CN112661452A - Regenerated UHPC (ultra high performance polycarbonate) cement mortar and preparation method thereof - Google Patents

Abstract

The invention discloses a regenerated UHPC (ultra high Performance concrete) cement mortar and a preparation method thereof, belonging to the field of building materials. The concrete comprises the following components in parts by weight: 100 parts of regenerated UHPC cement, 35-40 parts of water, 180 parts of fine aggregate and 220 parts of water reducing agent and 0.5-0.8 part of water reducing agent. The waste UHPC is crushed, screened, ground and chemically excited to prepare the regenerated UHPC cement, and the raw materials are sequentially put into a mixer according to the components and the parts by weight of the cement mortar to be stirred and maintained to prepare the regenerated UHPC cement mortar.

Description

Regenerated UHPC (ultra high performance polycarbonate) cement mortar and preparation method thereof

Technical Field

The invention relates to the technical field of green building materials, in particular to a preparation method of regenerated UHPC (ultra high Performance concrete) cement mortar.

Background

With the development of Chinese economy, city construction enters a peak stage. The demand of a large amount of engineering construction for concrete and mortar is increased, and the generated construction waste is also increased. At present, the utilization rate of construction waste resources is low, and the treatment difficulty is high. Because the waste concrete contains sand and stones, the regenerated micro powder accounts for 5-20% of the mass of the waste concrete and is a byproduct of recycling construction waste, the research on large-scale utilization of cement mortar prepared from the micro powder is relatively less.

The invention discloses a regenerated micro-powder mortar and a preparation method thereof (application date: 201610575100.6, publication date: 106186959A. the regenerated micro-powder mortar comprises 3-5 parts of cement, 1-10 parts of regenerated micro-powder cement mixture, 2-8 parts of regenerated micro-powder, 3-10 parts of fly ash, 27-130 parts of regenerated fine aggregate and 4-22 parts of water

Compared with common concrete, the ultra-high performance concrete contains little or no coarse aggregate, and the concrete contains a large amount of unhydrated cement particles and inert SiO with potential activity₂. Therefore, the UHPC performance can be fully exerted by grinding particles with smaller particle size by using the waste ultrahigh-performance concrete.

Disclosure of Invention

The invention aims to provide a recycled UHPC cement mortar and a preparation method thereof, which solve at least part of the problems in the background technology.

In order to achieve the above object, the present invention adopts the following technical solutions.

The regenerated UHPC cement mortar is composed of the following raw materials in parts by weight: 100 parts of regenerated UHPC cement, 33-40 parts of water, 180 parts of fine aggregate and 220 parts of water reducing agent and 1.5-2.4kg of water reducing agent;

according to one embodiment of the present invention, wherein the fine aggregate is river sand or recycled UHPC fine aggregate, the particle size distribution is 1.15-4.75mm, the size distribution is continuous, and the gradation is good.

According to one embodiment of the invention, the water reducing agent is a high-efficiency polycarboxylic acid water reducing agent, the pH value is 6-8, and the density is 1.07-1.11 g/ml.

According to one embodiment of the invention, the recycled UHPC cement is prepared by crushing, sieving, grinding and adding a chemical activator to UHPC, the particle size of the recycled UHPC cement is less than 75 μm, and the specific surface area is more than 450cm²/g。

According to one embodiment of the present invention, wherein said chemical trigger is Ca (OH) at a concentration of 0.5% -2%₂Or 2% -4% of Na₂SiO₄。

According to another aspect of the present invention, there is provided a method for preparing recycled UHPC cement mortar, comprising the steps of:

s1, crushing, screening and grinding the waste UHPCThen obtain d₉₀UHPC recycled micropowder with particle size less than 75 μm.

S2, adding Ca (OH) with the micro powder mass of 0.5% -2% into the UHPC regenerated micro powder obtained in the step S1₂2% -4% of Na₂SiO₄The activator is stirred and mixed evenly, thus preparing the recycled UHPC cement.

S3, weighing the raw materials according to the following parts by weight, 300kg of regenerated UHPC cement, 120kg of water 100-;

s4, pouring the recycled UHPC cement and the fine aggregate into a stirrer in sequence, and stirring for 30S

And S5, mixing the water and the water reducing agent, and pouring the mixture into a stirrer to stir.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention develops the recycled UHPC cement by utilizing the waste ultrahigh-performance concrete, thereby replacing the common Portland cement, not only solving the problem of increasingly treating the waste ultrahigh-performance concrete in the future and being beneficial to environmental protection, but also changing waste into valuables, effectively reducing the demand of the cement and having better popularization value.

(2) The water cement ratio of the prior ultra-high performance concrete is often w/c<0.27 and the amount of water used is less than the amount of water required for complete hydration of the cement. The concrete contains a large amount of unhydrated cement particles and inert SiO with potential activity₂The direct reutilization of the recycled aggregate is the waste of the material, and the recycled UHPC cement developed from the ultra-high performance concrete can effectively utilize the material property.

