CN114873944A

CN114873944A - Preparation method of temperature and pH dual-sensitive retarder based on agricultural solid waste resources

Info

Publication number: CN114873944A
Application number: CN202210117208.6A
Authority: CN
Inventors: 唐振; 卢爽; 李国强; 王肇嘉; 黄天勇
Original assignee: Beijing Building Materials Academy of Sciences Research
Current assignee: Beijing Building Materials Academy of Sciences Research
Priority date: 2022-02-08
Filing date: 2022-02-08
Publication date: 2022-08-09

Abstract

A preparation method of a temperature and pH double-sensitive retarder based on agricultural waste recycling uses modified agricultural waste as a pH switch and plays a role in retarding. The organic matter on the surface of the modified agricultural waste is used as a temperature-sensitive switch. The agricultural waste needs to be pretreated by methods such as enzyme catalysis, extraction, flash explosion, hydrothermal treatment and the like. The organic matter is synthesized by adopting methods such as grafting, copolymerization, block and the like based on the actual required temperature. The invention aims to solve the problem of degradation of a concrete structure and performance caused by uneven temperature distribution of mass concrete, and further provides a novel temperature and pH double-sensitive retarder which is applied to the concrete.

Description

Preparation method of temperature and pH dual-sensitive retarder based on agricultural solid waste resources

Technical Field

The invention aims to solve the problem of concrete structure deterioration caused by uneven temperature distribution of mass concrete, and particularly relates to a preparation method of a temperature and pH double-sensitive retarder based on agricultural solid waste resources.

Background

China is vigorously promoting and developing infrastructure and urbanization construction, and the problem of performance degradation of a concrete structure caused by uneven temperature distribution of mass concrete in the construction process cannot be ignored. The problem of temperature rise in mass concrete is mainly caused by the fact that cement hydration heat cannot be dissipated in time. The existing solution mainly focuses on adding retarder or external cooling, and the external cooling only accelerates heat dissipation, so that the problem of internal and external temperature difference is not fundamentally solved. And simple addition of a common retarder can influence the initial setting time of concrete and hinder the construction progress.

The existing temperature-sensitive retarder capsule mainly utilizes organic matters such as alkane with proper melting points to coat the traditional retarder, the dissolution of the organic matters such as alkane is not beneficial to the development of the mechanical property of concrete, and the organic matters such as alkane are easy to lose efficacy in the transportation and storage processes. The method aims to effectively solve the problem of performance deterioration of a concrete structure caused by uneven temperature distribution of mass concrete and realize harmless and recycling of agricultural wastes. Based on the physicochemical properties of concrete, the invention selects an organic matter which can adjust and control temperature and can be used reversibly as an external temperature-sensitive switch, the modified agricultural waste is used as a pH switch and plays a role in retarding, a novel temperature and pH dual-sensitive retarder is prepared and applied to the concrete, when a certain local temperature in the mass concrete exceeds a set temperature and a set pH value, the retarder in the area is released, the hydration process of cement and the generation of hydration heat are slowed down, and therefore, the harm caused by the temperature rise in the mass concrete is avoided.

Disclosure of Invention

The invention aims to solve the problem of concrete structure deterioration caused by uneven temperature distribution of mass concrete, and further provides a novel temperature and pH double-sensitive retarder which is applied to the concrete.

In order to achieve the purpose, the invention is realized by the following technical scheme: a temperature and pH double-sensitive retarder based on agricultural waste recycling is prepared by taking modified agricultural waste as a pH switch and playing a role in retarding, taking organic matter on the surface of the modified agricultural waste as a temperature-sensitive switch, and loading the temperature-sensitive organic matter on the surface.

As a further optimization of the scheme, the used agricultural wastes need to be pretreated by enzyme catalysis, extraction, flash explosion and hydrothermal methods.

As a further optimization of the scheme, the organic matter needs to be synthesized by adopting a grafting, copolymerization and blocking method based on the actual required temperature.

As a further optimization of the scheme, the preparation method is to load organic matters on the surface of the agricultural waste by methods such as surface grafting, coating, vapor deposition and the like.

