Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings

In Europe, the Wide Wheel abrasion (WWA) test and the B?hme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation (R ² = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly (R ² = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity ≥1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multi-directional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse-grained granitic rocks having cleavable minerals such as plagioclase and orthoclase feldspars.     

Andradite and andradite-grossular solid solutions in very low-grade regionally metamorphosed rocks in Southern New Zealand

Almost pure andradite and intermediate members of the andradite-grossular series (gros_40–49, and _47–54, py_0–3, alm_0–3, spess_0–2, hydrogarnet_0–3), often framboidal in habit, are widespread in metabasites including lavas, minor intrusions, and volcanic sandstones and breccias metamorphosed under prehnite-pumpellyite and pumpellyite-actinolite facies conditions, possibly extending into the zeolite facies. Coexisting phases include iron-rich epidotes (100 Fe*/Fe*+Al=22–34), pumpellyite, prehnite, actinolite, and chlorite, electron microprobe analyses of which are given, as well as quartz, albite, and calcite. Zoisite (100 Fe*/Fe*+Al=1–5) and iron-poor epidote (100 Fe*/Fe*+Al=11–18) occur in 2 rocks in pseudomorphs after plagioclase together with more iron-rich epidote, but not in close association with the garnets. Coexisting pumpellyite is iron-rich (FeO* 9–14%) in the prehnite-pumpellyite facies and iron-poor (FeO* 5%) in the pumpellyiteactinolite facies. Chlorites and actinolites vary widely and sympathetically in FeO/MgO+FeO ratio. Andradite is also described from a stilpnomelane-actinolite-hematite-bearing andradite quartzite of the pumpellyite-actinolite facies. Conditions of formation involved temperatures of 300 to 400 ° or less, at pressures up to a few kilobars. A wide range of oxygen fugacities is possible, but in the fluid phase was low. Grandite and chlorite are incompatible in the pumpellyite-actinolite and greenschist facies in the presence of quartz but the 2 minerals occur together in some pumpellyite-actinolite facies assemblages as a result of incomplete reaction and/or local deficiency in silica. In the greenschist facies the association is replaced by epidote-actinolite±hematite and sodic amphibole. Whereas at medium to high grades of metamorphism andradite and grandite are characteristic of skarns irrespective of , at very low grades they are found in mafic volcanic rocks and volcanogenic sediments as well as in certain cherty rocks of unusual composition, rodingites, and serpentinites, where was very low.     

Authigenic quartz and albite in Devonian limestones: origin and significance

Euhedral quartz and albite crystals are common in Devonian (Givetian-Frasnian) shallow-marine shelf carbonates from the Belgian Ardennes. Several features such as morphology, the presence of carbonate inclusions, inversion temperatures and occurrence in the insoluble residues of stylolitic surfaces indicate that these crystals have developed authigenically. Oxygen isotope ratios point to an intermediate deep burial realm of origin at temperatures of 60–90°C. The predominance of illite and the almost total absence of smectite clay minerals is interpreted as an indication that illitization produced the silica needed for authigenesis. The mineral composition of inclusions indicates that the carbonate host rock must have consisted of low-Mg calcite already at the time of authigenesis. These inclusions represent an earlier diagenetic stage than the present carbonate rock, since they were protected from further diagenetic alteration by the surrounding quartz. The calcite inclusions display a higher Sr/Ca and Mg/Ca ratio than the carbonate host-rock. Because neomorphic diagenesis of the carbonate continued after silicate authigenesis, the contents of Mg and Sr in the calcite of the host carbonate are even lower. The authigenic feldspar mineralogy seems to be determined by the composition of the host-sediment.     

Stabilization of clayey soils with Tunisian phosphogypsum: effect on geotechnical properties

