固化夯土材料强度特性与耐久性能试验

随着生态建筑的大力推广,夯土技术被广泛应用.基于改良夯筑方法,针对含有不同黏土矿物的膨润土、高岭土和天然土的夯土试样,开展以水泥和石灰为固化剂的11种不同配比,4种养护龄期(3、7、28、56d)条件下的无侧限抗压强度(un-confined compressive strength,UCS)试验和吸水试验,研究固化夯土材料强度特性以及耐久性能.研究结果表明:随养护龄期的增加,膨润土试样的强度逐渐增强,高岭土试样的强度先增加而后小幅衰减,而对于天然土试样,仅当水泥和石灰等量配比时,其强度先增加而后减小,其余配比条件下,试样强度逐渐增强;对于同一类试样,水泥在试样耐久性和抗风化能力方面相较于石灰表现出更好的固化作用,但石灰含量的变化对试样强度的影响效果各不相同;整体而言,3种试样中高岭土表现出最优的强度和耐久度,其次是天然土,膨润土试样的强度和耐久度最差.进一步对实验结果进行了拟合并得到固化夯土试样无侧限抗压强度增长函数模型,该函数能良好地描述其夯土材料强度增长规律.

Experimental on Strength Characteristics and Durability of Stabilized Rammed Earth

With the promotion of ecological architecture, the rammed earth technology is widely used. In order to study strength characteristics and durability of stabilized rammed earth, bentonite, kaolin and natural soil which contain different clay minerals are utilized to produce various types of rammed earth specimens based on improved ramming methods. The unconfined compressive strength tests and ab-sorption tests are carried out in 4 different times of curing (3, 7, 28 and 56 days). In addition, 11 kinds of stabilized blending ratios are made by varying the amounts of cement and lime. The results indicate that the longer curing time is, the stronger unconfined compres-sive strength (UCS) of bentonite specimens will be. With the increase of the curing time, the UCS of the kaolinite specimens increase at first and then decrease slightly. However, in terms of natural soil specimens, the UCS increases at first and then decrease only when they contain the same amount of cement and lime, whereas to other blending ratios the UCS increases gradually. Furthermore, cement exhibit superior durability and resistance to weathering characteristics when compared to lime. On average, the strength and durability of natural soil-containing specimens was not as superior as that of kaolinite-containing specimens, but was significantly higher than that of bentonite-containing specimens. On the other hand, it was found that the strength growth model of UCS fitted by experimental re-sults could describe reasonably the development of stabilized rammed earth.