Effect of Ultrafine Cement (UFC) on the Corrosion Resistance of Cement Soil in Peat Soil Environment
Abstract
:1. Introduction
2. Test Design
2.1. Experiment Material
- (1)
- The soil used for the test is the alluvial and diluvial clay soil on the north slope of the Jingyuan Student Apartment, Chenggong Campus, Kunming University of Science and Technology. The undisturbed soil sample is brownish-yellow. The basic physical property indicators are shown in Table 1. The base parameters of the soils in this table will be used as input conditions for sampling in subsequent tests. The X-ray fluorescence (XRF) analysis results are shown in Table 2. The X-ray diffraction test (XRD) results are shown in Figure 2, which shows that the main crystal phases of alluvial clay soil are quartz, kaolinite, muscovite, goethite, and anatase. The test results show that the soil sample has a single composition and low organic matter content. Therefore, selecting this soil sample as a raw material has little influence on the test results.
- (2)
- Tianjin Guangfu Chemical Reagent Factory (Tianjin, China) produces the humic acid (HA) reagent, and the actual humic acid content is 41.68%. Its microstructure is shown in Figure 3, it can be seen that the humic acid aggregates are loose and porous, and its structural connection is weak.
- (3)
- Pingxiang Hongtudi Humic Acid Co., Ltd. (Pingxiang, China) produces the fulvic acid reagent. The actual content of fulvic acid is 60%. Its microstructure is shown in Figure 4. It can be seen that the fulvic acid aggregates are colloidal.
- (4)
- Distilled water is used for mixing samples and fulvic acid and soaking solution in the test.
- (5)
- The cement selects Shilin brand P·O 42.5 grade ordinary Portland cement (OPC) is produced by Huaxin Cement Co., Ltd. (Wuhan, China).
- (6)
- Ultra-fine cement (UFC) is made as the abovementioned ordinary cement through physical processing and grinding, and its specific surface area is more significant than 9000 cm2/g and d90 < 10 μm. The main chemical components and mass fractions of the two types of cement are shown in Table 3, the cumulative distribution curve in Figure 5, and the particle size distribution curve in Figure 6. Through data analysis, it can be seen that the main chemical components and contents of the two are the same. However, UFC has a more concentrated particle size distribution than OPC.
2.2. Test Method and Sample Preparation
2.3. Testing Process
- (1)
- UCS test
- (2)
- SEM test
- (3)
- PCAS microscopic quantitative test
3. Test Results and Analysis
3.1. Effect and Mechanism Analysis of UFC on the Corrosion Resistance of Cement Soil in the Peat Soil Environment
3.2. SEM and PCAS Test Results and Analysis
3.3. SEM and PCAS Test Results and Analysis
4. Conclusions
- (1)
- The UCS test results show that with the soaking time increase, the cement soil sample’s strength curve gradually increases to the peak strength and then decreases. That is, the strength change curve presents two stages: the strength-enhancing phase and the corrosion phase. The soaking times corresponding to the peak intensities were significantly different. With an increase in UFC content, the strength change per unit time of the sample, the growth rate of the strength of the unit UFC proportion, and the strength decrease in the rate of 90–360 d all show that compared with the sample without UFC, UFC can significantly reduce the intensity reduction rate of the sample. The sample can still maintain high strength under long-term immersion time, and the optimal dosage of UFC is 10%. It shows that UFC significantly inhibits the erosion of fulvic acid solution on cement soil samples, thus reflecting the excellent corrosion resistance of UFC.
- (2)
- The results of SEM and PCAS tests show that the microstructure of cement soil gradually weakens with the increase in soaking time. However, the UFC particle size is small, the particle size distribution is narrow, the hydration reaction rate is fast, and the hydration degree is high. The excellent characteristics of high concentration and a large amount of hydration products weakened the adverse effects of humic acid on the cement soil structure to a certain extent. Although the number of large pores gradually increased, it did not significantly change the integrity of the cement soil structure. It still exhibits a relatively compact honeycomb overall structure, which correlates well with the strength test (UCS) results.
