CN104591643A - Preparation method of expansion rate-controllable steel pipe and steel-slag concrete column - Google Patents

Abstract

The invention discloses a preparation method of an expansion rate-controllable steel pipe and steel-slag concrete column, and belongs to the technical field of civil engineering. The method is that steel-slag sand is used for replacing all fine aggregates, and ordinary portland cement, steel-slag sand, gravels and water are utilized to prepare the expansion rate-controllable steel pipe and steel-slag concrete column. The method specifically comprises the preparation steps of selecting a steel pipe and steel-slag concrete at a certain strength grade according to the requirement of the bearing capacity of the steel pipe and steel-slag concrete column; determining self stress of the steel pipe; calculating to determine the free expansion rate of the slag-steel concrete; calculating to determine the average particle size of the steel-slag stand; selecting the steel-slag sand with reasonable graduation; calculating to determine the quantity of the used portland cement, the steel-slag sand, the gravels and the water according to a design method of a mixing ratio of ordinary concrete; and preparing the steel pipe and steel-slag concrete column, pouring the steel pipe and steel-slag concrete column and maintaining the steel pipe and steel-slag concrete column. With the adoption of the prepared steel pipe and steel-slag concrete column, the core concrete can early be in a three-directional pressing state, and therefore, the bearing capacity and ductility of the steel pipe concrete can be obviously improved.

Description

A kind of preparation method of steel pipe steel slag concrete post of controllable expansion rate

Technical field

The invention belongs to technical field of civil engineering, be specifically related to a kind of preparation method of steel pipe steel slag concrete post of controllable expansion rate, this coupled column is applicable to the rod structure in covil construction, industrial premises and bridge structure.

Background technology

Steel core concrete column has the advantages such as bearing capacity is high, anti-seismic performance good, easy construction, is used widely in field of civil engineering.But, in steel core concrete column, because core concrete can produce volumetric shrinkage in setting and harden process, the cohesive force caused between steel pipe and core concrete is declined, have a strong impact on every mechanical property of steel core concrete column.

At present, it is mix swelling agent in core concrete that conventional solution mainly contains two kinds: one, swelling agent mix the early expansion being only conducive to core concrete, owing to lacking moisture in later stage core concrete, will cause between steel pipe and core concrete occur bonding depart from.Two is in core concrete, mix the admixture and adulterant that ensure late expansion, and on the one hand, mixing of admixture, increases construction cost and difficulty; On the other hand, adding of adulterant, make concrete sclerosis and hydration process more complicated, be difficult to the best effect reaching expection.

A kind of industrial residue produced when slag is steel-making, it had both had certain hardness and fineness, had again certain activity.Therefore, available Steel-slag is for the fine aggregate in concrete, form steel pipe steel slag expansion concrete, not only solve the imbalance between supply and demand problem of natural aggregate, reduce construction costs, save natural resources, ensure the concrete expansion of steel pipe inner core again, make core concrete enter three dimension stress state in advance, significantly improve bearing capacity and the ductility of concrete filled steel tube.

Summary of the invention

The shortcoming that the present invention is directed to the existence of existing steel core concrete column expansion technique method, with not enough, provides a kind of preparation method of steel pipe steel slag concrete post of controllable expansion rate.The present invention makes full use of the lateral reactivity of slag, overcomes prior art method and expands and the deficiencies such as admixture swelling agent, admixture or adulterant for producing, significantly reduce construction costs and difficulty of construction, meet the property indices requirement of Expansive Concrete Filled Steel Tube.

The preparation method of the steel pipe steel slag concrete post of a kind of controllable expansion rate of the present invention, it utilizes Steel-slag Sand to replace whole fine aggregate, adopt ordinary Portland cement, Steel-slag Sand, rubble and water to prepare the steel pipe steel slag concrete post of controllable expansion rate, specifically comprise the following steps:

(1) according to the requirement of steel pipe steel slag concrete columns bearing capacity, select steel pipe and the steel slag concrete of some strength grade, calculate the steel pipe seif-citing rate σ produced because steel slag concrete expands according to formula (1) _e.