(3) The regenerated UHPC cement is prepared by two modes of chemical excitation and mechanical excitation, on one hand, the aim of exciting the potential activity of cement particles can be achieved by providing an alkaline environment or reactive ions, on the other hand, the fineness of the cement particles is increased to effectively activate the activity of the cement particles, so that the mechanical property and the durability of the concrete containing the regenerated UHPC cement are improved.

(4) The addition of the water reducing agent can obviously improve the rheological property of the cement mortar containing the regenerated UHPC, avoid the condition of uneven stirring of the mixture, reduce the parameter requirement on a compulsory stirrer and reduce the process difficulty.

Drawings

FIG. 1 shows a flow of preparing a recycled UHPC cement mortar.

Detailed Description

The invention is described in detail below with reference to the figures and the embodiments.

Example one

A preparation method of regenerated UHPC cement mortar comprises the following steps:

s1, crushing, screening and grinding the waste UHPC to obtain d₉₀UHPC recycled micropowder with particle size less than 75 μm.

S2, adding Ca (OH) with the mass of 1% of the micropowder into the UHPC regenerated micropowder obtained in the step S1₂Adding the activator into a stirrer, and uniformly stirring and mixing to prepare the regenerated UHPC cement.

S3, weighing the raw materials according to the following parts by weight, 300kg of regenerated UHPC cement, 120kg of water, 620kg of river sand or regenerated UHPC fine aggregate and 2.0kg of high-efficiency polycarboxylic acid water reducing agent;

s4, pouring the recycled UHPC cement and the fine aggregate into a stirrer in sequence, and stirring for 30S

And S5, mixing the water and the high-efficiency polycarboxylic acid water reducing agent, pouring the mixture into a stirrer, stirring and curing.

Example two

A preparation method of regenerated UHPC cement mortar comprises the following steps:

s1, crushing, screening and grinding the waste UHPC to obtain d₉₀UHPC recycled micropowder with particle size less than 75 μm.

S2, adding Na with the mass of 2% of the micropowder into the UHPC regenerated micropowder obtained in the step S1₂SiO₄Adding the activator into a stirrer, and uniformly stirring and mixing to prepare the regenerated UHPC cement.

S3, weighing the raw materials according to the following parts by weight, 300kg of regenerated UHPC cement, 105kg of water, 580kg of river sand or regenerated UHPC fine aggregate and 2.0kg of high-efficiency polycarboxylic acid water reducing agent;

s4, pouring the recycled UHPC cement and the fine aggregate into a stirrer in sequence, and stirring for 30S

And S5, mixing the water and the high-efficiency polycarboxylic acid water reducing agent, pouring the mixture into a stirrer, stirring and curing.

The above embodiments are only for illustrating the preferred embodiments of the present application, and do not limit the scope of the present application, and those skilled in the art should make general changes and substitutions within the scope of the present application.

Claims (6)

1. The regenerated UHPC cement mortar is characterized by comprising the following raw materials in parts by weight: 100 parts of regenerated UHPC cement, 33-40 parts of water, 180 parts of fine aggregate and 220 parts of water reducing agent and 0.5-0.8 part of water reducing agent.

2. The recycled UHPC cement mortar of claim 1, wherein: the fine aggregate is river sand or regenerated UHPC fine aggregate, the particle size distribution is 1.15-4.75mm, the continuous particle size is obtained, and the gradation is good.

3. The recycled UHPC cement mortar of claim 1, wherein the water reducing agent is a high-efficiency polycarboxylic acid water reducing agent, the PH value is 6-8, and the density is 1.07-1.11 g/ml.

4. A recycled UHPC cement according to claim 5 characterised in that: the regenerated UHPC cement is prepared by crushing, screening and grinding UHPC and adding a chemical activator, the particle size of the regenerated UHPC cement is less than 75 mu m, and the specific surface area is more than 450cm²/g。

5. A recycled UHPC cement according to claim 7 characterised in that: the chemical activator is Ca (OH) with the concentration of 0.5 to 2 percent₂Or 2% -4% of Na₂SiO₄。

6. A method for preparing a recycled UHPC cement mortar using any one of claims 1 to 6, comprising the steps of:

s1, crushing, screening and grinding the waste UHPC to obtain d₉₀UHPC recycled micropowder with particle size less than 75 μm.

S2, adding Ca (OH) with the micro powder mass of 0.5% -2% into the UHPC regenerated micro powder obtained in the step S1₂2% -4% of Na₂SiO₄The activator is stirred and mixed evenly, thus preparing the recycled UHPC cement.

S3, weighing the raw materials according to the following parts by weight, 300kg of regenerated UHPC cement, 120kg of water 100-;

s4, pouring the recycled UHPC cement and the fine aggregate into a stirrer in sequence, and stirring for 30S

And S5, mixing the water and the water reducing agent, and pouring the mixture into a stirrer to stir.

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