阅读说明：本技术 一种利用废弃超高性能混凝土制备再生uhpc水泥的方法 (Method for preparing regenerated UHPC cement by using waste ultrahigh-performance concrete ) 是由 黄靓 张瀚文 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种利用废弃超高性能混凝土制备再生UHPC水泥的方法,包括以下步骤：将废弃的超高性能混凝土进行除杂、粉碎、筛分后得到再生UHPC粗骨料、再生UHPC细骨料和再生UHPC微粉待用；将再生UHPC细骨料和微粉利用研磨机研磨并筛分后得到再生UHPC微粉,添加激发剂进行均匀搅拌混合后最终得到再生UHPC水泥。本发明能够把废弃的超高性能混凝土变废为宝,通过上述的步骤把废弃的超高性能混凝土加工成可再次使用的再生UHPC水泥,能够减少普通硅酸盐水泥的使用量,还能解决因废弃的超高性能混凝土造成的环境问题,实现资源的合理利用。(The invention discloses a method for preparing regenerated UHPC cement by using waste ultrahigh-performance concrete, which comprises the following steps: removing impurities from the waste ultrahigh-performance concrete, crushing and screening to obtain regenerated UHPC coarse aggregate, regenerated UHPC fine aggregate and regenerated UHPC micro powder for later use; grinding the recycled UHPC fine aggregate and the micropowder by using a grinder, sieving to obtain recycled UHPC micropowder, adding an excitant, uniformly stirring and mixing to finally obtain the recycled UHPC cement. The method can change waste ultrahigh-performance concrete into valuable, and the waste ultrahigh-performance concrete is processed into reusable recycled UHPC cement through the steps, so that the use amount of common Portland cement can be reduced, the environmental problem caused by the waste ultrahigh-performance concrete can be solved, and the reasonable utilization of resources is realized.)

1. A method for preparing regenerated UHPC cement by using waste ultrahigh-performance concrete is characterized by comprising the following steps:

and S1, removing impurities from the waste ultrahigh-performance concrete.

And S2, performing primary crushing and secondary crushing on the ultra-high performance concrete subjected to impurity removal in the S1 mode.

And S3, screening the crushed ultrahigh-performance concrete of the S2 by using a 4.75mm screening machine to obtain regenerated UHPC coarse aggregate of more than 4.75mm, regenerated UHPC fine aggregate of less than 4.75mm and micro powder.

And S4, grinding the recycled UHPC fine aggregate and micropowder of the S3 by using a grinder, and screening to obtain the recycled UHPC micropowder.

And S5, uniformly mixing the regenerated UHPC micro powder of S4 and an exciting agent to finally obtain the regenerated UHPC cement.

And S6, packaging and storing the mixed regenerated UHPC cement in the S5.

2. The method for preparing recycled UHPC cement by using the waste ultra-high performance concrete according to claim 1, characterized in that the primary crushing mode adopts a jaw crusher to crush, and the secondary crushing mode adopts an impact crusher.

3. The method for preparing recycled UHPC cement by using the waste ultra-high performance concrete as claimed in claim 1, wherein the screening machine can be a roller screening machine or a vibration screening machine.

4. The method for preparing recycled UHPC cement by using waste ultra-high performance concrete according to claim 1, characterized in that the grinding device is a sand mill, a pulverizer, a ball mill or the like, and the particle size of the micro powder after grinding is ensured to be d₉₀≤70μm。

5. The method for preparing recycled UHPC cement by using waste ultra-high performance concrete according to claim 1, characterized in that the excitant can select Ca (OH) with the concentration of 0.5% -2%₂2% -4% of Na₂SiO₄Or Ca (OH)₂And Na₂SiO₄The compound excitation of (2).

Technical Field

The invention relates to the technical field of green building materials, in particular to a method for preparing regenerated UHPC (ultra high Performance concrete) cement by utilizing waste ultra high performance concrete.

