Development of Steel Slag-Based Solidification/Stabilization Materials for High Moisture Content Soil

To solve the problems of high moisture content,high viscosity,and poor engineering mechanical properties of soil,this paper using with steel slag(SS)and desulfurization ash(DS)as initial raw materials,realizing the coop-erative treatment of solid waste and solidification of silt soil.The synergistic utilization of SS and DS can reduce the production cost of curing agent and promote its own consumption.According to blended cement of various SS contents and inspected compressive strength performances,the most suitable raw materials ratio was selected.The best formula for this curing agent is cement:steel slag=3:7 with 5%DS,and its 28-day compressive strength can reach 30 MPa.The experiment shows that the effect of DS and Na_(2)SO_(4) reagent with the same quality on early compressive strength improvement of cement and SS system is not much different.In this study,the mineral composition and microstructure of different gel system blocks were characterized by XRD,SEM and EDX,and a large number of webbed structures were found in the SEM test,which was not seen in previous studies.Besides,unconfined compressive strength(UCS),water resistance,and toxic characteristic leaching procedure(TCLP)were used to evaluate silt solidified soil properties.The results demonstrated that the solidified silt could meet not only the standard of general subgrade;but also has a partial stabilization effect of heavy metal ions.

A distributed measurement method for in-situ soil moisture content by using carbon-fiber heated cable

Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a distributed measurement system for in-situ soil moisture content （SM-DTS） is introduced.The system is based on carbon-fiber heated cable （CFHC） technology that has been developed to enhancethe measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristicvalue （Tt） can be defined from temperatureetime curves. A relationship among Tt, soil thermalimpedance coefficient and soil moisture content is then established in laboratory. The feasibility of theSM-DTS technology to provide distributed measurements of in-situ soil moisture content is verifiedthrough field tests. The research reported herein indicates that the proposed SM-DTS is capable ofmeasuring in-situ soil moisture content over long distances and large areas.

Evaluation of Soil Organic Carbon and Soil Moisture Content from Agricultural Fields in Mississippi

Independent observation of the effects of agricultural management practices on soil organic carbon (SOC) with soil moisture content (SMC) is essential to quantify their potential relationships for sustainable ecosystems. Soil water retention studies and soil carbon stocks have been mapped in some areas worldwide. However, few studies have been conducted in the southeastern US, particularly in Mississippi. The objectives of this research study were to collect soil samples from fields chosen to be representative of the watersheds they are contained within, analyze the soil samples for carbon content and soil moisture content, and evaluate the relationship between SOC and different parameters (land use, vertical distribution, temporal distribution, and soil moisture content). Field sites were chosen based on their compositional similarity shared with the watershed as a whole in the Town Creek watershed (TCW) and Upper Pearl River watershed (UPRW) in Mississippi. Monthly soil samples from different depths (6 inch, 12 inch, and 24 inch) were collected from crop, pasture, and forest field areas. Soil samples were analyzed using bench analysis, elemental analysis, and statistical analysis. This study was able to demonstrate the SOC distribution in the soil layers across all three land uses studied. It was also shown that there does seem to be an interactive effect of parameters such as land use type, vertical distribution, and time on carbon accretion within the soil. Results of this study also determined that the near surface (6-in) layer was found to contain significantly more carbon than either the 12 inch or 24 inch layers (p 0.01) across all field types. There was found to be a high degree of variability within the soil moisture data and correlation between SOC and SMC. It was found that carbon amount is not influenced by SMC but SMC could be influenced by SOC.

Performance evaluation of two types of heated cables for distributedtemperature sensing-based measurement of soil moisture content

Distributed temperature sensing(DTS)using heated cables has been recently developed for distributed monitoring of in-situ soil moisture content.In this method,the thermal and electrical properties of heated cables have a significant influence on the measurement accuracy of soil moisture content.In this paper,the performances of two heated cables,i.e.the carbon-fiber heated cable(CFHC)and the metalnet heated cable(MNHC),are studied in the laboratory.Their structures,uniformity in the axial direction,measurement accuracy and suitability are evaluated.The test results indicate that the MNHC has a better uniformity in the axial direction than CFHC.Both CFHC and MNHC have high measurement accuracy.The CFHC is more suitable for short-distance measurement(500 m),while the MNHC can be used for longdistance measurement(>500 m).

