论文总字数：22640字

摘 要

近几年，石灰石粉在水泥混凝土中的应用受到了广泛关注，以石灰石粉作为矿物掺和料也是混凝土行业可持续发展的一条路线。白云石是石灰岩中最常见的一种伴生矿物，其在碱性条件下易发生碱白云石反应，对水泥混凝土的耐久性可能存在威胁。因此研究碱白云石反应对水泥基材料的耐久性影响显得十分必要。

本文分别以石灰石粉、白云石粉以及石灰石粉和白云石粉（1:1）的混合物模拟不同白云石含量的石灰岩微粉，并等质量取代20 %的水泥。成型试件常温下在清水和质量分数5 %的Na₂SO₄溶液中养护至预定龄期，通过强度、膨胀率、XRD等测试来探究掺入白云石粉的体系中是否发生去白云石化反应，及其对水泥基材料抗硫酸盐侵蚀的影响。

实验研究结果表明：掺入20 %的石粉对水泥基材料的强度有严重的影响，水泥含量的减少直接导致水泥基材料强度的明显下降。但是单掺白云石粉试件下降较石灰石试件少，原因在于去白云石化反应对强度损失的补偿作用。同时去白云石化反应将导致试件产生较石灰石试件、纯水泥试件更大的膨胀。

关键词：石灰石粉 白云石粉 去白云石化反应 硫酸盐侵蚀

The effect of limestone powder and dolomite powder mixed as mineral admixture on the sulfate attack of materials based on cement

ABSTRACT

In recent years, limestone powder has been widely used in concrete. It’s a route for the sustainable development of cement industry to use limestone powder as mineral admixture. Dolomite is the most common form of limestone associated minerals, and alkali-dolomite reaction happens easily under alkaline condition. This reaction may be a threat for the durability of cement concrete. Therefore, it’s necessary to study the effect of alkali-dolomite reaction on the durability of cementious materials.
In this article, different dolomite content of dolomitic limestone was simulated by mixing limestone powder and dolomite powder (mass ratio is 1:1) and using limestone powder and dolomite powder only. Cement pastes and mortars specimens were casted by substituting 20% of cement by mass with mixed powder. All specimens were cured in water or 5% Na₂SO₄ solution respectively. Linear expansion, strengths and Composition of the specimens were determined at different exposure time. Then dedolomitization reaction and its impacts on the sulfate resistance of materials based on cement are researched.

Experimental results indicate that: 20% of limestone/dolomite powder additive has a serious impact on the strength of concrete. The compressive strength of concrete decreased when limestone/dolomite powder was added. But the decrease is lower to the specimens with dolomite powder added, when compared with those mixed with only limestone powder. Furthermore, the specimens contain dolomite powder only have a larger expansion than other specimens. These phenomenon can be explained by dedolomization reaction.

Key Words: Limestone powder; Dolomite powder; Dedolomitization reaction; Sulfate attack

目录

摘要 I

ABSTRACT II

第一章 绪论 1

1.1 引言 1

1.2 石灰石粉和白云石粉 2

1.2.1 石灰石粉 2

1.2.2 白云石粉 3

1.2.3 去白云石化反应 4

1.3 硫酸盐侵蚀机理 5

1.3.1 钙矾石结晶型 6

1.3.2 石膏结晶型 7

1.3.3 碳硫硅钙石型侵蚀 7

1.4 研究目的和内容 9

1.4.1 研究目的 9

1.4.2 研究内容 9

第二章 实验方法 10

2.1 实验原料及仪器 10

2.1.1 实验用主要原料 10

2.1.2 实验用主要仪器 10

2.2 实验步骤 11

2.2.1 成型 11

2.2.2 养护 12

2.3 性能测试 13

2.3.1 强度测试 13

2.3.2 线膨胀率测试 13

2.3.3 X射线衍射分析 14

第三章 实验分析 15

3.1 力学性能分析 15

3.2 膨胀率测试 19

3.3 XRD分析 19

第四章 结论与展望 22

4.1 结论 22

4.2 展望 22

参考文献 23

致谢 25

第一章 绪论

1.1 引言

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