Natural Stone Waste Powders Applied to SCC Mix Design

In order to comply with current trends concerning sustainability, saving of primary materials and energy\ud savings, this paper addresses Eco-concrete. The major focus thereby is on the increased efficiency of cement\ud use. Applying a new mix design method for concrete, cement contents can be decreased and partially be substituted\ud by other fine powders, preferentially by waste powders which have no mass application so far. This\ud paper is giving examples of successfully introduced waste powders and characterizes the concretes produced\ud with these powders. These innovative, low cement concrete types obtain medium strength and exhibit furthermore\ud self-compacting abilities. This paper additionally highlights possibilities for the direct use of natural\ud stone sludges or filter cakes. A new grading based design method, developed in the authors’ research\ud group, enables the efficient use of all materials available. The method is applicable to self-compacting concretes,\ud earth-moist concretes and conventionally vibrated concretes

Self-cleaning surfaces as an innovative potential for sustainable concrete

Concrete technology is subject of continuous development and improvement. One of the very recent contributions to durability and sustainability of concrete is the self-cleaning ability. This effect is achieved by applying photocatalytic materials to the concrete mix. This paper describes the effect of self-cleaning and air purification. Since about 10 years concrete paving stones, provided with this function, are available. With the development of a test setup and using nitric oxide (NO) as model pollutant an approach was found to quantitatively assess the air-purifying ability of those paving stones. This seems to be of interest since a real comparative analysis of air purifying concrete products is not available and the establishment of a measurement standard for concrete products is still in a draft-state. A brief technical description of this test setup will be presented to the reader. Using this innovative setup, the influences on the degradation efficiency are studied and a basic reaction model is derived

Structural ultra-lightweight concrete – from laboratory research to field trials

This article presents the laboratory development and subsequent field trials of a novel structural ultra-lightweight concrete. The concrete is developed aiming at the application in monolithic buildings (i.e. no insulation layer required), which would facilitate the construction and recycling processes, as well as provide new opportunities to architects and structural engineers. The development of the ultra-lightweight concrete presented in this study includes the optimization of its composition (ultra-lightweight aggregates, binders, admixtures) and is targeted on the concrete properties such as the compressive strength, density and thermal conductivity. In order to reduce the risk of an excessive overheating of concrete during its early hydration process caused by its self-insulating properties, the binder composition and amount was further investigated and optimized. Finally, a material of an ultra-low density (< 800 kg/m3), ultra-low thermal conductivity (as low as 0.14 W/(m·K)) and a compressive strength of 10 MPa was developed. Subsequently, several batches of 2 m3 of concrete were produced in a ready-mix concrete plant and a L-shaped test-wall was cast. The temperature development as well as hardened concrete properties were monitored. The field tests show that, although there still are some issues to overcome (e.g. workability), the developed material has a very good potential to enter the concrete market and find new applications

Water-powder mixtures at the onset of flowing

The knowledge of water demands of the manifold concrete ingredients is of vital interest for the design of concrete mixes. Physical properties like workability or strength and durability in hardened state are controlled by the total water content. Water demand is defined as the volumetric ratio of water to solid material at a certain state, which is defined by the selected test method. Given that powders provide the b far highest percentage of specific surface area in a concrete mixture, their water demand is of special interest. In literature diverse methods for the determination of powders’ water demands can be found. However, it appears that the spread-flow test, sometimes referred to as mini-slump flow test, has achieved general acceptance in concrete technology. In this research the spread-flow test has been analyzed in more detail. In this way new measures are derived which contribute to a deeper understanding of wet granular mixtures at the onset of flowing. The deformation coefficient which will be derived by the spread-flow test was confirmed to correlate with the product of Blaine surface and intrinsic density of the individual powders when the mixture is flowing only under its own weight. Similarly, correlations with equal accuracy have been found with a computed specific surface based on measured particle size distributions instead of the Blaine surface. Using flow experiments it was possible to derive an overall factor for assessing the non-spherical shape of the powder particles. A good correlation of this computation algorithm was derived compared to the standard Blaine method. Finally, a constant water layer thickness around the powder particles was derived for all powders at the onset of flowing. This implies the possibility to predict flow behavior of mortar and concrete mixtures only based on the knowledge of their granular characteristics