Spatial variability of soil resistivity and rational sampling for corrosion assessment of carbon steel in Daqing area

Soil resistivity is one of the key indicators of the corrosive classification assessment on metal materials in soil environment. This paper presents variance characters of various quantity of soil resistivity samples data based on the semi-variance function methods of Geo-statistical Analysis by analyzing the regional soil resistivity sampling data in Daqing area. Furthermore, the variance of the soil resistivity as well as entire soil circumstance due to different sampling amounts are also analyzed and compared by means of using the characteristic parameters of the semi-variance function. In addition, this work also studied the rational sampling quantities according to various measurement errors required and evaluated the local soil corrosivity on carbon steel based on the actual measuring data in this area.

Comparing tractive performance of steel and rubber single grouser shoe under different soil moisture contents

Steel and rubber are two kinds of materials which are often used for the tracks of off-road vehicles.The objective of this study was to compare tractive performances of steel and rubber grouser shoes under different soil moisture contents.In this study,the tractive performance of single grouser shoe was predicted by soil parameters and three-dimensional shearing model.The soil used in this study was clay soil,and ten different soil moisture contents ranged from 8.58%to 54.36%were applied for investigation of soil parameters.For each soil moisture content,the penetration test,direct shearing test,density and soil moisture content measurement have been performed to obtain the required soil parameters.The experimental results showed that thrust and running resistance of steel single grouser shoe had similar trends to those of rubber single grouser shoe.The thrust of rubber single grouser shoe was always greater than that of steel single grouser shoe with the increase of soil moisture content,and as well as the running resistance.However,the traction of rubber single grouser shoe had a different trend to that of steel single grouser shoe.The traction of steel single grouser shoe was always greater than that of rubber single grouser shoe at any given moisture content except at the stage of less than 15%moisture content.From the experimental results,it can be concluded that the steel single grouser shoe performed better than rubber single grouser shoe in traction for the soil used in this study.

不同水分条件下氨基酸添加对温带暗棕壤碳氮含量和甲烷排放的影响

【目的】解析土壤pH值与土壤氮以及CH_(4)排放速率与土壤碳氮含量间的相互关系,为明确碳氮转化及温室气体排放规律、优化温带森林暗棕壤的水分管理提供依据。【方法】以温带森林暗棕壤为研究对象,采用室内培养法,设置水分条件为土壤饱和持水量(WHC)的40%、60%、90%,通过向温带暗棕壤中添加两种不同性质的氨基酸,探讨其对土壤碳氮含量及CH_(4)排放的潜在影响,运用Pearson相关分析法分析土壤碳氮含量、pH值及CH_(4)排放速率间的相关性。【结果】(1)氨基酸处理显著增加了土壤可溶性有机碳(DOC)含量、铵态氮(NH_(4)^(+)-N)含量及CH_(4)排放速率。亮氨酸处理使DOC、NH_(4)^(+)-N含量分别升高21.39%、45.10%,CH_(4)排放速率较CK升高3.20倍,甲硫氨基酸使DOC、NH_(4)^(+)-N含量分别升高21.39%、72.71%,CH_(4)排放速率较CK升高7.00倍;(2)不同氨基酸对土壤硝态氮(NO_(3)^(-)-N)含量的影响存在差异。亮氨酸处理使土壤NO_(3)^(-)-N含量升高了8.41%,但其对于土壤硝化作用的影响可能存在滞后性,而甲硫氨基酸能够显著抑制土壤硝化作用,NO_(3)^(-)-N含量显著降低了37.90%;(3)土壤不同水分条件对土壤DOC、NH_(4)^(+)-N、NO_(3)^(-)-N含量及CH_(4)排放速率均存在显著影响。90%WHC使DOC含量升高11.95%~19.91%,使NH_(4)^(+)-N升高19.83%~35.46%,使NO_(3)^(-)-N降低10.05%~23.79%,使CH_(4)排放速率升高至另外两种水分条件的1.48~2.06倍。60%WHC条件使NH_(4)^(+)-N升高13.05%,使NO_(3)^(-)-N含量升高24.62%。60%WHC可能是温带暗棕壤硝化作用的最适含水量,90%WHC条件有利于DOC积累,同时对NO_(3)^(-)-N的产生存在明显抑制作用;(4)土壤pH与N H4+-N含量呈极显著正相关,与NO_(3)^(-)-N含量呈正相关。CH_(4)排放速率与NO_(3)^(-)-N含量呈极显著负相关,与NH_(4)^(+)-N含量呈负相关,与DOC含量呈极显著正相关。【结论】不同性质氨基酸添加在温带森林暗棕壤碳氮含量及CH_(4)排放中发挥的作用不尽相同。一定范围内,土壤水分含量的升高有利于土壤NH_(4)^(+)-N、NO_(3)^(-)-N、DOC的积累及CH_(4)的排放,但土壤高含水量条件对NO_(3)^(-)-N的产生具有抑制作用。因此,在研究温带森林暗棕壤碳含量、CH_(4)排放及氮转化机制时,建议关注不同氨基酸的差异性作用,同时考虑水分的变化。