Background

In 2019, the cement yield in China is 23.3 hundred million tons, large-scale infrastructure construction lasts for many years, and the demand for cement is still large. However, cement in the conventional sense not only consumes a large amount of limestone, clay, coal and the like in the production process thereof, but also emits billions of tons of CO into the environment₂、SO₂And NO_XAnd the like, and cause serious pollution to the environment. Therefore, the cement industry must strictly limit the amount of portland cement clinker to be mixed in the future, and use little or no portland cement clinker to produce hydraulic cementitious materials to replace ordinary cement.

Jiang Li et al disclose a preparation method of recycled concrete micro-powder (application No. 201910114705.9, application publication No. CN 109704607A). The method comprises the steps of removing impurities from waste concrete, crushing, removing magnetic substances, screening to obtain regenerated micro-powder, and then placing the regenerated micro-powder particles into a calcining furnace to calcine for 5-8 hours; and cooling the calcined regenerated micro-powder particles in a cooling mode, and adding a composite activator for uniform mixing to obtain the regenerated concrete micro-powder. The invention solves the environmental problem caused by waste concrete and realizes the reasonable utilization of resources.

Zuojunqin et al disclose a method for preparing recycled concrete micropowder (application No. 201711062430.6, application publication No. CN 107892497A). The method comprises the steps of crushing the concrete after impurities are removed into concrete particles by a crusher, sorting the concrete particles in a targeted manner to remove coarse aggregates, grinding the concrete particles for a certain time by using sorted set cement, sieving the ground concrete particles to obtain regenerated micro-powder particles, calcining the regenerated micro-powder particles at high temperature for a certain time, cooling the regenerated micro-powder particles, and adding an exciting agent to treat the cooled regenerated micro-powder particles to obtain the regenerated concrete micro-powder. The preparation method enables the activity of the recycled concrete micro powder to meet the activity requirement of the conventional admixture, and improves the recycling rate of waste concrete resources.

Because the content of the regenerated micro powder accounts for 5-20% of the regenerated construction waste and the content of unhydrated cement is low, the popularization prospect of the regenerated micro powder as a cementing material is great. And the UHPC does not contain coarse aggregate, and contains a large amount of unhydrated cement and mineral admixture capable of generating pozzolanic reaction, so that the recycled UHPC cement developed by using the waste ultrahigh-performance concrete not only solves the recycling problem of the waste ultrahigh-performance concrete, but also effectively solves various problems brought by the cement.

Disclosure of Invention

The invention aims to provide a method for preparing regenerated UHPC cement by using waste ultra-high performance concrete, which solves at least part of the problems in the prior art.

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

A method for preparing regenerated UHPC cement by using waste ultrahigh-performance concrete is characterized by comprising the following steps:

and S1, removing impurities from the waste ultrahigh-performance concrete.

And S2, performing primary crushing and secondary crushing on the ultra-high performance concrete subjected to impurity removal in the S1 mode.

And S3, screening the crushed ultrahigh-performance concrete of the S2 by using a 4.75mm screening machine to obtain regenerated UHPC coarse aggregate of more than 4.75mm, regenerated UHPC fine aggregate of less than 4.75mm and micro powder.

And S4, grinding the recycled UHPC fine aggregate and micropowder of the S3 by a grinder and sieving to obtain the recycled UHPC micropowder.

And S5, uniformly mixing the regenerated UHPC micro powder of S4 and an exciting agent to finally obtain the regenerated UHPC cement.

And S6, packaging and storing the mixed regenerated UHPC cement in the S5.

Furthermore, the primary crushing mode adopts a jaw crusher to crush, and the secondary crushing mode adopts a counterattack crusher.

Further, the screening mode can adopt a vibration screening machine or a roller screening machine.

Further, the preparation method of the recycled UHPC cement is characterized in that the grinding device is a sand mill, a flour mill and a ball mill, and the particle size of the ground micro powder is ensured to be d₉₀≤70μm。

Further, the activator can be Ca (OH) with concentration of 0.5% -2%₂2% -4% of Na₂SiO₄Or Ca (OH)₂And Na₂SiO₄The compound excitation of (2).

