CHF固化剂稳定黏土的力学性质研究

本文采用重庆地区黏土和当地的水泥、石灰和CHF固化剂,进行最优配合比设计,对CHF固化剂水泥石灰稳定土的力学性能进行研究和分析。研究发现,CHF固化剂对水泥-石灰稳定土的无侧限抗压强度和劈裂强度有一定的改善作用,其中对无侧限抗压强度的影响较明显,对劈裂强度的影响不明显。     

冶金污泥用于路基回填土的试验研究

以冶金污泥资源化为宗旨,对冶金污泥固化/稳定化后用于路基回填土进行研究。试验研究表明,通过适宜固化处理工艺,冶金污泥能够满足路基回填土物理化学、力学以及重金属浸出安全性等要求。选用水泥、石灰和粉煤灰作固化剂（内掺）,适宜掺量为20%（水泥5%、粉煤灰10%、石灰5%）和掺量为25%（15%水泥、10%粉煤灰）,对于公路等级较低的公路,还可以进一步减少固化剂掺量,以降低成本。     

固化剂对道路铁尾矿基层强度的影响

本文研究了水泥、石灰、粉煤灰等固化组分在单掺、双掺、复掺条件下对道路铁尾矿基层强度的影响;测试了固化材料的7d浸水抗压强度,通过XRD和SEM等方法探讨了固化机理.研究表明,不同固化组分对铁尾矿基层强度有很大影响,本研究的固化剂在掺量大于8％时,浸水抗压强度即可满足二级及二级以下公路底基层强度标准;固化后材料中有氢氧化钙、硅酸钙等新相生成,C-S-H凝胶与铁尾矿颗粒形成网状交叉结构.     

基于钙镁盐的底泥高效脱水固化方案

水泥系固化剂(水泥、石灰、钙镁盐等)由于低廉价格、脱水固化效果好成为目前较为主流的疏浚底泥固化剂.以CaO和MgO为主要成分的M1固化剂与有机调理剂聚丙烯酰胺(PAM)复配处理疏浚底泥,其无侧限抗压强度与塑性指数均可满足路基回填土的相关性能要求;经响应面试验设计分析,复配试剂最佳工艺条件为:M1投加量1.0wt％,PA...     

新型废渣软土固化剂的试验研究

通过配合比正交试验和优化,将脱硫石膏、钢渣、矿渣复合形成固化剂(简称GSC);采用扫描电镜对其水化产物进行微观分析;并通过无侧限抗压试验对GSC固化土与水泥土作了强度对比分析.研究结果表明,钢渣作为胶凝材料对GSC固化剂强度影响最大;发现GSC固化剂安定性、凝结时间可以满足使用要求,其水化产物和水泥相似;GSC固化土无侧限抗压强度随龄期的增长规律与水泥土一致,但早期强度比水泥土低;调节GSC的用量和水灰比大小可以实现与水泥相同的固化效果.     

水泥固化铬污染土强度及浸出试验研究

为了解决重金属铬污染带来的土壤及地下水污染问题,以沈阳铬渣堆场污染土为研究对象,进行水泥固化重金属铬污染土中Cr(VI)和Cr(Ⅲ)试验研究,测定了水泥掺量、养护龄期、铬不同含量及价态对固化土体的无侧限抗压强度及淋滤特性影响.结果表明,水泥是Cr(VI)和Cr(Ⅲ)污染土的有效固化剂,水泥掺量以20%为宜;Cr(VI)和Cr(Ⅲ)对固化土强度都具有弱化效应,Cr(Ⅲ)弱化效应更明显;SEM图从微观上解释了水泥固化铬污染土强度的变化,该变化与无侧限抗压强度试验结果一致.     

一种软土地基固化剂的研制与应用

涉及一种软土地基固化剂及其制备方法,该固化剂由硅酸盐水泥熟料、焦炭、生石灰、脱硫石膏、乳化硅油和细砂组成。结合软土固化所需水化物组成的特殊性以及固化土结构形成过程的特点,通过调节自身组分添加量,并制备一种表面活性剂形成复合软土固化剂,不仅能够产生胶凝性水化物和胶结土团粒,同时降低土壤-水的界面张力,使原有颗粒分散作用更加迅速,改善水化物生成过程的协调性。同时,根据国家钢铁行业去产能的政策,仅含少量的水泥和石灰等传统固化剂,解决了焦炭的出路问题,在保障焦炭企业经济利益和环境保护两方面的同时,使焦炭得到了充分的应用。     

废弃钻井液固化处理技术研究

以FeCl_3破胶后的废弃钻井液为固化处理对象,采用粉煤灰、石灰、水泥以及黄土作为固化剂的基础原料,探究了各种原料用量及配比对废弃钻井液固化处理效果的影响,并确定了固化剂的最佳配比。结果表明,在50 g粉煤灰,8 g石灰,50 g黄土,5 g水泥的用料比例下,固化效果最佳。固化产物7 d抗压强度最高可达0.734 MPa,固化产物浸出液CODCr最低为35.5 mg/L,可以实现污染物的有效固结。     

