Ba₂SiO₄セメント硬化体の耐硫酸性

抄録

The test prisms of 10×10×40mm were made of Ba₂SiO₄ mortars with a Ba₂SiO₄-sand ratio of 1:2 and a water-Ba₂SiO₄ ratio of 0.65. After humid air curing for 3 days, the test prisms were immersed in 0.1, 0.3, 1.0, 3.0, 10.0 and 30.0wt. % H₂SO₄ solution for 1 to 28 days. The sulfuric acid resistance was estimated from the compressive strength and the change in weight of immersed test prisms. The reaction products were identified by X-ray diffraction method and microscopic observation.
The results obtained were summarized as follows.
(1) When the test prisms were immersed in 0.1 and 0.3% H₂SO₄ solutions for 28 days, their compressive strengths fell respectively to 13 and 12kg/cm² from 313kg/cm² and their weight decreased. On the other hand, when the test prisms were immersed in 3.0 and 10.0% H₂SO₄ solutions for 28 days, their compressive strengths became 148 and 84kg/cm² respectively and their weight increased.
(2) The above mentioned high resistance against 3.0 and 10.0% H₂SO₄ solution resulted mainly from the compact textures of BaSO₄ and amorphous silica, which were formed by the reaction between Ba₂SiO₄ and H₂SO₄.
(3) The low resistance against 0.1 and 0.3% H₂SO₄ solutions was mainly due to the porous textures of BaSO₄ and amorphous silica. These porous textures were formed by the reaction of H₂SO₄ and barium silicate hydrate which were produced from Ba₂SiO₄ during the period of immersion. They were also formed by precipitation of BaSO₄ on the outer parts of test prisms.