CN102923997A - Method for preparing high-strength semi-regenerative coarse aggregate concretes - Google Patents

Abstract

The invention discloses a method for preparing high-strength semi-regenerative coarse aggregate concretes, and belongs to the technical field of regenerative coarse aggregate concretes. The preparation method comprises the step of preparing the high-performance semi-regenerative coarse aggregate concretes with good working performance, high early strength and good development in long-term strength by regulating the mixing amount of additives, mineral powder and coal ash in reference to the using amount of rubber materials of the common concretes.

Description

High more than half regenerated coarse aggregate preparation method of concrete

Technical field

The present invention relates to high more than half regenerated coarse aggregate preparation method of concrete, relate in particular under high efficiency water reducing agent, adopt the Composite Double of admixture first level flour coal ash and breeze to mix technology, the above strong concrete of partly regenerating of preparation 50Mpa belongs to regenerated coarse aggregate concrete technology field.

Technical background

Half regenerated coarse aggregate concrete is to replace 30%-50% natural aggregate in the normal concrete, prepared a kind of regeneration concrete with regenerated coarse aggregate.From the concrete of demolishing buildings through manual sort, fragmentation, cleaning, classification, the regeneration aggregate that forms continuous grading replaces natural aggregate, a large amount of building wastes have not only been processed, reduced it to the pollution of environment and the waste of land resources, and rubbish re-used Practical Project, saved natural sandstone consumption.Therefore but regeneration concrete is the green building product that a kind of efficient circulation is utilized.To the research of regeneration concrete with use the concern that more and more is subject to Chinese scholars.

Yet, because regeneration aggregate itself has the characteristic that is different from natural aggregate, such as the crack that regeneration aggregate produces in shattering process, make the crush index of regeneration aggregate low; The original old grout of regeneration aggregate surface attachment makes the porosity of regeneration aggregate higher than natural aggregate; Contain the impurity such as more silt particle in the regeneration aggregate.These characteristics produce adverse influence to the intensity of regeneration concrete, and under identical proportioning, the intensity of regeneration concrete generally is lower than normal concrete.To mixture ratio design of recycled aggregate concrete, generally with reference to the method for design of normal concrete, the scholar who has proposes to adopt the closely knit method of stonestone frame at present, and the present invention is with reference to adopting the standby regeneration concrete of absolute volume legal system on the normal concrete cement amount basis.The intensity of the regeneration concrete that existing domestic scholars is prepared is generally below C40, and to high-intensity regenerated coarse aggregate concrete preparation seldom, American scholar is prepared regenerated coarse aggregate concrete more than the C60 by adding the silicon ash at present.Proportion research for present High Strength Regenerated Concrete is not enough, the present invention is by adding an amount of first level flour coal ash and breeze (〉=S95) in proportioning, it is good to prepare serviceability, early strength is high, the later strength development is fast, the high more than half regenerated coarse aggregate concrete concrete of ultimate compression strength more than 50Mpa.

Summary of the invention

It is low to the object of the invention is to solve existing half regenerated coarse aggregate concrete strength, can not satisfy the problem of actual requirement of engineering, two technology of mixing based on the absolute volume method, it is good to prepare serviceability, early strength is high, the later strength development is fast, but the slump meets the large fluidity high strength half regenerated coarse aggregate concrete of pumping requirement.The present invention mixes an amount of first level flour coal ash and super finely ground slag (〉=S95) when adopting and adding high efficiency water reducing agent (water-reducing rate 〉=25%) in proportioning, under the condition of low water binder ratio, improves concrete workability and improves ultimate compression strength.

The technical solution used in the present invention is as follows for achieving the above object.

