CN102923997B - 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 strong concrete of partly regenerating more than 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 normal concrete, prepared a kind of regeneration concrete with regenerated coarse aggregate.The concrete from demolishing buildings through manual sort, fragmentation, cleaning, classification, the regeneration aggregate that forms continuous grading replaces natural aggregate, a large amount of building wastes are not only processed, its pollution to environment and the waste of land resources are reduced, and rubbish is re-used to Practical Project, save natural sandstone consumption.Therefore regeneration concrete is a kind of green building product can efficient circulation utilizing.The research of regeneration concrete and application are more and more received to the concern of Chinese scholars.

But, because regeneration aggregate itself has the characteristic that is different from natural aggregate, 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; In regeneration aggregate, contain the impurity such as more silt particle.These characteristics produce adverse influence to the intensity of regeneration concrete, and under identical proportioning, the intensity of regeneration concrete is generally lower than normal concrete.To mixture ratio design of recycled aggregate concrete, generally, with reference to the method for design of normal concrete, some scholars propose to adopt the closely knit method of stonestone frame at present, and the present invention is with reference to adopting absolute volume legal system for regeneration concrete on 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 by adding silicon ash to prepare regenerated coarse aggregate concrete more than C60 at present.For the proportion research deficiency of present High Strength Regenerated Concrete, the present invention by adding appropriate first level flour coal ash and breeze (>=S95) in proportioning, prepare serviceability good, early strength is high, 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

The object of the invention is to solve existing half regenerated coarse aggregate concrete strength low, can not meet the problem of actual requirement of engineering, based on two technology of mixing of absolute volume method, prepare serviceability good, early strength is high, later strength development is fast, and the slump meets large fluidity high strength half regenerated coarse aggregate concrete that can pumping requirement.The present invention mixes appropriate first level flour coal ash and super finely ground slag (>=S95) in adopting and add high efficiency water reducing agent (water-reducing rate >=25%) in proportioning, under the condition of low water binder ratio, improve concrete workability and improve 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, comprises the following steps:

(1) determine each material consumption,

First determine the consumption of cement; One-level doping quantity of fly ash, with reference to normal concrete, adopts exceeding quantity coefficient method of substitution, and 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%; 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 (can determine or (JGJ55-2011) value of middle sand coarse aggregate ratio of reference " normal concrete design discipline " by practical experience) of normal concrete, does not have historical experience sand coarse aggregate ratio to fill coarse aggregate space by sand, and slight surplus, calculates by 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 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 the definite each 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 stirrer internal surface is wetting, then regenerated coarse aggregate is added in stirrer, open stirrer and a part of water is evenly added and in stirrer, stirs 2-3 minute.

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

According to practical situation, do not meet service requirements in step (4) if stir mobility after 5-10 minute, also can comprise the steps: again that the high efficiency water reducing agent of (5) interpolation flyash, breeze, cement total mass 0.1%-0.2% stirs; After adding high efficiency water reducing agent, also do not meet the demands, the water that adds flyash, breeze, cement total mass 1%-3% regulates its mobility.The concrete mixture of half regenerated coarse aggregate is left standstill to 20 points of left and right, observe the loss of its slump.If the slump meets service requirements, by the mixture moulding of vibrating.In above-mentioned steps (5) if basis on the slump do not meet service requirements, repeating step (5) again.

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

Compared with preparing half regenerated coarse aggregate concrete with existing method, the present invention has following features

1 reduces under agent efficient, adopts and adds first level flour coal ash and breeze (>=S95) Composite Double to mix technology.Add efficient minimizing agent, effectively reduce water-cement ratio, this is to obtain strong concrete prerequisite; Add first level flour coal ash to improve concrete workability; Add breeze (>=S95), excited cement activity, improves concrete strength.Under the condition of low water binder ratio, obtain large mobile concrete, 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 applied by engineering.

3, regeneration aggregate be there is no except particle diameter to strict especially requirement, suitability of the present invention is more extensive.

Embodiment

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

Embodiment 1

Choosing of 1 material

Preferentially choose the regeneration aggregate of particle diameter continuous grading within the scope of 5-25mm, water-intake rate 3.23%, water ratio 1%, crush index 12.51%, apparent density 2290kg/m3, porosity 44.3%.Preferentially choose the general aggregate of particle diameter in 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, between 5%-9%, contains stone rate 15%-25%, apparent density 2670kg/m3.Silver water breeze (S95) apparent density 1227kg/m3.42.5 grades of northern water cements, 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) determine 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 use of cement measures 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 to 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 as table 1-2.

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

315L half regeneration concrete trial mix process

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

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

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

(4) if mobility 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 after adding high efficiency water reducing agent (water-reducing rate 28%), and the water that adds the 1%-3% of glue material total amount regulates its mobility.The concrete mixture of half regenerated coarse aggregate is left standstill to 20 points of left and right, observe the loss of its slump.If the slump meets service requirements, by the mixture moulding of vibrating.

(5) if the slump does not meet 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, respectively organize half regeneration concrete 1m ³proportioning is as table 1-3; 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

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, comprises the following steps:

(1) determine that first each material consumption determine the consumption of cement; One-level doping quantity of fly ash, with reference to normal concrete, adopts exceeding quantity coefficient method of substitution, and 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%; 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 coarse aggregate space, and slight surplus, calculates by 1-1 formula; 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 the definite each 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 stirrer internal surface is wetting, then regenerated coarse aggregate is added in stirrer, open stirrer and a part of water is evenly added and in stirrer, stirs 2-3 minute;

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

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

3. according to the method for claim 2, it is characterized in that, in above-mentioned steps (5) if basis on the slump do not meet 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 within the scope of the preferred 5-25mm 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%.