论文总字数：37485字

摘 要

因为天然砂资源有限，机制砂的使用逐渐得到重视。但机制砂的应用尚有诸多问题，其中石粉对混凝土拌合物流变性能的影响较为突出。本文以雅砻江流域某水电站所用机制砂石粉为研究对象，系统探究石粉对水泥浆体流变性能的影响规律及作用机制。

首先研究石粉对不同水泥-减水剂体系浆体流动性的影响规律。外掺石粉导致水泥浆体初始流动度降低，达到相同的初始流动度，需相应增加减水剂用量；石粉使PCE1减水剂体系水泥浆体的流动度损失增大，对PCE2和PCE3减水剂体系的流动度经时变化仅有微弱影响；控制石粉掺量和初始流动度相同，减水剂的掺量依次为：FDNgt;PCE3gt;PCE2gt;PCE1，流动度保持能力依次为：PCE3gt;PCE2gt;PCE1。

其次研究石粉对不同水泥-减水剂体系浆体流变参数的影响规律。结果表明：石粉导致水泥浆体屈服应力提高，塑性粘度增加，对浆体的剪切增稠性无明显影响；石粉使PCE1体系水泥浆体的屈服应力经时增加更明显，对PCE2体系的屈服应力经时变化无明显影响，对塑性粘度经时变化影响微弱。

从水泥浆体吸附减水剂的角度，分析石粉影响不同水泥-减水剂体系浆体屈服应力的机理。石粉增加了聚合物在颗粒表面的吸附量和饱和吸附量，聚合物在颗粒表面的覆盖率下降，导致减水剂的分散能力减弱，粉体颗粒表面平均分开距离降低，浆体屈服应力增大，且石粉对PCE1初始分散能力的削弱作用更强；石粉造成PCE1分散保持能力降低，颗粒表面平均分开距离随时间显著减小，浆体屈服应力经时增加更明显，对PCE2分散保持能力无不利影响；对比PCE1和PCE2，控制减水剂掺量和石粉掺量相同，长侧链、低侧链密度的PCE1吸附性能较差，但初始分散性能较好。

关键词：石粉，流动性，屈服应力，塑性粘度，吸附

Abstract

Due to the limited natural sand resources, the use of manufactured sand has been paid more and more attention. However, there are some problems in the application of manufactured sand, among which stone powder has a significant impact on the performance of concrete. In this paper, the stone powder in the machine-made sand used in a hydroelectric station in Yalong River Basin is taken as the research object, and the influence law and mechanism of stone powder on the rheological properties of cement paste are systematically explored.

Firstly, the influence of stone powder on the fluidity of cement slurry with different water reducer is studied. The addition of stone powder will reduce the initial fluidity. To achieve the same initial fluidity after adding stone powder, it is necessary to increase the dosage of water reducer. The fluidity loss of PCE1 system increases with the addition of stone powder, and the fluidity of PCE2 and PCE3 system change slightly over time. When the content of stone powder and the dosage of water reducer remain unchanged, the dosage of water reducer is FDN gt; PCE3 gt; PCE2 gt; PCE1, and the fluidity loss is PCE1 gt; PCE2 gt; PCE3.

Secondly, the effect of stone powder on rheological parameters of cement slurry with different water reducer is studied. The results show that the stone powder will lead to the increase of yield stress and viscosity. The time-dependent yield stress of PCE1 system increases more obviously after adding stone powder. The time-dependent yield stress of PCE2 system is not affected by stone powder. Stone powder will not have a significant impact on the change of viscosity over time.

The effect mechanism of stone powder on yield stress of cement paste is analyzed from the view of adsorption of superplasticizer on cement paste. Stone powder increases the adsorption capacity and saturated adsorption capacity of superplasticizer on particle, and the coverage on particle surface decreases, which leads to the decrease of average separation distance of particle surface and the increase of the yield stress. Stone powder decreases the initial dispersion ability of PCE1 more strongly. The addition of stone powder leads to the decrease of dispersion retention ability of PCE1, the decrease of average separation distance on particle surface with time, and the increase of the yield stress, which has no adverse effect on PCE2. Compared with PCE1 and PCE2, under the same dosage of superplasticizer and stone powder, PCE1 with long side chain and low side chain density has poor adsorption performance, but its initial dispersion performance is better.

KEY WORDS: stone powder, fluidity, yield stress, plastic viscosity, adsorption

目 录

摘要 Ⅰ

Abstract Ⅱ

第一章 绪论 1

1.1研究背景 1

1.1.1天然砂资源短缺 1

1.1.2机制砂的应用 1

1.1.3工程背景 2

1.2水泥浆体流变性能的研究现状 3

1.2.1混凝土流变学 3

1.2.2水泥净浆流变性能的测试方法 3

1.3机制砂影响流变性能的研究现状 4

1.3.1石粉含量对流变性能的影响 4

1.3.2石粉含泥量（MB值）对流变性能的影响 5

1.3.3石粉岩性对流变性能的影响 6

1.3.4颗粒形状对流变性能的影响 6

1.3.5级配及细度模数对流变性能的影响 7

1.4存在的主要问题 7

1.5研究目标及意义 8

1.5.1研究目标 8

1.5.2研究意义 8

1.6研究内容 9

第二章 试验原材料及试验方法 10

2.1试验原材料 10

2.1.1水泥 10

2.1.2石粉 10

2.1.3减水剂 13

2.2试验方法 13

2.2.1水泥净浆流动度测试 13

2.2.2水泥净浆流变曲线测试 14

2.2.3总有机碳（TOC）测试 14

第三章 石粉对水泥-减水剂体系流动度及经时损失的影响 15

3.1石粉掺量对水泥-减水剂体系流动度的影响 15

3.2石粉掺量对水泥-减水剂体系流动度损失的影响 16

3.3本章小结 17

第四章 石粉对水泥-减水剂体系流变参数的影响 18

4.1石粉对水泥-减水剂体系初始流变参数的影响 18

4.2石粉对水泥-减水剂体系流变参数经时变化的影响 22

4.3本章小结 24

第五章 石粉影响水泥-减水剂体系屈服应力的作用机理 25

5.1石粉影响水泥-减水剂体系初始屈服应力的机理 25

5.2石粉影响水泥-减水剂体系经时屈服应力的机理 28

5.3本章小结 31

第六章 结论与展望 33

6.1结论 33

6.2展望 34

参考文献 35

致 谢 39

第一章 绪论

1.1研究背景

1.1.1天然砂资源短缺

混凝土目前在房屋修筑、道路桥梁施工等领域得到普遍应用。近年来，因为西部地区工程建设的逐步开展，对混凝土的需求量也与日俱增。随着中国城市化的进行和“一带一路”战略的实施，混凝土在今后相当长的时期仍将是各种基础设施建设的重要材料^[1]。

细骨料约占混凝土体积总量的30%～40%，是混凝土的主要组分，其性质好坏对新拌混凝土和硬化后混凝土的性能有重要影响^[2]。细骨料主要分为天然砂和机制砂。天然砂是在自然条件下生成，经人工开采和筛分后粒径小于4.75 mm的岩石颗粒，除去风化、软质的岩石颗粒外的河砂、湖砂、山砂等都属于天然砂^[3]。目前天然砂在市场上早已供不应求，难以满足日益增长的建设需要。

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