PEREIRA-DE-OLIVEIRA, LUIZ1

1) Associate professor, University of Beira Interior, Centre of Materials and Building Technologies C-MADE, luiz.oliveira@ubi.pt

The questions of masonry grout infill workability are a problem that needs to be solved, when narrow dimension voids in masonry units need to be filled. Normally, two solutions are used: the W/C ratio is increased or by the use of superplasticizer. The masonry units, as porous media, are strongly hygroscopic and capable to reduce the grout infill W/C ratio. This reduction may undermine the cement paste hydration if even an adequate grout consistency is attained. By consequence, the prediction of resultant W/C ratio in the grout mixtures is an important parameter to help the mix design and the grout placing. This study is focussed on the grout water transfer into the masonry units and about the effect of the variables concerning this mechanism. With this goal, an analytical model, based on Darcy, Laplace and Poiseuille laws, was first developed and justified by an experimental study where some variables such as grout W/C ratio, temperature and masonry unit porosity were studied. In conclusion, it was possible to define a model to predict how the mixing grout water behaved in the grout infill as a function of time and the variables studied.

Keywords: masonry grout infill, water transfer, water loss