Phosphogypsum and cement have been reported to improve the physicochemical properties of clayey soils. The present study aimed to investigate the behavior of various soils with different particle sizes and chemical and mineralogical compositions in the presence of phosphogypsum and cement mixed at various proportions. These hydraulic binders were assayed on three different soil samples, and their effects were examined using a battery of standardized tests, including the Atterberg limit, uniaxial compressive strength, Californian Bearing Rate (CBR) test, thermogravimetric analysis (TGA), microstructure observation (SEM), and X-ray diffraction tests. The results revealed a significant effect associated with the variation of phosphogypsum content in the soils. Keeping the cement content constant in the mixture, the continuous addition of phosphogypsum was noted to allow shifting the domain of plasticity to the highest water contents, which reduces the sensitivity of the soil to water and to increase the strength of soil. An increase of CBR index with the addition of phosphogypsum and cement is obtained. This treatment could have positively influenced the optimum moisture content and the maximal dry density. The mixture of soil-phosphogypsum and cement could give new forms such as ettringite and hydrate indicators of the improvement of the mechanical properties of the soil. This improvement varies from one soil to another, depending on its granularity and its mineralogy. The mineralogical composition of the soil, particularly kaolinite, amount, and size grading, have direct effects on the physical and mechanical properties of the soils under investigation.     

Geochronological and isotopic records of crustal storage and assimilation in the Wolverine Creek–Conant Creek system,Heise eruptive centre,Snake River Plain

Understanding the processes of differentiation of the Yellowstone–Snake River Plain (YSRP) rhyolites is typically impeded by the apparent lack of erupted intermediate compositions as well as the complex nature of their shallow interaction with the surrounding crust responsible for their typically low O isotopic ratios. A pair of normal-δ¹⁸O rhyolitic eruptions from the Heise eruptive centre in eastern Idaho, the Wolverine Creek Tuff and the Conant Creek Tuff, represent unique magmatic products of the Yellowstone hotspot preserving abundant vestiges of the intermediate differentiation steps leading to rhyolite generation. We address both shallow and deep processes of magma generation and storage in the two units by combining high-precision ID–TIMS U–Pb zircon geochronology, trace element, O and Hf isotopic studies of zircon, and Sr isotopic analyses of individual high-Mg# pyroxenes inherited from lower- to mid-crustal differentiation stages. The zircon geochronology confirms the derivation of both tuffs from the same rhyolitic magma reservoir erupted at 5.5941 ± 0.0097 Ma, preceded by at least 92 ± 14 ky of continuous or intermittent zircon saturation approximating the length of pre-eruptive magma accumulation in the upper crust. Some low-Mg# pyroxenes enclosing zircons predate the eruption by at least 45 ± 27 ky, illustrating the co-crystallisation of major and accessory phases in the near-liquidus rhyolitic melts of the YSRP over a significant period of time. Coeval zircon crystals are isotopically heterogeneous (two populations at εHf ~?5 and ?13), requiring the assembly of isotopically distinct melt pockets directly prior to, or during, the eruption. The primitive Mg# 60–90 pyroxenes are out of isotopic equilibrium with the host rhyolitic melt (⁸⁷Sr/⁸⁶Sr_i = 0.70889), covering a range of ⁸⁷Sr/⁸⁶Sr_i = 0.70705–0.70883 corresponding to ratios typical of the most radiogenic YSRP basalts to the least radiogenic YSRP rhyolites. Together with the low εHf in zircon, the Sr isotopic ratios illustrate limited assimilation dominated by radiogenic Archean crustal source materials incorporated into variably evolved YSRP melts as they progress towards rhyolitic compositions by assimilation–fractional crystallisation.     

离子色谱法测定水样中S~(2-)、SO_3~(2-)、SO_4~(2-)、S_2O_3~(2-)

该种方法利用离子色谱仪的电导检测器与电化学检测器串联 ,十几分钟即可连续完成水中S2 - 、SO2 - 3 、SO2 - 4、S2 O2 - 3 的测定 ,方法具有快速、高效、方便、灵敏、选择性好等特点。方法的检出限分别为 :S2 - 12 5 μg/L ;SO2 - 3 2 2 4 μg/L ;SO2 - 45 0 μg/L ;S2 O2 - 35 0 μg/L。相对标准偏差在 1 5 %～ 6 9%之间 ,能够满足水中S2 - 、SO2 - 3 、SO2 - 4、S2 O2 - 3四种阴离子分析测试的需要。     

A Modeling Study of the Effects of Anomalous Snow Cover over the Tibetan Plateau upon the South Asian Summer Monsoon

