CN114605118B - Seawater sea sand concrete and matching proportion design method and preparation method thereof - Google Patents
Seawater sea sand concrete and matching proportion design method and preparation method thereof Download PDFInfo
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- CN114605118B CN114605118B CN202210275584.8A CN202210275584A CN114605118B CN 114605118 B CN114605118 B CN 114605118B CN 202210275584 A CN202210275584 A CN 202210275584A CN 114605118 B CN114605118 B CN 114605118B
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00198—Characterisation or quantities of the compositions or their ingredients expressed as mathematical formulae or equations
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/24—Sea water resistance
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Abstract
The invention discloses seawater sea sand concrete and a matching proportion design method and a preparation method thereof, wherein the matching proportion design method comprises the following steps: definition ofStrength activity coefficient K of mineral admixture f And the activity coefficient K against the permeability of iodide ion D (ii) a According to the target strength of the seawater and the sea sand and the amount W of the seawater s And a first cement amount C f Obtaining W s /C f A value of (d); according to the target iodine ion diffusion coefficient of the seawater and sea sand concrete and the dosage C of the second cement D And the amount of seawater W s The relationship of (1):
to obtain C D /W s A value of (d); wherein the content of the first and second substances,
is the target iodine ion diffusion coefficient, t, of seawater and sea sand concrete 1 、y 0 、A 1 Is a constant; by C f ＝C+K f X FA and C D ＝C+K D Obtaining the cement dosage C, the mineral admixture dosage FA and the seawater dosage W which simultaneously meet the target strength and the target iodine ion diffusion coefficient of the seawater and seawater sand concrete s The mixing ratio of (A) to (B). The invention takes the iodine ion permeability index and the strength index as target performance to participate in the mix proportion design, and designs the concrete mix proportion which simultaneously meets the strength and durability indexes.
Description
Technical Field
The invention relates to the field of concrete, in particular to seawater and sea sand concrete and a design method and a preparation method of a matching proportion thereof.
Background
At present, the demand for sand and stone is increased greatly, the natural resources of river sand are greatly reduced, the river sand is deficient, and the price of sand and stone is increased obviously. Meanwhile, the contradiction between supply and demand of water resources is serious, the utilization efficiency of the water resources is low, and the problems of loss of potential supply sources of fresh water, water quality reduction, pollution of surface water and underground water sources and the like are caused due to over-development of the water resources. The method for preparing the concrete by using the seawater is effective development of unconventional water resources, utilizes the seawater resources, solves the problem of shortage of fresh water resources, has important significance, and has certain price advantage because the original seawater only needs to consider the water collection cost and the seawater quality, does not need to consider the cost generated by desalting through equipment and technical means, and does not need to carry out technological processes of precipitation, disinfection, filtration and the like. The sea sand resource has large reserve, is similar to the macro and micro structure of river sand, and is a good substitute sand source of the river sand.
Therefore, the seawater sand which is a substitute sand source of river (river) sand and the seawater which is a substitute water source of tap water have good concrete market prospect and application prospect, but the iodine ions contained in the seawater sand can cause steel bar erosion, so that the performance of a reinforced concrete structure is reduced, even the durability of the reinforced concrete structure can be seriously influenced, the structure is seriously deteriorated in the using process, the service of the structure is influenced, so that high-price repairing is needed, and the cost is huge, so that the design of the seawater sand concrete with good durability has very important significance. The design method of the concrete mix proportion adopted in the prior engineering is mostly executed according to the requirements of JGJ55-2011 'design rule of common concrete mix proportion', but the method is mainly a concrete mix proportion design method taking strength as a control index, for the design of the durability mix proportion, the durability of the concrete is improved only by limiting the maximum water-cement ratio and the minimum using amount of a cementing material in the specification, and the durability index is not integrated into the mix proportion design, namely, the method cannot take the quantitative durability index as the basis of the design of the concrete mix proportion. Therefore, the traditional mix proportion design method cannot integrate the durability index of the concrete into the mix proportion design process, and the requirement of dual control of the strength and the durability of the concrete is difficult to achieve, so that the seawater-sand concrete mix proportion design method capable of controlling the strength and the durability simultaneously has important significance.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide seawater sea sand concrete and a mixing ratio design method and a preparation method thereof, and aims to solve the problem that the conventional mixing ratio design method cannot integrate the durability index of the concrete into the mixing ratio design process, so that the requirement of dual control of the strength and the durability of the concrete is difficult to achieve.
