碱含量对水泥基材料开裂敏感性的影响

doi:10.11988/ckyyb.20230430

院报 ›› 2024, Vol. 41 ›› Issue (9): 153-160.DOI: 10.11988/ckyyb.20230430

碱含量对水泥基材料开裂敏感性的影响

李洋¹^,²(), 张国锋³, 张晖¹, 殷海波¹, 方何淇¹

¹ 工程质量检测中心,武汉 430072
² 武昌理工学院城市智能建造学院,武汉 430223
³ 中国南水北调集团江汉水网建设开发有限公司,武汉 430048

收稿日期:2023-04-21 修回日期:2023-06-28 出版日期:2024-09-01 发布日期:2024-09-20
作者简介:
李洋(1986-),男,湖北仙桃人,高级工程师,博士,研究方向为水泥基材料收缩开裂与预防、水泥基材料微结构分析、水工建筑物全过程质量控制等。E-mail:liyang@mail.crsri.cn
基金资助:
中央级公益性科研院所基本科研业务费项目(CKSF2019166/JC)

Influence of Alkali Content on the Cracking Sensitivity of Cement-based Materials

LI Yang¹^,²(), ZHANG Guo-feng³, ZHANG Hui¹, YIN Hai-bo¹, FANG He-qi¹

¹ Engineering Quality Testing Center, Changjiang River Scientific Research Institute,Wuhan 430072,China
² School of Intelligent Construction, Wuchang University of Technology,Wuhan 430223, China
³ JianghanWater Network Construction and Development Limited Company of China South-to-North Water DiversionCorporation Limited, Wuhan 430048, China

Received:2023-04-21 Revised:2023-06-28 Published:2024-09-01 Online:2024-09-20

摘要/Abstract

摘要：

选择低热硅酸盐水泥、中热硅酸盐水泥和普通硅酸盐水泥作为研究对象,利用外掺Na₂SO₄和K₂SO₄将其总碱含量调节至0.8%和1.2%,利用椭圆环法,并从干燥收缩性能、水化产物形貌、显微硬度及水化产物微观力学的角度,探究了碱对不同水泥基材料开裂敏感性的影响。结果表明:随着碱含量的提高,不同水泥基材料的开裂敏感性增加;低热硅酸盐水泥具有较高的抗裂能力,且适当地提高碱含量,有助于提高其抗裂性能;干燥收缩性并不能完全揭示碱对不同水泥基材料开裂敏感性的影响机制。碱对不同水泥基材料开裂敏感性的提高还与其微观特性有关,通过促使水化产物形貌发生转变,提高其显微硬度,降低水泥基材料浆体适应变形的能力;通过降低唯一具有胶凝特性的水化硅酸钙(C-S-H)簇间粘结力,降低水泥基材料浆体抵抗开裂的能力。

关键词: 水泥基材料, 碱含量, 开裂性能, 收缩性能, 显微硬度, 微观力学

Abstract:

The total alkali content of low-heat Portland cement, medium-heat Portland cement, and ordinary Portland cement was adjusted to 0.8% and 1.2% by adding Na₂SO₄ and K₂SO₄ respectively. The impact of alkali on the cracking sensitivity of various cement-based materials was investigated using the elliptical ring method by analyzing drying shrinkage performance, hydration product morphology, micro hardness, and micromechanics of hydration products. Results revealed that an increase in alkali content led to higher cracking sensitivity in various cement-based materials. Low-heat Portland cement exhibited strong crack resistance, and a suitable increase in alkali content could enhance its crack resistance performance. The drying shrinkage performance alone could not fully elucidate how alkali affected the cracking sensitivity of different cement-based materials. The microscopic mechanism behind alkali’s role in enhancing the cracking sensitivity of various cement-based materials included: (1) promoting the transformation of hydration product morphology and elevating micro hardness, thereby reducing the deformation adaptability of cement-based material pastes; (2) decreasing the inter-cluster bonding strength of hydrated calcium silicate (C-S-H), a component with distinct gelling properties, thereby diminishing the crack resistance of cement-based material pastes.

Key words: cement-based material, alkali content, cracking properties, shrinkage properties, micro hardness, micromechanics

中图分类号:

TV4水工材料

李洋, 张国锋, 张晖, 殷海波, 方何淇. 碱含量对水泥基材料开裂敏感性的影响[J]. 院报, 2024, 41(9): 153-160.

