CN108205046B - A kind of evaluation method of cement-based material chloride binding stability - Google Patents
A kind of evaluation method of cement-based material chloride binding stability Download PDFInfo
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Abstract
The invention belongs to building materials test technical fields, disclose a kind of evaluation method of cement-based material chloride binding stability.Cement-based material sample broke to be measured, drying are placed on Cl‑Concentration is to impregnate in NaCl-NaOH simulation hole solution that 0.7mol/L, pH are 13.3, until reach chloride ion adsorption equilibrium, sample and drying are taken out after filtering；It is then respectively adding the NaOH-HNO that pH value is 13.3,9.0,8.0,4.0,1.03Cl is dipped in desorption solution‑Concentration balance, filtering, Cl in each filtrate is measured using potentiometric titrimeter respectively‑Cl in solution is desorbed by different pH value in content‑Various hydrated products are to Cl in concentration evaluation cement-based material‑Combination stability.Evaluation method of the invention is similar to practical Service Environment, and test accuracy is high.
Description
Technical field
The invention belongs to building materials test technical fields, and in particular to a kind of cement-based material chloride binding stability is commented
Valence method.
Background technique
Currently, the problem of reinforced concrete structure durability, is paid more and more attention.A large number of studies show that caused by chloride ion
Steel bar corrosion is the major reason for causing reinforced concrete structure to fail, and armored concrete is usually the knot of concrete package reinforcing bar
Structure, the chloride ion in external environment gradually inwardly spread and are gathered in rebar surface by the crack and hole of cement-based material,
When the chloride ion for being diffused into rebar surface reaches a certain concentration, the protective layer of reinforcing bar is destroyed, and causes steel bar corrosion, and raw
Make cement-based material cracking destruction at dilatancy product.
During cement-based material internal migration, part chloride ion is adsorbed by hydrolysis product of cement, no longer to moving to the interior
It moves.This part chloride ion be referred to as combines chloride ion, because the mode difference in conjunction with hydrolysis product of cement be divided into physical absorption and
Two kinds of chemosetting.It improves and combines amount of chloride ions, it is possible to reduce continue the free chloride ion migrated to rebar surface, help to push away
Slow rebar surface reaches the time of critical concentration, to improve reinforced concrete structure durability.However in environment pH decline
In the case of, hydrated product and the product for combining chloride ion can decompose, and can also be again transformed into certainly in conjunction with chloride ion
By chloride ion, Chloride Attack effect is accelerated.
Typically now using water soluble method and acid extracting (JTJ270-98 " marine traffic engineering concrete test regulation ") to cement base
Chloride ion existence form and content are tested in material.Containing for total chloridion in cement-based material can be measured using acid extracting
Amount, water soluble method measure the chloride ion content of physical absorption, and the difference of the two is to be chemically combined chloride ion content.Two methods knot
It closes with the contribution for characterizing physical absorption and chemosetting and combining to cement-based material chloride ion energy, showing of result of study
It learns combination stability and is better than physical absorption, the chloride binding of cement-based material is also tentatively reflected by acid extracting and water soluble method
Stability.
But current methods Shortcomings, it for sample dissolution is nitric acid that concentration is 6mol/L, pH value in acid extracting
Less than 1, so harsh Service Environment will not be faced substantially in actual use in cement-based material.Therefore, using acid
The free chloride ion content discharged again can be over-evaluated when the stability of molten method evaluating chemical curing of chloride ion, it is mixed so as to cause reinforcing bar
Xtah Crude Clay structure service life predicted value is relatively low.In addition, cement-based material is generally strong basicity, only with strong acid environment to its chlorine from
Sub- combination stability carries out evaluation and lacks science, can not reflect the corresponding relationship of chloride binding stability and Service Environment.
Chloride binding stability directly determines the content of free chloride ion in cement-based material, is related to chloride ion and exists
The prediction of migration and concrete service life in concrete, thus it is a kind of similar to practical Service Environment there is an urgent need to establish
And can reflect cement-based material chloride binding method for estimating stability corresponding with Service Environment.
Summary of the invention
In place of the above shortcoming and defect of the existing technology, the purpose of the present invention is to provide a kind of cement matrixs
Expect the evaluation method of chloride binding stability.This method has comprehensively considered the Service Environment of cement-based material, more scientifically
Evaluate the corresponding relationship of chloride binding stability and environmental pH.
The object of the invention is achieved through the following technical solutions:
A kind of evaluation method of cement-based material chloride binding stability, includes the following steps:
(1) cement-based material sample broke to be measured, drying are placed on Cl-Concentration is that 0.7mol/L, pH are 13.3
It is impregnated in NaCl-NaOH simulation hole solution, until reaching chloride ion adsorption equilibrium, sample and drying is taken out after filtering；
(2) by the sample of step (1) after dry be added separately to after crushed pH value be respectively 13.3 ± 0.1,9.0 ±
0.1,8.0 ± 0.1,4.0 ± 0.1,1.0 ± 0.1 NaOH-HNO3It is desorbed in solution, is dipped to Cl-Concentration balance, filtering, is adopted
Measure Cl in each filtrate respectively with potentiometric titrimeter-Cl in solution is desorbed by different pH value in content-Concentration evaluates cement matrix
Various hydrated products are to Cl in material-Combination stability.