The technical scheme of the invention is as follows:
the invention provides a method for designing the matching proportion of seawater and sea sand concrete, which comprises the following steps:
defining the strength activity coefficient K of mineral admixtures f The ratio of the 28d compressive strength value of the mineral admixture to the 28d compressive strength value of the cement with the same mass and the activity coefficient K of the iodine ion permeability resistance of the mineral admixture D Is the ratio of the iodine ion diffusion coefficient of the mineral admixture to the iodine ion diffusion coefficient of the cement with the same mass;
determining the required target strength of the seawater sea sand concrete, and according to the target strength of the seawater sea sand concrete and the seawater consumption W s And a first cement amount C f Calculating to obtain the seawater consumption W s With the amount of the first cement C f Ratio W of s /C f ；
Determining the required target iodine ion diffusion coefficient of the seawater sea sand concrete, and according to the target iodine ion diffusion coefficient of the seawater sea sand concrete and the seawater consumption W s And a second cement amount C D The relationship of (c):
calculating the amount W of seawater s With a second cement dosage C D Ratio W of s /C D (ii) a Wherein, the first and the second end of the pipe are connected with each other,
is the target iodine ion diffusion coefficient, t, of seawater and sea sand concrete 1 、y 0 、A 1 Is a constant;
by C f ＝C+K f X FA and C D ＝C+K D X FA, calculating to obtain the cement which simultaneously satisfies the target strength and the target iodine ion diffusion coefficient of the seawater and sea sand concreteDosage C, dosage FA of mineral admixture and dosage W of seawater s The proportion of the components is shown in the specification.
Optionally, the mineral admixture has a strength activity coefficient
The iodine ion permeability resistant activity coefficient of the mineral admixture
Wherein e and d are influence coefficients of the strength of the mineral admixture, and f and g are influence coefficients of the iodine ion permeability of the mineral admixture.
Optionally, the value range of e is 0.87 to 0.97, the value range of d is 0.57 to 0.67, the value range of f is 0.92 to 1.02, and the value range of g is 0.46 to 0.56.
Optionally, the seawater sea sand concrete target strength and the amount W of seawater s And a first cement amount C f Satisfies the following formula:
wherein f is cu,0 ＝f cu，k +1.645σ，α a 、α b Is a regression coefficient, f cu，0 Configuring the strength of seawater and sea sand concrete, f cu，k As target strength value of seawater sea sand concrete, f ce，g Is cement strength grade value, sigma is standard deviation of seawater and sea sand concrete strength, gamma g Is a mineral admixture influence coefficient, gamma x Is the sea water sea sand 28d cement mortar strength influence coefficient, gamma c Is the surplus coefficient of the cement strength grade value.
Optionally, said γ is x The value range of (A) is 0.70-1.30.
Optionally, if the raw material of the seawater-sea sand concrete adopts multiple mineral admixtures, the gamma is g Is the product of the influence coefficients of various mineral admixtures; if the raw material of the seawater and sea sand concrete adopts single mineral admixtureThen said γ is g The influence coefficient of the single mineral admixture is shown; if the raw material of the seawater and sea sand concrete does not adopt mineral admixture, gamma g The value of (b) is 1.
Optionally, the t 1 ＝-0.13216±0.00634、y 0 ＝10.01252±0.18491、A 1 ＝0.11113±0.02682。
Optionally, the method further comprises the steps of: according to the obtained cement dosage C, mineral admixture dosage FA and seawater dosage W which simultaneously meet the target strength and the target iodine ion diffusion coefficient of the seawater and seawater sand concrete s And calculating the mixing proportion of the sea sand dosage, the coarse aggregate dosage and the additive dosage required in the sea water and sea sand concrete according to the JGJ55-2011 design rule of the mixing proportion of the common concrete.
The invention provides seawater and sea sand concrete, wherein the raw material components of the seawater and sea sand concrete comprise cement, seawater, sea sand, mineral admixture, coarse aggregate and admixture. The mixing proportion of the raw material components of the seawater sea sand concrete is calculated according to the design method of the mixing proportion of the seawater sea sand concrete.
The third aspect of the invention provides a preparation method of seawater sea sand concrete, which comprises the following steps: according to the mixing proportion calculated by the design method of the mixing proportion of the seawater and seawater sand concrete, the cement, the seawater sand, the mineral admixture, the coarse aggregate and the admixture are put into a stirring device by a primary feeding method or a secondary feeding method for stirring, and the seawater and seawater sand concrete is obtained.
Has the beneficial effects that: the invention provides seawater sea sand concrete and a matching proportion design method and a preparation method thereof.
Drawings
FIG. 1 is a flow chart of a method for designing the matching ratio of seawater and sea sand concrete according to the embodiment of the invention.
