"my country's composite material manufacturing industry scraps (here mainly refers to glass fiber composite materials and carbon fiber composite materials) and scrap products have an annual output of 300,000 to 400,000 tons of solid waste; in 2020, about 6 million tons of composite scrap products will expire, It is increasing year by year, and it is predicted that by 2030, it will exceed 30 million tons; wind turbine blades and nacelle covers will gradually appear off-line after 2024, and by 2040, the off-line volume of composite materials will exceed 4 million tons.” According to China Material Recycling Statistics from the fiber composite material regeneration branch of the association show that it is imperative to rationally recycle waste composite materials.

According to Peng Longgui, a professor at Xi'an University of Science and Technology, for waste glass fiber composite materials, 210 kilograms of carbon dioxide can be reduced for every ton processed; and 1 ton of waste wind power blades can be made into pallet boxes, which can save about 0.6 cubic meters of wood and reduce emissions by 1.098. tons of carbon dioxide. The project "Technical Research and Engineering Application Demonstration of Recycled Glass Fiber Reinforced Cement-Based Composite Materials", led by Ding Wenjiang, an academician of the Chinese Academy of Engineering, and led by Peng Longgui, a professor of Xi'an University of Science and Technology, won the key special project of the 2020 National Key R&D Plan "Solid Waste Recycling" Funding can comprehensively solve the problem of large-scale recycling, treatment, disposal and reuse of glass fiber composite solid waste, and turn waste into treasure.

Regenerated glass fiber + polymer dispersant

Peng Longgui's team pyrolyzed waste resin-based glass fiber composites to form recycled glass fibers, which were cut with self-designed controllable shearing technology and equipment for recycled glass fibers, strictly controlling the length and length distribution of the cut fibers, and obtained Regenerated glass fibers distributed as a function of different length-to-diameter ratios. Then, a polymer dispersant with one end being hydrophilic and the other end containing multiple close-packed high-density cationic groups was synthesized by molecular design.

Under the double action of water medium and cement-based alkalinity, the polymer dispersant can evenly disperse the recycled glass fiber in the fresh cement-based composite material slurry through electrostatic force, which enhances the working performance, mechanical properties and Durability.

The cement-based composite material slurry mixed with recycled glass fiber can be widely used in infrastructure, water conservancy, civil construction and other engineering constructions.

The research results of recycled glass fiber reinforced cement-based composite materials have been successfully applied in the first phase project of Foshan Urban Rail Transit Line 2, TJ5 Linyue depot and TOD comprehensive development project. It is understood that this achievement has solved four major difficulties in construction:

First, when the open U-shaped channel frame structure is used for the underpass, there are problems such as large foundation pit excavation depth, poor geological conditions, and high risks, and the requirements for concrete impermeability are high.

Second, the amount of concrete poured at one time in this project is as high as 3,000 to 5,000 cubic meters. The amount of concrete is huge, and the requirements for concrete crack resistance are high.

The third is that the structural beams and slabs used in the project are about 480,000 square meters, and each pouring time is about 16 hours, which needs to span the high temperature period at noon, so the crack resistance of the concrete is highly required.

Fourth, the size of the steel beam used is 2 meters x 1 meter, the height of the steel column is 21 meters, and the reinforcement is densely arranged. The combination of steel and concrete is a difficult point to control.

According to Peng Longgui, this technology increases the crack reduction rate of concrete to 71.9%, and reduces the dry shrinkage rate from 0.038% to 0.021%. From the perspective of engineering cost control, the cost of using recycled glass fiber + polymer dispersant is only the use of polymer 1/3 of the cost of propylene (PP) fiber, and at the same time, the strength of concrete has been improved; if the mix ratio of concrete is further optimized, the cost of use can basically be equal to that of ordinary concrete.