考虑最大骨料粒径影响的轻骨料混凝土抗压强度及尺寸效应研究

Study on Compressive Strength and Size Effect of Lightweight Aggregate Concrete Considering the Influence of Maximum Aggregate Size

摘要: 为了研究轻骨料最大骨料粒径对立方体试块抗压强度与尺寸效应的影响，文章将轻骨料混凝土看作由砂浆、轻骨料、粘结界面组成的三相复合材料，分别建立了边长为100 mm、150 mm、200 mm、300 mm的轻骨料混凝土细观骨料模型，通过数值模拟研究了不同试件尺寸及不同轻骨料最大骨料粒径的混凝土在单轴受压下的抗压强度，并分析其对尺寸效应的影响。结果表明，当最大骨料粒径处于13 mm~20 mm区间时，抗压强度普遍随粒径增大而上升，且通常在粒径20 mm左右时达到峰值；最大骨料粒径超过20 mm时，抗压强度则开始呈现逐渐下降的趋势。此外，Bažant尺寸效应理论能够较好地描述本研究的单轴抗压强度尺寸效应规律，且最大骨料粒径的增加会削弱尺寸效应现象。

Abstract: To investigate the influence of the maximum aggregate size (MAS) of lightweight aggregate on the compressive strength and size effect of cube specimens, this paper treats lightweight aggregate concrete (LWAC) as a three-phase composite material consisting of mortar, lightweight aggregate, and the interfacial transition zone (ITZ). Meso-scale aggregate models of LWAC with side lengths of 100 mm, 150 mm, 200 mm, and 300 mm were established, respectively. Numerical simulations were conducted to study the uniaxial compressive strength of concrete with different specimen sizes and different maximum lightweight aggregate sizes, and their impact on the size effect was analyzed. The results show that when the MAS is within the range of 13 mm to 20 mm, the compressive strength generally increases with increasing particle size, typically peaking around 20 mm. When the MAS exceeds 20 mm, the compressive strength begins to exhibit a gradual declining trend. Additionally, Bažant’s size effect law fits the observed strength-size trend well, and a larger MAS reduces the size effect.