Detailed Description
The invention provides seawater sea sand concrete and a design method and a preparation method of the matching proportion thereof, and the invention is further described in detail below in order to make the purpose, the technical scheme and the effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The embodiment of the invention provides a method for designing the matching proportion of seawater and seawater sand concrete, in particular to a method for designing the matching proportion of seawater and seawater sand concrete based on the requirements of strength and durability, as shown in figure 1, wherein the method comprises the following steps:
s1, defining strength activity coefficient K of mineral admixture f The ratio of the 28d (namely 28 days) compressive strength value of the mineral admixture to the 28d compressive strength value of the cement with the same mass, and the activity coefficient K of the iodine ion permeability resistance of the mineral admixture D Is the ratio of the iodine ion diffusion coefficient of the mineral admixture to the iodine ion diffusion coefficient of the cement with the same mass;
s2, determining the required seawater sea sand concrete target strength, and according to the seawater sea sand concrete target strength and the seawater consumption W s And a first cement amount C f Calculating to obtain the seawater consumption W s With the amount of the first cement C f Ratio W of s /C f ；
S3, determining a required target iodine ion diffusion coefficient of the seawater and sea sand concrete, and according to the target iodine ion diffusion coefficient of the seawater and sea sand concrete and the seawater consumption W s And a second cement amount C D The relationship of (c):
calculating the amount W of seawater s With a second cement dosage C D Ratio of (A to (B)Value W s /C D (ii) a Is the target iodine ion diffusion coefficient, t, of seawater and sea sand concrete 1 、y 0 、A 1 Is a constant;
s4, using C f ＝C+K f xFA and C D ＝C+K D X FA, calculating to obtain the cement dosage C, the mineral admixture dosage FA and the seawater dosage W which simultaneously satisfy the target strength and the target iodine ion diffusion coefficient of the seawater and seawater sand concrete s The proportion of the components is shown in the specification.
The inventor of the invention firstly uses the iodine ion permeability index as the index of the mixing proportion design of the seawater and sea sand concrete, and creatively discovers the target iodine ion diffusion coefficient and the seawater consumption W of the seawater and sea sand concrete s And a second cement amount C D Satisfies the following relationship:
specifically, in the embodiment, the iodine ion permeability index and the strength index are used as target properties to participate in the mix proportion design, and the mix proportion of the seawater sea sand concrete which simultaneously meets the dual indexes of strength and iodine ion permeability (represented by iodine ion diffusion coefficient) is designed, so that the problem that the existing mix proportion design is difficult to achieve the dual control requirements of strength and durability of the concrete is solved. In this embodiment, the iodine ion permeability index is used as an index for measuring the durability performance of the concrete, but the method for evaluating the durability performance is not limited to the iodine ion permeability, and permeability indexes of other ions can also be used as an index for measuring the durability performance of the concrete.
In step S1, in one embodiment, the mineral admixture has a strength activity factor
The iodine ion permeability resistant activity coefficient of the mineral admixture
Wherein e and d are mineral admixture strength shadowThe coefficient of influence f and g are the coefficient of influence of the permeability of the iodine ions of the mineral admixture.
In specific implementation, when the mineral admixture is selected from fly ash, the value range of e is 0.87-0.97, the value range of d is 0.57-0.67, the value range of f is 0.92-1.02, and the value range of g is 0.46-0.56.
In step S2, in one embodiment, the target strength of the seawater sea sand concrete and the amount W of seawater s And a first cement amount C f Satisfies the following formula:
wherein, f cu,0 ＝f cu，k +1.645σ，α a 、α b Is a regression coefficient, f cu，0 Configuring value f for seawater and sea sand concrete strength cu，k Is a target strength value f of seawater sea sand concrete ce，g Is cement strength grade value, sigma is standard deviation of seawater and sea sand concrete strength, gamma x Is the sea water sea sand 28d cement mortar strength influence coefficient, gamma g Is a mineral admixture coefficient of influence, gamma c Is the surplus coefficient of the cement strength grade value.
In specific practice, α a 、α b Values can be taken according to JGJ55-2011 'design rule for mix proportion of common concrete' table 5.1.2. Sigma is the standard deviation of the strength of the seawater sea sand concrete, and when the strength grade of the designed seawater sea sand concrete is less than or equal to C20, the sigma is 4.0; when the strength of the designed seawater sea sand concrete is between C25 and C45, sigma is 5.0; when the strength of the designed seawater sea sand concrete is between C50 and C55, the sigma is 6.0. Gamma ray c The value range of the surplus coefficient is the cement strength grade value, and can be referred to JGJ55-2011 design rule for mixing proportion of common concrete.
The above ratio is formed by
Is calculated to obtain, wherein f cu,0 ＝f cu，k +1.645σ，f b ＝γ g f ce ，f ce ＝γ x γ c f ce，g ,f b Is 28d mortar compressive strength of cementing material, f ce The cement mortar is a cement 28d mortar compressive strength value.
The invention aims at the preparation of concrete by using seawater and sea sand as a part of raw materials, and because the seawater and sea sand contain chloride ions, on one hand, the chloride ions in the seawater and sea sand can accelerate the hydration of cement and possibly have a positive effect on the strength, and on the other hand, a compound product obtained by carrying out various compound reactions on all substances including the chloride ions in the seawater and sea sand can possibly have a negative effect on the strength. In addition, the strength of the seawater sea sand concrete is influenced by factors such as the particle shape, fineness, particle size distribution and shell content of sea sand, and also by factors such as the chloride ion content, the iodide ion content, the sulfate ion content and the alkali content of sea water, so that the comprehensive action of the factors can cause the early and long-term strength change of the seawater sea sand concrete, and when the seawater sea sand is doped as a raw material for preparing the concrete, an influence coefficient gamma is multiplied in a calculation formula of cement 28d mortar strength x I.e. f ce ＝γ x γ c f ce，g Wherein, said γ is x Is in the range of 0.70-1.30, and by way of example, the γ is determined according to the actual application x It may be 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, etc.
