increase durability in general for the inventive mixtures applicants prefer a water cement ratio in the range of about 0 3 to 0 5 by weight those skilled in the art will appreciate that the water to cement ratio must take into account the amount of both portland cement and perlite and any other supplementary cementitious material such as fly ash silica fume ground granulated blast furnace slag and metakaolin the foregoing examples show a number of surprising and useful properties of the inventive material compared to previously available materials including previous materials that contain perlite in various forms using a standard 5000 psi mix design the inventive additive consistently produces concrete with more than twice the compressive strength of regular concrete in addition the flexural strength of the same material averages 60 more than a comparable conventional 5000 psi concrete the combination of high early strength and reduced permeability are desirable properties which are not obtained with fly ash or slag which exhibit low early strengths or with silica fume permeability reduction tends to level off compared to perlite containing grouts and wellbore fluids the inventive materials contain coarse aggregate which allows them to be used for structural applications the inventive material is significantly stronger than low density thermally insulating concrete while markedly more spall resistant than conventional structural concrete it will be understood that expanded perlite in the desired particle size range typically characterized by a volume weighted mean particle size of approximately 10 100 u03bcm may be obtained by grinding expanded perlite.