机制生态改性生土坯砖砌体基本力学性能试验

针对生土坯砖砌体房屋抗震性能差、材料强度较低等特点，对选用水玻璃、钾明矾、尿素、可再分散性乳胶粉、秸秆等无污染材料进行复合改性的机制生态改性生土坯砖砌体的基本力学性能进行了研究。对4组共30个机制生土坯砖砌体试件进行了抗压和抗剪强度试验，分析了机制生土坯砖砌体的破坏形态，探究了机制生土坯砖砌体的抗压本构关系，修正了适用于机制生态改性生土坯砖砌体的平均抗压强度取值公式。结果表明：与机制未改性生土坯砖砌体相比，机制生态改性生土坯砖砌体的抗压强度、抗剪强度和延性分别提高了23%，17%和7%；机制生土坯砖砌体的应力-应变曲线与杨卫忠砌体本构方程拟合度较高；当砌体块体类别为机制生土坯砖时，与块体类别有关的参数分别取值0.42和0.46，此时该研究提出的砌体抗压强度计算公式适用于机制未改性生土坯砖砌体和机制生态改性生土坯砖砌体。

Experiment on the basic mechanical properties of mechanical eco-modified adobe brick masonry

Abstract: An adobe masonry structure has widely been distributed for a long time in the rural areas of northwest China. The conventional building forms share some advantages, including convenient material access, thermal insulation, economic and environmental protection, as well as green and energy saving. However, some limitations are also remained, such as low material strength, unstable quality, and low structural integrity. Particularly, the living conditions in rural areas is ever-increasingly concerned under the current national strategies of rural revitalization, energy conservation, and emission reduction. Alternatively, a mechanical adobe is highly expected to serve as a masonry structure in the future, due mainly to its stable quality, convenient construction, and performance close to masonry. In this study, some experiments were carried out to determine the mechanical properties of a mechanical and eco-friendly modified adobe brick masonry. Typical non-polluting materials were added to enhance the seismic performance and strength of adobe brick masonry building, such as sodium silicate, potassium alum, urea, re-dispersible latex powder, and straw. A compressive and shear strength test was performed on the mechanical adobe brick masonry, where the specimens were divided into two groups of 12 compressive and two groups of 18 shear experiments. An investigation was made to obtain the failure mechanism and mechanical properties of adobe brick masonry. The uniaxial compression stress-strain relationship of mechanical adobe brick masonry was analyzed, where the conventional formula was revised to calculate the average compressive strength and bearing capacity. The experimental results showed there was splitting along the vertical ash joints and mostly ductile failure in the compression specimens of mechanical eco-modified adobe brick masonry. By contrast, the shear specimen of un-modified adobe brick masonry was mainly manifested as the double-sided shear failure along the interface between mud and adobe, where the failure was characterized by high instantaneity. Furthermore, the compressive and shear strength of mechanical adobe brick masonry increased by 23% and 17%, respectively, after the addition of eco-modified materials. In addition, the ductility of mechanical eco-modified adobe brick masonry was 7% higher than that of un-modified one. A compressive constitutive model was well fitted with the geometric feature points of stress-strain curves for the mechanical eco-modified adobe brick masonry, particularly meeting the characteristics of smooth and continuous curves at the peak points. Obviously, the constitutive equation was fully suitable for the mechanical unmodified and eco-modified adobe brick masonry, especially for numerical simulation. Additionally, the formula of compressive strength was well suited to the mechanical unmodified and eco-modified adobe brick masonry, when the parameter was 0.42 and 0.459. Correspondingly, the resulting data using the revised formula was all relatively larger than that of the theoretical calculation. In any way, the updated formula can reserve the specimen in a large range of safety, together with excellent applicability for the rural revitalization in northwest China.