碳含量对船体钢耐蚀性的影响

通过干湿循环腐蚀试验模拟热带海洋大气环境,采用光学显微镜、扫描电子显微镜、X射线衍射、动电位极化曲线、阻抗谱测试等表征手段,研究了不同碳含量对船体钢耐蚀性的影响。结果表明,降碳会减少钢中珠光体含量,使腐蚀产物中具有稳定结构的α-FeOOH的比例增加,从而提高基体的电位,并使得腐蚀产物膜层电阻和电荷转移电阻增大,形成粘附性好、稳定、致密的锈层,表现出良好的耐蚀性。

不同含水量及冻结温度对黑土冻融循环过程有机碳矿化的影响

[目的]冻融过程土壤呼吸在年土壤呼吸总量中占有重要比例,研究探讨土壤冻融过程中含水量、冻结温度和冻融循环次数对土壤碳矿化动态的影响。[方法]以黑龙江省嫩江县鹤山农场九三水土实验站黑土为研究对象,开展室内冻融程度模拟试验,进行7次冻融循环,设置100%田间持水量(100%WHC)、60%田间持水量(60%WHC)和30%田间持水量(30%WHC)3种土壤含水量;10℃恒温处理(对照)、-5℃冻结处理(轻度冻结)和-15℃冻结处理(重度冻结)3种环境温度。[结果]冻融循环次数、含水量和冻结温度对CO_(2)排放量有显著影响,影响度分别为-0.63,0.21,0.14。解冻过程显著增加土壤碳矿化量;轻度冻结时,前3次冻融循环60%WHC土壤碳矿化量比100%WHC和30%WHC分别提高33.0%,35.2%,后4次冻融循环差异不明显;重度冻结时,前2次冻融循环100%WHC土壤碳矿化量,比60%WHC和30%WHC土壤分别提高25.2%,68.0%,后5次冻融循环差异不明显。[结论]冻融循环次数对土壤CO_(2)排放量影响最大,含水量次之,冻结温度最小。冻融作用增加低含水量土壤的CO_(2)累积排放量;降低高含水量土壤的CO_(2)累积排放量;而对中等含水量土壤,轻度冻结增加CO_(2)累积排放量,重度冻结降低CO_(2)累积排放量。一级动力学方程对冻融土壤CO_(2)排放量的拟合效果较好(R^(2)>0.997),含水量和冻结温度对有机碳矿化潜力C0值有显著影响。

Corrosion behavior of low-carbon Cr micro-alloyed steel for grounding grids in simulated acidic soil

