CN-115831269-B - Hybrid steel fiber self-compaction concrete mix proportion secondary design method based on solid phase surface filling layer customization

CN115831269BCN 115831269 BCN115831269 BCN 115831269BCN-115831269-B

Abstract

The invention discloses a secondary design method of a mix steel fiber self-compaction concrete mix proportion based on solid phase surface filling layer customization, on the basis mix proportion of fiber-free self-compaction concrete, and introducing steel fibers, and carrying out secondary mix proportion design through a secondary design envelope curve to finally obtain the final mix proportion of the steel fiber self-compacting concrete. The design method can include material variability of different fiber diameters, aggregate systems and the like, can realize mixed doping of fibers, reduces fluctuation of working performance of the mixture caused by doping amount of the materials and the fibers, greatly improves stability, optimizes control of working performance of the freshly mixed self-compacting concrete, greatly reduces proportioning and debugging quantity, can realize rapid blending of the self-compacting fiber concrete, and has guiding effect on application and targeted customization of proportioning of the fiber concrete in actual engineering.

Inventors

LEI MINGFENG
LIU LINGHUI
GONG CHENJIE
LI SHUISHENG
Gan Shuqing
ZHANG HU
SHI CHENGHUA
YANG ZIHAN

Assignees

中南大学

Dates

Publication Date: 20260505
Application Date: 20220628

Claims (10)