Since the mineral admixture applicable to the invention is not limited to fly ash and granulated blast furnace slag powder, but is applicable to more mineral admixtures, the influence coefficient gamma of the mineral admixture introduced is g I.e. f b ＝γ g f ce 。
In specific implementation, if the raw materials of the seawater and seawater sand concrete adopt various mineral admixtures, the gamma-ray g Is the product of the influence coefficients of various mineral admixtures; if the multiple mineral admixtures are selected from the group consisting of silica fume, mineral powder, granulated blast furnace slag powder, fly ash, and the like g The determination is carried out according to the measured strength data of the seawater and sea sand concrete 28 d; if the raw materials of the seawater sea sand concrete are adoptedA single mineral admixture, said gamma g For the influence coefficient of single mineral admixture, for example, when the raw material of the seawater sea sand concrete adopts fly ash, when the addition amount of the fly ash is increased from 0 percent to 40 percent in 10 percent increment step by step, gamma g The value ranges of the compounds are 1, 0.9-0.95, 0.8-0.85, 0.7-0.75 and 0.6-0.65 in sequence. (ii) a If the raw material of the seawater and sea sand concrete does not adopt mineral admixture, gamma g The value of (b) is 1.
In step S3, in this embodiment, the diffusion coefficient of the target iodide ions in the seawater sea sand concrete and the amount W of seawater used s And a second cement amount C D Satisfies the following formula:
wherein, t 1 、y 0 、A 1 Is a constant number, A 1 、t 1 And y 0 The value ranges of the compounds are respectively 0.11113 +/-0.02682, -0.13216 +/-0.00634 and 10.01252 +/-0.18491.
The target iodine ion diffusion coefficient of the seawater and sea sand concrete.
In the embodiment, the target iodine ion diffusion coefficient of the seawater sea sand concrete
In step S4, assuming that the cement dosage required by the concrete to meet the target strength when the single cement is mixed is C f The amount of cement required to satisfy the target iodine ion permeability is C D . When the cement and the mineral admixture are doped, the dosage of the mineral admixture is multiplied by the corresponding activity coefficient to obtain the equivalent dosage of the cement, the mineral admixture is equivalent to the cement by utilizing different activity coefficients of the mineral admixture for the performance of the seawater and seawater sand concrete,finally, an equation set with balanced cement consumption is obtained. Specifically, the strength activity coefficient of the mineral admixture obtained by the method is
Iodine ion permeability coefficient of activity of mineral admixture
Water to glue ratio
Substitution into C f ＝C+K f X FA and C D ＝C+K D X FA, the system of equations is obtained:
after calculation, the cement dosage C, the mineral admixture dosage FA and the seawater dosage W which simultaneously meet the target strength and the target iodine ion diffusion coefficient of the seawater and seawater sand concrete can be obtained s The proportion of the two components is shown in the specification.
In one embodiment, the method for designing the mixing ratio of seawater and seawater sand concrete further comprises the following steps: according to the obtained cement dosage C, mineral admixture dosage FA and seawater dosage W which simultaneously meet the target strength and the target iodine ion diffusion coefficient of the seawater and seawater sand concrete s The mixing proportion of the sea sand and the coarse aggregate and the admixture in the sea water and sea sand concrete is calculated according to JGJ55-2011 design rule for mixing proportion of common concrete. The sea sand dosage, the coarse aggregate dosage and the additive dosage can be calculated by referring to JGJ55-2011 'design rule for mixing proportion of common concrete', and the details are not repeated here.
It should be noted that after determining the seawater sea sand concrete mixing proportion meeting the strength and durability requirements according to the seawater sea sand concrete mixing proportion design method, the compressive strength test and the durability test of the concrete are respectively performed according to T50081 "common concrete mechanical property test method" and GBT 50082-2009 "common concrete long-term performance and durability test method standard", and the obtained actual measurement result of the strength and the durability is compared with the target design result, and if the actual measurement result cannot reach the target design result, the initial mixing proportion can be adjusted. The matching proportion is adjusted according to the difference between the actual measurement result and the design result of the seawater sea sand concrete, and the matching proportion of the seawater sea sand concrete needs to be adjusted according to the following conditions:
1. if the strength test result of the seawater sand concrete does not reach the expected design target, the strength configuration value f of the designed seawater sand concrete can be improved cu，0 And the dosage of other raw materials in the mixing proportion is calculated again.
2. If the durability test result of the seawater sea sand concrete does not reach the expected design target, the water-cement ratio of the concrete can be properly reduced on the basis of meeting the strength requirement.
3. If the test results of the strength and the durability of the seawater sea sand concrete do not reach the expected design targets, whether the raw materials reach the performance indexes of the raw materials required for preparing the seawater sea sand concrete should be checked.
