水泥工业项目水土保持准入条件

 通过对水泥工程的类型、组成、占地以及施工和生产工艺、土石方量及弃渣的分析,总结出水泥工程在建设与生产过程中的水土流失特点,水泥工程在建设期间的水土流失重点区域是厂区,而在生产运行期则是石灰石和黏土矿,此外在水泥生产厂区还会产生大量的粉尘。水泥工程除了应遵循"生产建设项目水土保持准入条件通用条款"中的条件外,对照涉及水泥产业的法律、法规、规范、政策、标准、发展纲要和行业发展规划,提出了水泥工程项目的否决、限批和缓批的13条水土保持准入条件。根据水土保持新国标和有关法规的规定,结合典型案例分析,提出须修正主体设计的5项准入条件和须修改水土保持方案的4项准入条件。     

3种不同规模化培养模式对湛江等鞭金藻生产力及色素含量的影响

为进一步提高湛江等鞭金藻室外规模化培养效率,对管道式光生物反应器、聚乙烯桶和水泥池3种微藻室外规模化培养模式下湛江等鞭金藻的藻密度进行了评估比较.试验将接种藻密度控制为10.0×104 cells/mL,培养周期为16 d.结果显示:管道式光生物反应器培养模式下,生产力相对最高为0.0543 g/L/d、比生长速率为0...     

废旧刨花与废旧纤维的水泥水化特性

对废旧刨花、废旧纤维、新鲜刨花三者的水泥水化特性进行了试验和分析。结果表明,预处理可明显改善木质材料与水泥亲和性,从阻凝系数和水化时间看,其作用效果依次为1%NaOH、热水、冷水;材料特性对水泥水化特性有影响,从阻凝系数和水化时间看,新鲜刨花对水泥-木质材料混合物的阻凝系数最小,到达最高水化温度时间最短,其次是废旧纤维,废旧刨花最后;经过预处理的木质材料,其水泥水化适合系数都大于68%,都适合半干法生产水泥复合板。     

浅谈公路水泥稳定碎石基层施工中的质量控制

对水泥稳定碎石基层施工中的原材料控制、水泥剂量控制、摊铺、碾压、养生、接缝等进行了论述,阐明只有严格按照规范和设计施工才能有效地保证基层的整体质量。     

水泥厂对周边农田污染的影响调查

水泥厂在生产过程中产生的大气污染对周边环境影响较大。经调查发现水泥厂附近的小麦中氟含量超标较严重,还发现汞超标。建议开展排污企事业与农田的安全距离研究。     

水泥粘土力学性能的试验研究

利用内蒙古河套灌区粉质粘土拌制水泥土,通过对水泥土试块进行无侧限抗压强度试验,定量分析了水泥掺量和龄期对水泥土强度的影响,并获取了材料应力-应变全过程曲线,探讨了该地区水泥土的变形特性,以期获得适合内蒙古河套地区土质的水泥土配比。试验表明,水泥土的无侧限抗压强度随着龄期的增长呈增大的趋势,养护龄期7~21 d时无侧限抗压强度增长较快;水泥的加入可以有效的改善土体性能,且随水泥掺量的增长呈总体增长趋势。     

清华大学超低能耗示范楼绿化屋面的温度分布特征

屋顶绿化是改善城市环境的有效途径之一,绿化后的屋顶,由于植物本身对太阳辐射的反射和遮挡作用,造成绿化屋面与水泥屋面的差异,这种热力或动力差异,首先通过垂直方向的湍流交换和辐射传递过程,把下垫面的特征量输送到上方气层,从而改变近地层的温、湿特征和风速分布,通过背景风场和热力环流的平流输送及其他间接作用,改变该地区的气候要素场,进而改善城市气候(骆高远,2001).     

