Research on Strength and Microstructure Feature of Solidified Saline Soil in Inshore with Slag Cementitious Material

2012 ◽  
Vol 174-177 ◽  
pp. 1232-1237
Author(s):  
Cheng Bin Liu

Saline soil in inshore is a kind of special soil with poor engineering properties such as salt expansion and subsidence. The main purpose of this subject is to find a new material to solidify saline soil, so as to solve the fundamental problems that exist in the solidified saline soil at present. Through the chemical analysis, the unconfined compressive strength, SEM analysis experiment, this paper studied the strength and microstructure of solidified soil with the slag cementitious material. The test results showed that the 7th day’s strength of the test blocks which were cured in the standard case reached to 8.34MPa, the water-related stability was 1.62 times than the soil-cement when the mixing mass is 10%. The soil generated a large number of needle-bar-like crystals in the SEM graph. The research has shown that mixing slag cementitious material into the saline soil can reduce the soluble salt content of saline soil, increase water-related stability and improve the strength of the soil.

2021 ◽  
Vol 13 (14) ◽  
pp. 7758
Author(s):  
Biao Qian ◽  
Wenjie Yu ◽  
Beifeng Lv ◽  
Haibo Kang ◽  
Longxin Shu ◽  
...  

To observe the effect of recycled sand and nano-clay on the improvement of the early strength of soil-cement (7d), 0%, 10%, 15% and 20% recycled sand were added. While maintaining a fixed moisture content of 30%, the ratios of each material are specified in terms of soil mass percentage. The shear strength of CSR (recycled sand blended soil-cement) was investigated by direct shear test and four groups of specimens (CSR-1, CSR-2, CSR-3 and CSR-4) were obtained. In addition, 8% nano-clay was added to four CSR groups to obtain the four groups of CSRN-1, CSRN-2, CSRN-3 and CSRN-4 (soil-cement mixed with recycled sand and nano-clay), which were also subjected to direct shear tests. A detailed analysis of the modification mechanism of soil-cement by recycled sand and nano-clay was carried out in combination with scanning electron microscopy (SEM) and IPP (ImagePro-Plus) software. The test results showed that: (1) CSR-3 has the highest shear strength due to the “concrete-like” effect of the incorporation of recycled sand. With the addition of 8% nano-clay, the overall shear strength of the cement was improved, with CSRN-2 having the best shear strength, thanks to the filling effect of the nano-clay and its high volcanic ash content. (2) When recycled sand and nano-clay were added to soil-cement, the improvement in shear strength was manifested in a more reasonable macroscopic internal structure distribution of soil-cement. (3) SEM test results showed that the shear strength was negatively correlated with the void ratio of its microstructure. The smaller the void ratio, the greater the shear strength. This shows that the use of reclaimed sand can improve the sustainable development of the environment, and at the same time, the new material of nano-clay has potential application value.


Author(s):  
Weerakaset Suanpaga

The purpose of this study is to determine the appropriated mixed proportion of asphalt concrete using Polymer Reclaimed Asphalt Pavement, new aggregate and Advera (PRAP-Warm Mixed) that were mixed at warm temperature. Then the Mechanical Properties of new mixed asphalt concrete samples were tested following the standards of the Department of Highway, Thailand. In experimental design, the range of mixing temperature varied as 140°C, 145°C, 150°C, 155°C, and percentage of Advera added varied at 0.20, 0.25, 0.30 and 0.35 percent by weight of aggregate. The engineering properties of PRAP samples obtained from this study showed that the optimum mixing ratio was 0.20 percent at 140°C has a Stability value of 2530 lbs, a flow of 12 in a particle size of VMA 16.2, a strength index, 85 percent of the test results are in line with the requirements of the Department of Highways. Then using 70 percent of PRAP-warm mix with 30 percent of new material at 140°C and add 0.20 percent of Advera that is the best-mixed proportion. The normal temperature of PMA mixing is higher than 170°C, in this case using PRAP-Warm mix can reduce temperature lesser than 150°C then this mixing process can save fuel consumption. Thus this study is useful for environmental perspectives.


2014 ◽  
Vol 1030-1032 ◽  
pp. 969-973 ◽  
Author(s):  
Hai Jian Sun ◽  
Shi You Zhang

Natural foundation in loess areas is collapsible; however, composite foundation with rammed soil-cement pile can be used to meet the load requirements of the building. Immersion-compression test and field static loading test were carried out to measure the treatment effect. The test results showed that: the collapsible of loess foundation can be eliminated by treatment with rammed soil-cement pile when the loading pressure is between 200 to 500 kPa. Engineering properties of the foundation soil between piles are improved. The parameters improve more obvious with the pile spacing getting smaller. The bearing capacity of composite foundation increased to 291 kPa, compared with natural loess foundation. The research results can be applied to design and construction of compacted soil cement pile composite foundation in loess area.


2014 ◽  
Vol 574 ◽  
pp. 303-306
Author(s):  
Hai Yan Zhao ◽  
You Quan Jiao ◽  
Yuan Zhang ◽  
Gui Ren Nan

Aimed at engineering problems lied in inshore saline soil in the northern part of China, the store environment is analysed, and the relation between the salinity and the engineering property index is studied. The result shows that the plasticity index and the compression coefficient of the northern inshore saline soil reduce with the increase of the salt content, and the shear strength attains a limit value with the increase of the salt content.