$N=(1+3\frac{{\mathrm{\σ}}_e}{f_{\mathrm{co}}})A_c{f}_{\mathrm{co}}(1+1.5\mathrm{\θ})---\left(1\right)$

Wherein: N is steel pipe steel slag concrete columns bearing capacity;

A _cfor core concrete section area;

F _cofor steel slag concrete ultimate compression strength;

θ is the constraint transformation of steel pipe to core concrete, a _sand f _ybe respectively section area and the yield strength of steel pipe.

(2) the seif-citing rate σ of the steel pipe determined according to step (1) _e, the degree of free swelling ε of steel slag concrete is calculated according to formula (2) _c.

${\mathrm{\ϵ}}_c=\frac{{\mathrm{\σ}}_e}{E_s}\·\frac{\mathrm{\ω}{E}_c+E_s}{E_c}---\left(2\right)$

Wherein: E _cfor concrete Young's modulus;

E _sfor the Young's modulus of steel pipe;

r and t is respectively the radius of core concrete and the wall thickness of steel pipe.

(3) by carrying out regression analysis to the data in accompanying drawing 1, the relation between steel slag concrete rate of expansion and Steel-slag Sand median size can be obtained, as shown in formula (3).According to the rate of expansion of the steel pipe steel slag concrete that step (2) is determined, calculate the median size of Steel-slag Sand according to formula (3), then select the Steel-slag Sand of rational gradation composition.

$D_m=0.063{\mathrm{\ϵ}}_c^2-0.307{\mathrm{\ϵ}}_c+0.609---\left(3\right)$

Wherein: D _mfor the median size of Steel-slag Sand.

(4) according to the method for design of common concrete proportioning, the consumption determining silicate cement, Steel-slag Sand rubble and water can be calculated, then silicate cement, Steel-slag Sand and rubble be put into concrete mixer and stir 60 ~ 70 seconds in advance.

(5) evenly poured into by water in the steel slag concrete after step (4) process and stir, measure the slump of steel slag concrete, increase additional water consumption, additional water consumption is 50 ~ 100kg/m ³, what make it meet steel slag concrete builds requirement.

(6) steel slag concrete be stirred is poured in steel pipe, and fully vibrate with vibrating spear, to ensure the density of steel slag concrete.

(7) for preventing the loss of moisture in steel pipe steel slag concrete post in maintenance processes, ensure the expansion of free CaO in further hydration reaction process in slag, one deck epoxy resin is coated with on the steel pipe steel slag concrete column end surface of having built, maintenance certain hour, to its complete setting and harden, can make steel pipe steel slag concrete produce the swell increment of expection.

Compared with prior art, the present invention has the following advantages:

(1) slag is a kind of industrial residue produced in steelmaking process, utilizes slag to replace fine aggregate in concrete, not only can save natural aggregate, avoid environment and natural resources to wreck, and can solve the problem such as disposal of solid waste.

(2) Steel-slag Sand has certain water-intake rate, the self-constriction of steel slag concrete hydrated product can be reduced on the one hand, in hydration process, the aquation that portion of water is beneficial to the free CaO later stage in slag can be discharged afterwards to a certain extent by water consumption on the other hand, make full use of the expansion character of slag.

(3) free CaO isoreactivity material is contained in slag, volumetric expansion will be produced in concrete coagulation process of setting, make the core concrete in steel pipe enter three dimension stress state in advance, form steel pipe active constraint core concrete, bearing capacity and the ductility of concrete filled steel tube can be significantly improved.

(4) the present invention overcomes the deficiency that existing expansion of steel pipe concrete technological method exists, do not need to add swelling agent or adulterant in concrete, the construction costs of remarkable reduction concrete filled steel tube and difficulty of construction, have good economic benefit and social benefit.

