gypsum plaster sample, the mass content of type III anhydrous gypsum is w；
Described w=(15.11*m/m1) * 100%.
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