1. A secondary design method of a mixed steel fiber self-compaction concrete mixing proportion based on solid phase surface filling layer customization is characterized by comprising the following steps of 1) obtaining performance parameters of raw materials and determining a non-fiber self-compaction concrete base mixing proportion parameter, 2) calculating the thickness of a non-fiber self-compaction fiber concrete surface filling layer by adopting an experimental test and/or a compressible filling model, 3) introducing gaps of a steel fiber and aggregate mixed stacking body to draw a secondary design envelope curve of the steel fiber self-compaction concrete solid phase surface filling layer, and 4) calculating and adjusting the secondary mixing proportion according to the secondary design envelope curve process; The secondary design envelope curve of the steel fiber self-compaction concrete solid phase surface filling layer comprises the following parameters of the relative thickness of the steel fiber surface superfluous sand layer filling layer And scaling factor of solid phase surface excess slurry filling layer after fiber is doped Two secondary mix parameters; Relative thickness of the excessive sand layer filling layer on the surface of the steel fiber And scaling factor of solid phase surface excess slurry filling layer after fiber is doped Is defined as: Is made of excessive steel fiber surface layer thickness of sand layer filling layer Excess sand layer filling layer thickness relative to the surface of the fiber-free self-compacting concrete coarse aggregate Is a ratio of (2); excess slurry filling layer thickness on the surface of solid phase component after being doped into steel fiber Excess slurry filling layer thickness relative to coarse and fine mixed aggregate surface layer Is a ratio of (2); The surface excess slurry filling layer thickness The calculation process of (1) is as follows: ; Wherein, the The thickness of the surplus slurry filling layer which is the surface layer of the coarse and fine mixed aggregate is m; Is the first The unit volume doping amount of the type fiber is m 3 ; Is the first The scaling coefficient of the solid phase surface surplus slurry filling layer doped outside the seed fiber is dimensionless.
2. The secondary design method of the mixing proportion of the self-compacting concrete based on the solid-phase surface filling layer customization is characterized in that the raw materials comprise steel fibers, aggregates, cement, fly ash, slag, silica fume, additives and water, and the performance parameters of the raw materials comprise apparent density of coarse aggregates Bulk density of coarse aggregate Filling rate of coarse aggregate system Filling rate of fine aggregate system Void fraction of coarse aggregate System Void fraction of fine aggregate System Apparent density of fine aggregate Bulk density of fine aggregate Coarse aggregate grading parameter, fine aggregate grading parameter, coarse aggregate form parameter, fine aggregate form parameter and steel fiber volume weight Morphological parameters of steel fiber and apparent density of cement Apparent density of fly ash Apparent density of slag Apparent density of silica fume Density of water And density after admixture configuration 。
3. The secondary design method of the mixing proportion of the self-compacting concrete based on the customized mixed steel fiber of the solid surface filling layer of claim 2, wherein the filling rate of the coarse aggregate system is as follows And coarse aggregate system void fraction The calculation process of (1) is as follows: Formula 1: ; formula 2: ; Formula 3: ; The fine aggregate filling rate And void fraction of fine aggregate skeleton system The calculation process of (1) is as follows: formula 4: ; formula 5: ; formula 6: ; In the formulas 1 to 6: The bulk density of the coarse aggregate is kg/m 3 ; the weight of the coarse aggregate is kg; the filling rate of coarse aggregate is dimensionless; For testing the volume of the vessel used, the dimension was m 3 ; The dimension of the absolute volume of the coarse aggregate after the test container is filled is m 3 ; the void ratio of the coarse aggregate skeleton system is dimensionless; the weight of the coarse aggregate is kg; the filling rate of coarse aggregate is dimensionless; For testing the volume of the vessel used, the dimension was m 3 ; The dimension of the aggregate is m 3 which is the absolute volume of the aggregate in the container; the void ratio of the skeleton system is dimensionless; the calculation process of the coarse aggregate grading parameter comprises the steps of dividing coarse aggregate with particle size larger than 5mm into 2-3 sections, and determining the volume ratio of each particle size section To represent the grading distribution of coarse aggregates; The fine aggregate grading parameter is calculated by dividing aggregate with the diameter of 0.08-5 mm into 6 sections, and calculating the accumulated screen surplus rate of each section, namely the particle size The percent passage of the particles is reported as And repeating the averaging a plurality of times, wherein, Fitting using Funk-Dinger formula: Formula 7: ; in formula 7: the cumulative screen residue rate of each interval is the dimension; The particle size is m, which is the smallest particle size of particles in the fine aggregate; the size of the particle is m, which is the maximum particle size of the particles in the fine aggregate; The grading index to be fitted is dimensionless; the mesh size is the mesh size of the particle size interval i; The calculation process of the coarse aggregate morphological parameters and the fine aggregate morphological parameters comprises the following steps: ① The size proportion is calculated by adopting Heywood particle theory, and the calculation process is as follows: formula 8: ; Formula 9: ; Formula 10: ; ② The specific surface area of the coarse aggregate is calculated by adopting a discrete method, and the calculation process is as follows: Formula 11: ; ③ The specific surface area of the fine aggregate is calculated by adopting a continuous method, and the calculation process is as follows: formula 12: ; In 8 to 12: the aggregate length and dimension are m; the aggregate width and dimension are m; The aggregate thickness is m; And Is a projection size proportionality coefficient, and is dimensionless; the projection diameter is an amplification factor relative to the sieving diameter, and is dimensionless; The specific surface area of the coarse aggregate is m -1 ; is a shape area coefficient, and is dimensionless; is a shape volume coefficient, dimensionless; The ratio of each particle size interval is dimensionless; the mesh size is the mesh size of the particle size interval i, and the dimension is m; the cumulative screen residue rate of each interval is the dimension; The specific surface area of the fine aggregate is m -1 ; the morphological parameters of the steel fiber comprise fiber length, fiber diameter and fiber specific surface area, wherein the fiber length and the fiber diameter are obtained through measurement, and the calculation process of the fiber specific surface area is as follows: Formula 13: ; in formula 13: the specific surface area of the steel fiber is m -1 ; The fiber diameter is m -1 .