Accompanying drawing explanation

Fig. 1 is steel slag concrete degree of free swelling and Steel-slag Sand median size graph of a relation.

Embodiment

Below in conjunction with steel pipe steel slag concrete post specific examples, the present invention is described in detail.

Slag is a kind of industrial waste, the present invention selects slag to be horse steel slag, the chemical composition that employing X-ray fluorescence spectra analysis (XRF) records slag is as shown in table 1, as can be seen from Table 1, the chemical composition of slag is similar to cement, have certain hydraulically active, main mineral facies comprise C ₃s, C ₂s, RO, C ₂f is the principal element of the expansion that in steel pipe, steel slag concrete produces.The present invention adopts Steel-slag Sand to replace whole fine aggregate, utilizes the lateral reactivity of Steel-slag Sand, makes fully to expand in further hydration reaction process containing free CaO in slag, thus reaches the object that core concrete enters three dimension stress state in advance.In the present invention, the particle size range of Steel-slag Sand is 0.15 ~ 0.6mm, and fineness modulus controls 2.7 ~ 3.0, belongs to medium sand II district.

The chemical composition (%) of table 1 slag

Title	CaO	Fe2O3	SiO2	MgO	P2O5	MnO	Al2O3	TiO2	V2O5	SO3
											Slag	52.71	19.53	12.97	4.31	2.57	2.21	2.12	1.59	1.04	0.308
Standard deviation	0.25	0.20	0.17	0.10	0.08	0.07	0.07	0.06	0.05	0.015

Cement is the gelling material of steel slag concrete and the exciting agent of activity of steel slag, and the present invention adopts Ma'an Mountain's conch board ordinary Portland cement, and below C50 selects label to be 42.5 cement, and more than C50 selects label to be 52.5 cement.

Rubble is the coarse aggregate in the present invention, and the present invention selects the rubble of the interval particle diameter of 5 ~ 31.5mm continuous grading, and wherein 4.75 ~ 16mm accounts for 20%, and 16 ~ 31.5mm rubble accounts for 80%, and the apparent density of rubble is 2690kg/m ³.

Water is mainly used in the concrete mix of steel slag expansion and maintenance, and normally must not condense containing affect cement in water and the detrimental impurity of sclerosis, every tap water that can drink and the natural water cleaned, can be used for mixing and maintenance steel slag concrete.On the basis of mix-design water consumption, increase certain additional water consumption, additional water consumption is 50 ~ 100kg/m ³.

Steel pipe adopts the weldless steel tube of Q235, and diameter of steel tube D is 140mm, the height L of steel pipe is respectively 500,1000,1500mm, the wall thickness t of steel pipe is respectively 2.1mm, and the yield strength of steel pipe is 176MPa, and steel tube elastic modulus is 2 × 10 ⁵mPa, steel pipe Poisson's ratio is 0.297.

On the basis determining each material behavior of steel pipe steel slag concrete post, according to the step (1) in the preparation method of steel pipe steel slag concrete, select the steel pipe of Q235 and the steel slag concrete of C20, calculate the seif-citing rate σ of steel pipe according to formula (1) _efor 1.42MPa; The degree of free swelling ε of steel slag concrete is calculated according to step (2) _cbe 2.8 × 10 ^-4; Calculate according to step (3) and determine that the median size of Steel-slag Sand is 0.243mm, wherein the Steel-slag Sand of the interval particle diameter of 0.15 ~ 0.3mm grating accounts for 75%, and the interval particle diameter Steel-slag Sand of 0.3 ~ 0.6mm grating accounts for 25%; Calculate according to step (4) and determine that the proportioning of each component of steel slag concrete is as shown in table 2; According to step (5) preparation steel slag concrete, required additional water consumption is 80kg/m ³, recording steel slag concrete slump is 400mm, and what meet steel slag concrete builds requirement; Then build according to step (6) ~ (7), maintenance steel pipe steel slag concrete post.