As a further optimization of the scheme, the organic matter loaded on the surface of the agricultural waste is one or more of isopropyl acrylamide, methyl acrylate and polyurethane.

As a further optimization of the scheme, the initiator required by the modification process is one of peroxybenzoic acid, peroxyacetic acid, azobisisobutyronitrile and ammonium persulfate.

Advantageous effects

The invention provides a preparation method of a temperature and pH dual-sensitive retarder based on agricultural waste recycling, which has the following beneficial effects:

1. the invention provides a preparation method of a temperature and pH double-sensitive retarder based on the actual requirement of mass concrete construction, and an outer-layer temperature-sensitive switch and an inner-layer pH switch can effectively prevent the retarder from losing efficacy caused by improper transportation and storage.

2. The invention adopts agricultural wastes as a pH switch and plays a role in retarding coagulation. The modification is carried out based on the self physical and chemical properties, so that the reutilization of the agricultural solid waste is realized, and the economic benefit and the environmental benefit are both achieved.

3. When a certain local temperature in the mass concrete exceeds the set temperature and the pH value, the temperature and pH double-sensitive retarder in the area is released, so that the hydration process of the cement and the release of hydration heat are slowed down, and the harm caused by the temperature rise in the mass concrete is avoided.

Detailed Description

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

Any feature disclosed in this specification (including any accompanying claims, abstract) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

Firstly, a hydrothermal method is selected to carry out pretreatment on coconut shells and rice husks. The reaction temperature is 40-80 ℃, the reaction time is 5-12 hours, and the solid-to-liquid ratio is 1:10-1: 20. In the hydrothermal method, sodium hydroxide and an oxidant are used for synergistic treatment, and the oxidant is one of hydrogen peroxide and sodium periodate. After the treatment by the hydrothermal method, the surface of the agricultural waste can have corresponding functional groups and structures, so that the modified agricultural waste is subjected to pH switch and has the function of retarding coagulation. And then loading the organic matter on the surface of the agricultural waste treated by the hydrothermal method by adopting a surface grafting method. The organic matter loaded on the surface of the agricultural waste is isopropyl acrylamide and methyl acrylate monomers, and the initiator is azobisisobutyronitrile and ammonium persulfate. The reaction temperature is 70-120 ℃, and the reaction time is 3-10 hours. And the last novel temperature and pH dual-sensitive retarder is synthesized and applied to concrete, so that the problem of temperature rise inside mass concrete is relieved.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The preparation method of the temperature and pH double-sensitive retarder based on agricultural solid waste recycling is characterized in that modified agricultural waste is used as a pH switch and plays a role in retarding, and organic matter on the surface of the modified agricultural waste is used as a temperature sensitive switch.

2. The preparation method of the temperature and pH dual sensitive retarder based on agricultural solid waste resource as claimed in claim 1, wherein the agricultural waste is one of rice husk, coconut fiber and hemp fiber.

3. The preparation method of the temperature and pH dual-sensitive retarder based on agricultural solid waste recycling according to claim 1, wherein the agricultural waste is pretreated by enzyme catalysis, extraction, hydrothermal method and the like.

4. The preparation method of the temperature and pH double-sensitive retarder based on the agricultural solid waste resource is characterized in that the selected enzyme is one or more of laccase, xylanase, hemicellulase and cellulase.

5. The preparation method of the temperature and pH double sensitive retarder based on agricultural solid waste resources according to claim 1, wherein the organic matter is synthesized by adopting methods of grafting, copolymerization, blocking and the like based on actual required temperature.

6. The preparation method of the temperature and pH dual-sensitive retarder based on agricultural solid waste recycling according to claim 1, wherein the preparation method is to load organic matters on the surface of agricultural waste by surface grafting, coating and vapor deposition methods.

7. The method for preparing the temperature and pH dual-sensitive retarder based on agricultural solid waste resources as claimed in claim 6, wherein the surface grafting method is one of chemical grafting and photo-grafting.

8. The preparation method of the temperature and pH double sensitive type retarder based on agricultural solid waste resources as claimed in claim 1, which is characterized in that the temperature and pH double sensitive type retarder is directly added in the stirring process of preparing concrete materials.