4. The secondary design method of the mixing proportion of the self-compacting concrete based on the solid-phase surface filling layer customization, which is characterized in that the mixing proportion parameters of the non-fiber self-compacting concrete base comprise the absolute volume of coarse aggregate And mass of Absolute volume of fine aggregate And mass of Volume of slurry Weight of the cementing material Weight of cement Weight of fly ash Weight of granulated blast furnace slag Weight of silica fume Weight of water 。
5. The secondary design method of the mixing proportion of the hybrid steel fiber self-compacting concrete based on the customization of the solid phase surface filling layer, which is characterized in that the calculation of the fiber-free self-compacting fiber concrete aggregate surface filling layer comprises the steps of respectively calculating the void ratio of an aggregate mixed stack Void volume of aggregate mixed stack Thickness of filling layer of superfluous sand layer on surface of coarse aggregate And excess slurry filling layer thickness of coarse and fine mixed aggregate surface layer 。
6. The secondary design method for the mixing proportion of the self-compacting concrete based on the solid-phase surface filling layer is characterized by comprising the following steps of: The aggregate mixed stacking body gap CPM model calculation adopting interaction correction; The thickness of the filling layer of the excessive sand layer on the surface of the coarse aggregate is The calculation process of (1) is as follows: Formula 14: ; Formula 15: ; Formula 16: ; Formula 17: ; Formula 18: ; In formulas 14 to 18: The dimension of the coarse aggregate is m 3 ; The dimension of the aggregate is m 3 which is the absolute volume of coarse aggregate; the dimension of the aggregate is m 3 which is the absolute volume of the fine aggregate; is a loose accumulation volume of fine aggregate, and the dimension is m 3 ; the void ratio of the coarse aggregate skeleton system is dimensionless; filling the stacked volume of the layer for the excessive sand layer, wherein the dimension is m 3 ; the thickness of the filling layer of the excessive sand layer on the surface of the coarse aggregate is m; Void volume of the aggregate mix stack And the thickness of the excess slurry filling layer of the surface layer of the coarse and fine mixed aggregate The calculation process of (1) is as follows: Formula 19: ; Formula 20: ; Formula 21: ; In the formulas 19 to 21: the dimension of the aggregate is m 3 which is the absolute volume of coarse aggregate; the dimension of the aggregate is m 3 ; The stacking void ratio of coarse and fine mixed aggregate particles is dimensionless; The specific surface area of the coarse aggregate is m -1 ; The specific surface area of the fine aggregate is m -1 ; The dimension of the slurry is m 3 ; the thickness of the surplus slurry filling layer which is the surface layer of the coarse and fine mixed aggregate is m.
7. The secondary design method of the hybrid steel fiber self-compaction concrete mixing ratio based on the solid phase surface filling layer customization, which is characterized in that the calculation process of the interaction modified CPM model is as follows: determining the absolute volume fraction of fine aggregate in an aggregate system : Formula 22: ; calculating the volume ratio of the particle size interval i : Formula 23 for the coarse aggregate, ; For a fine aggregate, ; In the formulas 23-24, i is a fine aggregate particle size interval; is a coarse aggregate particle size interval; Calculating the virtual filling rate of each particle size interval : Formula 25: ; calculating virtual filling rate of virtual skeleton system : Formula 26: ; formula 27: ; Formula 28: ; Calculating the actual filling rate of the aggregate particle skeleton : Formula 29: ; formula 30: ; In the formulas 25 to 30: Is the virtual filling rate of the particle size interval i, dimensionless; the loose filling rate of the aggregate in each particle size interval is dimensionless; Is a skeleton compaction coefficient, has no dimension, Is the ratio of the average particle sizes of the particle size intervals j and i, And The looseness effect coefficient and the wall effect coefficient between particle size intervals i and j are respectively; is the number of total particle size intervals divided.
8. The secondary design method for the mixing proportion of the self-compacting concrete of the hybrid steel fiber based on the customization of the solid-phase surface filling layer, which is disclosed in claim 1, is characterized in that: The design process of the secondary design envelope curve of the steel fiber self-compaction concrete solid phase surface filling layer is as follows: ① Calculating the filling rate of a coarse aggregate system under the disturbance of steel fibers by adopting a hard fiber exogenous doping correction CPM model And void fraction Fine aggregate system filling rate under disturbance of steel fiber And void fraction Calculating the dense stacking volume ratio of coarse aggregate in the solid phase mixed stacking system The calculation process is as follows: Formula 31: ; volume ratio of fine aggregate in steel fiber-aggregate mixed system The calculation process of (1) is as follows: Formula 32: ; Formula 33: ; Formula 34: ; Formula 35: ; Formula 36: ; formula 37: ; ② Adopting CPM model to calculate aggregate filling rate under disturbance of steel fiber And aggregate bulk void fraction The calculation process is as follows: the aggregate compact stacking volume ratio in the fiber concrete mixture system is as follows The calculation process is as follows: formula 38: ; The volume of the slurry in the fiber concrete mixture system is The excess slurry volume of the solid phase surface is The calculation process is as follows: formula 39: ; Formula 40: ; Aggregate-fiber solid phase stacking volume in fiber concrete mixture system is The absolute volume of the coarse aggregate is The absolute volume of the fine aggregate is The calculation process is as follows: Formula 41: ; formula 42: ; formula 43: ; ③ Respectively calculating the number of powder systems And the mass of each component in the fiber concrete mixture body under unit volume, the calculation process is as follows: Formula 44: ; Formula 45: ; formula 46: ; formula 47: ; Formula 48: ; formula 49: ; Formula 50: ; formula 51: ; Formula 52: ; formula 53: ; In formulas 31 to 53: the solid phase mixed stacking system has a dense stacking volume ratio of coarse aggregate and no dimension; Is the first Steel fibers of the type, dimensionless; is the total type quantity of steel fibers and is dimensionless; Is the first The unit volume doping amount of the type fiber is m 3 ; Is the first The specific surface area of the type fiber is m -1 ; Is the first The relative thickness of the excessive sand layer filling layer on the surface of the steel fiber of the type fiber is dimensionless; Is the first Individual fiber lengths of the types of fibers; Is the first The number of fibers per unit volume of the type of fibers is dimensionless; the thickness of the filling layer of the excessive sand layer on the surface of the fiber-free concrete coarse aggregate is m; the thickness of the filling layer is the thickness of the fiber-free self-compacting concrete surplus slurry, and the dimension is m; the filling rate of the coarse aggregate system under the disturbance of steel fibers is dimensionless; the void ratio of the coarse aggregate system under the disturbance of steel fibers is dimensionless; the filling rate of the fine aggregate system under the disturbance of steel fibers is dimensionless; The void ratio of the fine aggregate system under the disturbance of steel fibers is dimensionless; The dimension of the stacking volume of the coarse aggregate in the solid phase mixed system is m 3 ; the dimension of the absolute volume of the coarse aggregate in the solid phase mixed system is m 3 ; The dimension of the stacking volume of the filling layer of the excessive sand layer on the surface of the steel fiber-coarse aggregate in the solid phase mixed system is m 3 ; the dimension of the aggregate is m 3 , which is the stacking volume of fine aggregate in the solid phase mixed system; the dimension of the absolute volume of the fine aggregate in the solid phase mixed system is m 3 ; the volume ratio of the fine aggregate in the steel fiber-aggregate mixed system in the solid phase mixed system is dimensionless; the aggregate filling rate under the disturbance of steel fibers is dimensionless; the void ratio of the aggregate stack under the disturbance of the steel fiber is dimensionless; The thickness of the filling layer of the surplus slurry on the surface of the solid phase component is m; Is the first Scaling coefficient of solid phase surface surplus slurry filling layer doped outside seed fiber is dimensionless; the aggregate compact stacking volume in the fiber concrete mixture system is the proportion, dimensionless; The specific surface area of the coarse aggregate is m -1 ; The specific surface area of the fine aggregate is m -1 ; The dimension of the slurry volume in the fiber concrete mixture system is m 3 ; The dimension of the excess slurry volume on the solid phase surface is m 3 ; the dimension of the aggregate-fiber solid-phase stacking volume in the fiber concrete mixture system is m 3 ; the dimension of the coarse aggregate is m 3 , which is the absolute volume of coarse aggregate in the fiber concrete mixture system; the absolute volume of fine aggregate in a concrete mixture system is m 3 ; Is a powder coefficient, and is dimensionless; The dimension of the concrete is m 3 ; Is water-gel ratio, dimensionless; the proportion of the additive in the cementing material is dimensionless; the mass ratio of cement in the powder is dimensionless; The mass ratio of the fly ash in the powder is dimensionless; The slag powder is non-dimensional and has the mass ratio of slag in the powder; the mass ratio of the silica fume in the powder is dimensionless; the mass of the cementing material in the self-compacting concrete mixture of the hybrid steel fiber is kg; the cement mass in the self-compacting concrete mixture of the hybrid steel fiber is kg; the mass of the fly ash in the self-compacting concrete mixture of the hybrid steel fiber is kg; Slag mass in the self-compacting concrete mixture of the hybrid steel fiber is kg; the mass and dimension of silica fume in the self-compacting concrete mixture of the hybrid steel fibers are kg; the water mass in the self-compacting concrete mixture of the hybrid steel fiber is kg; the mass of fine aggregate in the self-compacting concrete mixture of the hybrid steel fiber is kg; the mass of coarse aggregate in the self-compacting concrete mixture of the hybrid steel fiber is kg; the mass of the kth type steel fiber in the self-compacting concrete of the hybrid steel fiber is kg.
9. The secondary design method for the self-compaction concrete mixing ratio of the hybrid steel fiber based on the solid phase surface filling layer customization, which is disclosed in claim 8, is characterized in that the hard fiber doping correction CPM model comprises the following parameter correction processes: ① Calculating the perturbation volume of single fiber to peripheral aggregate : Formula 54: ; Formula 55: ; formula 56: ; formula 57: ; ② Calculating the virtual filling rate of each aggregate particle size interval i under fiber disturbance : Formula 58: ; Formula 59: ; Formula 60: ; in the formulas 54 to 60: Is the first The equivalent sphere particle diameter of the type steel fiber is m; Is the first The diameter and dimension of the type steel fiber are m; -first The length of the type steel fiber is m; Is the first The equivalent grain size ratio of the type steel fiber to the aggregate in each grain size section is dimensionless; the micro-disturbance volume coefficient of the single fiber to the peripheral aggregate is dimensionless; The size of the micro-disturbance volume of the single fiber to the peripheral aggregate is m 3 ; The unit volume doping amount of the micro steel fiber is m 3 ; Is the first in concrete The number of the seed fibers is dimensionless; the disturbance action coefficient of each aggregate particle size interval i, which is influenced by fibers, is dimensionless; the loose filling rate of the aggregate in each particle size interval is dimensionless; is a skeleton compaction coefficient, and has no dimension.
10. The secondary design method for the mixing proportion of the self-compacting concrete based on the customized solid-phase surface filling layer of the hybrid steel fiber according to claim 1, wherein the secondary mixing proportion calculation and adjustment process comprises the following steps of setting 、 And when the strength test passes, outputting the initial secondary mix ratio as a final mix ratio, and when the strength test fails, adjusting the fiber-free self-compacting concrete foundation mix ratio until the strength test passes, and outputting the initial secondary mix ratio as the final mix ratio.

