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Compressibility and swelling characteristics of Al-Khobar Palygorskite, eastern Saudi Arabia 总被引：1，自引：0，他引：1
Expansive soils are found in different locations in eastern Saudi Arabia. The area is arid with high temperatures, highly variable humidity and an excessive rate of evaporation compared to the low precipitation. This resulted in the formation of water sensitive soils. In the present investigation, line valve buildings for a sweet water feeder (1118 mm in diameter) were constructed on a highly expansive material consisting mainly of brown palygorskite and gray palygorskite with thin sheets of gypsum and limestone. Block samples from both palygorskites were brought to the laboratory and cores as well as remolded samples were obtained from the blocks. The two palygorskites were found to be highly plastic and have a very high swelling potential. The liquid limit (LL) and plastic limit (PL) values for the brown palygorskite are 261% and 140%, respectively. The gray palygorskite has a LL of a 285% and a PL of 123%. The oedometer free swell tests for the two palygorskites produced an expansion ranging between 31.8% and 42.5% for the remolded samples. However, the expansion for cores ranges between 8.3% and 19.3%. The constant volume pressure tests produced a stress in excess of 4240 kPa. The swell potential reached a steady state after four days while the swelling pressure reached a steady state in about 3 h. The paper addresses the geology of the area, the characterization of the geomaterial including mineralogical composition using X-ray diffraction and SEM techniques and the swelling characteristics of the material. 相似文献
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M.?J.?Varas-MurielEmail author E.?Molina-Ballesteros 《International Journal of Earth Sciences》2004,93(1):132-143
During the Tertiary, the Hercynian basement of the Iberian Peninsula was uneven due to Alpine tectonism which led to the development of a set of horsts and grabens forming its main geological structure. One of these grabens is the Ciudad Rodrigo Basin, located close to the Portuguese border. The south-western margin of this graben is filled with arkosic sandstones of continental origin that, once deposited, underwent important low-grade diagenetic processes related to the surface processes. The main diagenetic processes were hydrolysis, replacement by carbonate, and argillization to palygorskite. These three processes led to the differentiation of three main levels within the outcrops studied: (1) the Lower Level, where the original clayey sandstone outcrops, displaying fairly hydromorphic traits; (2) the Middle Level, where part of the clayey matrix has been replaced by dolomitic carbonate; and (3) the Upper Level, where palygorskite is the new neoformed clay. The change in porosity seems to have been the controlling factor, since it governs the dynamics of the solutions inside the rocks. These conditions changed from being diffusion-driven, at the start of the diagenesis, to flow-driven as porosity increased. 相似文献
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A palygorskite unit was discovered in a road cut of undifferentiated Tertiary limestone between the villages of El Pariso
and San Roman (18°49.309N, 88°37.861W) in the southeastern Yucatán Peninsula, Mexico. This is the southern most locality of
a clay-rich sedimentary unit reported in the literature for the Tertiary carbonates of the Yucatán Peninsula. This occurrence
indicates a much wider range of palygorskite-rich clay deposition than previously recognized. The lithology is 99% clay and
1% sand to silt size diagenetic quartz grains. The clay consists of approximately 85% palygorskite, 15% montmorillonite and
trace amounts of titanium oxides. EDS analyses on palygorskite are largely consistent with sedimentary palygorskites from
other coastal marine settings, however palygorskite has a low total Fe content (average = 0.40 wt% expressed as Fe2O3) compared to many other sedimentary palygorskites. Montmorillonite chemical compositions are typical and compared to the
palygorskite have substantially higher Fe2O3 concentrations (average = 3.90 wt%). The low percentage of coarse grains in the lithology combined with a high proportion
of palygorskite and lack of detrimental trace minerals suggest the deposit is of industrial grade; however, it has limited
reserves (6,000 m3). The unit could be potentially used in a wide array of environmental applications which are needed in the region including
liners for landfills and constructed wetlands. The unit is in a geographic location which would serve the expanding economy
