CN-121248233-B - Nano modified rebound-resistant full-hole slag sprayed concrete

Abstract

The invention relates to the technical field of hydraulic concrete materials, and in particular discloses nano modified rebound-resistant full-cavity slag sprayed concrete which comprises the following raw materials, by weight, 665 parts of cavity slag aggregate, 950 parts of cavity slag sand, 396-436.5 parts of ordinary Portland cement, 225 parts of water, 10 parts of a polycarboxylic acid water reducer and 8.5 parts of an accelerator, wherein the cavity slag aggregate is subjected to modification treatment by a nano admixture, and the nano admixture consists of nano kaolin, nano silicon dioxide and a precise PCE solution. According to the invention, the rebound-resistant sprayed concrete is prepared by modifying the hole slag aggregate by adopting the nano admixture, so that the full quantitative resource utilization of the tunnel excavation hole slag is realized, the problems of occupation of land by pile slag and potential ecological pollution are effectively alleviated, the cement consumption in the concrete is reduced, the construction cost is reduced, the rebound rate of the sprayed concrete is obviously reduced, the compactness of the concrete is improved, and the compression resistance and crack resistance of the concrete are enhanced.

Inventors

• CHEN RONGHUA
• HUANG ZHUOJIE
• LIU ZHIHONG
• LIU LUQIANG
• CHEN CHENGQI
• HUANG YUECHAO
• CHEN JIANGUO
• SONG ZHANDONG
• LIU JIAWANG
• CHEN GUIBIN
• HUANG XIAOBING
• Zeng xiong

Assignees

• 广西壮族自治区水利电力勘测设计研究院有限责任公司
• 广西壮族自治区水利科学研究院

Dates

Publication Date

20260508

Application Date

20251201

Claims (1)

1. 1. The nano modified rebound-resistant full-cavity slag sprayed concrete is characterized by comprising the following raw materials, by weight, 665 parts of cavity slag aggregate, 950 parts of cavity slag sand, 396-436.5 parts of ordinary Portland cement, 225 parts of water, 10 parts of a polycarboxylic acid water reducer and 8.5 parts of an accelerator, wherein the cavity slag aggregate is further subjected to modification treatment by a nano admixture, and the nano admixture consists of nano kaolin, nano silicon dioxide and a precise PCE solution; The dosage of the nanometer admixture is 1-54 parts, wherein the mass ratio of the nanometer kaolin to the nanometer silicon dioxide to the precise PCE solution is 1:1:0.02; the precise PCE solution comprises the following components of TPEG-3000, acrylic acid, acrylamide, polyether modified polysiloxane and ammonium persulfate; The mass ratio of the components of TPEG-3000, acrylic acid, acrylamide, polyether modified polysiloxane and ammonium persulfate in the precise PCE solution is 300:26:5:1:2; The specific preparation method of the precise PCE solution comprises the following steps: (1) Adding TPEG-3000 and a proper amount of deionized water into a four-neck flask, slowly heating to 30 ℃ and continuously magnetically stirring until the system is in a uniform transparent state to obtain a TPEG aqueous solution; (2) Premixing acrylic acid and acrylamide in a beaker, adding a proper amount of deionized water for dilution to prepare a mixed monomer aqueous solution, and dissolving ammonium persulfate in the deionized water to prepare an initiator solution with the mass fraction of 6.7% for later use; (3) Adding half of polyether modified polysiloxane into the TPEG water solution, continuously bubbling 15 min by introducing high-purity nitrogen to remove dissolved oxygen, then heating the reaction system to 80 ℃ and keeping constant temperature, starting to dropwise add mixed monomer water solution at constant speed, and continuing to carry out heat preservation reaction 1h under the condition of 80 ℃ after the dropwise addition is finished to fully polymerize the monomer; the tunnel slag aggregate is prepared by taking waste tunnel slag of tunnel excavation as a raw material, crushing and screening the waste tunnel slag to obtain the tunnel slag aggregate with the grain size of 5-15 mm; the specification of the ordinary Portland cement is P.O42.5; the water reducing rate of the polycarboxylic acid water reducer is 25%; the TPEG-3000 is polyethylene glycol monomethyl ether methacrylate.