- (3)
- The complete test results show that an increase in the UFC proportion will significantly improve cement soil’s durability in peat soil. Based on previous studies [3,4,5,6,7,8], this study adopts the test method of adding UFC to form a composite curing agent and discusses the influence of UFC content changes on the humic acid erosion res istance of cement soil in a peat soil environment from the perspective of strength test and microscopic test. Therefore, in future research and actual engineering of the peat soil environment in Dianchi Lake and Erhai Lake in Yunnan, we can combine the conclusions of this study with exploring more reasonable and effective ways to improve the mechanical properties and durability of cement soil in peat soil environment and reduce the amount of cement. Due to the significant CO2 emissions generated during cement production, the moderate use of UFC will also reduce total cement consumption and decrease CO2 emissions, promoting sustainable societal development.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Test Soil | Natural Moisture Content (%) | Liquid Limit (%) | Plastic Limit (%) | Natural Density (g·cm−3) | The Specific Gravity of Soil Particles (Gs) |
---|---|---|---|---|---|
Cohesive Soil | 18.60 | 39.20 | 23.00 | 1.96 | 2.84 |
Test Soil | Chemical Composition and its Mass Fraction/% | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
SiO2 | Fe2O3 | Al2O3 | TiO2 | K2O | MgO | CaO | Na2O | MnO | P2O5 | Loss on Ignition | |
Cohesive Soil | 46.57 | 21.22 | 20.80 | 8.90 | 0.48 | 0.48 | 0.16 | 0.04 | 0.14 | 0.57 | 0.64 |
Material Type | Chemical Composition and Its Mass Fraction/% | |||
---|---|---|---|---|
CaO | SiO2 | Al2O3 | Fe2O3 | |
OPC | 65.5 | 18.4 | 5.3 | 2.9 |
UFC | 65.5 | 18.0 | 5.4 | 2.9 |
Test Type | Cement Rate β/% | HA Content λ/% | Soaking Solution Type | Dosage of UFC γ/% | Soaking Time/d |
---|---|---|---|---|---|
UCS | 20 | 0, 15, 30 | FA solution (pH = 5.0, 6.0) Distilled water (pH = 7.0) | 0, 10, 20, 30, 40, 50 | 28, 90, 180, 270, 365 |
SEM, PCAS | 20 | 15 | FA solution (pH = 6.0) | 10 | 28, 90, 180, 270, 365 |
Cement Rate/β | Fulvic Acid Solution pH Value | HA. Content | 90~365 d Sample Strength Reduction Rate/% | |||||
---|---|---|---|---|---|---|---|---|
γ = 0% | γ = 10% | γ = 20% | γ = 30% | γ = 40% | γ = 50% | |||
20% | pH = 5.0 | λ = 0% | 43.6 | 33.6 | 32.5 | 29.7 | 28.7 | 28.2 |
λ = 15% | 45.1 | 33.5 | 31.8 | 29.1 | 27.8 | 26.6 | ||
λ = 30% | 54.7 | 48.7 | 44.9 | 43.7 | 39.7 | 39.2 | ||
pH = 6.0 | λ = 0% | 38.3 | 29.7 | 28.5 | 27.1 | 26.7 | 24.9 | |
λ = 15% | 32.0 | 19.2 | 18.8 | 17.7 | 16.8 | 15.6 | ||
λ = 30% | 43.1 | 35.0 | 31.8 | 27.9 | 27.4 | 26.2 |
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Guo, Y.; Cao, J.; Sun, H.; Ding, W.; Hua, G.; Wei, W.; Huang, S. Effect of Ultrafine Cement (UFC) on the Corrosion Resistance of Cement Soil in Peat Soil Environment. Materials 2023, 16, 5520. https://doi.org/10.3390/ma16165520
Guo Y, Cao J, Sun H, Ding W, Hua G, Wei W, Huang S. Effect of Ultrafine Cement (UFC) on the Corrosion Resistance of Cement Soil in Peat Soil Environment. Materials. 2023; 16(16):5520. https://doi.org/10.3390/ma16165520
Chicago/Turabian StyleGuo, Yongfa, Jing Cao, Huafeng Sun, Wenyun Ding, Guofeng Hua, Wei Wei, and Siyang Huang. 2023. "Effect of Ultrafine Cement (UFC) on the Corrosion Resistance of Cement Soil in Peat Soil Environment" Materials 16, no. 16: 5520. https://doi.org/10.3390/ma16165520