THE VALORISATION OF THE CRT GLASS AS POZZOLANA AND FINE RECYCLED SAND INTO GROUTS FOR LOW LEVEL RADIOACTIVE WASTE ENCAPSULATION.

It is known that cementation by use of special composition fluid mortars (grouts) offers the means to encapsulation of low and medium level radioactive waste, in solid state as well as in different forms of sludges and precipitates/gels or activated materials. The work hereby proposes to obtain such cement grouts of special composition which make use, as secondary raw materials of cathode ray tubes (CRT) glass as pozzolana and of fine recycled sand for low level radioactive waste encapsulation. In obtaining the grouts, two types of aggregates sort 0/2mm were used: river aggregate and crushed concrete recycled aggregate. The compositional optimization was aimed towards obtaining a good homogeneity of grouts, a low segregation, Marsh flowing time up to 60sec. and with as high as possible a percentage in volume of CRT glass. The variation of properties that present interest in the hardened mortars such as: bending and compression strength, water absorption, dimensional variation in time, were interpreted from the compositional point of view by taking into account the nature of the aggregate, the changing of the sand/cement and water/cement ratio, the rapport between aggregate sorts, the percentage of replacement of the aggregate with CRT glass filler (<0,125mm), the type of admixture used. Furthermore, the microstructural characterization of grouts, was accomplished with the help of an scanning electron microscope (SEM) equipped with EDAX detector. [ABSTRACT FROM AUTHOR]