オレフィン系合成高分子 (EB) による粘質土壌の物理性の改良について

抄録

With the modernization of agriculture, the improvement of heavy clayey soils with high water content have become an important problem to be solved. Now, however, it is considered that these heavy clayey soils which give inferior conditions to eathworks, cultivation and plant growth are hard to be improved especially in reclaimed lands.
From this point of view, the author and his co-workers have investigated the improvement of these soils by the use of a soil conditioner.
This is a summary of the investigation for improvement of the physical properties of these soils by the use of a new synthetic soil conditioner (EB).
The synthetic soil conditioner (EB) used has the following two characteristics;(1) a cation polyelectrolyte and (2) a water-soluble high polymer.
The materials used were (1) Kamigamo Clay (from the Forestry Experimental Station of Kyoto University) (2) Reclaimed Land Clay (from Hachiro-gata Reclaimed Land, Ak: ta Prefecture).
The experimental results are as follows;
(1) The flocculation of clay particles by a caion polyelectrolyte may probably be due to an ionic bond between the negative charge of the clay surface and the cation polymer, and it can form a water stable aggregation with the cross-link format: on (bridge action).
(2) The interaction between clay particles and EB are dependent not only on the rate of EB to the weight of dry clay, but also on the rate of dilution of EB added. Therefore the sedimentation volume of the samples is dependent on the rate of EB to clay, and also on the rate of dilution of EB added.
(3) Owing to forming a water stable aggregation, the permeability of the samples are increased more than 100 fold, and the water holding capacity is increased.
(4) The air drying treatment after adding EB promotes aggregation, which may be expected after addition of even a little amount of EB.
(5) The flocculation of clay particles causes a change in the rheological properties of soils, i. e. both the liquid limit and the plastic limit are remarkably increased.
(6) The maximum dry density by compaction test may be decreased due to the addition of EB, but the optimum water content is a higher value than the untreated soils. And the unconfined compression strength has a maximum peak at a higher water content. These results are extremely important to earthworks concerning these heavy clayey soils with high water content, especially at reclaimed land.
(7) The sample with polymer added may be strong against slaking. And these samples nre remcrkably stable againt water erosion.
(8) The optimum quant: ty of EB added is in the range of 8-10%, but this value can vary according to soil samples and initial mo: sture conditions. In the case of air drying treatment, it was found that adding EB of 3-4% of the soil by weight was very effective to improve soils.
Thus, from the results of these experimental investigations, it can be concluded that this new synthetic soil conditioner, EB, is one of the best soil conditioners for improvement of heavy clayey soils with high water content.
And we hope that used EB can contribute to an epock-making change in the improvement and the conservation of these soils.