High more than half regenerated coarse aggregate preparation method of concrete may further comprise the steps:

(1) determine each material consumption,

At first determine the consumption of cement; The one-level doping quantity of fly ash adopts the exceeding quantity coefficient method of substitution with reference to normal concrete, and the first level flour coal ash replaces cement quality 10%-30%, and first level flour coal ash exceeding quantity coefficient is got 1.1-1.2; Contents of ground slag accounts for cement quality 10%-25%; The high efficiency water reducing agent consumption accounts for binder total amount 1.8%-3%, the preferred water reducer water-reducing rate 28% of described high efficiency water reducing agent; C65 half regenerated coarse aggregate water-binder ratio is controlled between 0.28-0.33, every cubic metre of cement consumption 450kg-500kg; C60 half regenerated coarse aggregate water-binder ratio between 0.34-0.39, every cubic meter of concrete cement consumption 350kg-400kg; C55 half regenerated coarse aggregate water-binder ratio between 0.40-0.45, every cubic meter of concrete cement consumption 300kg-350kg; Sand coarse aggregate ratio adopt normal concrete sand coarse aggregate ratio (can by practical experience determine or with reference to " normal concrete design discipline " (JGJ55-2011) in the value of sand coarse aggregate ratio), do not have the historical experience sand coarse aggregate ratio to fill the coarse aggregate space by sand, and slight surplus, press the calculating of 1-1 formula.

${\mathrm{\β}}_s=\mathrm{\α}\frac{P_g{\mathrm{\ρ}}_s}{P_g{\mathrm{\ρ}}_s+{\mathrm{\ρ}}_g}---1-1$

β _s-sand coarse aggregate ratio

ρ _s-sand apparent density

ρ _g-coarse aggregate apparent density

P _g-coarse aggregate porosity

α-push coefficient aside adopts machinery to vibrate and gets 1.1-1.2, manually vibrates and gets 1.2-1.4;

$\frac{m_{\mathrm{co}}}{{\mathrm{\ρ}}_c}+\frac{m_{\mathrm{go}1}}{{\mathrm{\ρ}}_{g1}}+\frac{m_{\mathrm{go}2}}{{\mathrm{\ρ}}_{g2}}+\frac{m_{\mathrm{so}}}{{\mathrm{\ρ}}_s}+\frac{m_{\mathrm{fo}}}{{\mathrm{\ρ}}_f}+\frac{m_{\mathrm{ko}}}{{\mathrm{\ρ}}_k}+\frac{m_{\mathrm{wo}}}{{\mathrm{\ρ}}_w}+10a=1000---1-2$

${\mathrm{\β}}_s=\frac{m_{\mathrm{so}}}{m_{\mathrm{so}}+m_{\mathrm{go}1}+m_{\mathrm{go}2}}---1-3$

m _Co, m _Go1, m _Go2, m _So, m _Fo, m _Ko, m _Wo-be respectively every cubic meter of concrete cement, coarse aggregate, regenerated coarse aggregate, sand, flyash, breeze, the quality of water,

ρ _c, ρ _G1, ρ _G2, ρ _s, ρ _f, ρ _k, ρ _w-be respectively cement, coarse aggregate, regenerated coarse aggregate, sand, flyash, breeze, the density of water,

A-Air Content of Air-entrained Concrete percent by volume does not add air entrapment agent a=1,

β _s-sand coarse aggregate ratio;

Above-mentioned first level flour coal ash technical requirement is such as table 1-1

Fineness	Water demand ratio	Loss on ignition	Water ratio	Sulfur trioxide content
					<=12%	<=95	<=5%	<=11%	<=3%

(2) according to the theoretical consumption of each definite material of step (1), then calculate again the consumption proportion of actual each material according to the water ratio of actual measurement sand and coarse aggregate.

(3) first that the stirrer internal surface is wetting, then regenerated coarse aggregate is added in the stirrer, open stirrer and the water of a part evenly added in the stirrer and stirred 2-3 minute.

(4) after the regenerated coarse aggregate suction, then coarse aggregate, sand, flyash, breeze, cement are added in the stirrer, open stirrer, high efficiency water reducing agent is added to the water mixes, then water is slowly added in the stirrer and stir.

According to practical situation, flowability does not meet service requirements after 5-10 minute if stir in step (4), can comprise the steps: that also the high efficiency water reducing agent of (5) interpolation flyash, breeze, cement total mass 0.1%-0.2% stirs again; Also do not meet the demands after adding high efficiency water reducing agent, add the water of flyash, breeze, cement total mass 1%-3% and regulate its flowability.The concrete mixture of half regenerated coarse aggregate was left standstill about 20 minutes, observe the loss of its slump.If the slump satisfies service requirements, with the mixture moulding of vibrating.In above-mentioned steps (5) if the basis on the slump do not satisfy service requirements, repeating step (5) again.

The regeneration aggregate of continuous grading in the preferred 5-25mm scope of regeneration aggregate,

Prepare half regenerated coarse aggregate concrete with existing method and compare, the present invention has following features

1 under efficient minimizing agent, adopts adding first level flour coal ash and breeze (〉=S95) Composite Double to mix technology.Add the efficient agent that reduces, effectively reduce water-cement ratio, this is to obtain the strong concrete prerequisite; Add the first level flour coal ash and improve concrete workability; Add breeze (〉=S95), excited cement is active, improves concrete strength.Under the condition of low water binder ratio, obtain the large concrete that flows, overcome the low shortcoming of intensity of regeneration concrete.

2 under the glue material total amount condition suitable with normal concrete, has improved the intensity of regeneration concrete, has reduced the cost of regeneration concrete, makes that regeneration concrete is easier to be used by engineering.

3, regeneration aggregate is not had strict especially requirement except particle diameter, suitability of the present invention is more extensive.

Embodiment

Based on above method steps, prepared 7 group of half regenerated coarse aggregate concrete, measure the ultimate compression strength of the concrete 3d of half regenerated coarse aggregate, 7d, 28d.Intensity reached 50% of 28 days intensity in 3 days, intensity reached 28 days intensity 70% in 7 days, satisfy engineering to the requirement of early age strength of concrete, half regenerated coarse aggregate concrete crushing strength was all more than 50Mpa in 28 days, intensity is up to 75.1Mpa, significantly improves the existing concrete intensity of half regenerated coarse aggregate.

Embodiment 1

Choosing of 1 material

Preferentially choose the regeneration aggregate of particle diameter continuous grading in the 5-25mm scope, water-intake rate 3.23%, water ratio 1%, crush index 12.51%, apparent density 2290kg/m3, porosity 44.3%.Preferentially choose particle diameter at the general aggregate of 5-25mm continuous grading, water ratio 1%, apparent density 2760kg/m3.Xingda's first level flour coal ash, density 2300kg/m3.Sand is nature medium sand, and water ratio contains stone rate 15%-25%, apparent density 2670kg/m3 between 5%-9%.Silver water breeze (S95) apparent density 1227kg/m3.42.5 the northern water cement of level, apparent density 3100kg/m3.High-efficiency water-reducing agent of poly-carboxylic acid (water-reducing rate 28%) density 1130kg/m3, solid content 10%.Water is tap water, density 1000kg/m3.

2 mix calculations

(1) determines sand coarse aggregate ratio

Try to join the actual sand coarse aggregate ratio of experience according to history and get 47%.

(2) determine cement amount and water-cement ratio

Every cubic metre of usefulness of cement is measured 420kg, first level flour coal ash replacement rate 15%, and exceeding quantity coefficient 1.13, cement consumption 356kg/m3 after replacing,, breeze (S95) adds 13.5% of cement quality, and water-cement ratio gets 0.37, high efficiency water reducing agent (water-reducing rate 28%) consumption 2.1%.

(3) calculate sand consumption, common coarse aggregate and regenerated coarse aggregate consumption

Step (1), (2) are drawn gel material content, water consumption and high efficiency water reducing agent (water-reducing rate 28%) consumption substitution formula 1-2, and 1-3 calculates sand, natural coarse aggregate and regenerated coarse aggregate consumption.