Description

Hybrid steel fiber self-compaction concrete mix proportion secondary design method based on solid phase surface filling layer customization Technical Field The invention relates to the technical field of building materials, in particular to a secondary design method for a mixing proportion of self-compacting concrete of hybrid steel fibers based on customization of a solid phase surface filling layer. Background The concept of self-compacting concrete is firstly proposed by the professor H.okamura in 1986, the self-compacting concrete meeting rheological property without being stirred can be prepared by fixing aggregate volume, adjusting water cement ratio and additive content parameters and combining rheological experiments, and the self-compacting concrete is designed to form a classical 5-large proportioning theory system, namely, 1) an empirical proportioning method through proportioning parameter adjustment and working performance test, 2) a proportioning design method based on a compressive strength and proportioning proposal section, 3) a proportioning design method based on aggregate particle filling rate theory and filling compaction degree, 4) a statistical analysis model based on experimental data, and 5) a slurry rheological model based on surplus slurry property and thickness, wherein the theory system is in a standard and guide level, and an empirical proportioning reference section is provided for the self-compacting concrete proportioning. The concrete/self-compacting concrete reinforced by the sand aggregate has insufficient toughness, is easy to be broken and cracked when being pulled, and particularly is easy to be broken and cracked at stress concentration positions such as joints, corners and the like when being applied to an assembled underground structure, so that the durability of the structure is obviously reduced. Aiming at the problem, the toughness of the matrix can be enhanced by externally doping fibers in the concrete, so that the cracking resistance of the concrete structure is improved. After the fiber is added, the dosage of coarse aggregate can be slightly adjusted to meet the workability requirement for the traditional vibrating concrete, but the self-compaction effect is achieved, the filling performance, stability, clearance passing performance and other working performance requirements of the concrete mixture are extremely high, and the fiber is doped to cause the degradation of the framework grain composition, so that the working performance of the freshly mixed concrete mixture is greatly reduced. Therefore, when preparing the fiber self-compacting concrete, the original self-compacting concrete mixing proportion needs to be greatly blended so as to meet the workability requirement. However, for fiber concrete, no standardized proportioning design guidelines or suggestions exist at present, and no good reference basis exists. In early researches, the mix proportion of the self-compacting steel fibers is mostly carried out by adopting an empirical test mode, for example, gru newald introduces early research concepts and achievements such as fiber disturbance volume, fiber equivalent particle diameter, maximum fiber doping amount, and the like, the aggregate particles of the self-compacting fiber concrete are subjected to trial adjustment, the maximum doping amount of corresponding fibers is controlled, 10 designed mix proportion is subjected to comparative screening by combining a test means, so as to obtain the mix proportion of the self-compacting fiber concrete meeting the working performance, and Jen proposes a three-step empirical design method of the fiber self-compacting concrete, namely, the base mix proportion adopts the high-flow self-compacting concrete with slump flow expansion of about 700mm, the filling performance reduction caused by the doped fibers is slowed down by increasing the sand ratio and the mortar volume, and the additive configuration is optimized to further increase the filling performance. However, the method is usually carried out aiming at specific materials, a large amount of early test researches are needed to determine related parameters and mixing ratios, the method cannot be directly adopted when the fiber doping amount and the fiber type are adjusted, and the popularization and application difficulty in practical engineering is high. Thanks to the deep cognition of the rheological property of the self-compacting concrete mixture and the proposal of a slurry rheological mixing proportion design method, researchers gradually bring the self-compacting fiber concrete into the proportion design system, ferrara processes steel fibers into spherical aggregates with equal area through a specific surface area equivalent method, a fiber equivalent particle size calculation method is provided, the calculation method is brought into aggregate particle grading, and a minimum slurry thickness calculation method based on a slurry rheological mode