废弃钻井液固化处理技术研究

以FeCl_3破胶后的废弃钻井液为固化处理对象,采用粉煤灰、石灰、水泥以及黄土作为固化剂的基础原料,探究了各种原料用量及配比对废弃钻井液固化处理效果的影响,并确定了固化剂的最佳配比。结果表明,在50 g粉煤灰,8 g石灰,50 g黄土,5 g水泥的用料比例下,固化效果最佳。固化产物7 d抗压强度最高可达0.734 MPa,固化产物浸出液CODCr最低为35.5 mg/L,可以实现污染物的有效固结。     

土壤固化剂胶砂性能和强度性能的测试与研究

把土壤固化材料、水泥、黏土的化学成分做一个比较、分析,再对其胶砂性能作一番测试,比较海螺P.O42.5、桐乡P.S32.5、土壤固化材料三种材料的胶砂测试结果.最后对土壤固化剂的强度性能作一个研究,比较掺量的多少对固化性能的影响.     

固化废弃软黏土的强度特性及水稳定性研究

为了提高水泥和粉煤灰固化高含水率废弃软黏土的固化效果,选取水玻璃作为外加剂,吸水性强的生石灰作为分散剂,采用无侧限抗压强度试验、X 射线衍射、扫描电镜试验研究掺量与龄期对固化软黏土水稳定性和强度特性的影响。试验结果表明,3%(质量分数)的水泥、7%(质量分数)的粉煤灰、2%(质量分数)的生石灰与2%(质量分数)的水玻璃复合时能较好提高高含水率软黏土固化后的强度和水稳定性,其强度能达到水泥粉煤灰类基底层最低强度(1 MPa)。在水泥、粉煤灰和水玻璃质量掺量相同情况下,生石灰质量掺入比由0%增加至2%,其强度增大约375 kPa,且有利于后续固化剂的均匀搅拌,说明生石灰的减水和分散效应在固化土中起主导作用。此外,扫描电镜结果显示加入复合固化剂后大集聚体消失,产生大量的片状结构,大孔隙被填充,土体的强度也随之提高。     

粉煤灰贝利特水泥用作土壤固化材

以高含水粘性土为对象，研究了活性贝利特水泥的固化处理效果及固化土的强度发展特性。结果表明，这种水泥具有较普通水泥低的固化土强度发展速率，是一种良好的迟硬性土壤固化材，特别适用于高含水软弱粘性土的整体固化后再二次开挖的施工场合。     

Swell-shrink and strength behaviors of lime and cement stabilized expansive organic clays

Organic soils are mostly composed of decayed plant matter and weathered rock material. Often, these soils are known for their inferior engineering behavior including very high compressibility and low shear strength. In order to improve these properties, organic soils are, by and large, modified with calcium based stabilizers such as lime, cement and fly ash. However, transportation agencies in the United States have mentioned that the anticipated improvements were never achieved or the improvement obtained disappeared quickly with time. Therefore, a research study was initiated to understand the behavioral mechanisms of lime and cement stabilized organic soils. Eight natural expansive soils bearing different organic contents (varying between 2 and 6%) were selected for the present investigation. First, optimum dosages of lime and cement were determined for the selected soils. Then treated and untreated (control) specimens were prepared to study their physical and engineering behaviors of the soil specimens at varied curing periods. There is a drastic increase in unconfined compressive strength (UCS) of lime and cement treated specimens until 28 days of curing. Beyond which, a negligible improvement in UCS property was recorded for lime treated specimens and a slight decrease in UCS for cement treated soils was noticed. This reduction in strength for cement treated specimens could be attributed to the reduction in pH concentration with curing as well as the formation of inorganic calcium humic acid at this stage.     

水化产物钙矾石在软土地基加固中的增强作用

通常加固软土地基是使用第一的水泥用为固化剂。研究与实践表明,由于软土中孔隙量很高,采用工业废石膏与水泥配合加固软土,其中产生的水化产物钙矾石可以高效率的填充孔隙,对固化工的强度增长有显著的增强作用,从而得固人疆土工与单纯用水泥加固相比有大幅度的提高,钙矾石形成过程中,液相ＣａＯ,ＯＨ浓度决定钙矾石的形貌和膨胀性能,不同土样对ＣａＯ,ＯＨ消耗量不同,导致固化上液相中ＣａＨ,ＯＨ,浓度不同,因而,对不     

利用窑灰生产高效土壤稳定水泥的研究

研究了用纯窑灰、掺ＣａＳｏ４－ＣａＦ２复合矿经剂的窑灰煅烧熟料与适量石膏混合配制的窑灰水泥稳定土的力学性能,并探讨了煅烧温度和石膏掺量对窑灰水泥稳定土强度的影响。结果表明,窑灰水泥对土壤的稳定效果显著优于普通水泥。用于稳定土的水泥其技术指标与普通水泥有很大差异,可允许水泥中含有一定数量的ｆ－ＣａＯ,ＳＯ和碱含量。     

流态固化土用无熟料胶凝材料的性能研究

流态固化土是近年来为提高市政、建筑工程狭窄空间回填质量而发展的一种新材料。本文采用钢渣粉、CFB脱硫灰、稻壳灰等多种低品质固废作为无熟料胶凝材料制备流态固化土,并对流态固化土的无侧限抗压强度、干燥收缩性能、重金属浸出性能、微观结构等开展相关试验。研究表明:采用无熟料胶凝材料制备的流态固化土,其拌合物流动扩展度和无侧限抗压强度可满足一般填筑工程的要求,硬化体的干燥收缩值明显低于同掺量的水泥固化土,且无重金属浸出毒性超标的风险;在多种固废协同作用下,土颗粒聚集成团,孔隙明显减小,絮状的凝胶与针棒状的钙矾石晶体相互交织,附着在土颗粒表面,联结土颗粒,使得固化土的强度显著提高。     

活化牡蛎壳固化余泥渣土及其机理分析

为实现牡蛎壳和余泥渣土两种固废资源的利用,提出了预处理的牡蛎壳经磷酸或磷酸氢二铵(DAP)活化后固化土体,制得牡蛎壳固化土。试验测定了不同配比的牡蛎壳固化土的力学性能,研究牡蛎壳固化土的边坡抗冲刷性能,并使用扫描电镜和X射线衍射仪观察固化土的微观结构,分析其固化机理。结果表明,掺磷酸、DAP能提高牡蛎壳固化土的抗压强度,其中掺加DAP的效果更好。材料最佳配比(质量分数)为:73.6%土,18.4%牡蛎壳(粒径≤1 mm),8%DAP。其烘干抗压强度达到2.14 MPa,是牡蛎壳稳定余泥渣土抗压强度的2.43 倍,软化系数达到0.5,改变了原土遇水崩解的特性。在室内边坡冲刷试验中,掺DAP牡蛎壳固化土与素土相比,有效降低了坡面冲刷的产沙量。微观结构分析表明,磷酸、DAP分别与牡蛎壳作用生成磷酸钙晶体、羟基磷灰石,两者都能胶结土粒,从而固化土体。     

工业废料稳定路基土的无侧限抗压强度及环境影响评价

随着社会的发展,道路工程建设规模日益庞大,常用的石灰、水泥等固化剂价格较高,然而电石渣、粉煤灰这两种工业废料应用于道路建设中,将很好地提高资源的回收再利用率,同时降低建设成本。本文研究了电石渣和粉煤灰固化土的最优配合比,并探讨了电石渣代替石灰用于固化土的可行性,另外,在电石渣-粉煤灰固化土中掺入聚丙烯纤维,探究了聚丙烯纤维的最优掺量。无侧限抗压试验结果表明,电石渣与粉煤灰的最优配比为1:1,聚丙烯纤维的最优掺量为0.6%(质量分数)。在此基础上探究了电石渣-粉煤灰固化土在雨淋条件下对环境的影响程度。pH试验结果表明,电石渣-粉煤灰固化土的pH值最大为12.28,其环境影响程度满足国家标准规范要求,可以在实际工程中得以应用。此研究为工业废料应用于道路基层提供了一定的借鉴意义。     

Experimental study on instability of bases on natural and lime/cement-stabilized clayey soils

In many sub-tropical and tropical arid regions of the world, marly soils (marls) and lime or cement stabilization of marl soils are used as a convenient and expedient means of developing foundation base courses and inexpensive wearing courses for transport purposes. The failure of many of these natural and stabilized marls to perform their function has been reported. Mechanical factors, commonly used to explain the causes of the foundation failures, are unsatisfactory and have not been accepted. This study uses physicochemical (reaction) factors to explain the general basic causes of the deterioration of support capability for these types of soils. The presence of palygorskite and sepiolite in marl soil provides it with some very unique features in its natural state, particularly when it is stabilized with lime or cement. The formation of an expansive mineral, ettringite, as a transformation product of palygorskite increases the swelling potential of the stabilized soil. A set of physico-chemical and mechanical experiments, which include slake durability, specific surface area measurement (SSA), California bearing ratio (CBR), atterberg limits testing, and X-ray diffraction (XRD), were performed. In addition, the impact of curing on the stabilized soil behaviour was investigated. The results show that the immersion of the natural marl reduces the dry CBR value to at least one-fourth the dry value. Furthermore, the XRD results indicate that with increasing time and availability of dissolved aluminum and sulfate, ettringite forms in stabilized soil and then the rate of ettringite growth increases. Based on the findings of these experiments, the various interactions, reactions and factors contributing to the stability and instability of marl soils, and lime/cement stabilized marls are discussed. It is concluded that the general traditional soil stabilization evaluation methods are not capable of accounting for the failures that occur in stabilized marl. It is shown that soil mineralogy and pore fluid analysis, in conjunction with X-ray diffraction testing, can be combined to provide a set of practical ways to monitor the possibilities of these failures.