This dataset provides mechanical test data for quartz sand (“MAM1ST-300”, Sibelco, Mol, Belgium), gypsum powder (plaster; “Goldband”, Knauf), kaolin clay powder, garnet sand, and mixtures of quartz sand and gypsum powder, used at the Analogue Laboratory of the Department of Geography at the Vrije Universiteit Brussel, Brussels, Belgium, for simulating brittle rocks in the upper crust (Poppe et al., 2019). The measured properties are density ρ, tensile strength T0, shear strength σ, obtained by density measurements, ring-shear tests (RST; at Helmholtz Centre Potsdam GFZ, Germany), direct shear tests, traction tests (at University of Maine, Le Mans, France) and extension tests. The obtained tensile strengths and shear strengths reconstruct two-dimensional failure envelopes for each material. By fitting linear Coulomb and non-linear combined Griffith failure criteria to the characterised failure envelopes (Jaeger et al., 2007), the internal friction coefficient µC, Coulomb cohesion CC and Griffith cohesion CG are obtained. The influence of the material emplacement technique has been investigated in Poppe et al. (2021) to which this data set is supplementary, by repeat characterisation of the above physical parameters under three emplacement conditions, i.e. sieving, pouring (non-dried state) and compaction after pouring (oven-dried state).
We find that densities of the materials and mixtures range from ~1600 kg.m³ (sieved) and ~1700 kg.m³ (compacted) for pure quartz sand to ~600 kg.m³ (poured) to ~900 kg.m³ (compacted) for pure plaster. Tensile strengths range from ~166 Pa (sand) to ~425 Pa (plaster). Velocity ring-shear tests on a 90 wt% quartz sand – 10 wt% plaster mixture show a minor shear rate-weakening of <2% per ten-fold increase in shear velocity. The materials show a behavior ranging from Mohr-Coulomb behavior for the materials with coarser grain size (sands) to combined Griffith-Mohr-Coulomb behavior for the powder materials (plaster, kaolin), with the sand-plaster mixtures occupying a spectrum between both end-members. Peak friction coefficients range from ~0.5 (sand) to ~0.6 (plaster) with a maximum of ~0.9 (80:20 wt% sand:plaster), peak Coulomb cohesions range from 13 Pa (sand) to 248 Pa (plaster), peak Griffith cohesions range from ~10 Pa (sand) to ~425 Pa (plaster).
Objective: To develop the market for solid biofuels within the EU standards are urgently needed. Based on a mandate given by the EC, CEN TC 335 'Solid Biofuels' currently develops such standards based on the available knowledge. In the meantime several Technical Specifications (TS) (or pre-standards) are available. They have to be upgraded to European Standards (EN) within the next 3 years. Other TS's are on its way. But applications in industry have shown that additional information has to be integrated and/or considerable gaps in knowledge still exist. This makes it difficult to develop the still missing TS's and/or to upgrade the TS's to EN's. Against that background the goal of the BioNorm II project is it to support the ongoing standardi sation efforts especially for the development of improved solid biofuel specifications concerning - specifications given by the combustion unit, and - rules for conformity of the products with their specified requirements. To achieve this, the following aspects will be addressed within this project in detail: - development of sampling and sample reduction methods for further materials as well as sampling plans, - improvement of existing reference test methods, - development of new reference test methods, - development of rapid on-site test methods, - development of improved quality measures especially adapted to solid biofuels. Additionally the results of this pre-normative work will be transferred directly into the ongoing standardisation process to allow for the development of improved EN's and acceptable TS's.