2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Yan Zhu ◽  
Xiangjuan Yu ◽  
Lei Gao ◽  
Jiajia Chen ◽  
Michael Dino Cotugno

Saline soil is a special soil that consists of fine particles and has poor engineering properties. It causes salt heaving and is collapsible and corrosive. The treatment of this type of soil for the use as a resource for roadbed fillings has been one of the most important engineering topics in highway construction near coastal areas. This study introduces a new type of aqueous polymer, called ZM, which is used to amend and stabilize saline soil. To test the effects of ZM-solidified saline soil, unconfined compressive strength (UCS) tests were carried out on unmodified and ZM-modified saline soil specimens, respectively. The test results show that the ZM additive significantly improves the UCS. Based on the increase of the ZM admixture, the UCS increases with the curing time. The main increment of the UCS occurs within the first seven days of curing. In addition, the salt content has a great influence on the UCS. With increasing ZM concentration and curing time, the water stability and wetting-drying cycling resistance improve. Based on the X-ray diffraction results, the diffraction peaks of ZM-modified saline soil insignificantly change compared with those of unmodified saline soil. However, the SEM images indicate the formation of membrane structures in ZM-modified saline soil. The modification process produces denser and more stable soil because the reaction products fill voids inside the soil and form a viscous membrane structure on the soil surface.


2013 ◽  
Vol 815 ◽  
pp. 273-278
Author(s):  
Shu Feng Bao ◽  
Jian Hua Huang

To full understand engineering properties of soils on Boubyan island in Kuwait, some in-situ tests were performed along the highway and railway line, meanwhile some laboratory tests for soil samples from the different depth. It was concluded that its properties was low void ratio, low moisture content, low plasticity, low sensitivity, low permeability and high salt content. The soil classification belonged to CL and Marine-chloride-highly saline-soil.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Azizul Moqsud

AbstractIn this research, bioremediation of tsunami-affected polluted soil has been conducted by using collective microorganisms and recycled waste glass. The Tohoku earthquake, which was a mega earthquake in Japan triggered a huge tsunami on March 11th, 2011 that caused immeasurable damage to the geo-environmental conditions by polluting the soil with heavy metals and excessive salt content. Traditional methods to clean this polluted soil was not possible due to the excess cost and efforts. Laboratory experiments were conducted to examine the capability of bioremediation of saline soil by using recycled waste glass. Different collective microorganisms which were incubated inside the laboratory were used. The electrical conductivity (EC) was measured at different specified depths. It was noticed that the electrical conductivity decreased with the assist of the microbial metabolisms significantly. Collective microorganisms (CM2) were the highly capable to reduce salinity (up to 75%) while using recycled waste glass as their habitat.


2018 ◽  
Vol 53 ◽  
pp. 04021
Author(s):  
SHAO Yong ◽  
LIU Xiao-li ◽  
ZHU Jin-jun

Industrial alkali slag is the discharge waste in the process of alkali production. About one million tons of alkali slag is discharged in China in one year. It is a burden on the environment, whether it is directly stacked or discharged into the sea. If we can realize the use of resources, it is a multi-pronged move, so alkali slag is used to improve solidified marine soft soil in this paper. The test results show that the alkali residue can effectively improve the engineering properties of marine soft soil. Among them, the unconfined compressive strength and compressive modulus are increased by about 10 times, and the void ratio and plasticity index can all reach the level of general clay. It shows that alkali slag has the potential to improve marine soft soil and can be popularized in engineering.


1988 ◽  
Vol 68 (2) ◽  
pp. 209-221 ◽  
Author(s):  
C. Chang ◽  
T. G. SOMMERFELDT ◽  
T. ENTZ

Knowledge of the variability of soluble salt content in saline soils can assist in designing experiments or developing management practices to manage and reclaim salt-affected soils. Geostatistical theory enables the use of spatial dependence of soil properties to obtain information about locations in the field that are not actually measured, but classical statistical methods do not consider spatial correlation and the relative location of samples. A study was carried out using both classical statistics and geostatistical methods to delineate salinity and sand content and their variability in a small area of irrigated saline soil. Soil samples were taken for electrical conductivity (EC) and particle size distribution determinations at 64 locations from a 20 × 25-m area, on an 8 × 8-grid pattern at depth intervals of 0–15, 15–30, 30–60, 60–90 and 90–120 cm. The high coefficient of variation (CV) values of both EC and sand content indicated that the soil was highly variable with respect to these soil properties. The semivariograms of sand content of the first two depth intervals and EC of all the depth intervals showed strong spatial relationships. Contour maps, generated by block kriging, based on spatial relationships provide estimated variances which are smaller than general variances calculated by the classical statistical method. The interpolated EC results by both ordinary and universal kriging methods were compared and were almost identical. The kriged maps can provide information useful for designing experiments and for determining soil sampling strategy. Key words: Salinity, texture, variability, geostatistics, semivariogram, kriging


2011 ◽  
Vol 261-263 ◽  
pp. 1831-1835
Author(s):  
Guo Gang Qiao ◽  
Da Jun Yuan ◽  
Bo Liu

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.


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