Details

Autor(en) / Beteiligte

• Yuan, Hua
• Liu, Kang
• Zhang, Changguang
• Zhao, Zhiliang

Titel

Mechanical properties of Na-montmorillonite-modified EICP-treated silty sand

Ist Teil von

• Environmental science and pollution research international, 2022-02, Vol.29 (7), p.10332-10344

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2022

Link zum Volltext

Quelle

SpringerLink (Online service)

Beschreibungen/Notizen

• The effects of Na-montmorillonite (Na-Mt) content and curing age on enzyme-induced carbonate precipitation (EICP)–treated soil were studied. First, the effects of Na-Mt addition on the urease activity, Ca 2+ precipitation rate, and pH of the solution were analyzed through tube tests. Then, Na-Mt-modified EICP was used to reinforce silty sand in the Yellow River flooding area in China. The solidification effect and action mechanism of Na-Mt were investigated via the unconfined compressive strength (UCS) test, calcium carbonate content (CCC) measurement, X-ray diffraction, and scanning electron microscope analyses, wherein soil treated by conventional EICP and soil treated with Na-Mt alone were considered the control group. Na-Mt improved the urease activity and Ca 2+ precipitation rate, lowered the pH, increased the CaCO 3 production through chelation, then regulated the morphology of the CaCO 3 crystals and facilitated the formation of densely aggregated calcite. The CCC and mechanical parameters increased rapidly during the first 7 days of curing, and then slowed down. The incorporation of 8% Na-Mt enhanced the UCS and Ca 2+ utilization ratio at curing age of 7 days by 1.4 and 2.72 times, respectively, compared with that of traditional EICP; and the optimal Na-Mt content was identified to be 8%. At Na-Mt contents lower than 8%, the mathematically expressed improvement effect of the Na-Mt-modified EICP on the soil strength was greater than the arithmetic sum of that when these two approaches applied individually; this result confirms that the Na-Mt-modified EICP technique proposed herein is an efficient approach for solidifying fine-grained soil.