Fibrous roller-compacted concrete with recycled materials - Feasibility study

This paper presents fundamental work done to enable fibre reinforcement of roller-compacted concrete (RCC). Procedures for mixing and casting two types of steel fibres in RCC were developed. Fresh properties, uniaxial compressive and bending behaviour were examined in a pilot study dealing with cement content, fibre type and dosage. It was found that different fibre types and dosages require different moisture contents. It is concluded that low cement content (less than 300 kg/m3) steel-fibre-reinforced roller-compacted concrete (SFR-RCC) mixes do not have sufficient paste and are prone to fibre agglomeration, hence SFR-RCC mixes richer in paste and at optimum moisture content are recommended. Mixes with cement content of 300 kg/m3 coped better with fibre reinforcement. Despite causing some loss in compressive strength, fibres help enhance the flexural performance and even SFR-RCC mixes with recycled masonry and concrete aggregates performed equally well as natural aggregate mixes. A fullscale trial has been conducted to confirm the findings. This paper is followed by a companion paper dealing with a comprehensive parametric study leading to the development of σ-ε models for SFR-RCC

The potential of high-rate GPS for strong ground motion assessment

We show that high-rate GPS can have a vital role to play in near real-time monitoring of potentially destructive earthquakes. We do this by investigating the potential of GPS in recording strong ground motions from earthquakes in Switzerland and Japan. The study uses finite-fault stochastic ground motion simulation based on Fourier amplitude spectra and duration models previously developed for both countries, allowing comparisons in terms of both Fourier and time domain characteristics (here the Peak Ground Velocity, PGV). We find that earthquakes of magnitude Mw>5.8 can be expected to be recorded by GPS in real-time at 10 km distance, i.e. their Fourier spectrum exceeds the noise of the instruments enough to be used in strong motion seismology. Post-processing of GPS time series lowers the noise and can improve the minimum observable magnitude by 0.1-0.2. As GPS receivers can record at higher rates (> 10 sps), we investigate which sampling rate is sufficient to optimally record earthquake signals and conclude that a minimum sampling rate of 5 sps is recommended. This is driven by recording events at short distances (below 10 km for magnitude 6 events and below 30 km for magnitude 7 events). Furthermore, the Maximum Ground Velocity derived from GPS is compared to the actual PGV for synthetic signals from the stochastic simulations and the 2008 Mw=6.9 Iwate earthquake. The proposed model, confirmed by synthetic and empirical data, shows that a reliable estimate of PGV for events of about magnitude 7 and greater can be basically retrieved by GPS in real-time and could be included for instance in ShakeMaps for aiding post-event disaster management

Patents, pills and public health Can TRIPS deliver?

Includes bibliographical referencesAvailable from British Library Document Supply Centre- DSC:02/42278 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo