Stabilizing soft clay using geo-foam beads and cement bypass dust

Soft clays are usually classified according to their undrained shear strength,Su.Values of Su less than 12.5 kPa are associated with very soft clays.In addition to their low shear strength,soft clays exhibit high compressibility upon loading.Therefore,soft clays are considered to be problematic for foundation purposes.Geo-foam is an industrial material that is characterized by a very low unit weight(20 kg/m^(3) on average)compared to that of the soil.The density of expanded polystyrene(EPS)ranges from 1.0%to 2.5%,which results in a compressive strength ranging between 70 kPa and 140 kPa and an elastic modulus ranging between 5 MPa and 12 MPa.EPS geofoam blocks are used in a wide range of geotechnical applications as a lightweight fill material.The main objective of this study was to investigate the geotechnical properties of soft clays containing geo-foam beads and cement bypass dust(CBPD).We also investigated the viability of preparing low-strength excavatable fill mixtures.To study the effect of(geofoam beads+CBPD)/soft clay on the fluid-state and hardened properties of new fill,we conducted experiments on two groups of mixtures(A&B).Each mixture contained different ratios of geo-foam beads and CBPD so that we could study the effect of the additive on the flow consistency,dry unit weight,unconfined compressive strength,and shear strength of the mixture.The test results showed that the unconfined compressive strength of the studied mixtures without geo-foam ranged from 271.8 kPa to 1405.14 kPa at CBPD concentrations between 3.88%and 18.63%.The cohesion values for the group containing geo-foam ranged from 50 kPa to 20 kPa at geo-foam percentages between 0.32%and 1.35%.The friction angle of the group containing geo-foam ranged from 10 kPa to 22 kPa at CBPD percentages between 0.32%and 1.35%.Cement bypass dust can be successfully used to process self-compacting,self-leveling,excavatable and flowable fill material.

地电化学提取有效性及提取条件试验——以半干旱草原风成砂浅覆盖景观区为例

地电化学方法作为覆盖区矿产资源勘查的一种有效手段,其原理是在人工外加电场作用下,将近地表介质中呈电活动态的物质选择性地提取,通过研究电提取元素组合、含量分布及异常特征,进而提供找矿信息的一种勘查方法。笔者通过在内蒙古洛恪顿矿区开展地电化学勘查研究,验证了地电化学法在内蒙古东乌旗风成砂覆盖区勘查的有效性,并通过对不同提取时间、不同密度的载体物质等提取条件的对比研究,确定在该区进行地电化学勘查的提取时间为24 h,载体物质选用高密度泡塑。

湿法消解预处理地电化学泡塑样品有效性研究

灰化法和微波消解法作为地电化学泡塑样品的预处理方法适用于多数元素,但二者都存在局限性,如灰化法的高温加热过程会造成As、Hg等元素的损失影响测定结果,微波消解法则因用样量小(0.1 g),存在样品代表性和检出限方面的问题。湿法消解是一种传统的样品预处理方法,具有消解完全、元素损失量低、样品代表性好等优点,可以有效解决以上两种方法的不足。但因为加入高氯酸消解泡塑(有机物)样品过程中易爆炸和酸空白等问题,一直没有在泡塑样品的预处理中得到推广。本文选取内蒙古洛恪顿热液型铅锌多金属矿床一条地电化学勘查剖面,用20 m L硝酸+5 m L高氯酸和5 m L王水对泡塑样品(约0.5 g)进行预处理,氢化物发生原子荧光光谱法和高分辨电感耦合等离子体质谱法测定元素含量。结果表明:大多数元素的空白含量都比较低,地球化学剖面图上有良好的异常显示;湿法消解处理泡塑样品是可行的,分析泡塑样品主要使用这种预处理方法。

地质聚合物基泡沫陶瓷材料的制备

为开发建筑用泡沫陶瓷保温材料,基于超轻质泡沫地质聚合物的制备工艺,探索了高温烧结制备地质聚合物基泡沫陶瓷材料的工艺途径,研究了泡沫地质聚合物坯体的干燥和烧成制度对泡沫陶瓷性能的影响。结果表明,采用3 d室内自然干燥,5℃/h的速度升温到105℃并保温24 h的干燥制度,可避免泡沫地质聚合物坯体在干燥过程中的开裂;试样烧结过程中,600℃后以60℃/h的升温速度缓慢升温到1000℃并保温2 h,可避免制品开裂。所制泡沫陶瓷干密度262 kg/m3、抗压强度2.34 MPa、导热系数0.099W/(m·K),符合JG/T 042—2013要求。