of the region. This resource has the potential to have great impact on the quality of the local environment and the economy
of a region under great environmental threat. 相似文献
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以钛酸四丁酯为前驱体,天然凹凸棒石为载体,采用溶胶凝胶法制备了TiO_2/凹凸棒石复合光催化剂,并用XRD、TEM对其进行表征.以亚甲基蓝染料为模拟污染物,采用300 W汞灯为紫外光源,以光催化实验来评价该催化剂的活性,并研究了H_2O_2的引入对光催化活性的影响.实验结果表明,H_2O_2能显著提高染料的脱色效率:亚甲基蓝的初始浓度为50 mg/L,催化体系为2 mmol/L H_2O_2+0.5 g/L TiO_2/凹凸棒石+UV(紫外线),光催化10 min后其脱色率为95%,相对于单独的0.5 g/L TiO_2/凹凸棒石+UV催化体系,其脱色率提高了约50%.全波段扫描显示,加入H_2O_2后,亚甲基蓝在290 nm对应的苯环吸收蜂急剧下降,665 nm对应的最大吸收峰则近乎消失,且没有新的吸收峰产生. 相似文献
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甘肃省天水地区上第三系含坡缕石白土的研究 总被引：1，自引：0，他引：1
天水地区新第三纪湖相白土除含少量碎屑矿物石英、长石外,主要由伊利石、绿泥石、蒙皂石等粘土矿物及白云石、方解石等碳酸盐矿物组成。北部地区含有坡缕石,最多约40％,南部含有方沸石。白土中的粘土和碳酸盐矿物颗粒细小,有序度差。坡缕石由胶体结晶,或由碎屑云母转变而成。白土的形成温度约20～50℃,介质是咸水-半咸水,具碱性。当B、Sr/Ca值及盐度较高,而Sr/Ba、Br/Cl、δ~(18)O值及温度较低时,有利於形成坡缕石。 相似文献
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To study the soil-geomorphology relationships and the effect of past and present climate on soil formation, 10 representative pedons on different landforms, including rock pediment, mantled pediment, piedmont plain, playa margin and playa, were studied. Non-saline clay flat, saline clay flat with and without puffy grounds, wet zone, and salt crust were among the geomorphic surfaces observed in Sirjan playa. Soil moisture varies from mesic (on rock and mantled pediments) to aridic regimes (on piedmont plain, playa margins, playa and mantled pediment). Soil temperature regime in the area is mesic except on playa surfaces and mantled pediment which are thermic. Results of the study showed that soil salinity increased from the rock pediment to playa surfaces. The maximum EC of 314 dS/m was observed in the puffy ground clay flat. Kaolinite, illite, smectite, chlorite and palygorskite clay minerals were identified using XRD analysis. Coatings and infillings of CaCO3 were observed in pediment and gypsum lenticels and interlocked plates were found on piedmont plain and playa. Clay coatings and infillings in the piedmont plain suggest the presence of a more humid paleoclimate in the history of the area. 相似文献
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安山质熔结凝灰岩中凹凸棒石断层岩的矿物学特征 总被引：5，自引：0，他引：5
郯庐断裂带肥东段龙山安山质熔结凝灰岩中产出一种白色断层岩。X-射线粉末衍射(XRD)、红外光谱(TER)、扫描电子显微镜(SEM)、透射电镜(TEM)、电子能谱仪(EDS)、X-射线荧光光谱(XRF。)等结构、形貌和成分分析证明，这些白色断层岩主要由凹凸棒石组成(含量大于90％)，属于凹凸棒石断层岩。凹凸棒石呈现40-60纳米的细长纤维，其中的少量杂质是纳米粒度的石英和钠长石。纳米粒度的石英和钠长石形态特征显示它们可能由安山质熔接凝灰岩中原生矿物机械破碎形成。这些凹凸棒石断层岩形成于火山热液活动同一期断层递进变形过程中，经历了三个阶段。首先是安山质熔结凝灰岩在断裂作用下形成碎粉岩，然后是碎粉岩在构造应力和火山热液作用下水化形成凹凸棒石，最后凹凸棒石又在断层活动晚期发生变形。 相似文献
9.
Ahmed Al-Futaisi Ahmad Jamrah Amer Al-Rawas Saif Al-Hanai 《Environmental Geology》2007,51(8):1317-1327
In this paper, Shuwaymiyah palygorskite in the Sultanate of Oman has been characterized mineralogically by X-ray diffraction
(XRD) and electron microscopy, chemically by oxide compositions, structural formulae, and cation exchange capacity (CEC),
and physically by specific surface area and adsorption isotherms. Batch adsorption studies were performed to evaluate the
adsorption performance of methylene blue (MB) basic dye on the local clay mineral. The quantitative XRD analysis indicates
that the purity of some selected samples of palygorskite clay is very high (about 70% of the clay minerals are palygorskite
and 30% kaolinite). The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images clearly support
this conclusion. The adsorption equilibrium revealed that Shuwaymiyah palygorskite clay can uptake up to 51 mg of MB per 1 g
mass of clay. MB adsorption is best fitted by Langmuir isotherm, and a pseudo-second-order kinetic model can be efficiently
used to predict the kinetic of adsorption of MB by the palygorskite. The results obtained from these laboratory-scale adsorption
tests indicate the promising adsorption capability of the Omani palygorskite. 相似文献
10.
This paper focuses attention on the some basic aspects of the role of clay fraction of marly soils including palygorskite and sepiolite upon marl behaviour. The clay fraction of marl is generally dominated by palygorskite and/or sepiolite. It is the performance of these clay soil fractions that are the root cause of many of the problems encountered in the use of such soils as load-bearing materials. This makes it necessary to investigate the role of palygorskite and sepiolite on marly soil's performance. In this paper, some geotechnical and geoenvironmental aspects of marl behaviour is investigated and a new definition and classification of marly soils is presented. This classification focuses attention on the presence of palygorskite or sepiolite as the major fraction of marl, which governs its geoenvironmental and geotechnical behaviour. 相似文献