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Particle shape is evaluated on three scales corresponding to form, roundness and roughness. Shape at each of these scales uniquely influences material behavior. The shape of sand grains is largely formed as magma cools. Subsequent cleavage and abrasion change the roundness and roughness of particles. Published results indicate that particle shape influences several aspects of granular systems behavior including stiffness, strength, the evolution of strength anisotropy, dilation, and the development of strain localization. The crushing of granite creates a particulate material with a unique angular shape. A wide range of experimental studies implemented as part of this research permit assembling a unique database of material parameters and comparing the behavior of several crushed and natural sands. In general, the low roundness of crushed sands leads to higher maximum void ratios, lower small strain stiffnesses, and higher critical state friction angles than more rounded natural sands. It also impacts mortar strength and workability. Previous studies have emphasized size-controlled segregation. New experimental results show that differences in particle shape can also lead to segregation in a binary granular material. Round or spherical particles are more mobile than angular or flat particles. Then, the greater motion of round or spherical particles in a binary mixture subjected to horizontal or vertical vibration results in their segregation from their angular or flat neighbors. Particle shape may change significantly with stress in the case of soft particles. Therefore, the presence of shape-deformable particles decreases the stiffness of binary rigid-soft particle mixtures. However, macro-scale measurements with rigid-soft mixtures show higher stiffness than would be expected by volume averaging techniques. A subsequent microscale study shows the formation of backbone chains made of the rigid particles, partially supported by the soft particles which prevent the buckling of the load-carrying chains.

Thesis--Auburn University, 2010. / Abstract. Vita. Includes bibliographic references (p.104-107).

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O objetivo desta pesquisa é mostrar que a brita sofre significativa variação de preço saindo da pedreira até chegar à sua utilização final. A grande parte desse aumento não diz respeito às atividades de mineração, mas sim às atividades logísticas, principalmente à distribuição física. As restrições ao tráfego de veículos de cargas são bastante intensificadas nos grandes centros urbanos, como a cidade de São Paulo. Medidas restritivas adotadas, como a proibição de circulação em determinadas áreas, horários pré-estabelecidos, rodízio municipal e especificação de tipos e tamanhos de veículos, provocam a necessidade de uma frota maior e mais diversificada e mais pessoal. Além disso, há subutilização da frota pelos dias, horários e locais das restrições, resultando na realimentação do que justamente se quer combater: congestionamentos e poluição. Congestionamentos devidos ao envelhecimento da frota rodante, já que as empresas supriram as limitações do rodízio municipal com a não desativação de veículos usados, que seriam substituídos por novos. Com vários anos de uso, estes quebram freqüentemente nas ruas, avenidas e corredores, prejudicando o trânsito. Poluição causada por motores velhos que, além de mais combustível, queimam também óleo lubrificante, deixando intermináveis rastros de vazamentos nas vias públicas. Quem tem que arcar com tudo isso é o consumidor final, que paga mais caro, espera mais e tem que se adaptar aos horários de entrega que as autoridades, agora com a nova legislação, só permitem, geralmente, durante o período noturno. / The objective of this research is to demonstrate that crushed stone has a significative variation in price from the quarry to its final use. Most of such increase is not related to mining activities but to logistics activities, mainly physical distribution. This variation is highly intensified in conurbations and big cities such as São Paulo, where there are traffic restrictions to cargo vehicles. The circulation in certain areas at determined times being prohibited due to the municipal number-plate alternating system in specifying types and sizes of vehicles, generates a need for a larger and more diversified fleet, not to mention more personnel. Besides that, there is underutilization of the fleet because of the days, time and places of restrictions provoking more traffic jams and pollution rather than eliminating them, which is exactly what is desired. Traffic jams due to the aging of the fleet in use, once the companies have incorporated used vehicles to compensate for the municipal number–plate system. Being in use for long such vehicles frequently breakdown on streets and avenues thus impairing the traffic. Pollution is caused by old engines that besides more fuel also burn lubricating oil, not to mention the traces of oil leaks left on public streets and avenues. Such burden is left for the final consumer to carry by spending more money waiting longer and having to adapt to the time authorities offer now with a new legislation in general at night.

The objective of this thesis is to examine the difference in workability in fresh concrete, when crushed fine aggregate replaces natural gravel. The shape of the fine aggregate,  packing and flow of six crushed material and three natural materials will be determined by easy studies, the results will be compared with a slump cone test.

<p> </p><p>The objective of this thesis is to examine the difference in workability in fresh concrete, when crushed fine aggregate replaces natural gravel. The shape of the fine aggregate,  packing and flow of six crushed material and three natural materials will be determined by easy studies, the results will be compared with a slump cone test.</p>

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Les médicaments sont souvent écrasés pour pouvoir être pris par les personnes âgées qui ont des troubles de la déglutition ou des troubles du comportement. La Haute Autorité de Santé a publié la liste des médicaments autorisés à être écrasés. Ce travail a deux objectifs : Le 1er objectif est de déterminer l’impact des médicaments écrasés sur le goût de volontaires sains, afin de déterminer quels médicaments sont acceptables ou à déconseiller dans les aliments. Le 2ème objectif est de rechercher in vitro si certains médicaments inhibent ou au contraire stimulent la croissance microbienne et risquent d’altérer le biofilm oral. 1/ Le Test Hédonique est une étude clinique médicamenteuse de phase 1 sur volontaires sains. Seize volontaires sains ont testé les 10 médicaments les plus prescrits dans les EHPAD et identifiés comme pouvant être écrasés ou ouverts. Nous avons montré que les médicaments écrasés modifient le goût des aliments. 2/ L’analyse microbiologique : Nous avons testé in vitro si les 30 médicaments les plus prescrits en EPADH. Nous avons testé d’abord leur impact sur les souches de référence (normes AFNOR) et ensuite sur des souches orales (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans). Seulement huit des trente médicaments testés inhibent la croissance des souches microbiennes. Ces huit médicaments ont été secondairement testés au contact de biofilms monoespèces (C. albicans et S. salivarius) en formation ou préformés. Cette étude nous a montré que les médicaments écrasés ont un impact direct sur les 5 souches bactériennes et sur C. albicans. Ces médicaments ont aussi eu un impact sur l’intégrité des biofilms. / Frail elderly people are often polymedicated and they also frequently suffer from swallowing disorders (dysphagia). As a precaution, these patients are often given blended food and nursing staff is also obliged to crush their medication. The present work aimed to investigate the taste of the ten drugs and the antimicrobial properties of the 30 most prescribed drugs in nursing homes. 1/ Gustative analysis: This one-step observational study was designed like a food or wine tasting. A jury of 16 healthy volunteers was recruited among medical staff. They had to test the 10 most prescribed crushed drugs in nursing homes. We found that the taste of some drugs may be unbearable when they are crushed and mixed into food, and caregivers should avoid mixing a bad-tasting drug with the other drugs. 2/ Microbiology Study: Microbial growth inhibition of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus salivarius, Gemella haemolysans and Candida albicans was screened by the diffusion method on agar plates. Eight drugs inhibited microbial growth. They were secondly tested on C. albicans and S. salivarius biofilms grown in liquid medium. We found that crushed medications could inhibit microbial growth, biofilm formation and diminish biofilm viability.