The effect of anomalous snow cover over the Tibetan Plateau upon the South Asian summer monsoon is investigated by numerical simulations using the NCAR regional climate model (RegCM2) into which gravity wave drag has been introduced. The simulations adopt relatively realistic snow mass forcings based on Scanning Multi-channel Microwave Radiometer (SNINIR) pentad snow depth data. The physical mechanism and spatial structure of the sensitivity of the South Asian early summer monsoon to snow cover anomaly over the Tibetan Plateau are revealed. The main results are summarized as follows. The heavier than normal snow cover over the Plateau can obviously reduce the shortwave radiation absorbed by surface through the albedo effect, which is compensated by weaker upward sensible heat flux associated with colder surface temperature, whereas the effects of snow melting and evaporation are relatively smaller.The anomalies of surface heat fluxes can last until June and become unobvious in July. The decrease of the Plateau surface temperature caused by heavier snow cover reaches its maximum value from late April to early May. The atmospheric cooling in the mid-upper troposphere over the Plateau and its surrounding areas is most obvious in May and can keep a fairly strong intensity in June. In contrast, there is warming to the south of the Plateau in the mid-lower troposphere from April to June with a maximum value in May.The heavier snow cover over the Plateau can reduce the intensity of the South Asian summer monsoon and rainfall to some extent, but this influence is only obvious in early summer and almost disappears in later stages.     

三峡水库气候效应及2006年夏季川渝高温干旱事件的区域气候模拟

针对2006年夏季川(四川)渝(重庆)地区的高温干旱事件，使用RegCM3区域气候模式，采用双重嵌套和次网格(SUB-BATS)方法，进行中国和三峡地区2005—2006年气候50 km和10 km(通过SUB-BATS方法达到2 km)分辨率数值模拟，并在此基础上进行了三峡地区下垫面改变(三峡水库建成蓄水)的气候效应模拟试验，重点分析了模式对中国和三峡地区夏季气候和气候异常的模拟能力，以及三峡水库对气温和降水的影响。结果表明，模式能较好模拟出中国和川渝地区的气候及以2006年川渝地区高温干旱为代表的气候异常，双重嵌套和SUB-BATS方法的应用，使模式能够提供局地和区域气候更详细的信息。有无三峡水库的对比试验表明，水库对周边区域气温、降水的影响很小，大部分格点上的变化达不到90%统计信度检验标准，气温变化中少数通过检验的格点基本集中于水库水体本身，邻近区域内气温和降水的变化随距库区的距离变远而变得更弱。除了库区本身降温和降水减少外，模拟结果中出现的变化更多表现为模式中出现的噪音。2006年夏季的川渝高温干旱，更多是由于大的环流场造成的，与局地强迫的关系不大，三峡水库在其中所起的作用非常微弱，可以忽略不计。     

Evaluation of methods of spatial interpolation for monthly rainfall data over the state of Rio de Janeiro,Brazil

Five deterministic methods of spatial interpolation of monthly rainfall were compared over the state of Rio de Janeiro, southeast Brazil. The methods were the inverse distance weight (IDW), nearest neighbor (NRN), triangulation with linear interpolation (TLI), natural neighbor (NN), and spline tension (SPT). A set of 110 weather stations was used to test the methods. The selection of stations had two criteria: time series longer than 20 years and period of data from 1960 to 2009. The methods were evaluated using cross-validation, linear regression between values observed and interpolated, root mean square error (RMSE), coefficient of determination (r ²), coefficient of variation (CV, %), and the Willmott index of agreement (d). The results from different methods are influenced by the meteorological systems and their seasonality, as well as by the interaction with the topography. The methods presented higher precision (r ²) and accuracy (d, RMSE) during the summer and transition to autumn, in comparison with the winter or spring months. The SPT had the highest precision and accuracy in relation to other methods, in addition to having a good representation of the spatial patterns expected for rainfall over the complex terrain of the state and its high spatial variability.     

Basin organization of nature management for solving hydroecological problems

Presented are the development of the concept and projects of the basin nature management and the organization of their implementation in the whole region using the basin-administrative approach. Based on the multidimensional analysis and forecast of river runoff variations using the artificial neural networks, the typification of catchments is carried out mainly defined by such factors as its area, order of the river, and degree of anthropogenic load. Depending on the hydrological functioning type, the adapted complexes of Hydroecological activities are determined. The need in the integration of the geodata for each river basin with the inherent morphological and process characteristics as well as of the results of Hydroecological monitoring enables to recommend the structure of the database of the basin organization of nature management in the regions of Russia based on the European experience in the river network monitoring in the context of the EU Water Framework Directive and of the creation of the single infrastructure of the spatial data.