· 621 ·第38卷第4期

水泥–粉煤灰泡沫混凝土抗压强度与气孔结构的关系

方永浩,王锐,庞二波,周玥

(河海大学力学与材料学院,南京 210098)

摘要:研究了粉煤灰和泡沫掺量对水泥–粉煤灰泡沫混凝土的干体积密度和抗压强度的影响,用读数显微镜和图像分析软件分析了泡沫混凝土的气孔结构,重点研究了泡沫混凝土的抗压强度与气孔结构关系。结果表明用粉煤灰取代水泥会降低泡沫混凝土的抗压强度,但其影响程度随混凝土气孔率的增大而减小:当粉煤灰取代率从20%(质量分数,下同)增加到50%时,不添加泡沫的混凝土的抗压强度从58.9MPa降低到了40.2MPa;气孔体积分数为0.27~0.30的1kg干胶凝材料(水泥加粉煤灰)添加600mL泡沫时,混凝土的抗压强度从32.7MPa降低到了23.6MPa,而气孔体积分数为0.62~ 0.66左右的1kg干胶凝材料添加2L泡沫时,混凝土的抗压强度仅从3.06MPa降低到2.47MPa,强度降低率分别为32.0%,28.0%和19.3%;泡沫混凝土的抗压强度与其基体的硬化水泥浆体强度、Feret孔径大于10µm的气孔的体积分数和形状因子具有良好的相关性。建立了泡沫混凝土的抗压强度与气孔结构参数的数学关系式。

关键词:泡沫混凝土;强度;气孔结构;水泥;粉煤灰.

中图分类号:TU528 文献标志码:A 文章编号:0454–5648(2010)04–0621–06

RELATIONSHIP BETWEEN COMPRESSIVE STRENGTH AND AIR-VOID STRUCTURE

OF FOAMED CEMENT-FLY ASH CONCRETE

F AN

G Yonghao,WANG Rui,P ANG Erbo,ZHOU Yue

(College of Mechanics and Materials, Hohai University, Nanjing 210098, China)

Abstract: The effects of fly ash and foam volume on the dry apparent density and compressive strength of foamed cement-fly ash concrete were studied. The air-void structures of the foamed concretes were investigated by a reading microscope and image process software. The relationship between the compressive strength and the air-void structures was studied. The results show that replacement of cement with fly ash will reduce the compressive strength of the foamed concrete. When the replacement of cement with fly ash increased from 20% (in mass, the same below) to 50%,the compressive strength of the concrete without foam decreased from 58.9to 40.2MPa, and that of the concrete with the air-void fraction of 0.27–0.30 added with 600mL foam in 1kg dry binder, i.e., the cement and fly ash, decreased from 32.7 to 23.6MPa; while that of the concrete with the air-void fraction of 0.62–0.66 added with 2 L foam in 1kg dry binder decreased only from 3.06 to 2.47MPa; The strength reducing rates are 32.0%, 28.0% and 19.3%, respectively; The compressive strength of the foamed cement-fly ash concrete is highly correlated to the air-avoid structure factors. A model describing the relationship between compressive strength and air-void structure parameters of the foamed concrete was proposed.

Key words: foamed concrete; strength; air-void structure; cement; fly ash

泡沫混凝土具有体积密度小,且保温、隔热与耐火性、隔音性和抗震性优良的特点,既可工厂化生产成各种形状的预制品,又可现场浇筑,在各类建筑、尤其是建筑节能中具有广泛的应用前景,受到了人们的广泛关注。[1–5]作为一种建筑材料,强度仍是泡沫混凝土的主要性能之一。多孔材料的强度,不仅决定于其基体材料的强度,也取决于其孔结构,包括孔隙率、孔尺寸和孔形状。[6–7]泡沫混凝土作为一种高气孔含量的材料,气孔的结构对其强度更是起着决定性的作用。Kearsleya等[8]研究了孔隙率对泡沫混凝土强度的影响,用硬化水泥浆体研究中常采用的多孔材料强度与孔隙率的关系式[7,9–10]进行回归分析,均得到了较好的相关性。Kunhanandan等[11]研究了泡沫混凝土的气孔特征,

泡沫混凝土具有体积密度小,且保温、隔热与耐火性、隔音性和抗震性优良的特点,既可工厂化生产成各种形状的预制品,又可现场浇筑,在各类建筑、尤其是建筑节能中具有广泛的应用前景,受到了人们的广泛关注。[1–5]作为一种建筑材料,强度仍是泡沫混凝土的主要性能之一。多孔材料的强度,不仅决定于其基体材料的强度,也取决于其孔结构,包括孔隙率、孔尺寸和孔形状。[6–7]泡沫混凝土作为一种高气孔含量的材料,气孔的结构对其强度更是起着决定性的作用。Kearsleya等[8]研究了孔隙率对泡沫混凝土强度的影响,用硬化水泥浆体研究中常采用的多孔材料强度与孔隙率的关系式[7,9–10]进行回归分析,均得到了较好的相关性。Kunhanandan等[11]研究了泡沫混凝土的气孔特征,

收稿日期:2009–10–07。修改稿收到日期:2009–11–27。

基金项目:国家十一五科技支撑计划(2006BAJ04A04–02);江苏省自然科学基金(Bk2009345)资助项目。

第一作者:方永浩(1956—),男,教授。Received date:2009–10–07. Approved date: 2009–11–27. First author: FANG Yonghao (1956–), male, professor.

E-mail: fangyonghao195609@http://www.doczj.com/doc/cbeeea1dc5da50e2524d7fb9.html

第38卷第4期2010年4月

硅酸盐学报

JOURNAL OF THE CHINESE CERAMIC SOCIETY

Vol. 38,No. 4

April,2010