摘 要

碳化固化技术是近几年来提出的一种低碳搅拌处置软弱土的新型技术。本文利用粉土和粉质粘土作为加固对象，用水泥作为固化剂，利用简化的碳化装置进行碳化固化，结合目前已有的研究成果，运用室内试验与理论分析相结合的方法，来分析养护及碳化后试样的力学特性、物理特性、化学特性、电学特性。主要研究成果如下：

1. 养护后和碳化后粉土的无侧限抗压强度都随着掺量的增加而增加，养护后的强度大部分都高于碳化后的强度但是在固化剂掺量为15%的部分有些许的减小。粉土在固化剂掺量为10%的时候养护后的强度比碳化后的强度高了50%。粉质粘土在固化剂掺量为10%的时候养护比碳化高了67%而固化剂掺量为20%的时候碳化后比养护后强度高了41%。
2. 粉土在掺量为15%之前养护后的含水率低于碳化后，在15%到20%之间含水率趋于平等。在固化剂掺量为5%时相差最大碳化后含水率比养护后高了14%。粉质黏土在掺量为5%的时候养护后含水率高于碳化后含水率为11%，而到了10%以后养护后含水率低于碳化后含水率为20%，在掺量为20%是含水率几乎相等。
3. 随着固化剂掺量的增加、二氧化碳压力的增强、碳化时间的增长，试样的无侧限抗压强度随之提高，含水率随之下降。
4. 粉土干密度随着固化剂掺量增加而变大，粉质粘土干密度随着固化剂掺量先降低后增大都是在1.63到1.67上下浮动，在固化剂含量为20%时两种土的干密度几乎相等。
5. 两种土样的pH都比碳化前的降低，粉土pH随着固化剂掺量增加从而上升，而粉质粘土是在10.75到12.55上下浮动。
6. 随着固化剂掺量的增加，粉土的电导率随之提高。粉质粘土先上升后下降，在固化剂掺量为15%的时候比其它的掺量的2倍。

关键词：地基处理；碳化；水泥固化土；无侧限抗压强度

Study on the effects of carbonization on physical and mechanical properties of cement solidified silt

Abstract

Carbonization curing technology is a kind of innovative technology which has been proposed in recent years. This paper use silt and silty clay as reinforcement objects, use cement as curing agent, and simple carbonization device for carbonization and solidification. At the same time, based on the existed research results, this thesis uses the indoor test and method of theoretical analysis to analyze the samples including curing and carbonization of mechanical properties, physical properties, chemical properties and electrical properties. The main research results are listed as followings:

1. After curing and carbide, the unconfined compressive strength of silty soil increases with the rising of dosage, and most of the curing strength is higher than that of carbonation. But it would decrease slightly when the curing agent content is 15%. And the strength after curing is 50% higher than that after carbonization when the content of curing agent is 10%. The curing strength of silty clay is 67% higher than that of carbonization when the dosage of curing agent is 10% and 41% higher than that after curing when the dosage of curing agent is 20%.
2. The water content of the silt after curing is lower than that of carbonization when the dosage is 15%, but it tends to be equal when the dosage is between 15% and 20%. When the dosage of curing agent is 5%, the water content after maximum carbonization is 14% higher than that of after curing. Silty clay, when the dosage is 5%, the water content after curing is higher than that of after carbide is 11%, but when the dosage is 10%, the water content after curing is lower than that of carbide 20%, and when the dosage is 20%, the results of content are almost equal.
3. With the increase of dosage of curing agent, carbon dioxide pressure and carbonization time, the unconfined compressive strength of the sample increases, but the water content decreases.
4. Silty soil dry density with the increase dosage of curing agent, silty clay dry density increases with the curing agent content reduced then increased is from 1.63 to 1.67, When the curing agent content is 20%,two kinds of soil dry density is almost equal.
5. The pH of both soil samples is lower than that before carbonization. The pH of silty soil rises with the increase of the content of curing agent, while that of silty clay fluctuates from 10.75 to 12.55.
6. With the increase of the content of curing agent, the conductivity of silt increases. Silty clay first rises and then falls, and when the dosage of curing agent is 15%, it is twice that of other dosage.

Key words: Foundation treatment; Carbonation; Cement-solidified soil; Unconfined compressive strength.

目 录

摘 要 I

Abstract II

目 录 IV

第1章 绪论 1

1.1 研究背景 1

1.1.1 水泥在软土加固中的应用 1

1.1.2 水泥的固化机理 2

1.1.3 水泥固化剂的缺点 2

1.2 碳化固化水泥土国内外现状研究 3

1.2.1 碳化固化水泥土研究现状 3

1.3 存在的问题分析 6

1.4 研究的目的及意义 6

1.5 本文主要研究内容以及技术路线 6

1.5.1 研究内容 6

1.5.2 研究技术路线 7

第2章 试验内容与方法 8

2.1 试验材料 8

2.2 试样制备与碳化 10

2.2.1 试样制备 10

2.2.2 试样养护及碳化 13

2.3 试验方案 15

2.3.1 含水率及干密度测量 15

2.3.2 无侧限抗压强度测量 17

2.3.3 pH测量 18

2.3.4 电导率测量 20

第3章 养护及碳化水泥固化土研究 23

3.1 标准养护后试样分析 23

3.1.1 试样力学特性分析 23

3.1.2 试样物理特性分析 25

3.1.3 试样养护后pH分析 27

3.1.4 试样养护后电导率分析 28

3.2 固化剂掺量影响研究 29

3.2.1 固化剂掺量影响下的力学特性研究 29

3.2.2 固化剂掺量影响下的物理特性研究 31

3.2.3 固化剂掺量影响下pH研究 36

3.2.4 固化剂掺量影响下电导率研究 37

3.3 二氧化碳压力影响研究 38