The prediction of moisture transfer within concrete is necessary in order to evaluate its durability, because moisture transfer is related to shrinkage cracks and the transfer of chloride ions. Moisture transfer within concrete during drying has been analysed by many investigators using a non-linear diffusion equation. In the present paper, a comprehensive analytical procedure using a diffusion equation is established by comparing calculated results with experimental data for a wide range of concrete mix proportions. These experiments involved observing the effect of one-face drying and six-face drying on the water content profiles and mass decreases in prismatic specimens. The values of the coefficient required for the analysis are reported for a wide range of water/cement ratios, and the effect of these coefficients on the calculated results is discussed.

No abstract

We used a Pilodyn for estimating basic density in the green condition for the purpose of classifying logs of Cryptomeria japonica D. Don based on their density. The relationships between Pilodyn penetration depth in the radial direction Pr and basic density of blocks with pin penetration were examined in a wide basic density range of hardwoods and softwoods 199 779 kg/m 3 , and C. japonica 221 474 kg/m 3 . There were signifi cant negative correlations in hardwoods r 0.92, P 0.001 , softwoods r 0.86, P 0.001 and C. japonica r 0.82, P 0.001 . Thus, the basic density of the block could be estimated based on the penetration depth. Curvilinear regressions gave the best fi ts in hardwoods, softwoods and C. japonica and the estimated basic densities from the curvilinear regressions for the same Pr were close to each other. In C. japonica, Pr varied between sample groups with similar basic densities, and Pr was smaller in the group with greater earlywood width in spite of similar densities. We examined the applicability of the Pilodyn to estimating average density of C. japonica green logs. There was a signifi cant correlation between Pr and the disk-averaged basic density r 0.84, P 0.001 . The 95% confi dence limits of the disk-averaged basic density estimated from Pr were 47 kg/m 3 when Pr was measured once, in each of two directions. The variations of the disk-averaged basic density within logs were smaller than the confi dence limits except for those at the ground level. It was concluded that the Pilodyn could be used for classifying logs of C. japonica based on their density, although it is necessary to consider that the density variation from pith to bark could be varied by tree age, inherited characters and growth conditions.

No abstract

No abstract