Table 2 steel pipe steel slag expansion concrete mix

Table 3 is steel pipe steel slag concrete columns bearing capacity test-results.As can be seen from the table, compared with common steel tube concrete column, steel pipe steel slag concrete post surrender bearing power increase amplitude of the present invention is 8% ~ 27%, and ultimate bearing capacity increase rate is 10% ~ 24%.Therefore, the present invention not only significantly improves the bearing capacity of component, and makes full use of solid waste, reduces environmental pollution, significantly reduces construction costs, have good technique effect.

Table 3 steel pipe steel slag concrete columns bearing capacity test-results

Note: N in table _{u0 bends}and N _u0be respectively surrender bearing capacity and ultimate bearing capacity that test specimen calculates according to " concrete filled steel tube technical regulation " (CECS28:2012), N _{ur bends}and N _urbe respectively test specimen actual measurement surrender bearing capacity and ultimate bearing capacity.

Claims (1)

1. the preparation method of the steel pipe steel slag concrete post of a controllable expansion rate, it is characterized in that, utilize Steel-slag Sand to replace whole fine aggregate, adopt ordinary Portland cement, Steel-slag Sand, rubble and water to prepare the steel pipe steel slag concrete post of controllable expansion rate, specifically comprise the following steps:

(1) according to the requirement of steel pipe steel slag concrete columns bearing capacity, select steel pipe and the steel slag concrete of some strength grade, calculate the steel pipe seif-citing rate σ produced because steel slag concrete expands according to formula (1) _e;

$N=(1+3\frac{{\mathrm{\σ}}_e}{f_{\mathrm{co}}})A_c{f}_{\mathrm{co}}(1+1.5\mathrm{\θ})---\left(1\right)$

Wherein: N is steel pipe steel slag concrete columns bearing capacity;

A _cfor core concrete section area;

F _cofor steel slag concrete ultimate compression strength;

θ is the constraint transformation of steel pipe to core concrete, a _sand f _ybe respectively section area and the yield strength of steel pipe;

(2) the seif-citing rate σ of the steel pipe determined according to step (1) _e, the degree of free swelling ε of steel slag concrete is calculated according to formula (2) _c;

${\mathrm{\ϵ}}_c=\frac{{\mathrm{\σ}}_e}{E_s}\·\frac{{\mathrm{\ωE}}_c+E_s}{E_c}---\left(2\right)$

Wherein: E _cfor concrete Young's modulus;

E _sfor the Young's modulus of steel pipe;

r and t is respectively the radius of core concrete and the wall thickness of steel pipe;

(3) degree of free swelling of the steel slag concrete determined according to step (2), calculates the median size of Steel-slag Sand, then selects the Steel-slag Sand of rational gradation composition according to formula (3);

$D_m={0.063\mathrm{\ϵ}}_c^2-{0.307\mathrm{\ϵ}}_c+0.609---\left(3\right)$

Wherein: D _mfor the median size of Steel-slag Sand;

(4) according to the method for design of common concrete proportioning, the consumption determining silicate cement, Steel-slag Sand, rubble and water can be calculated, then silicate cement, Steel-slag Sand and rubble be put into concrete mixer and stir 60 ~ 70 seconds in advance;

(5) evenly poured into by water in the steel slag concrete after step (4) process and stir, measure the slump of steel slag concrete, increase certain additional water consumption, required additional water consumption is 50 ~ 100kg/m ³, what make it meet steel slag concrete builds requirement;

(6) steel slag concrete that step (5) is stirred is poured in steel pipe, and fully vibrate with vibrating spear, to ensure the density of steel slag concrete;

(7) for preventing the loss of moisture in steel pipe steel slag concrete post in maintenance processes, ensure the expansion of free CaO in further hydration reaction process in slag, one deck epoxy resin is coated with on the steel pipe steel slag concrete column end surface of having built, maintenance, to the complete setting and harden of steel slag concrete, can make steel pipe steel slag concrete produce the swell increment of expection.