Further, cement-based material described in step (1) refers to cement slurry, mortar or concrete.
Further, it is crushed described in step (1) and refers to and be crushed to 0.63~2mm particle, the drying refers to 25 ± 1
It is dried under vacuum to constant weight at DEG C, then sample is placed in the drier of soda lime and silica gel, sample is prevented to be carbonized.
Further, crushing described in step (2), which refers to, grinds to by 160 mesh square hole screens.
Further, Cl in solution is desorbed by different pH value described in step (2)-Concentration is evaluated each in cement-based material
Kind hydrated product is to Cl-Combination stability detailed process are as follows: pH value be 13.3 ± 0.1 NaOH-HNO3Solution is desorbed to impregnate
The Cl of dissolution-Amount is regarded as the Cl of hydrated product physical absorption-Amount；PH value is mainly calcium hydroxide in 9.0~13.3 ranges
It decomposes, the Cl dissolved out within the scope of this-Amount is regarded as Ca (OH)2To Cl-Binding capacity；PH in 8.0~9.0 ranges mainly
Friedel salt decomposes, the Cl dissolved out within the scope of this-Amount is Friedel salt to Cl-Binding capacity；PH is main in 4.0~8.0 ranges
It is C-S-H gel decomposition, the Cl dissolved out within the scope of this-Amount is C-S-H gel to Cl-Binding capacity；PH is in 13.3~1.0 ranges
The Cl of dissolution-Amount is hydrated product to Cl-In conjunction with total amount.
Evaluation method of the invention have the following advantages that and the utility model has the advantages that
(1) compared to conventional test methodologies, evaluation method of the invention is similar to practical Service Environment, and can reflect and take
Use as a servant the corresponding cement-based material chloride binding stability of environment.
(2) present invention proposes that the chloride ion curing degree in different pH environments is steady to the combination of chloride ion in cement-based material
It is qualitative to be evaluated, the relationship of cement-based material combined chloride ion stability and environment is established, while using constant-current titration
Mode reduces manual operation error, improves test accuracy.
Specific embodiment
Below with reference to embodiment, the present invention is described in further detail, and embodiments of the present invention are not limited thereto.
Embodiment
A kind of evaluation method of the cement-based material chloride binding stability of the present embodiment, the specific steps are as follows:
(1) particle by the slag cements net slurry sample broke after conserving 28 days to about 2mm, and the vacuum at 25 ± 1 DEG C
It dries to constant weight, then sample is placed in the drier of soda lime and silica gel, sample is prevented to be carbonized；Weigh about 125g slag water
Cement paste particle (is accurate to 0.1mg), is soaked in the Cl of 500mL-Concentration is the NaCl-NaOH that 0.7mol/L, pH are 13.3
In solution, soaking time 28 days to reach chloride ion adsorption equilibrium；The sample that filtering is up to adsorption equilibrium takes out, and 25 ±
It is dried under vacuum to constant weight at 1 DEG C, then sample is placed in the drier of soda lime and silica gel, sample is prevented to be carbonized.
(2) drying sample for being up to adsorption equilibrium by hand with agate mortar is ground to all through 160 mesh square hole screens, is claimed
Taking 15g powder sample, (quality m) is placed in conical flask, and the hydrogen-oxygen that 100mL pH is 13.3 is then accurately measured with volumetric flask
Change sodium solution and pour into flask, is standing and soaking for 24 hours after acutely vibrating 2min, filters suspension with filter paper, accurately measure certain volume
Filtrate (Vf) and using chloride ion content (n in potentiometric titrimeter measurement filtratef)。
(3) NaOH-HNO of 100mL difference pH value (i=9,8,4,1) is accurately measured respectively with volumetric flask3Solution is desorbed,
It pours into and (in the conical flask of quality m), covers bottle stopper equipped with 15g powder sample to prevent from evaporating, while vibrating for 24 hours, with filter
Paper filters suspension, accurate to measure certain volume filtrate (Vi) and using chloride ion content (n in potentiometric titrimeter measurement filtratei,i
=9,8,4,1)；Pass through Cl in different desorption solution-Various hydrated products are to Cl in concentration evaluation cement-based material-Combination it is steady
It is qualitative.Specific evaluation procedure is as follows:
1, the Cl that solution impregnates dissolution is desorbed in the NaOH that pH value is 13.3 in step (2)-Amount is regarded as hydrated product object
Manage the Cl of absorption-Water soluble chloride ion content, is considered as the content C of physical adsorption chloride ion in cement-based material by amountp, then:
Wherein, CpFor physical adsorption chloride ion content (mg/g) in cement-based material；MClFor the atomicity of chlorine, take
35.45g/mol。
2, the total the amount of dissolution C of cement-based material chloride ion under different pH environmentsTiAre as follows:
Wherein, CTiWhen for pH being i, the total the amount of dissolution of cement-based material chloride ion (mg/g).
