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The fresh concrete water-cement ratio (w/c) determination tool is urgently needed for use in the QC/QA process at the job site. Various techniques have been used in the past to determine this parameter. However, many of these techniques can be complicated and time consuming. Furthermore, extensive calibration is often needed to correlate the properties measured by these techniques with w/c. During the course of the present study, the method for the use of the unit weight for the determination of w/c of fresh concrete has been developed and evaluated on both laboratory and field concretes. Additionally, the accuracy of using microwave oven technique for w/c determination reported by previous research was confirmed. Finally, the accuracies of unit weight and microwave oven techniques for the determination of w/c were compared.