Description

Nano modified rebound-resistant full-hole slag sprayed concrete Technical Field The invention belongs to the technical field of hydraulic concrete materials, and particularly relates to nano modified rebound-resistant full-hole slag sprayed concrete. Background In the hydraulic tunnel excavation process, a drilling and blasting method is widely applied as a main construction means, and the blasting effect of the drilling and blasting method can lead to surrounding rock to generate a large amount of rock hole slag with internal crack development and irregular morphology. These hole slags are traditionally transported to waste slag factories for landfill disposal, which not only increases transportation and treatment costs, but also brings environmental burden. If the aggregate can be recycled and used as aggregate of sprayed concrete, the waste is changed into valuable, the engineering investment can be saved, and considerable economic benefits are created, so that the method is environment-friendly. The sprayed concrete is a core material of the tunnel primary support, and the construction quality of the sprayed concrete has an important influence on the performance of an engineering structure. However, conventional shotcrete generally suffers from excessive rebound (typically up to 20% -25% and even higher). The rebound not only causes huge waste of materials and improves the construction cost, but also worsens the construction environment, threatens the health of operators, and influences the uniformity and the whole bearing capacity of the spraying structure. In this regard, functional materials (minerals, metal oxides, organic compounds, etc.) are often added as admixtures to shotcrete in engineering to improve the concrete properties and reduce the rebound rate. For example, patent CN115478880B proposes a construction method for reducing rebound rate of sprayed concrete, wherein the proportion ratio is 1:3.5-5, aggregate sand content is 45% -60%, water-cement ratio is 0.4-0.5, and the bonding degree between slurries is enhanced by adding a mixture fusion agent with main components of silicon dioxide, calcium hydroxide, calcium oxide, magnesium hydroxide, carbon nanotubes and cellulose into the raw materials of the original sprayed concrete, so that rebound rate is reduced. The patent CN114538820B discloses a rebound suppression method for sprayed concrete based on full-flow control, wherein the material parameters are that the consumption of a cementing material is 480-530 kg/m 3, the water-cement ratio is 0.35-0.40, the sand ratio is more than or equal to 60%, and rebound suppression key materials consisting of hydroxypropyl methylcellulose, triethanolamine, sodium sulfate, polycarboxylic acid high-efficiency water reducer powder and water are added into the concrete mixing ratio to adjust the fluidity and early strength of the sprayed concrete, so that the sprayed concrete meets the low rebound injection requirement. However, the research and application of the prior art are mainly based on conventional aggregates with good morphology and excellent grading, and the technical thought is focused on optimizing a cementing material system, but the fundamental challenges brought by the special properties of the aggregates are not fully considered. The content of needle-shaped particles (about 22%) and the content of stone powder (about 30%) in the cavity slag aggregate are obviously higher than the requirements (the needle-shaped particles content is less than or equal to 12% and the stone powder content is less than or equal to 10%) on the aggregate in the technical regulations for sprayed concrete application (JGJ/T372-2016), so that insufficient slurry binding force and weakening of mechanical engagement effect between the aggregates are easily caused in fresh concrete, and the balance of 'adhesion-agglomeration-flexibility' performance required by sprayed concrete is jointly destroyed, so that the problems of serious rebound and slurry dropping are caused. Therefore, the development of a novel nano admixture specially designed for the characteristics of the cavity slag aggregate is urgently needed at present, and the problems of high rebound rate and mechanical property degradation caused by high needle flake content and high stone powder content are effectively solved, so that the large-scale and efficient recycling utilization of the cavity slag in sprayed concrete is promoted. Therefore, the invention develops a novel nanometer admixture compounded by the nanometer nucleating agent and the nanometer regulating agent, which is used for a full-cavity slag aggregate shotcrete system. The material strengthens the ITZ (ITZ is a transition zone between a cement matrix and an aggregate interface) structure through the micro-filling effect and the pozzolan activity of the nano nucleating agent, optimizes the thixotropic property of slurry, ensures that the slurry has good pumpability during spraying, has t