The embodiment of the invention also provides seawater sea sand concrete, wherein the raw material components of the seawater sea sand concrete comprise cement, seawater, sea sand, mineral admixture, coarse aggregate and admixture, and the mixing proportion of the raw material components of the seawater sea sand concrete is calculated according to the design method of the mixing proportion of the seawater sea sand concrete in the embodiment of the invention. In this embodiment, the seawater sea sand concrete can satisfy the requirements of strength and durability at the same time.
In one embodiment, the mineral admixture is selected from at least one of fly ash, granulated blast furnace slag powder, silica fume, limestone powder, zeolite powder, but not limited thereto.
In one embodiment, the cement is selected from portland cement or ordinary portland cement.
In one embodiment, the admixture includes, but is not limited to, water reducing agents, air entraining agents, pumping aids, set retarders, antifreeze agents, expansion agents, and the like.
In specific implementation, the raw material components need to be subjected to related tests before being stirred for use, and the specific test items are as follows:
1. the test items of sea sand include particle size distribution, fineness modulus, mud content, mud block content, firmness index, mica content, light matter content, sulfide and sulfide ion content, organic matter content, iodide ion and alkali content, radioactivity and the like.
2. The detection items of the seawater comprise pH value, floating substances, chromaticity, turbidity, five-day biochemical oxygen demand, soluble total solid, suspended substances, sulfate ion, iodide ion content, alkali content, radioactivity and the like.
3. The inspection items of other raw materials are executed according to the relevant standards in the state.
In specific implementation, the raw material components meet the following parameters:
sea sand for preparing sea water sea sand concrete: the grading of sea sand particles is a II-zone grading zone, and medium sand (fineness modulus is 2.3-3.0) is selected; apparent density of sea sand is not less than 2500kg/m 3 (ii) a The loose bulk density is not less than 1400kg/m 3 (ii) a Porosity no greater than 44%; by mass percentage, the mud content of the sea sand is less than or equal to 3.0 percent, the mud block content is less than or equal to 1.0 percent, the mica content is less than or equal to 2.0 percent, the light substance content is less than or equal to 1.0 percent, and the sulfide and sulfate content is less than or equal to 1.0 percent; the firmness index is less than or equal to 10 percent; the maximum nominal diameter of shells in the sea sand is not more than 5mm, and the sea sand concrete with strength grade over C60 is prepared, the shell content in the sea sand is less than or equal to 4% by mass, the sea sand concrete with strength grade between C30 and C60 is prepared, the shell content in the sea sand is less than or equal to 8% by mass, the sea sand concrete with strength grade between C15 and C25 is prepared, the shell content in the sea sand is less than or equal to 10% by mass, and the method corresponding to the above-mentioned indexes test is in accordance with the current industry standard' sand for common concrete, stone quality and stone qualityThe standard of the test method is specified in JGJ 52, and the content of iodide ions in sea sand is simultaneously measured as an additional basis for designing the durability of the concrete structure.
Seawater used for preparing seawater sea sand concrete: the pH value (25 ℃) is more than or equal to 4.5, and obvious oil films, floating foams and other floating substances cannot be obtained by visual inspection on the seawater; the chroma is less than or equal to 30, and the turbidity is less than or equal to 10NTU; biochemical oxygen demand (BOD 5) is less than or equal to 4mg/L in five days; the total soluble solid is less than or equal to 50000mg/L, the suspended substance of seawater applied to the preparation of reinforced concrete is less than or equal to 2000mg/L, the sulfate ion is less than or equal to 3000mg/L, the suspended substance of seawater applied to the preparation of plain concrete is less than or equal to 5000mg/L, and the sulfate ion is less than or equal to 3000mg/L; in the test of each index, the pH value, the chromaticity, the turbidity and the total dissolved solid are respectively tested by a standard buffer solution colorimetric method or a glass electrode method with the execution standard of GB/T5750.4, a platinum-cobalt standard colorimetric method, a scattering method-formalin standard method and a weighing method (the drying temperature is 180 +/-3 ℃); five-day biochemical oxygen demand (BOD 5) was tested using dilution and inoculation with the execution standard GB/T7488; the seawater suspension is tested by a gravimetric method with an execution standard of GB 11901; the concentrations of sulfate ions and iodide ions were measured by performing the barium sulfate turbidimetry with the standard GB/T5750.5 and the silver nitrate volumetric method, respectively; the alkali content was measured by performing flame photometry with the standard GB/T176. Meanwhile, the strength of the cement mortar 3d and 28d prepared by adopting a seawater sample is not lower than 90% of that of the cement mortar 3d and 28d prepared by adopting drinking water, and the radioactivity of the seawater conforms to the relevant provisions of the national standard GB 5749 of sanitary Standard for Drinking Water.
Selection and quality of cement for preparing seawater and sea sand concrete are as follows: the seawater sea sand concrete adopts portland cement or ordinary portland cement, the cement quality meets the regulations of the current national standard 'general portland cement' GB 175, and the machine entering temperature of the cement at a mixing plant is not higher than 60 ℃.
