| Large amounts of construction waste can be produced in the process of city construction and reforming in our country. The quantity is huge during recycling powder broken in the process of construction waste, because it has complex composition, performance volatility, low activity etc, it is difficult to be used for these powder at present. If the powder is discharged indiscriminately not only occupied land resources, and can cause secondary pollution, so how to efficient and reasonable use of the construction waste powder is an urgent task. Controlled low strength materials is a new type of cement based backfill material, its main properties such as low strength, high fluidity similar to parts of the construction waste powder properties, it has certain feasibility to use construction waste powder preducing CLSM.This paper analyzes the physical performance of construction waste powder, the properties of cement mortar is studied on construction waste powder replacing part of cement, and the construction waste powder is used to research the mixture ratio design method of CLSM, based on the different dosage of cement, fly ash, limestone powder and admixture, the mechanical properties of CLSM is studied, and on the basis of obtaining reasonable content of each composition attempt to preduce the CLSM using construction waste powder. In this paper, the main contents and results are as follows:(1) The basic physical properties and microstructure analysis of construction waste powder are analyzed, it is concluded that the construction waste powder is expected to be as inert mineral mixed material.(2) The properties of cement mortar is studied on construction waste powder replacing part of cement, including the water requirement of normal consistency, activity index, strength and the influence of flow performance. Activity index of construction waste powder is 42%, the results show that the activity index of construction waste powder is increased, the strength requirement is not high that can be used as mixed material, when powder to replace more than 50% of the cement, the cement mortar strength satisfies the requirement of CLSM basic strength.(3) It is researched on the work performance, discusses the mixture ratio design method of the CLSM, put forward with the water-cement ratio, water-solid ratio and ash-powder ratio as the main design parameters of mix proportion design method. Studied the different water-cement ratio, water-solid ratio and ash-powder ratio on the fluidity and bleeding rate of CLSM, when the water-cement ratio is invariant, the fluidity of CLSM also increases with the ratio of ash powder increased. This paper measured the exudation rate of CLSM from 5% to 15% range, with the water-solid ratio increaseing, exudation rate has been increased, when water-solid ratio is invariant, but with the increasing of the ratio of ash powder helps to reduce the bleeding rate, when the ash-powder ratio is 0.3 at the same time, water-solid ratio within the range of 0.24 to 0.27, the exudation rate of CLSM is improved. Within two hours, the fluidity of CLSM significantly reduced by the extension of time.(4) It is studied on the dosage of cement, fly ash, lime stone powder for the influences of the strength of CLSM, the results show that significantly increase the compressive strength with the cement dosage increasing, the cement dosage of CLSM need to be controlled 20% below or less of the construction waste powder dosage to meet the requirements of low intensity; the dosage of fly ash doesn’t impact on the 3-d,7-d strength of CLSM obviously, within the scope of the study of dosage of fly ash, the dosage of fly ash is relatively appropriate by controlling about 10% of the construction waste powder dosage; Limestone powder content controlled within the 3% of construction waste powder dosage, increase consumption will promote the development of strength, strength decrease trend over the range, the limestone powder dosage for controlling about 5% of the construction waste powder dosage.(5) It is studied on influences of the strength of CLSM by adding to water reducing agent or early strength agent separately, with the increasing of dosage of water reducing agent, the results show that the 3-d,7-d and 28-d flexural and compressive strength of CLSM first increases and then trends, thus the optimum content of water reducing agent is 2% of cement dosage appropriately; With early strength agent increasing make early strength significantly increased, and has a little effects on the 28-d compressive strength, according to the experimental results, the optimum content of early strength agent is 0.12% of cement dosage.(6) The thought of mixture ratio design of CLSM is determined, the CLSM preparation process parameter is obtained preliminarily:fly ash content is 10% of the construction waste powder dosage, limestone powder content is 5% of the construction waste powder dosage, water reducing agent content is 2% of the dosage of cement, early strength agent content is 0.12% of the dosage of cement, the dosage of construction waste powder is 1350g, water-cement ratio is 1.75, ash-powder ratio is 0.2. The fluidity of CLSM is 262mm by configured,28-day compressive strength is 7.23MPa, exudation rate is 5.3%, basically meet the working performance of CLSM. |
PDF Full Text Request