An assessment of the effect of grading of perlite on ultimate strength in lightweight concrete.

[摘要] This research project is an investigation into the effect of the grading of perlitelightweight aggregates on the resultant concrete strengths.Lightweight concretes are reviewed.Perlite, as a lightweight aggregate, is assessed.Grading theory for aggregates and in particular lightweight aggregate is analysed.A series of mix designs are proposed with manipulation of the grading of the perlite asthe only variable. This is so that variations in compressive strength and density maybe assessed in terms of the grading of the perlite.Those mixes are undertaken and tested for compressive strength and dry density.In this research project compressive strength is considered a benefit, while mass isconsidered a disadvantage.The performance of a lightweight concrete is assessed firstly in terms of the PowerFactor. The Power Factor is the compressive strength divided by the dry density of aconcrete.The performance of lightweight concretes produced with Perlite aggregate is assessedsecondly in terms of the Cement Content factor. The Cement Content Factor is thePower Factor divided by the Cement Content. This factor has the effect of creating acommon denominator of the cement content.An evaluation of the results yields the conclusions detailed in chapter Eight, theprincipal two being:• The optimal perlite grading tested was a monodisperse, single size fraction, ofbetween 600 and 1180 microns.• The most practical measure for manufacturers to improve the performance oflightweight

[发布机构] University of the Witwatersrand