CN105272354A - Curing method for high-volume fly ash concrete - Google Patents

Abstract

The invention belongs to the technical field of concrete curing, and discloses a curing method for high-volume fly ash concrete. High-volume fly ash cement is uniformly stirred according to the specified water-binder ratio, the stirred concrete is loaded into a mold made of PEEK materials, and the molded concrete together with the mold is cured on the standard condition; the concrete together with the mold is covered with a plastic film1-2 h after final setting is performed on the concrete; the covered concrete is placed into a microwave oven, and microwave curing is performed according to the curing period of 'A*3+B*10+C*8'; after microwave curing is performed, the concrete is taken out, demolding is performed 3 h after the microwave curing is ended, the concrete is placed into a normal temperature chamber, and watering curing is performed for 3 d. When the same effect is achieved as steam heat curing, the method has the advantages of being short in curing period and low in energy consumption.

Description

A kind of maintenance process of high volume fly ash concrete

Technical field

The invention belongs to concrete pouring technical field, be specifically related to a kind of maintenance process of high volume fly ash concrete.

Background technology

Flyash is a kind of active admixture, and Substitute For Partial the reinforcement of concrete, in concrete, shows active effect, shape effect, micro aggregate effect and interfacial effect, can effectively improve concrete workability and weather resistance.Usually, it is 10 ~ 25wt% that flyash replaces concrete ratio, and in order to play economic benefit and the environmental protection effect of flyash by a larger margin, in 1985, CANMET proposes the concept of high volume fly ash concrete.But along with flyash replaces the increase of concrete ratio, the development of prefabricated component early strength is quite slow, thus cause site operation striking time to extend, the adverse consequencess such as the turnover of Prefabrication template is slow, had a strong impact on the enthusiasm that concrete production enterprise produces high volume fly ash concrete, the early strength therefore improving high volume fly ash concrete becomes the task of top priority.

For the feature that high volume fly ash concrete early strength is relatively low, from physics and chemistry angle, several approach improving high volume fly ash concrete early strength can be proposed: 1. mechanical activation flyash is that original state flyash is carried out the flyash after " benefitization " process through loading small grinder.The undressed levigate flyash of original state flyash general reference, original state flyash is after mechanical activation, and uniformity obtains larger improvement.2. chemical activation flyash is exactly the activity exciting flyash with chemical activator.In flyash concrete, conventional chemical activator has Na ₂sO ₄, CaSO ₄, CaCl ₂deng.For Class F fly ash, mix appropriate Na ₂sO ₄, CaCl ₂.3., on the basis of mechanical activation flyash, add chemical activator and be called multiplicity reactivation flyash.4. steam heat maintenance.5. change proportioning, reduce water-cement ratio.

Greatly, chemi-excitation can introduce harmful ion for mechanical grinding and steam heat maintenance power consumption.At present, for the deficiency that high volume fly ash concrete early strength is low, intensity is improved mainly through vapor cure.But vapor cure is a kind of common thermal curing measure, and its heat trnasfer transmits from outside to inside, heat transfer speed is slow, and thermo-efficiency is low, and correspondingly hear rate is large.In order to utilize flyash in great mixed amount better, the real effect playing its energy-conserving and environment-protective, is necessary the research carrying out other maintenance technology.

Summary of the invention

The object of the present invention is to provide the maintenance process of the high volume fly ash concrete that a kind of thermo-efficiency is high, energy consumption is little.

