The present invention relates to a method and an apparatus for quality investigation of ready-mixed concrete, and more particularly to a method and an apparatus for predicting the quality of hardened concrete by measuring the weight ratio of water to cement in a just-prepared concrete mixture.
Procedure for an accepting test made on ready-mixed concrete at a construction field has usually consisted of making a slump test and sampling the received ready-mixed concrete for the purpose of investigating the compressive strength after the concrete has become hardened. However, the slump test does not always give a satisfactory result in predicting the quality of hardened concrete, while the compressive strength test can not be carried out until the sampled concrete mixture becomes hardened after a predetermined period of time has passed. Therefore, the conventional acceptance test of ready-mixed concrete can not preguarantee the quality of concrete before the concrete mixture deposited at a construction field becomes hardened. Encouraged by an upsurge of quality assurance movement there have been proposed many trial methods for predicting the quality of hardened concrete from the data of unhardened concrete. However, they have a problem in the correlation to compressive strength, in rapidity and easiness of test procedure, or in economical efficiency, and hence none of them has come to be practiced or used widely.