(4) half regenerated coarse aggregate theoreticals mix of concrete and actual proportioning

The actual water ratio 6.7% of sand, high efficiency water reducing agent (water-reducing rate 28%) solid content 10%.Theoretical proportioning is converted into actual proportioning such as table 1-2.

Table 1-2 half regenerated coarse aggregate concrete mix (unit: kg)

315L half regeneration concrete trial mix process

(1) takes by weighing the quality of each raw material of 15L according to table 1-2.

(2) first that the stirrer internal surface is wetting, then regenerated coarse aggregate is added in the stirrer, open stirrer and the water of a part evenly added in the stirrer and stirred 2-3 minute.

(3) the regenerated coarse aggregate suction is after 10 minutes, successively common coarse aggregate, sand, gelling material are added in the stirrer, open stirrer, high efficiency water reducing agent (water-reducing rate 28%) is added to the water mixes, then water is slowly added in the stirrer, and observe the performance of mixture.Stir after 5-10 minute, observe flowability and the water-retentivity of mixture.

(4) if flowability is too poor, the high efficiency water reducing agent (water-reducing rate 28%) that adds the 0.1%-0.2% of gelling material quality stirs, and does not also meet the demands behind the adding high efficiency water reducing agent (water-reducing rate 28%), adds the water of the 1%-3% of glue material total amount and regulates its flowability.The concrete mixture of half regenerated coarse aggregate was left standstill about 20 minutes, observe the loss of its slump.If the slump satisfies service requirements, with the mixture moulding of vibrating.

(5) if the slump does not satisfy service requirements, repeating step (4).

Embodiment 2-7

Embodiment 2-7 half regenerated coarse aggregate concrete preparation, the choosing of material, mix calculation are substantially the same manner as Example 1, calculate according to step 2, and each organizes half regeneration concrete 1m ³Proportioning is such as table 1-3; The trial mix process is with step 3.

Table 1-3 embodiment 2-7 organizes half regenerated coarse aggregate concrete concrete mix

Embodiment 1-7 half regenerated coarse aggregate concrete crushing strength measured value

Table 1-4 embodiment 1-7 half regenerated coarse aggregate concrete 3 days, 7 days and 28 days intensity measurement values

The proportioning numbering	3 days ultimate compression strength/Mpa	7 days ultimate compression strength/Mpa	28 days ultimate compression strength/Mpa
				Embodiment 1	31.3	40.9	61.7
Embodiment 2	28.3	31.0	53.4
				Embodiment 3	32.9	46.0	58.9
Embodiment 4	38.4	46.0	64.1
				Embodiment 5	41.7	51.7	68.5
Embodiment 6	50.3	60.0	75.1
				Embodiment 7	49.1	57.2	74.4

Claims (6)

1. high more than half regenerated coarse aggregate preparation method of concrete is characterized in that, may further comprise the steps:

(1) determines each material consumption

At first determine the consumption of cement; The one-level doping quantity of fly ash adopts the exceeding quantity coefficient method of substitution with reference to normal concrete, and the first level flour coal ash replaces cement quality 10%-30%, and first level flour coal ash exceeding quantity coefficient is got 1.1-1.2; Contents of ground slag accounts for cement quality 10%-25%; The high efficiency water reducing agent consumption accounts for binder total amount 1.8%-3%, the preferred water reducer water-reducing rate 28% of described high efficiency water reducing agent; C65 half regenerated coarse aggregate water-binder ratio is controlled between 0.28-0.33, every cubic metre of cement consumption 450kg-500kg; C60 half regenerated coarse aggregate water-binder ratio between 0.34-0.39, every cubic meter of concrete cement consumption 350kg-400kg; C55 half regenerated coarse aggregate water-binder ratio between 0.40-0.45, every cubic meter of concrete cement consumption 300kg-350kg; Sand coarse aggregate ratio adopts the sand coarse aggregate ratio of normal concrete or presses sand and fill the coarse aggregate space, and slight surplus, presses the 1-1 formula and calculates; Then the 30-50% that accounts for the total mass of regenerated coarse aggregate and aggregate according to 1-2 and 1-3 and regenerated coarse aggregate calculates each material magnitude relation;