For achieving the above object, the present invention is by the following technical solutions:

A maintenance process for high volume fly ash concrete, its step is as follows:

(1) water-cement ratio of large-doping-amount fly ash cement by regulation is stirred, the concrete be stirred is loaded in the mould adopting PEEK material to make;

(2) concrete of forming is put into standard curing room maintenance at the standard conditions together with mould;

(3) 1-2h after concrete final set, adopts covered rearing with plastic film together with mould;

(4) concrete covered is put into microwave oven, carry out microwave curing by the curing cycle of " A × 3+B × 10+C × 8 "; Wherein, A, B, C represent respectively: A-and with hot 10s, stopping 2min is once; B-with hot 20s, stopping 5min is once; C-with hot 30s, stopping 3min is once; × digitized representation multiplicity ,+representative adds up successively;

(5) after microwave curing, take out concrete, the 3h demoulding after termination microwave curing, then put it in normal temperature room, watering maintenance 3 days.

Microwave technology is the hertzian wave that microwave oven sends, and can be absorbed by polar material (as water), be heat energy by electric energy conversion, play heat-cured effect from inside, thus improve heat utilization efficiency, compare vapor cure technology, when reaching same effect, significantly reduce hear rate.

High volume fly ash concrete refers to that flyash replaces the ratio of cement clinker between 40 ~ 60wt%; Early strength refers to ultimate compression strength during concrete 1d length of time; Microwave curing refers to adopt microwave technology to carry out maintenance to concrete.

The present invention adopts microwave curing high volume fly ash concrete, when reaching same effect with steam heat maintenance, not only has curing cycle short, and has the low advantage of power consumption.

Embodiment

Embodiment 1

A maintenance process for high volume fly ash concrete, its step is as follows:

(1) by 500g flyash, 500g Portland clinker, 320g water, put into clean slurry stirrer together to stir, the concrete be stirred is loaded in the mould adopting PEEK material to make, its specification is that 25mm × 25mm × 25mm(is long × wide × thick), in moulding process, vibration compacting should be noted;

(2) concrete of forming is put into standard curing room (temperature 20 ± 1 DEG C, humidity >=95%) maintenance at the standard conditions together with mould;

(3) 2h after concrete final set, adopts covered rearing with plastic film together with mould;

(4) concrete covered is put into microwave oven, carry out microwave curing by curing cycle different table 1 Suo Shi; Wherein, A, B, C represent respectively: A-and with hot 10s, stopping 2min is once; B-with hot 20s, stopping 5min is once; C-with hot 30s, stopping 3min is once; × digitized representation multiplicity ,+representative adds up successively;

(5) after microwave curing, take out concrete, the 3d demoulding after it is cooled to room temperature and stops microwave curing, is placed in normal temperature the maintenance 3d that sprinkles water, measures the ultimate compression strength in each length of time.

The Comparative result in different microwave curing cycle is in table 1.

As can be seen from Table 1, along with the prolongation in microwave curing cycle, the ultimate compression strength of test specimen increased before this, after reduce again, wherein when the microwave curing cycle is A × 3+B × 10+C × 8, the ultimate compression strength of test specimen is maximum, illustrate that this microwave curing cycle best, under this microwave curing cycle, the running time of microwave oven only about 8 minutes during microwave curing, namely not only to have curing cycle short for microwave curing, and there is the low advantage of power consumption, record the concrete product (time of distance blunge in each length of time, it is 47.9MPa that ultimate compression strength down together) is respectively 1d, 3d is 48.9MPa, 28d is 54.3Mpa.

Comparative example 2

For research " different maintenance method " impact on concrete product performance, make parallel check experiment with " normal curing, 60 DEG C of thermal curing 24h and A × 3+B × 10+D × 8 microwave curings ".

Normal curing: after cement, flyash and water being stirred, loads in the mould adopting PEEK material to make, and its specification is that 25mm × 25mm × 25mm(is long × wide × thick), in moulding process, should vibration compacting be noted; The concrete of forming is put into standard curing room (temperature 20 ± 1 DEG C, humidity >=95%) maintenance at the standard conditions together with mould, and maintenance is the demoulding immediately after one day, is then placed in normal temperature the maintenance 3d that sprinkles water, and measures the ultimate compression strength in each length of time.