The Application of Multivariate Statistical Methods for the Evaluation of Soil Profiles (8 pp)

Background, Aim and Scope   Contamination of soils does not only occur on their surface over large areas, but also in depth. Therefore a characterization of soil state after pollution demands a three-dimensional soil sampling, by what a large number of samples has to be analyzed. Analytical results could be evaluated by multivariate statistical methods, which have already been used for the evaluation of data sets containing results from soil sampling of two dimensions like areas or single profiles. In this case study, multivariate statistical methods were applied to investigate structure and interactions between features in a data set containing results of three-dimensional soil sampling. The investigated soil profiles were contaminated by emissions of a former cement and phosphate fertilizer plant. The aim of this study was to determine the remaining extent of contamination and to analyze whether pollutants are mobilized and vertically transported within the profiles. Materials and Methods: Three soil profiles were sampled in the surroundings of the plant. Grain size, organic and carbonatic bonded carbon, pH value, and the total contents of Ca, Cd, Co, Cu, F, Fe, K, Mn, Mg, Na, Ni, P, Pb, and Zn were determined. The resulting data set was evaluated by cluster analysis, linear discriminant analysis, and principal components analysis. The sequential extraction procedure according to Zeien and Brümmer was applied to analyze the binding properties of Ca, Cd, Cu, Na, Pb, and Zn from selected samples. Results: Cd was identified as contaminant of the top soils. The pH values of the bottom soils were determined to be in alkaline range, which is unnaturally high. Variables were clustered according to enrichment of variables in top soils. The samples were classified regarding their pollution state and their substrate by cluster analysis, which was confirmed by linear discriminant analysis. Geogenic and anthropogenic sources of variables as well as relationships between variables like the binding of heavy metals at organic matter were detected by using principal components analysis. The binding of heavy metals at organic matter in the top soils was confirmed by the results of the applied sequential extraction. A vertically altered distribution of Na binding was determined. Discussion: According to the current soil conditions, the uptake of heavy metals had probably occurred by the over ground part of plants during the deposition. The distribution of Na should likely result from the vertical transport of Na, which would also explain the high pH values of the bottom soils by ion exchange. Altogether, the main amount of deposited Ca, F, Na, P, and heavy metals is likely nearly insoluble bound in the top soils. Conclusions: Ten years after the end of production, the pollution of top soils in the surroundings of the former plant is still high. However, regarding the ecotoxicological relevance the now explored interactions between several soil features and elements strongly indicate that there is no short-term to medium-term risk of a mobilization of the deposited elements with the exception of Na. Recommendations and Perspectives: The results of this case study prove that multivariate statistical methods are powerful tools to explore interactions of variables and relationships in a data set derived from three dimensional soil sampling. The methods applied in this work can be highly recommended for evaluations of large data sets resulting from two- or three-dimensional samplings. Multivariate statistical methods enable the characterization of soils and their pollution state in a simple and economic way.     

水泥粉煤灰碎石(CFG)桩复合地基固结分析

在分析CFG桩材质与施工工艺的基础上,将其固结过程分为初期与后期2个阶段,并分别按碎石桩、水泥土桩进行了固结分析,由此提出了CFG桩复合地基的固结度统一计算公式.结合某工程实例的实测沉降数据进行了固结对比分析.结果表明:CFG桩复合地基的固结特性介于碎石桩和水泥土桩两者之间,固结过程基本与沉降同步,且桩周土的竖向固结是引起CFG桩复合地基沉降的主要因素,而桩周土的径向固结作用一般可忽略.     

热压温度和养护时间对快速固化水泥刨花板性能的影响

以定向刨花板厂的大片杨木刨花经简易粉碎设备粉碎分选得到的刨花和42.5强度等级的普通硅酸盐水泥为原料,Na2SiO3为添加剂,通过热压制板的方法,研究了热压温度和养护时间对快速固化水泥刨花板性能的影响。结果表明:①在85~95℃范围内,热压温度对厚板(20 mm)的物理力学性能无显著影响,而对薄板(12 mm)的弹性模量和吸水厚度膨胀率影响显著。②水泥刨花板卸出压机后的自然养护时间对快速固化水泥刨花板物理力学性能的影响主要取决于板在养护期间水泥的水化情况。厚板卸出压机后的含水率高,养护期间水泥水化好,养护时间对性能的影响显著;薄板卸出压机后含水率低,养护期间水泥水化不如厚板好,养护时间对性能无显著影响。表7参10