To improve the corrosion resistance of steels for grounding grids, a low-carbon Cr micro-alloyed steel was developed （C 1 steel）, and corrosion behavior of Q235 steel and newly developed C1 steel in simulated acidic soil was investigated. The corrosion rate was evaluated with the mass loss measurements, while the corrosion morphology of surface and cross section of rust layer was observed by scanning electron microscopy. The corrosion products were analyzed by energy- dispersive X-ray spectrometry, X-ray diffraction and X-ray photoelectron spectroscopy, and the polarization curve was measured using potentiodynamic polarization method. Results indicated that C 1 steel displayed good corrosion resistance in the simulated acidic soil, of which the corrosion rate was only 30% of that of Q235 steel after corrosion for 360 h. The analysis of rust layer showed that lower carbon content in steel could reduce the tendency of micro cell corrosion and appropriate amount of chromium could improve the corrosion potential of metal matrix. Moreover, the analysis of X-ray photoelectron spectroscopy revealed that the chromium enriched in inner rust layer of C1 steel existed mainly in the form of Fe2CrO4, which facilitated the formation of Cr-goethite and improved the protection of corrosion products.

Al含量对含铝奥氏体不锈钢在高温超临界二氧化碳中均匀腐蚀性能的影响研究

为进一步提升奥氏体不锈钢作为超临界二氧化碳核反应堆候选包壳材料的耐腐蚀性能,对比研究了3种不同Al含量的含铝奥氏体不锈钢及不含Al基材在650℃/20 MPa的超临界二氧化碳环境中的均匀腐蚀行为。结果表明,材料的腐蚀增重随Al含量增加而降低,不同Al含量材料的腐蚀增重均近似服从抛物线生长规律。Al含量低于1.5wt%时,材料表面生成双层富Fe氧化膜,保护性差,渗碳层厚度可达约12μm;Al含量高于2.5wt%时,材料表面生成保护性氧化膜,外层富Cr、内层富Al,氧化膜及基体中仍存在渗碳行为,渗碳层厚度减小至约6μm。造成差异的原因是较高Al含量能有效促进保护性富Al氧化膜的形成,抑制Fe的向外扩散和C的向内扩散,进而提升材料的耐氧化和渗碳属性。

黄河孟津段河岸带土壤有机碳分布特征及影响因素分析

【目的】探究黄河孟津段河岸带土壤有机碳空间分布差异及规律,为黄河河岸带土壤固碳和生态修复提供理论依据。【方法】以河岸带表层土壤为研究对象,采用克里金插值法和冗余分析对土壤有机碳空间分布及影响因素进行分析,探讨土壤有机碳含量与微地形、土壤物理性质及植被组合的相关关系。【结果】研究区土壤有机碳含量和土壤有机碳密度的平均值分别为1.94 g·kg^(-1)和0.11 kg·m^(-2),空间变异系数分别为69.9%和83.6%,均属于中等程度变异。研究区土壤有机碳含量在随垂直河流方向距离V1—V5样带的增加而增加,V5样带土壤有机碳含量显著高于V1—V3这3个样带。相关性分析和冗余分析中,研究区土壤有机碳含量与垂直河流距离、土壤含水率、土壤黏粒呈极显著正相关,与土壤砂粒呈极显著负相关,与植物群落、海拔无显著相关。【结论】河岸带土壤有机碳含量随垂直河流方向距离的增加而增加,空间自相关性强,河岸带微地形、土壤黏粒和土壤含水率显著影响土壤有机碳的空间分布。

Simulated Corrosion Test of Q235 Steel in Diatomite Soil

Through the study of the corrosion behavior of Q235 steel in actual Yingtan soil and two simulated acidic soils with different water contents, the calculation of corrosion mass losses, and the analysis of the corrosion mor- phologies and products by means of scanning electron microscope （SEM） and X-ray diffraction （XRD）, the results demonstrated that the diatomite soil could simulate the corrosion in actual soil veritably. In both actual soil and simu- lated soil with 16.4% water content, the corrosion rates of Q235 steel were approximately 0.1 mm/a, the corrosion morphologies were mainly extension and connection of corrosion spots on sample surface, and the corrosion products were composed of a-FeOOH, γ-FeOOH, Fe3 O4 and Fe2O3. When other media conditions remained unchanged, the corrosion area of Q235 steel was larger in simulated soil with 34.5 % water content, and the corrosion rate reached 0.48 mm/a after 360 h of corrosion, which was nearly 5 times as the value in actual soil. Compared with the corro- sion products in actual soil, the proportion of γ-FeOOH in simulated soil with 34.5 % water content was higher, and the wα-FeOOH/wγ-FeOOH ratio was 1. 4, which was only 1/3 of the value in actual soil.

