Abstract

Wood frame walls typically need a vapour barrier at the warm side to avoid interstitial condensation due to vapour diffusion and air leakages from the interior. A more vapour open material than the traditional vapour barriers, here called vapour retarder, could allow condensed moisture, built-in-moisture or moisture from minor leakages to dry to the interior in addition to the outward drying. The application of permeable vapour retarders in wood frame walls have been investigated in this study by the use of a hygrothermal simulation tool. A traditional wood frame wall usually has good drying possibilities to the exterior. If a vapour retarder should have an effect on the total drying, it must not be too vapour tight. The purpose of this study was to find some threshold value for the maximum vapour resistance of a vapour retarder—when a requirement is that it should have a relatively large effect of the total drying of the wall. The increased risk for condensation as the vapour resistance decreases has however not been investigated in this study. In general it was found that permeable vapour barriers have relatively little effect on the total drying of ordinary wood frame walls in a Nordic climate.

Abstract

During this quarter, significant progress has been made in the following, fronts of coal log pipeline research, development and technology transfer: 1. Design of the special 300-ton coal log compaction machine was completed, Furthermore, much progress has been made in the design of the system needed to feed coal into the coal log compaction machine, and the design of the system to remove logs automatically as soon as they are compacted. 2. Coal mixtures containing different amounts of moisture were compacted into 1.91- inch-diameter coal logs rapidly (in 6 seconds). It was found that for the Mettiki coal tested, the optimum moisture is around 8%. Under the test conditions (room temperature and 3% binders), the rapidly compacted coal logs with 8% moisture had less than 4% weight loss in 350 cycles of circulation. 3. Completed evaluation of the effectiveness of using wall lubricants to enhance coal log quality. Both calcium sterarate and MoS{sub 2} were found to be effective. 4. It was found that when the interior of a mold is not cleaned after coal log has been compacted, the coal mixture film clinging to the wall hardens in time and form a hard crust which affects the quality of the next log to be produced. But, if the second log is produced immediately after the first, no hard crust is formed and the quality of the second log, is not affected. 5. Coal logs made with the coal crushed by the Gundlach Company were found to be better than coal logs made with the coal crushed by the CPRC`s hammer mill. 7. A 320-ft-long, 6-inch-diameter coal log pipeline test facility was constructed in Rolla during this period. 8. Completed the simulation of an 8-inch-diameter, 20-mile-long coal log pipeline recirculating loop driven by a pump bypass. 9. Continued improvement was accomplished in the hydraulic model of HCP and CLP to predict pressure drop and capsule velocity for both single capsules and capsule train. Also, work has started to extend the analysis to sloped pipelines. Document type: Report

Abstract

A number of methods for measuring moisture transport properties of cementitious materials were compared in a series of experiments. Two OPC mortars with two water-binder-ratios were wet cured for six months and used to produce specimens as discs with different thicknesses and diameters."br /" The cup methods were easy to use, reliable and fairly rapid but need a stable, surrounding, CO2-free climate, however. Evaluating the fundamental potential PSI eliminates the derivation that adds to the uncertainty."br /" Steady-state moisture distribution measurements are very time-consuming and the RH-profiling is a delicate matter. Moisture contents are scattering. Sorption experiments are very easy to perform but difficult to evaluate, because of the peculiar moisture-dependency of the diffusivity Dw and the difficulties to estimate the equilibrium conditions. Initial uniform conditions are difficult to obtain for low w/c-materials, except to initial self-desiccation."br /" Sorption experiments in small steps are uncertain; the initial and final conditions are difficult to define properly. Document type: Report