60 DEG C of thermal curing 24h: after cement, flyash and water being stirred, load in the mould adopting PEEK material to make, and its specification is that 25mm × 25mm × 25mm(is long × wide × thick), in moulding process, should vibration compacting be noted; 2h after concrete final set, after adopting covered rearing with plastic film together with mould, put into 60 DEG C of environment and carry out thermal curing, the demoulding immediately after thermal curing 24h, is then placed in normal temperature the maintenance 3d that sprinkles water, and measures the ultimate compression strength in each length of time.

A × 3+B × 10+D × 8 microwave curing: step is with embodiment 1.

Different maintenance method Comparative result is in table 2.

As can be seen from Table 2, " A × 3+B × 10+D × 8 " microwave curing and 60 DEG C of thermal curings 24 hours are quite, comparison with standard maintenance, they all make early stage (1d, 3d) ultimate compression strength of test specimen significantly improve, wherein the ultimate compression strength of 1d is about 350% of normal curing, but later stage (28d) ultimate compression strength reduces, and the later stage is about 90% of normal curing.

Comparative example 3

For research " microwave curing time opening " impact on concrete performance, carry out maintenance by maintenance process described in embodiment 1, but make parallel check experiment with " different microwave curing time opening ", the results are shown in Table 3.

The contrast of table 3 microwave curing time opening

As can be seen from Table 3, if the microwave curing time opening too early, namely numbering 1 is initial set first 1 hour beginning microwave curing, then test specimen meeting cracking destruction, along with the prolongation starting the microwave curing time, namely from initial set first 1 hour, just during initial set, just during final set, after final set 1 hour, the ultimate compression strength of test specimen increases gradually, but after extending to 2 hours by after final set 1 hour upon start, the amplitude that the ultimate compression strength of test specimen increases is only 0.6%, can be considered as no longer increasing, therefore the Best Times starting microwave curing to should be after final set between 1 ~ 2 hour, if too early, easily cause the loss of strength of test specimen, if too late, the microwave curing cycle can be extended.

Comparative example 4

For the impact of research " whether coating film " on concrete product performance, carry out maintenance by maintenance process described in embodiment 1, but make parallel check experiment with " coating film " and " not coating film ", the results are shown in Table 4.

As can be seen from Table 4, after adopting plastic film covering, ultimate compression strength rises to 46.9MPa from 30.5MPa, namely increases 53.6%, namely has growth by a relatively large margin, and therefore suggestion adopts membrance curing.

Comparative example 5

For research " after the termination microwave curing demould time " impact on concrete product performance, maintenance is carried out by maintenance process described in embodiment 1, but make parallel check experiment with " demoulding in 30 minutes after stopping microwave curing " and " demoulding in 3 hours after stopping microwave curing ", the results are shown in Table 5.

As can be seen from Table 5, microwave curing terminates rear demould time and extended to 3 hours by 30 minutes, and the ultimate compression strength of test specimen increases 10.1%, and namely microwave curing should be more suitable the demoulding in 3 hours after terminating.

Claims (1)

1. a maintenance process for high volume fly ash concrete, is characterized in that its step is as follows:

(1) water-cement ratio of large-doping-amount fly ash cement by regulation is stirred, the concrete be stirred is loaded in the mould adopting PEEK material to make;

(2) concrete of forming is put into standard curing room maintenance at the standard conditions together with mould;

(3) 1-2h after concrete final set, adopts covered rearing with plastic film together with mould;

(4) concrete covered is put into microwave oven, carry out microwave curing by the curing cycle of " A × 3+B × 10+C × 8 "; Wherein, A, B, C represent respectively: A-and with hot 10s, stopping 2min is once; B-with hot 20s, stopping 5min is once; C-with hot 30s, stopping 3min is once; × digitized representation multiplicity ,+representative adds up successively;

(5) after microwave curing, take out concrete, the 3h demoulding after termination microwave curing, then put it in normal temperature room, watering maintenance 3 days.