不同秸秆还田方式对玉米农田土壤CO_(2)排放量和碳平衡的影响

【目的】探究秸秆还田方式对土壤CO_(2)排放特征及碳平衡的影响,为东北地区农田土壤固碳减排和秸秆还田方式的选择提供科学依据。【方法】采用田间微区试验,以玉米为供试作物,设置3种秸秆还田方式:秸秆浅层还田(QH)、秸秆深层还田(SH)和秸秆覆盖还田(FG),无秸秆还田(CK)处理为对照。利用LI-8100A土壤碳通量自动测定仪监测玉米生长季不同秸秆还田方式下土壤CO_(2)的排放特征,探讨土壤温度、含水量、pH、微生物量碳及氮磷钾速效养分和全量养分对土壤CO_(2)排放的影响,并分析不同还田方式下的土壤碳平衡。【结果】在玉米生长季,各处理土壤CO_(2)排放速率均表现为先升高后降低的趋势。土壤CO_(2)累积排放量表现为FG>QH>SH>CK处理,相较于SH处理,FG和QH处理土壤CO_(2)累积排放量分别增加了14.0%和6.4%,各处理间差异显著(P<0.05)。不同还田方式下土壤CO_(2)排放速率与土壤温度、土壤含水量进行单因素模型拟合,均呈二次函数相关关系,且达到了显著水平(P<0.05),土壤温度和土壤含水量分别解释68.2%—73.7%和21.3%—82.8%的土壤CO_(2)排放速率变化,但土壤温度和土壤含水量的双因素复合模型能更好地解释土壤CO_(2)排放速率的变化,解释度达到78.5%—82.8%。相关性分析表明,土壤CO_(2)累积排放量与速效钾、微生物量碳呈极显著相关关系(P<0.01),与土壤有机质、碱解氮、全氮和pH呈显著的相关关系(P<0.05)。秸秆还田处理下土壤碳平衡均为正值,为大气CO_(2)碳汇。SH处理下土壤碳平衡和固碳潜力显著高于QH、FG处理,提高幅度分别为23.4%、475.7%和7.1%、30.7%(P<0.05),表现出较强的碳汇功能。在两年收获期,秸秆还田显著提高了玉米产量,其中SH处理最高,但与QH和FG处理间无显著差异。【结论】本试验条件下,综合考虑固碳减排效应和产量,3种秸秆还田方式相比,秸秆深层还田(SH)是一种较好的还田方式。

不同含水量红壤中X80管道钢的腐蚀行为

通过开路电位、动电位极化曲线、电化学阻抗谱等电化学测试研究了不同含水量红壤中X80管道钢的腐蚀行为。结果表明:X80管道钢的自腐蚀电位、腐蚀速率、腐蚀类型均与红壤含水量及X80管道钢表面吸附薄液膜密切相关。随红壤含水量增大,X80管道钢表面吸附液膜的连续性增大,开路电位下降,腐蚀电流密度增大,X80管道钢的腐蚀模式从局部腐蚀变为均匀腐蚀。

Cu对低碳钢耐腐蚀和抑菌性能的影响

低碳钢不仅要求其具有较高的强度和硬度,而且耐腐蚀性和抑菌性也至关重要。为了研究不同Cu含量的低碳钢在复杂工况环境下的耐腐蚀和抑菌性能,选取了4种不同组织钢种:MS1500、S-Ten2、F92和17-4PH。实验选择了酸性(pH=3)、中性(pH=7)、碱性(pH=11)和菌液(大肠杆菌和葡萄球菌)4种溶液来模拟材料应用的复杂环境,采用动电位极化、电化学阻抗谱测试和浸泡实验对比分析了它们在4种环境下的耐腐蚀性能,并在菌液环境中进行了材料抑菌实验。另外,通过对不同热处理后的S-Ten2低碳钢进行抑菌实验,进一步研究了不同Cu析出状态对低碳钢抑菌性能的影响。实验结果表明:F92和17-4PH 2种低碳钢在4种环境下均表现出了优异的耐蚀腐性能;在强碱环境下4种材料的耐腐蚀性能相近。S-Ten2在碱性环境下的耐腐蚀性能优于酸性和中性环境,而MS1500的耐腐蚀性能在所有实验环境下相对稳定。在葡萄球菌液中,F92和17-4PH的耐蚀性能优于MS1500和S-Ten2。通过对S-Ten2不同热处理后,大肠杆菌液中900℃-6 h-水淬和560℃-6 h-空冷的样品抑菌性优于700℃-5 min-固溶的样品,说明合理的热处理可以使Cu析出达到理想抑菌效果,但在葡萄球菌液中,3种不同热处理的样品抑菌性均不理想。