Coarse aggregate for preparing seawater sea sand concrete: besides meeting the relevant regulations of the existing industry standard JGJ 52, namely quality and inspection method standards of common concrete sand and stone, the following regulations are also met: the maximum particle size of the coarse aggregate is not more than 25mm. Two-stage or three-stage coarse aggregate matching can be adopted; coarse aggregate with alkali activity is strictly forbidden to be adopted in seawater and sea sand concrete; when non-pumping construction is adopted, the particle size of the coarse aggregate can be properly enlarged.
Mineral admixture for preparing seawater sea sand concrete: the seawater sea sand concrete adopts mineral admixtures such as fly ash, granulated blast furnace slag powder, silica fume and the like to replace a part of cement to be used as a cementing material; the fly ash meets the regulations of the current national standard 'fly ash for cement and concrete' GB/T1596; the granulated blast furnace slag powder is in accordance with the regulation of the current national standard 'granulated blast furnace slag powder used in cement and concrete' GB/T18046; the silica fume accords with the regulations in the national standard GB/T18736 mineral admixture for high-strength and high-performance concrete; other mineral admixtures need to meet the regulations of relevant standards and meet the performance requirements of seawater and sea sand concrete.
Additive for preparing seawater sea sand concrete: the water reducing agent, the air entraining agent, the pumping aid, the retarder and other additives meet the relevant regulations of the existing national standard of concrete admixture GB 8076; the antifreezing agent is required to meet the relevant regulation of the existing national standard of concrete antifreezing agent JC 475; the expanding agent should meet the relevant regulations of the existing national standard of concrete expanding agent GB 23439; other additives meet relevant regulations of corresponding product standards; before the admixture is used, a raw material compatibility test is carried out according to the regulation of the current national standard GB 50119 of concrete admixture application technical Specification, and the admixture can be used after meeting the requirements; the water reducing agent for seawater sea sand concrete is preferably a polycarboxylic acid water reducing agent, and the water reducing rate is not lower than 20%; air entraining agent or air entraining water reducing agent is preferably used in the seawater and sea sand concrete, admixture with early strength function is not preferably used, and inorganic salt admixture is not preferably used.
The embodiment of the invention also provides a preparation method of the seawater and sea sand concrete, which comprises the following steps: according to the mixing proportion calculated by the method for designing the mixing proportion of the seawater and seawater sand concrete, cement, seawater sand, mineral admixture, coarse aggregate and additive are put into a stirring device by a primary feeding method or a secondary feeding method for stirring, so as to obtain the seawater and seawater sand concrete.
Wherein, the one-time feeding method is to simultaneously feed the raw materials (cement, sea sand, coarse aggregate, mineral admixture and additive) into a stirrer for stirring. In order to reduce the phenomena of cement flying and wall sticking, the gravity type stirrer is used for pouring sea sand and/or coarse aggregate firstly, pouring cement and mineral admixture, then pouring coarse aggregate and/or sea sand, clamping the cement and mineral admixture in the middle of sandstone, and finally adding seawater for stirring. The secondary feeding method comprises a premixed cement mortar method and a cement sand-wrapped feeding method: (1) the premixed cement mortar method is that cement, sea sand, mineral admixture, sea water and admixture are first added into a stirring cylinder for full stirring to form homogeneous cement mortar, and coarse aggregate is then added to form homogeneous concrete. Compared with the concrete stirred by one-time feeding method, the strength of the concrete stirred by the method can be improved by 15 percent. If the concrete strength is the same, 15% -20% of cement can be saved; (2) the cement sand-wrapping feeding method is that firstly a certain amount of seawater is added, the surface of sea sand is regulated to a certain specified humidity, coarse aggregate is poured in and is uniformly stirred with wet sand, then all cement, sea sand and mineral admixture are poured in and are uniformly stirred, so that cement forms a layer of cement paste shell with low water-cement ratio on the surface of sand and coarse aggregate, finally the rest water and admixture are poured in and are mixed to prepare the concrete. The strength of the concrete stirred by the method is improved by 20-30% compared with that of the concrete stirred by the one-time feeding method, and the concrete is not easy to generate segregation phenomenon, has less bleeding and good workability.
The invention is further illustrated by the following specific examples.
Example 1
Seawater and sea sand are taken from a new Dapeng region waxberry pit in Shenzhen city, cement with the strength grade of 42.5, II-grade coal ash, 5-20mm high monument and a common polycarboxylic acid type water reducing agent are adopted as the water reducing agent, various raw materials are correspondingly detected according to relevant specifications, the detection types and the detection method of the raw materials are described in the specification, after the detection result meets the requirements, to design a C40 seawater sea sand concrete, the design strength exceeds 40MPa in 28 days, and the target iodine ion permeability is less than or equal to 15 (the unit is 1 multiplied by 10) -12 m 2 (s), slump is required to be in the range of 150 to 200 mm.