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

(1) the invention utilizes the recycled UHPC cement developed by the waste ultrahigh-performance concrete to solve the problem of recycling the waste ultrahigh-performance concrete and effectively solve the problem of scarcity of mineral admixture, thereby having better popularization value.

(2) At present, the water-cement ratio w/c of the ultra-high performance concrete is less than 0.27 under the normal condition, and the using amount of water is less than the water amount required by the complete hydration of cement, so that a large amount of unhydrated cement particles are contained in the concrete, the cement particles are directly used as recycled aggregate to be reused, the waste of the material is caused, and the material property can be effectively utilized by recycling the ultra-high performance concrete as the recycled gel material.

(3) By carrying out chemical and mechanical dual activation on the regenerated UHPC micro powder, on one hand, the purpose of exciting the potential activity of the regenerated UHPC micro powder can be achieved by providing an alkaline environment or reactive ions, and on the other hand, the particle fineness of the regenerated UHPC micro powder is increased to effectively activate the activity of the regenerated UHPC micro powder.

(5) In addition, the prepared regenerated UHPC cement does not need a high-temperature heating process, so that the energy consumption can be reduced, and the strategic target of sustainable development is met.

Drawings

The invention will be described in further detail with reference to the accompanying drawings

FIG. 1 is a flow chart of preparing a recycled UHPC cement by using recycled ultra-high performance concrete.

Detailed Description

In order to make the technical means and functions of the invention easy to understand, the invention is specifically described with reference to the following embodiments.

Example 1

A method for preparing regenerated UHPC cement by utilizing regenerated ultrahigh-performance concrete comprises the following steps:

and S1, removing impurities from the waste ultrahigh-performance concrete.

And S2, performing primary crushing and secondary crushing on the ultra-high performance concrete subjected to impurity removal in the step S1 by using a jaw crusher and an impact crusher.

And S3, screening the crushed ultrahigh-performance concrete of S2 by using a vibration screening machine to obtain recycled UHPC coarse aggregate of more than 4.75mm, recycled UHPC fine aggregate of less than 4.75mm and micro powder.

And S4, grinding the regenerated UHPC fine aggregate and the micropowder of the S3 for 10min by using a planetary ball mill at the rotating speed of 1500 rpm and with a stainless steel medium, and screening by using a vibrating screen to obtain the regenerated UHPC micropowder.

S5, uniformly mixing the regenerated UHPC micro powder of S4 and Ca (OH)2 with the addition concentration of 1 percent to finally obtain the regenerated UHPC cement.

S6, packaging and storing the regenerated UHPC cement in the S5.

Example 2

A method for preparing regenerated UHPC cement by utilizing regenerated ultrahigh-performance concrete comprises the following steps:

and S1, removing impurities from the waste ultrahigh-performance concrete.

And S2, performing primary crushing and secondary crushing on the ultra-high performance concrete subjected to impurity removal in the step S1 by using a jaw crusher and an impact crusher.

And S3, screening the crushed ultra-high performance concrete of S2 by using a vibration screening machine to obtain regenerated UHPC coarse aggregate of more than 4.75mm, regenerated UHPC fine aggregate of less than 4.75mm and micro powder.

And S4, grinding the regenerated UHPC fine aggregate and the micropowder of the S3 for 10min by using a sand mill, wherein the rotating speed is 1200 r/min, the medium is zirconia beads, and grinding and sieving by using a vibrating screen to obtain the regenerated UHPC micropowder.

S5, adding Na2SiO4 with the concentration of 3% into the regenerated UHPC micro powder of S4, and uniformly mixing to finally obtain the regenerated UHPC cement.

S6, packaging and storing the regenerated UHPC cement in the S5.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty, and thus the invention is not limited to the embodiments described above.