Shallow foundation performance in a calcareous sand

2010 ◽  
pp. 445-450
Keyword(s):  
Shallow Foundation ◽  
Calcareous Sand

scholarly journals Effect of Different Mineralization Modes on Strengthening Calcareous Sand under Simulated Seawater Conditions

2021 ◽  
Vol 13 (15) ◽  
pp. 8265
Author(s):  
Shiyu Liu ◽  
Bowen Dong ◽  
Jin Yu ◽  
Yanyan Cai ◽  
Xingqian Peng ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Construction Projects ◽  
Construction Material ◽  
X Ray Diffraction ◽  
Calcareous Sand ◽  
Sand Column ◽  
Sporosarcina Pasteurii ◽  
Phosphate Mineralization ◽  
Filling Water ◽  
Simulated Seawater

Calcareous sand, as a blow-fill or construction material, is widely used in island and reef construction projects in marine environments after treatment. When microorganism-induced mineralization is used to strengthen calcareous sand, salinity and other conditions in the marine environment will adversely affect microorganisms or their mineralization process. For this reason, the two environmental conditions created by deionized water and simulated seawater were introduced to explore their effects on the growth and urease activity of Sporosarcina pasteurii. Then, the changes in the permeability and mechanical strength of calcareous sand under different mineralization methods were compared by one-dimensional sand column tests. Finally, the reinforcement mechanism was compared and analyzed based on the results of scanning electron microscopy and X-ray diffraction tests. The results show that Sporosarcina pasteurii can induce carbonate and phosphate precipitation and mineralization to strengthen calcareous sand in simulated seawater. The mineralized products greatly reduce the permeability of calcareous sand and significantly improve the mechanical strength by wrapping calcareous sand particles, filling water seepage channels and cementing adjacent particles. The reinforcement effect of carbonate mineralization is better than that of phosphate mineralization, but phosphate mineralization has less impact on the environment during the treatment process.

scholarly journals Effects of Different Types of Fibers on the Physical and Mechanical Properties of MICP-Treated Calcareous Sand

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 268
Author(s):  
Jitong Zhao ◽  
Huawei Tong ◽  
Yi Shan ◽  
Jie Yuan ◽  
Qiuwang Peng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Glass Fiber ◽  
Physical And Mechanical Properties ◽  
Polyester Fiber ◽  
Engineering Properties ◽  
Fiber Types ◽  
Calcite Precipitation ◽  
Calcareous Sand ◽  
Hemp Fiber

Microbial-induced calcite precipitation (MICP) has been a promising method to improve geotechnical engineering properties through the precipitation of calcium carbonate (CaCO3) on the contact and surface of soil particles in recent years. In the present experiment, water absorption and unconfined compressive strength (UCS) tests were carried out to investigate the effects of three different fiber types (glass fiber, polyester fiber, and hemp fiber) on the physical and mechanical properties of MICP-treated calcareous sand. The fibers used were at 0%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, and 0.40% relative to the weight of the sand. The results showed that the failure strain and ductility of the samples could be improved by adding fibers. Compared to biocemented sand (BS), the water absorption of these three fiber-reinforced biocemented sands were, respectively, decreased by 11.60%, 21.18%, and 7.29%. UCS was, respectively, increased by 24.20%, 60.76%, and 6.40%. Polyester fiber produced the best effect, followed by glass fiber and hemp fiber. The optimum contents of glass fiber and polyester fiber were 0.20% and 0.25%, respectively. The optimum content of hemp fiber was within the range of 0.20–0.25%. Light-emitting diode (LED) microscope and scanning electron microscope (SEM) images lead to the conclusion that only a little calcite precipitation had occurred around the hemp fiber, leading to a poor bonding effect compared to the glass and polyester fibers. It was therefore suggested that polyester fiber should be used to improve the properties of biocemented sand.

Chemical stabilization of calcareous sand by polyurethane foam adhesive

2021 ◽  
Vol 295 ◽  
pp. 123609
Author(s):  
Gaoliang Tao ◽  
Jinghan Yuan ◽  
Qingsheng Chen ◽  
Wan Peng ◽  
Ronghu Yu ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Chemical Stabilization ◽  
Calcareous Sand

Three-dimensional pore characteristics and permeability properties of calcareous sand with different particle sizes

2021 ◽  
Vol 80 (3) ◽  
pp. 2659-2670
Author(s):  
Zhihan Fan ◽  
Cong Hu ◽  
Qianlin Zhu ◽  
Yonggang Jia ◽  
Dianjun Zuo ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Particle Sizes ◽  
Calcareous Sand ◽  
Pore Characteristics
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