Valorización de cenizas de lodo de depuradora como componente de hormigones para prefabricados

Se plantea la combinación binaria y ternaria de cenizas de lodo de depuradora (CLD) con ceniza volante, polvo de mármol y ceniza de cáscara de arroz, como sustitución parcial o como adición respecto al cemento Portland en hormigones, con una dosificación similar a la utilizada en la prefabricación de bloques (consistencia muy seca). Se llevaron a cabo ensayos físico-mecánicos sobre probetas de mortero y hormigón con edades de curado de 28 y 90 días: densidad, absorción y resistencia a compresión. Se comprueba que la sustitución de cemento por CLD supone una disminución de la densidad y de la resistencia respecto a la muestra patrón, sin embargo, las combinaciones con otros residuos mejoran notablemente las características de los materiales cementantes. La adición de CLD proporcionó densidades y resistencias similares a la muestra de control y reduce significativamente la absorción de agua.

230Th, 231Pa, and 10Be in particle size fractions of an opal-rich sediment of the Atlantic Southern Ocean

This study centers on the question: How sensitive are 231Pa/230Th and 10Be/230Th to sediment composition and redistribution? The natural radionuclides 231Pa, 230Th and 10Be recorded in deep sea sediments are tracers for water mass advection and particle fluxes. We investigate the influence of oceanic particle composition on the element adsorption in order to improve our understanding of sedimentary isotope records. We present new data on particle size specific 231Pa and 10Be concentrations. An additional separation step, based on settling velocities, led to the isolation of a very opal-rich phase. We find that opal-rich particles contain the highest 231Pa and 10Be concentrations, and higher 231Pa/230Th and 10Be/230Th isotope ratios than opal-poor particles. The fractionation relative to 230Th induced by the adsorption to opal-rich particles is more pronounced for 231Pa than for 10Be. We conclude that bulk 231Pa/230Th in Southern Ocean sediments is most suitable as a proxy for past opal fluxes. The comparison between two neighboring cores with rapid and slow accumulation rates reveals that these isotope ratios are not influenced significantly by the intensity of sediment focusing at these two study sites. However, a simulation shows that particle sorting by selective removal of sediment (winnowing) could change the isotope ratios. Consequently, 231Pa/230Th should not be used as paleocirculation proxy in cases where a strong loss of opal-rich material due to bottom currents occurred.

Report and recommendations of the Medical Advisory Committee on the administration of the OASI disability provisions.

"November 1960."

Zwei Frauenchöre : mit Orchester : op. 10 : Partitur mit Klavierauszug /

For women's chorus (SSA) and orchestra or piano.

La légende de Sainte Cécile : drame en trois actes, en vers : op. 22 /

French words.

Rulings.

Social security rulings on federal old-age, survivors, disability, and supplemental security income; and black lung benefits.

Social security rulings on Federal old-age, survivors, disability, supplemental security income, and black lung benefits.

1979, SSR-79-1 to SSR-79-38.

Income of the population 55 and over.

Latest issue consulted: 1990.

Disability survey 71 : recently disabled adults.

No. [1] is reprinted from Social Security bulletin, Sept. 1975, as DHEW publication no. (SSA) 76-11703. No. 2- comprise DHEW publication no. (SSA) 76-11716.

Diccionario cafre-tetense-portuguez; ou, Idioma fallado no districto de Tete e na vasta região do Zambeze Inferior; Mafara akukonkédua a chizungu na mu chisendzi cha ku Nyungue.

Mode of access: Internet.

Income maintenance research by state and federal agencies ...

Mode of access: Internet.

Social Security : observations on demonstration interviews with disability claimants : briefing report to the Chairman, Subcommittee on Social Security, Committee on Ways and Mean, House of Representatives /

"B-224648"--P. 1.

Social Security : views of agency personnel on service quality and staff reductions : briefing report to Congressional requesters /

Running title: Views of SSA personnel.

Heterogeneity in health and morality risk among early retiree men /

"SSA Publication No. 13-11712"--P. of cover.

Expenditures of the aged chartbook.

"May 2007"--P. [4] of cover.