The concrete mixing proportion design method provided by the invention is used for determining the mixing proportion of each raw material of the concrete, and the concrete calculation design process is as follows:
1. determining the target strength and the target iodine ion permeability of the concrete:
to design the C40 seawater sea sand concrete, it is required to satisfy the lowest strength and iodine ion permeability requirements, so in this embodiment, the concrete compressive strength is C40, and the iodine ion permeability coefficient is 15 (unit 1 × 10) -12 m 2 In/s) and a slump of 150mm.
2. Calculating the concrete strength configuration value:
according to a formula in JGJ55-2011 'design rule for mix proportion of common concrete':
f cu,0 ＝f cu，k +1.645σ
in this example f cu，k The standard deviation sigma is 5MPa, and the strength configuration value f of the concrete is obtained by calculation cu,0 Is 48MPa.
3. Calculating the amount W of seawater satisfying the target strength s And a first cement amount C satisfying strength f ：
When the cementing material is only mixed with cement, according to the design rule of JGJ 55-2011' common concrete mix proportion g May take 1, gamma c 1.16 was taken. Based on the existing measured data, gamma x 0.983 is taken. Since the selected 5-20mm high grade stone is crushed stone, the regression coefficient alpha a And alpha b Take 0.53 and 0.2, respectively. f. of ce，g The cement strength grade value is 42.5 according to the type of cement. Calculating to obtain W s /C f ＝0.483。
As the water reducing rate of the selected water reducing agent is 30 percent and the experimental design slump is 150mm, the water consumption W in the embodiment can be obtained according to JGJ 55-2011' design rule for mixing proportion of common concrete s ＝171.5kg/m 3 Thus, the first cement dosage C that satisfies the strength when fly ash is added as a replacement cement f ＝171.5/0.483＝355kg/m 3 。
4. Determining the amount of the second cement C which satisfies the target permeability to iodide ions when singly blended D ：
In this example, t is selected 1 、A 1 And y 0 Respectively-0.119, 0.08431 and 9.83.
According to the formula
In summary, the first cement dosage C satisfying the target strength f And a second cement amount C satisfying the target iodine ion permeability D Are each 355kg/m 3 And 350kg/m 3 。
5. Calculating the dosage of the cementing material which simultaneously meets the requirements of target strength and iodine ion permeability:
by using the formula equation set in step S4 of the invention:
will C f ＝355kg/m 3 、C D ＝350kg/m 3 Respectively substituting into a formula to obtain:
C＝295kg/m 3 ，FA＝95kg/m 3
6. calculating the mixing ratio of the seawater and sea sand concrete:
the amount of water W used was obtained according to the above-mentioned procedure of this example s Is 171.5kg/m 3 The cement consumption C is 295kg/m 3 The dosage of the fly ash FA is 95kg/m 3 Therefore, the water-to-glue ratio is 171.5/(295 + 95) =0.44. According to JGJ55-2011 'design rule for mixing proportion of common concrete' 5.4.2The sand ratio was determined to be 0.44, so that the amounts of sand and stone were 735.4kg/m, respectively 3 And 1103.1kg/m 3 . Finally, the concrete simultaneously satisfies the seawater sea sand concrete 28d compressive strength of 40MPa and the iodine ion permeability coefficient of 151 multiplied by 10 -12 m 2 The concrete mixing ratio of/s is as follows: the water consumption W was 171.5kg/m 3 The cement dosage is 295kg/m 3 The amount of the fly ash is 95kg/m 3 The amount of the sand is 735.4kg/m 3 The consumption of stones is 1103.1kg/m 3 。
Preparing seawater-sand concrete by adopting a one-time feeding method, feeding the raw materials (cement, seawater sand, high standard stone and mineral admixture) in the proportion into a stirrer together for stirring, adding seawater and a water reducing agent simultaneously after dry stirring for a period of time, stirring again, controlling the stirring time to be about 3-6min, after the concrete is stirred, inclining a stirring pot, pouring out a mixture, manually stirring for 1-2min by using a shovel in a mixture pool, and then testing the slump of the seawater-sand concrete according to the relevant requirements of GB/T50080-2002 'Standard of Performance test methods for ordinary concrete mixtures', wherein the slump is 160mm. Placing a mould on a vibration table according to the related requirements of T50081 ordinary concrete mechanical property test method, pouring stirred concrete into the mould, starting the vibration table until the surface of the mould is discharged and stops vibrating, then placing the mould in an environment with the temperature of 20 +/-5 ℃ for standing for a day and a night, numbering and removing the mould, immediately placing the mould in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than 95 percent for curing after removing the mould, testing the strength and the ion permeability of the seawater sea sand concrete test block in 28 days, and finally testing the 28d strength to 48.9MPa and the ion permeability to 12.41 (unit is 1 multiplied by 10) through testing the ion permeability -12 m 2 The unit is 1 multiplied by 10, the amount of the catalyst is less than or equal to 15 per second -12 m 2 /s) to meet the desired target requirements.
