| 摘要 |
<p>This method is used to determine the proportion of mixing water to be added in accordance with a measured value of the water content of a fine aggregate when making mortar by adding and kneading a fine aggregate and water to a powder of a hydraulic substance such as cement, or when making concrete by also adding and kneading a coarse aggregate to that mixture. The water content of the fine aggregate is obtained as a water content equivalent to the surface-dried water content according to JIS, or the maximum and minium absorption water contents absorbed in the surface of the fine aggregate and the saturated water content in voids within the fine aggregate, and the proportion of mixing water is determined in accordance with a predetermined multiple of the minimum surface absorption water content of the fine aggregate. The measurement of these water contents in the fine aggregate is done within a short period of time in such a manner that the fine aggregate is wetted and placed in a hermetically sealed container, a centrifugal force is applied to the container for a predetermined period of time to remove the absorption water, and then the water remaining in the fine aggregate is measured. In the production of mortar or concrete, when fine aggregate and primary water are added and kneaded to a powdered hydraulic substance to form a layer of the powdered hydraulic substance like a shell on the surfaces of the fine aggregate, and then secondary water is added and kneaded therewith, the water content of the fine aggregate is measured, and the proportion of primary water is determined in accordance with the measured value. </p> |
