Respectfully submitted,

result of a request from the State Highway Engineer to investigate the properties of manufactured limestone sand in Portland cement concrete. The report is somewhat basic in the treatment of particle shape and we believe, is a definite contribution along that line. Mr. Laughlin has related the crushing techniques and particle shapes to cement concrete consistency testing. It appears that good quality structural Portland cement con-crete can be produced from properly manufactured limestone sand. The limestone sand would have to be controlled within definite limits for both gradation and grain shape to produce concrete strengths consistent with pre sent standards. Manufactured limestone sand is not quarry waste materials or what is commonly referred to as lime-stone dust. Manufactured limestone sand could be considered for use in Portland cement concrete base, but we feel that in pavement slabs or bridge decks subjected to the abrasive action of traffic that polishing of the aggregates would probably become critical. We would be pleased to prepare mate.rial and construction specifications for manufactured lime stone sand and its uses in Portland cement concrete. WBD:dl Encs