LI Yang, ZHANG Guo-feng, ZHANG Hui, YIN Hai-bo, FANG He-qi. Influence of Alkali Content on the Cracking Sensitivity of Cement-based Materials[J]. Journal of Yangtze River Scientific Research Institute, 2024, 41(9): 153-160.

图/表 10

表1 不同水泥基材料氧化物组成和矿物组成

Table 1 Oxide composition and mineral composition of different cement-based materials

水泥类型	不同水泥基材料的质量分数/%
水泥类型	Al₂O₃	Fe₂O₃	SiO₂	CaO	MgO	Na₂O	K₂O	Na₂O_eq.	C₂S	C₃S	C₄AF	C₃A
P·LH42.5	3.82	5.03	22.59	59.47	4.71	0.16	0.38	0.40	40.47	32.21	15.30	1.62
P·MH42.5	4.21	4.79	21.70	61.91	3.87	0.12	0.35	0.35	27.11	46.53	14.58	3.06
P·O42.5	4.60	2.88	19.84	61.25	2.18	0.16	0.79	0.68	13.74	57.19	8.77	7.32

表2 水泥物理性能

Table 2 Physical properties of cement

水泥类型	比表面积/ (m²·kg^-1)	标准稠度用水量/%	凝结时间/min
水泥类型	比表面积/ (m²·kg^-1)	标准稠度用水量/%	初凝	终凝	3 d	7 d	28 d	3 d	7 d	28 d
P·LH42.5	336	23.8	245	336	—	5.1	8.4	—	21.6	45.3
P·MH42.5	325	24.8	238	290	5.5	7.2	9.3	22.8	32.7	48.7
P·O42.5	356	27.2	173	231	5.6	—	8.4	27.2	—	45.1

图1 不同水泥砂浆椭圆环收缩开裂试件和干缩试件

Fig.1 Elliptical ring shrinkage cracking samples and drying shrinkage samples of different mortars

图2 样品表面与探针针尖间力曲线示意图

Fig.2 Curves of forces between sample surface and probe tip

图3 不同碱含量和碱类型下水泥砂浆开裂时间

Fig.3 Cracking time of mortars containing different dosages and types of alkali

图4 不同碱含量和碱类型下水泥砂浆干缩发展曲线

Fig.4 Curves of drying shrinkage of mortars containing different dosages and types of alkali

表3 不同碱含量和碱类型砂浆干缩拟合曲线

Table 3 Fitting equations of drying shrinkage of mortars containing different dosages and types of alkali

编号	水泥类型	碱类型	碱含量/%	拟合曲线	决定系数R²
L8N	P·LH42.5	Na碱	0.8	y=76.867+240.34lnx	0.981 1
L12N		Na碱	1.2	y=86.985+234.26lnx	0.989 2
L8K		K碱	0.8	y=169.97+235.71lnx	0.985 2
L12K		K碱	1.2	y=273.71+242.82lnx	0.966 1
M8N	P·MH42.5	Na碱	0.8	y=200.15+218.77lnx	0.969 7
M12N		Na碱	1.2	y=174.95+248.08lnx	0.976 8
M8K		K碱	0.8	y=213.70+241.91lnx	0.975 5
M12K		K碱	1.2	y=222.12+259.33lnx	0.980 4
P8N	P·O42.5	Na碱	0.8	y=185.12+198.35lnx	0.960 9
P12N		Na碱	1.2	y=190.54+198.53lnx	0.964 3
P8K		K碱	0.8	y=136.56+218.07lnx	0.972 9
P12K		K碱	1.2	y=201.64+241.25lnx	0.977 6

图5 水泥净浆SEM图像

Fig.5 SEM images of cement pastes

图6 掺不同类型碱下水泥净浆3 d龄期显微硬度

Fig.6 Micro hardness of low-heat Portland cement pastes containing different types of alkali at 3-d age

图7 不同碱类型下低热水泥净浆C-S-H颗粒形貌和粘结力频率分布

Fig.7 AFM images and frequency distribution of bonding force of C-S-H clusters of low-heat Portland cement pastes containing different types of alkali

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碱含量对水泥基材料开裂敏感性的影响

Influence of Alkali Content on the Cracking Sensitivity of Cement-based Materials

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