Hf–Zr anomalies in clinopyroxene from mantle xenoliths from France and Poland: implications for Lu–Hf dating of spinel peridotite lithospheric mantle

Clinopyroxenes in some fresh anhydrous spinel peridotite mantle xenoliths from the northern Massif Central (France) and Lower Silesia (Poland), analysed for a range of incompatible trace elements by laser ablation inductively coupled plasma mass spectrometry, show unusually strong negative anomalies in Hf and Zr relative to adjacent elements Sm and Nd, on primitive mantle-normalised diagrams. Similar Zr–Hf anomalies have only rarely been reported from clinopyroxene in spinel peridotite mantle xenoliths worldwide, and most are not as strong as the examples reported here. Low Hf contents give rise to a wide range of Lu/Hf ratios, which over geological time would result in highly radiogenic εHf values, decoupling them from εNd ratios. The high 176Lu/177Hf could in theory produce an isochronous relationship with 176Hf/177Hf over time; an errorchron is shown by clinopyroxene from mantle xenoliths from the northern Massif Central. However, in a review of the literature, we show that most mantle spinel peridotites do not show such high Lu/Hf ratios in their constituent clinopyroxenes, because they lack the distinctive Zr–Hf anomaly, and this limits the usefulness of the application of the Lu–Hf system of dating to garnet-free mantle rocks. Nevertheless, some mantle xenoliths from Poland or the Czech Republic may be amenable to Hf-isotope dating in the future

Tragschichten aus mit hydraulischen Bindemitteln und/oder Bitumenemulsion gebundenem teerhaltigem Asphaltgranulat

Available from TIB Hannover: F95B419+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Bestimmung der Luftporenkennwerte Frischbeton

The present study investigates whether the air void parameters established in fresh concrete with a new Danish measuring device (DBT device) coincide with the parameters measured with the usual method in hardened concrete. To this end the air void parameters were determined on both fresh and hardened concrete in various series of tests and compared. A statistical analysis of the data revealed that, for the assessment of the air void system in fresh concrete with the new device, the spacing factor is suitable. The total air content in fresh concrete should continue to be determined with the usual air void vessel procedure as the result of the DBT device is influenced by the consistency for this parameter. (orig.)Available from TIB Hannover: ZA 4681(640) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Dauerhaftigkeit von Draenbeton fuer Betonfahrbahndecken

In order to reduce the noise emission of road traffic, an attempt has been made for quite some time to use open-pore pavement surfaces consisting of drainage concrete as a noise-reducing pavement surface course. In this case, the drainage concrete with a void content of approx. 20-25% is applied in a layer thickness of 4-8 cm on top of the already hardened subconcrete or 'fesh in fresh' on top of the concrete which has not yet set. Since the durability of the drainage concrete (including the bond behaviour between the drainage concrete and the dense subconcrete) had still not been investigated to an adequate degree, these questions were followed up in laboratory tests. The compressive, flexural and tensile splitting strengths are primarily influenced by the compaction, i.e. by the void content. The flexural and tensile splitting strengths can be increased by adding a polymer emulsion. The frost/de-icing salt resistance can also be improved by adding a polymer emulsion. However, it was only possible to achieve a sufficient frost/de-icing salt resistance by adding polymer emulsion and microsilica at the same time. The bond between the dense subconcrete and the drainage concrete is impaired by the frost/de-icing salt stress. (orig.)Summary in German and FrenchAvailable from TIB Hannover: ZA 4681(764) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Entwicklung eines Staubbindemittels fuer das Trockenspritzverfahren

TIB: RN 5828(21) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Feinkoernige Strassenbeton-Recyclingmaterialien als Zuschlag fuer neue Betondecken

In several countries recycled aggregate, taken from old concrete road surfaces, has been used in the road construction sector for a long time for making new concrete surfaces. Generally the aggregate is only used for the subconcrete, whilst the upper layer of concrete is almost exclusively made using conventional aggregates. The use is generally restricted to the concrete chipping over 4 mm or 2 mm. The resulting crushed concrete fine aggregate -which makes up approximately 30 to 40% of the total aggregate - is primarily used in frost blankets and hydraulically bound roadbases. However, in order to also enable a more valuable usage, for instance in subconcrete or also in the upper layer of concrete of road surfaces, comprehensive laboratory investigations had to be carried out on types of concrete with different proportions of crushed concrete fine aggregate. Starting materials from 3 motorway building sites were used in the test programme. The effect of the crushed concrete fine aggregate on the fesh concrete properties was tested (air content, workability) as well as the hard concrete properties (strength, durability, expansion, contraction). The following conclusions can be made from the results of the laboratory investigations. (orig.)Summary in FrenchAvailable from TIB Hannover: ZA 4681(779)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Staubbekaempfung im Tunnelbau: Gesteinsschneid- und Modellversuche Verbesserung der Arbeitsbedingungen von Tunnelbauarbeitern durch Untersuchung von Moeglichkeiten zur lueftungstechnischen Begrenzung der Staubausbreitung. Schlussbericht

Available from TIB Hannover: RN 5828(30) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Verwendung wasserdurchlaessiger Tragschichten im Bereich der Standspur unter Betonfahrbahndecken - technologische Untersuchungen. Verwendung wasserdurchlaessiger Tragschichten im Bereich der Standspur unter Betonfahrbahnen - Felduntersuchungen

Summary in EnglishAvailable from TIB Hannover: ZA 4681(694) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman