The water-cement ratio (w/cm) is one of the most influential parameters to determine the quality of concrete. A new test method has been developed that uses external heat to evaporate the water from the concrete before it has hardened. Data are presented for 258 mixtures with 23 aggregates, 9 cements, 5 supplementary cementitious materials, and 15 different admixtures. For the laboratory testing, the average measured w/cm is within 0.01 from the batched w/cm with a coefficient of variation (COV) of 3.2%. A subset of these mixes was evaluated with the AASHTO T 318 microwave test and the measured w/cm is 0.05 higher than the expected value and the COV is almost three times higher (8.9%). Field data is also presented from 27 mixtures and the measured w/cm shows good agreement with the batched values. The method, calculation, and practical applications of this new test method are presented.

水灰比（w / cm）是决定混凝土质量的最有影响力的参数之一。已经开发出一种新的测试方法，该方法利用外部热量在混凝土硬化之前将其蒸发掉。给出了258种混合物的数据，其中包括23种集料，9种水泥，5种补充胶凝材料和15种不同的外加剂。对于实验室测试，测量的平均w / cm与批次的w / cm相差0.01，且变异系数（COV）为3.2％。使用AASHTO T 318微波测试评估了这些混合物的一个子集，测得的w / cm比预期值高0.05，COV几乎高出三倍（8.9％）。还显示了来自27种混合物的现场数据，并且测量的w / cm显示与批次值良好的一致性。方法，计算，