In summary, the seawater sea sand concrete and the design method and the preparation method of the mixing proportion thereof provided by the invention have the advantages that the iodine ion permeability index and the strength index are taken as target performances to participate in the mixing proportion design, the mixing proportion of the seawater sea sand concrete which simultaneously meets the strength and iodine ion permeability indexes is designed, the seawater sea sand concrete which simultaneously meets the strength and durability requirements is prepared, and the problem that the existing mixing proportion design is difficult to achieve the dual control requirements of the strength and the durability of the concrete is solved.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (5)
1. A seawater sea sand concrete matching proportion design method is characterized by comprising the following steps:
defining the strength activity coefficient K of mineral admixtures f The ratio of the 28d compressive strength value of the mineral admixture to the 28d compressive strength value of the cement with the same mass and the activity coefficient K of the iodine ion permeability resistance of the mineral admixture D Is the ratio of the iodine ion diffusion coefficient of the mineral admixture to the iodine ion diffusion coefficient of the cement with the same mass;
determining the required target strength of the seawater sea sand concrete, and according to the target strength of the seawater sea sand concrete and the seawater consumption W s And a first cement amount C f Calculating to obtain the seawater consumption W s With the amount of the first cement C f Ratio W of s /C f ；
Determining the required target iodine ion diffusion coefficient of the seawater and sea sand concrete, and according to the target iodine ion diffusion coefficient of the seawater and sea sand concrete and the seawater consumption W s And a second cement amount C D The relationship of (c):
calculating the amount W of seawater s With a second cement dosage C D Ratio W of s /C D (ii) a Wherein the content of the first and second substances,
is the target iodine ion diffusion coefficient, t, of seawater and sea sand concrete 1 、y 0 、A 1 Is a constant;
by C f ＝C+K f X FA and C D ＝C+K D X FA, calculating to obtain the cement dosage C, the mineral admixture dosage FA and the seawater dosage W which simultaneously meet the target strength and the target iodine ion diffusion coefficient of the seawater and seawater sand concrete s The matching proportion of the components;
the target strength of the seawater sea sand concrete and the amount W of seawater s And a first cement amount C f Satisfies the following formula:
wherein f is cu,0 ＝f cu，k +1.645σ，α a 、α b Is a regression coefficient, f cu，0 Configuring the strength of seawater and sea sand concrete, f cu，k Is a target strength value f of seawater sea sand concrete ce，g Is cement strength grade value, sigma is standard deviation of seawater and sea sand concrete strength, gamma g Is a mineral admixture coefficient of influence, gamma x Is the sea water sea sand 28d cement mortar strength influence coefficient, gamma c The surplus coefficient is the cement strength grade value;
said t is 1 ＝-0.13216±0.00634、y 0 ＝10.01252±0.18491、A 1 ＝0.11113±0.02682；
Strength activity coefficient of the mineral admixture
The iodine ion permeability resistant activity coefficient of the mineral admixture
Wherein e and d are mineral admixture strength influence coefficients, and f and g are mineral admixture iodine ion permeability influence coefficients;
the value range of e is 0.87-0.97, the value range of d is 0.57-0.67, the value range of f is 0.92-1.02, and the value range of g is 0.46-0.56;
the gamma is x The value range of (a) is 0.70-1.30.
2. The method as claimed in claim 1, wherein if the raw material of the seawater sea sand concrete is a plurality of mineral admixtures, the γ is g Is the product of influence coefficients of various mineral admixtures; if the raw material of the seawater and sea sand concrete adopts single mineral admixture, the Gamma is g The influence coefficient of the single mineral admixture is shown; if the raw material of the seawater and sea sand concrete does not adopt mineral admixture, gamma g Has a value of 1.
3. The method for designing the mixing ratio of seawater and seawater sand concrete according to any one of claims 1 to 2, further comprising the steps of: according to the obtained cement dosage C, mineral admixture dosage FA and seawater dosage W which simultaneously satisfy the target strength and the target iodine ion diffusion coefficient of the seawater and seawater sand concrete s The mixing proportion of the sea sand and the coarse aggregate and the admixture in the sea water and sea sand concrete is calculated according to JGJ55-2011 design rule for mixing proportion of common concrete.
4. The seawater sea sand concrete is characterized in that raw material components of the seawater sea sand concrete comprise cement, seawater, sea sand, mineral admixture, coarse aggregate and additive, and the mixing ratio of the raw material components of the seawater sea sand concrete is calculated according to the design method of the mixing ratio of the seawater sea sand concrete in claim 3.
5. The preparation method of the seawater sea sand concrete is characterized by comprising the following steps: the seawater sea sand concrete is obtained by putting cement, seawater, sea sand, mineral admixture, coarse aggregate and additive into stirring equipment for stirring according to the mixing proportion calculated by the design method of the mixing proportion of the seawater sea sand concrete as claimed in claim 3 by a primary feeding method or a secondary feeding method.
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