${\mathrm{\β}}_s=\mathrm{\α}\frac{P_g{\mathrm{\ρ}}_s}{P_g{\mathrm{\ρ}}_s+{\mathrm{\ρ}}_g}---1-1$

β _s-sand coarse aggregate ratio

ρ _s-sand apparent density

ρ _g-coarse aggregate apparent density

P _g-coarse aggregate porosity

α-push coefficient aside adopts machinery to vibrate and gets 1.1-1.2, manually vibrates and gets 1.2-1.4;

$\frac{m_{\mathrm{co}}}{{\mathrm{\ρ}}_c}+\frac{m_{\mathrm{go}1}}{{\mathrm{\ρ}}_{g1}}+\frac{m_{\mathrm{go}2}}{{\mathrm{\ρ}}_{g2}}+\frac{m_{\mathrm{so}}}{{\mathrm{\ρ}}_s}+\frac{m_{\mathrm{fo}}}{{\mathrm{\ρ}}_f}+\frac{m_{\mathrm{ko}}}{{\mathrm{\ρ}}_k}+\frac{m_{\mathrm{wo}}}{{\mathrm{\ρ}}_w}+10a=1000---1-2$

${\mathrm{\β}}_s=\frac{m_{\mathrm{so}}}{m_{\mathrm{so}}+m_{\mathrm{go}1}+m_{\mathrm{go}2}}---1-3$

m _Co, m _Go1, m _Go2, m _So, m _Fo, m _Ko, m _Wo-be respectively every cubic meter of concrete cement, coarse aggregate, regenerated coarse aggregate, sand, flyash, breeze, the quality of water;

ρ _c, ρ _G1, ρ _G2, ρ _s, ρ _f, ρ _k, ρ _w-be respectively cement, coarse aggregate, regenerated coarse aggregate, sand, flyash, breeze, the density of water;

A-Air Content of Air-entrained Concrete percent by volume does not add air entrapment agent a=1;

β _s-sand coarse aggregate ratio;

(2) according to the theoretical consumption of each definite material of step (1), then calculate again the consumption proportion of actual each material according to the water ratio of actual measurement sand and coarse aggregate;

(3) first that the stirrer internal surface is wetting, then regenerated coarse aggregate is added in the stirrer, open stirrer and the water of a part evenly added in the stirrer and stirred 2-3 minute;

(4) after the regenerated coarse aggregate suction, then common coarse aggregate, sand, flyash, breeze, cement are added in the stirrer, open stirrer, high efficiency water reducing agent is added to the water mixes, then water is added in the stirrer and stir.

2. according to the method for claim 1, it is characterized in that, according to practical situation, flowability does not meet service requirements after 5-10 minute if stir in step (4), can comprise the steps: that also the high efficiency water reducing agent of (5) interpolation flyash, breeze, cement total mass 0.1%-0.2% stirs again; Also do not meet the demands after adding high efficiency water reducing agent, add the water of flyash, breeze, cement total mass 1%-3% and regulate its flowability.

3. according to the method for claim 2, it is characterized in that, in above-mentioned steps (5) if the basis on the slump do not satisfy service requirements, repeating step (5) again.

4. according to the method for claim 1, it is characterized in that the regeneration aggregate of continuous grading in the preferred 5-25mm scope of regeneration aggregate.

5. according to the method for claim 1, it is characterized in that breeze 〉=S95.

6. according to the method for claim 1, it is characterized in that high efficiency water reducing agent water-reducing rate 28%.