2020 Volume 74 Issue 1 Pages 412-419
The non-volatile matter of 35％ or higher as a total solid content of emulsions for cement modifier is required by JIS A 6203 （Polymer dispersions and redispersible polymer powders for cement modifiers）. On the other hand, the emulsions with low-solid content of less than 35％ have been used in the construction fields because such emulsions do not required the additional mixing water for preparing polymer cement mortars. However, such emulsions with low-solid content is not authorized by JIS A 6203 because of the lesser information about the storage stability of the emulsions. This paper deals with the properties of the acrylic-type emulsions with low-solid content stored at different temperatures and the strength properties of the polymer cement mortars using them for evaluating the storage stability of the acrylic-type emulsions with low-solid content. The emulsions with the total solid contents of 22.5 and 45.0％ are stored at 5, 20, and 40℃ for 28, 56 and 84d, and subjected to the test for physical properties. The polymer cement mortar specimens with the cement sand ratio of 1：3 and polymer-cement ratios of 0, 3, 5 and 10％ are prepared by using the 84d-stored emulsions. The specimens are cured at 2d-moist, 5d-underwater and 21d-dry conditions, and subjected to the tests for flexural, compressive and adhesive strengths. As results, regardless of the storage temperature and polymer-cement ratio, the physical properties of the acrylic-type emulsions with the total solid contents of 22.5％ and the strength properties of the polymer cement mortars using ones give almost the same properties of the acrylic-type emulsions with total solid contents of 45％ and the mortars using ones. The flexural, compressive and adhesive strengths of the polymer cement mortars using the acrylic-type emulsions with the total solids of 22.5％ with polymer-cement ratio of 10％ give grater values than the standardized strength values of JIS A 6203.