碳化作用对海砂混凝土中钢筋锈蚀的影响研究

海砂混凝土与河砂混凝土由于氯离子含量不同从而在性能方面产生了不同的差异。本文研究了海砂混凝土的碳化及其与氯离子的共同作用对钢筋锈蚀的影响,通过试验得到在不同氯离子含量和CO_(2)浓度下的碳化深度发展规律,以及在不同钢筋类别和氯离子浓度下的混凝土钢筋碳化前后腐蚀电位的变化情况,并分析了碳化与氯离子的共同作用原理。结果表明:氯离子对混凝土的碳化反应起到一定的抑制作用;在碳化与氯离子的共同作用下,会对混凝土中钢筋的锈蚀产生一定的不利影响。

低含水率和温度对X80管线钢在沈阳土壤模拟溶液中腐蚀行为的影响

为探究低含水率和温度对X80管线钢在沈阳草甸土土壤模拟溶液中对电化学腐蚀行为的影响,利用失重试验、交流阻抗技术、动电位极化技术方法测定其阻抗谱、极化曲线等数据并结合扫描电子显微镜(SEM)进行分析。结果表明随着含水率由10%升高至30%过程中,产物膜被破坏,从而逐渐加剧了X80管线钢的腐蚀,生成大腐蚀坑。含水率为30%时腐蚀最为严重。以极致腐蚀性含水率(30%)进行不同温度的电化学试验发现,随着温度的升高会加速X80钢在沈阳土壤中的腐蚀速率.室温(16℃)下,X80钢的产物膜较为致密,完整性较好,覆盖均匀,对试样起到保护作用,腐蚀程度较轻;当温度逐渐升高至异常温度(65℃)时,试件腐蚀速率明显加快,试样表面的产物膜破损严重,完整性和均匀性都较差,腐蚀产物大面积脱落,腐蚀行为加剧。

风沙土整治区不同林地覆被对土壤特性的影响

为了了解风沙土整治区不同林地覆被下的土壤特性,为沙地整治后的林木选种提供决策依据,在砒砂岩整治风沙土的工程项目中,按整治后5、10和15 a的年限分别采集表层(0~20 cm)土样,测定其土壤密度、含水量、有机质和碳酸钙。结果表明,在风沙土整治区,不同林地下土壤密度和碳酸钙的大小为:天然荒草地>柠条>沙棘,其中,沙棘的土壤密度比柠条小3.10%,比荒草地小10.04%;沙棘的土壤碳酸钙质量分数比柠条小13.82%,比荒草地小37.66%。不同林地下土壤含水量和有机质质量分数大小为:沙棘>柠条>天然荒草地。其中,沙棘的土壤含水量比柠条大21.71%,比荒草地大96.68%;沙棘的土壤有机质质量分数比柠条大9.48%,比荒草地的大55.64%。随着整治后林木种植年限的增加,其土壤密度和有机质质量分数均增加,土壤含水量以整治后10 a的最大,而土壤碳酸钙质量分数随整治年限的增加而降低。综上,林木的种植对砒砂岩整治风沙土后的土壤结构状况有所改善,其中又以种植沙棘为宜。

低碳营林方式对林地土壤理化性质的影响研究

文章旨在探讨不炼山、定植2年生容器大苗、造林后不抚育的低碳营林方式,对比传统型营林方式,分析不同的低碳营林方式对不同时期林地幼林生长、土壤容重、土壤含水率以及土壤有机质含量等土壤理化性质的影响。