几种纳米水泥砂浆氯离子渗透性对比试验研究

为研究纳米材料对水泥砂浆抵抗氯离子渗透性的改善作用,选用8种纳米材料等量替代水泥,采用快速氯离子迁移系数法(RCM法),测试并分析不同纳米水泥砂浆氯离子扩散系数的变化规律。结果表明:纳米偏高岭土、亲水性纳米SiO2及亲水性纳米CaCO3均有效提高了水泥砂浆抵抗氯离子渗透性能;疏水性纳米CaCO3对水泥砂浆氯离子渗透性无明显影响;纳米凹凸棒石黏土导致水泥砂浆抵抗氯离子渗透性能降低;小掺量(1%)纳米氧化铝和疏水性纳米二氧化硅能够提高水泥砂浆抵抗氯离子渗透性,当掺量增至3%时,水泥砂浆试件抵抗氯离子渗透性能降低。     

金属表面碳酸盐沉积层防腐机理研究

论述碳酸盐沉积层的自然形成过程,解释了碳酸盐层对金属表面的天然防护机理;提出利用碳酸盐层防腐的新概念,探索出了人为形成碳酸盐沉积层的技术路线。     

Assessment of the bio-cementation effect on shale soil using ultrasound measurement

The assessment of bio-cementation effect using nondestructive testing methods is important for the application of microbial-induced carbonate precipitation (MICP) technique. In this study, a special grouting system was designed to conduct the bio-grouting of shale soils on a testing model. The ultrasound technique was used to evaluate the effectiveness of bio-cementation. A method was derived to estimate the distribution of ultrasonic wave velocity values within the testing model based on the average values measured on the model surfaces. From the changes of isosurfaces of velocity values, the evolution of soil improvement within the model corresponding to the different number of grouting cycles was analyzed numerically and visually. The SEM imaging technique was used to illustrate the mechanism of influence of the calcium carbonate precipitation on the wave velocity of the bio-cemented specimen. The linear relationships were established among the ultrasonic wave velocity, unconfined compressive strength (UCS), and the amount of CaCO₃ precipitations formed in the MICP process. In combination with the application of the ultrasound measurement technique as demonstrated in this work, the relationship provides a very useful nondestructive testing tool to assess the effectiveness of bio-cementation within a large soil body.     

Mid-scale biocemented soil columns via enzyme-induced carbonate precipitation (EICP)

Biocemented soil columns were created at a reduced scale (mid-scale) using enzyme-induced carbonate precipitation (EICP) as a prelude to field scale deployment. Approximately 0.3 m diameter × 0.75 m long columns were created using a tube-à-manchette grouting technique in 0.6 m × 0.6 m × 1.2 m boxes filled with a dry washed quarry sand. Treatment solution composition and treatment protocol, including number of cycles of treatment and time interval between cycles, were established based upon laboratory testing. The urease enzyme used in the treatment solution was extracted from jack beans in a just-in-time manner on site. The biocemented soil columns were characterized in situ using shear wave velocity, needle penetrometer and pocket penetrometer testing, dimensional measurements, and by unconfined compression strength (UCS) and carbonate content measurements on specimens recovered from the columns. The in situ measurements indicated the target UCS of 500 kPa was achieved. However, the UCS tests on recovered specimens had inconsistent results, which may be attributed to sample disturbance. Overall, the results demonstrate that EICP is a viable method for creating biocemented soil columns for ground improvement.     

水灰比和碳酸锂对硫铝酸盐水泥水化历程的影响

研究了水灰比和碳酸锂对硫铝酸盐水泥水化历程的影响。水化放热历程测试结果表明:随着水灰比的增大,硫铝酸盐水泥的水化放热速率增大,水化放热量提高;碳酸锂的掺入使得水化诱导期消失,水泥在加入水后直接进入水化加速期,与水灰比的影响相比,碳酸锂的掺入对水化加速期放热速率的影响更为显著;同时,碳酸锂的掺入使得硫铝酸盐水泥的早期水化速率和水化放热量增加,后期水化放热量减小。X射线衍射测试结果表明:碳酸锂的作用仅是提高了硫铝酸盐水泥的水化进程和水化速率,对生成水化产物的种类无影响。     

矿物溶解动力学与全球环境

硅酸盐矿物和碳酸盐矿物是构成地壳的主要造岩矿物,论述了两类矿物溶解动力学的研究现状与展望,指出两类矿物的溶解和沉积过程中CO2吸收和释放,对全球环境有重要影响。     

The water quality of the River Thame in the Thames Basin of south/south-eastern England

The water quality of the River Thame, a tributary of the River Thames in the Thames basin, is described in relation to point and diffuse contaminant inputs and runoff from permeable and impermeable bedrock geology with their own characteristic water quality. The data is examined to see if the market town of Aylesbury in the upper part of the catchment influences water quality. Previous studies highlighted the influence of Aylesbury sewage treatment works (STW) on soluble reactive phosphorus (SRP) concentrations in the river before and after phosphorus (P) stripping at the STW. Variations in water quality along the river are described and the study indicates that, apart from SRP, water quality determinants seem to be relatively unaffected by Aylesbury. The Thame water quality is compared with other catchment typologies and it is very similar to that of the main stem of the Thames even though the Thames is mainly Chalk groundwater fed. Differences in water quality largely link to the amount of STW effluent within the rivers and to the endmember compositions of the groundwater and near surface water sources.     

碳酸盐岩地层岩石声学特性的试验研究与应用

选取并收集我国川东北地区和济阳坳陷古潜山构造的地层岩样及相对应的井下声波测井资料，测试了岩石的牙轮钻头可钻性、PDC钻头可钻性和声学特性，应用数理统计方法研究分析了岩石地面纵波速度VP、横波速度VS分别与牙轮钻头可钻性KdRC，PDC钻头可钻性KdPDC的相关关系及同块地层岩样地面纵波速度VP与井下测井纵波速度VPD的相关关系，建立了利用声波测井资料预测碳酸盐岩地层剖面可钻性的数学模型，选定符合率F值大于0．75为检验标准，经用现场声波测井资料代入预测模型进行计算，预测精度达91．7％，达到并超过了研究预期的技术指标。     

合成碳羟基磷灰石对废水中锰离子的吸附研究

利用废弃的蛋壳制备碳羟基磷灰石(CHAP),研究了其对废水中Mn2+的吸附作用,并探讨了CHAP用量、Mn2+浓度、温度、pH对吸附效果的影响.试验结果表明:在pH值为6、温度为30℃、搅拌时间为1 h、CHAP用量为3 g/L、Mn2+初始浓度为70 mg/L的条件下,CHAP对Mn2+的去除率可达到97.9%,吸附容量为22.84 mg/g;CHAP对Mn2+的吸附过程符合Langmuir和Fre-undlich吸附等温式,吸附反应是自发放热过程;H0准二级动力学模型能较好地描述CHAP对Mn2+的动力学吸附行为.     

碳酸二甲酯酯交换合成碳酸二月桂酯

用正交实验法,对碳酸二甲酯(DMC)与月桂醇酯交换合成碳酸二月桂酯的催化剂,进行了筛选,对反应条件进行了优化,发现K2CO3具有较高的催化活性,得到最佳反应条件为:催化剂碳酸钾(K2CO3)用量为原料总质量的0.5%,n(碳酸二甲酯)∶n(月桂醇)=1∶4,反应时间4 h,反应温度140℃。在该条件下DMC的单程转化率为59.4%,碳酸二月桂酯产率55.3%,甲基十二烷基碳酸酯产率4.1%,碳酸二月桂酯选择性93%,未反应的DMC与月桂醇可以循环使用。