3, cement-based material is chemically combined chloride ion content C under different pH environmentsCiAre as follows:
CCi=CTi-Cp,
Wherein, CCiWhen for pH being i, cement-based material is chemically combined chloride ion content (mg/g).
4, cement-based material chemical bonding the ratio between chloride ion content and total the amount of dissolution under different pH environments are defined as pH
The chloride ion curing degree BR of cement-based material when for ii(%), it may be assumed that
During cement-based material chloride binding estimation of stability, chloride ion curing degree is higher to illustrate chloride binding
It is more stable.
Pass throughThe chloride ion curing degree of slag cements net slurry when pH is i can be calculated.According to this
4 groups of experiments are arranged in the method for embodiment, and evaluation result is as shown in table 1.
1 embodiment experiment parameter of table
The above embodiment is a preferred embodiment of the present invention, but embodiments of the present invention are not by above-described embodiment
Limitation, other any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present invention,
It should be equivalent substitute mode, be included within the scope of the present invention.
Claims (4)
1. a kind of evaluation method of cement-based material chloride binding stability, it is characterised in that include the following steps:
(1) cement-based material sample broke to be measured, drying are placed on Cl-Concentration is the NaCl- that 0.7mol/L, pH are 13.3
It is impregnated in NaOH simulation hole solution, until reaching chloride ion adsorption equilibrium, sample and drying is taken out after filtering；
(2) by the sample of step (1) after dry be added separately to after crushed pH value be respectively 13.3 ± 0.1,9.0 ± 0.1,
8.0 ± 0.1,4.0 ± 0.1,1.0 ± 0.1 NaOH-HNO3It is desorbed in solution, is dipped to Cl-Concentration balance, filtering, using electricity
Position titrator measures Cl in each filtrate respectively-Cl in solution is desorbed by different pH value in content-Concentration is evaluated in cement-based material
Various hydrated products are to Cl-Combination stability；
Cl in solution is desorbed by different pH value described in step (2)-Concentration evaluates various hydrated products pair in cement-based material
Cl-Combination stability detailed process are as follows: pH value be 13.3 ± 0.1 NaOH-HNO3The Cl that solution impregnates dissolution is desorbed-Amount
For the Cl of hydrated product physical absorption-Amount；The Cl that pH value dissolves out in 9.0~13.3 ranges-Amount is Ca (OH)2To Cl-In conjunction with
Amount；The Cl that pH is dissolved out in 8.0~9.0 ranges-Amount is Friedel salt to Cl-Binding capacity；PH is dissolved out in 4.0~8.0 ranges
Cl-Amount is C-S-H gel to Cl-Binding capacity；The Cl that pH is dissolved out in 13.3~1.0 ranges-Amount is hydrated product to Cl-Knot
Close total amount.
2. a kind of evaluation method of cement-based material chloride binding stability according to claim 1, it is characterised in that:
Cement-based material described in step (1) refers to cement slurry, mortar or concrete.
3. a kind of evaluation method of cement-based material chloride binding stability according to claim 1, it is characterised in that:
It is crushed described in step (1) and refers to and be crushed to 0.63~2mm particle, the drying, which refers to, is dried under vacuum to perseverance at 25 ± 1 DEG C
Weight, then sample is placed in the drier of soda lime and silica gel, prevent sample to be carbonized.
4. a kind of evaluation method of cement-based material chloride binding stability according to claim 1, it is characterised in that:
Crushing described in step (2), which refers to, to be ground to by 160 mesh square hole screens.
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| CN108827989B (en) * | 2018-06-29 | 2020-01-17 | 山东大学 | Method for determining proportion of C-S-H gel adsorption-bound chloride ions in total bound chloride ions in cement paste |
| CN109827881B (en) * | 2019-02-26 | 2022-05-31 | 西南石油大学 | Rock hydration degree characterization method and system |
| CN110133175A (en) * | 2019-05-07 | 2019-08-16 | 山东大学 | The method of chloride ion content is combined under a kind of accurate Characterization difference carbonizing degree in cement slurry |
| CN114894873A (en) * | 2022-04-13 | 2022-08-12 | 华南理工大学 | Chloride ion sensing electrode and preparation method and application thereof |
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| CN103926300A (en) * | 2014-04-09 | 2014-07-16 | 北京工业大学 | Improved method for determining free chlorine ions in cement paste or mortar |
| CN106802318A (en) * | 2017-01-09 | 2017-06-06 | 北京工业大学 | A kind of assay method of hydrated cement paste chlorion fixed amount |
| CN106872641A (en) * | 2017-04-10 | 2017-06-20 | 东南大学 | A kind of cement-based material chloride binding amount method for measuring |
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