Cavity-enhanced optical detection of carbon nanotube Brownian motion

Optical cavities with small mode volume are well-suited to detect the vibration of sub-wavelength sized objects. Here we employ a fiber-based, high-finesse optical microcavity to detect the Brownian motion of a freely suspended carbon nanotube at room temperature under vacuum. The optical detection resolves deflections of the oscillating tube down to 50pm/Hz^1/2. A full vibrational spectrum of the carbon nanotube is obtained and confirmed by characterization of the same device in a scanning electron microscope. Our work successfully extends the principles of high-sensitivity optomechanical detection to molecular scale nanomechanical systems.Comment: 14 pages, 11 figure

Photocatalysis applied to concrete products - part 2 : influencing factors and product performance

The second part of this three-part article series addresses the influence of physicochemical parameters on the degradation performance of concrete products containing photocatalytic active TiO2. The influence of process conditions like irradiance, relative humidity, pollutant concentration and flow rate on the degradation mechanism is investigated. Furthermore, a short overview on photo catalytic powders (especially TiO2) and their influence on the degradation of NO are presented. In addition the application of TiO2 coatings and their microstructural analysis is explained

On the origin of the extremely different solubilities of polyethers in water

The solubilities of polyethers are surprisingly counter-intuitive. The best-known example is the difference between polyethylene glycol ([–CH2–CH2–O–]n) which is infinitely soluble, and polyoxymethylene ([–CH2–O–]n) which is completely insoluble in water, exactly the opposite of what one expects from the C/O ratios of these molecules. Similar anomalies exist for oligomeric and cyclic polyethers. To solve this apparent mystery, we use femtosecond vibrational and GHz dielectric spectroscopy with complementary ab initio calculations and molecular dynamics simulations. We find that the dynamics of water molecules solvating polyethers is fundamentally different depending on their C/O composition. The ab initio calculations and simulations show that this is not because of steric effects (as is commonly believed), but because the partial charge on the O atoms depends on the number of C atoms by which they are separated. Our results thus show that inductive effects can have a major impact on aqueous solubilities

Evidence for magnon BEC in superfluid 3He-A

International audienceThe phenomenon of phase-coherent precession of magnetization in superfluid 3He and the related effects of spin superfluidity are based on the true Bose-Einstein condensation of magnons. Several different states of coherent precession have been observed in 3He-B: homogeneously precessing domain (HPD); persistent signal formed byQ-balls at very low temperatures; coherent precession with fractional magnetization; and two new modes of the coherent precession in compressed aerogel. Here we demonstrate the evidence of magnons Bose-Einstein condensation in 3He-A in a compressed aerogel

Secukinumab versus adalimumab for psoriatic arthritis: comparative effectiveness up to 48 weeks using a matching-adjusted indirect comparison

Secukinumab and adalimumab are approved for adults with active psoriatic arthritis (PsA). In the absence of direct randomized controlled trial (RCT) data, matching-adjusted indirect comparison can estimate the comparative effectiveness in anti-tumor necrosis factor (TNF)-naïve populations. Individual patient data from the FUTURE 2 RCT (secukinumab vs. placebo; N = 299) were adjusted to match baseline characteristics of the ADEPT RCT (adalimumab vs. placebo; N = 313). Logistic regression determined adjustment weights for age, body weight, sex, race, methotrexate use, psoriasis affecting ≥ 3% of body surface area, Psoriasis Area and Severity Index score, Health Assessment Questionnaire Disability Index score, presence of dactylitis and enthesitis, and previous anti-TNF therapy. Recalculated secukinumab outcomes were compared with adalimumab outcomes at weeks 12 (placebo-adjusted), 16, 24, and 48 (nonplacebo-adjusted). After matching, the effective sample size for FUTURE 2 was 101. Week 12 American College of Rheumatology (ACR) response rates were not significantly different between secukinumab and adalimumab. Week 16 ACR 20 and 50 response rates were higher for secukinumab 150 mg than for adalimumab (P = 0.017, P = 0.033), as was ACR 50 for secukinumab 300 mg (P = 0.030). Week 24 ACR 20 and 50 were higher for secukinumab 150 mg than for adalimumab (P = 0.001, P = 0.019), as was ACR 20 for secukinumab 300 mg (P = 0.048). Week 48 ACR 20 was higher for secukinumab 150 and 300 mg than for adalimumab (P = 0.002, P = 0.027), as was ACR 50 for secukinumab 300 mg (P = 0.032). In our analysis, patients with PsA receiving secukinumab were more likely to achieve higher ACR responses through 1 year (weeks 16-48) than those treated with adalimumab. Although informative, these observations rely on a subgroup of patients from FUTURE 2 and thus should be considered interim until the ongoing head-to-head RCT EXCEED can validate these findings. Novartis Pharma AG