JPS6324957B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses soft perlite, such as perlite and rosinite, which has a high water absorption rate and has a large shrinkage when used as an aggregate for mortar and concrete, to create mortar with a low shrinkage rate without changing the specific gravity of the mortar or concrete. This invention relates to improvements in pearlite mortar and methods for making concrete. In the building materials and construction industry, lightweight fired minerals made by foaming and firing obsidian, pinestone, pearlite, etc., which are a type of volcanic glass, are collectively called pearlite, and the distinction is clearly defined in the Japanese Industrial Standard JIS. I haven't. However, although they are very similar in terms of chemical composition, these volcanic glasses have quite significant differences when fired and foamed products are used as aggregates for concrete, mortar, etc. Table 1 shows some of the differences.

【table】

[Table] As can be seen from Table 1, pearlite-based soft pearlite has high water absorption, so even if it is kneaded with the same water-cement ratio, fluidity will deteriorate due to water absorption and shrinkage will increase. Therefore, if pearlite-based soft pearlite mortar is made to have the same softness as obsidian-based pearlite mortar, the amount of water added will further increase, shrinkage will further increase, and drying shrinkage cracks will easily occur. The present invention uses pearlite-based soft pearlite and pinestone-based soft pearlite, which are easier to obtain than obsidian-based pearlite but have the drawbacks mentioned above, to achieve low shrinkage without changing the specific gravity of mortar or concrete. It was proposed for the purpose of manufacturing mortar and concrete. In order to achieve the above object, the inventor of the present invention, as a result of various studies, found that an artificial lightweight aggregate with a grain size of 5 mm or less obtained by firing shale or clay is mixed into the pearlite-based and pinestone-based soft pearlite. It was discovered that the desired purpose could be achieved by As a result of various tests, it was found that the flow value of mortar increases as the amount of artificial lightweight aggregate mixed into the soft pearlite increases, and this indicates that artificial lightweight aggregate has a higher water absorption rate than soft pearlite. This is thought to be due to the fact that the The amount of kneading also increases as the amount of artificial lightweight aggregate increases, and this is thought to be due to the fact that the actual area ratio of artificial lightweight aggregate is larger than that of soft pearlite and that there is a suitable amount of air entrainment. In addition, the unit weight of mortar is artificial lightweight aggregate 30o/
It does not increase much until vol is mixed in, and the specific gravity after hardening has the same tendency, and this is thought to be due to the ease with which air is entrained in the artificial lightweight aggregate. Furthermore, the compressive strength and bending strength of mortar are proportional to the specific gravity of mortar, and have almost no relation to the amount of artificial lightweight aggregate mixed. Furthermore, the shrinkage of mortar clearly decreases as the amount of artificial lightweight aggregate increases, and especially when artificial lightweight aggregate is mixed in at 30o/vol, the shrinkage is small even though there is no difference in the specific gravity of the mortar. is attracting attention. Based on the above results, the present inventors added 35o/vol of artificial lightweight aggregate with a grain size of 5 mm or less obtained by firing shale or clay to pearlite and pinestone-based soft pearlite.
This paper proposes a method for producing pearlite mortar and concrete characterized by incorporating the following: Tables 2 and 3 show the test results of the pearlite mortar and concrete, and the drawing is a chart showing the relationship between the age and free shrinkage rate of various mortars including the pearlite mortar. The mesa or mesa sand in the table is a trade name of Mesalite (Mitsui Mining and Mining Co., Ltd.), and is an artificial lightweight aggregate made by crushing and firing shale. The basic formulation adopted in the experiment is as follows. Ordinary Portland cement 50Kg Aggregate (perlite + mesalite) 4.75 Water 2.0Kg W/C 40% Also, the numbers in each graph in the chart indicate the mixing ratio (%) of soft pearlite, 100 is only soft pearlite,
0 indicates the case of only mesalite.

【table】

[Table] Note: The pearlite used is pearlite-based soft pearlite produced in Kyushu under the trade name Mitsui Pearlite (Mitsui Metal Mining Co., Ltd.).

【table】

[Table] As is clear from the above test results, shrinkage can be reduced without changing the specific gravity of the mortar even if artificial lightweight aggregate is mixed at 30o/vol. It was demonstrated that there is no difference in the strength of pearlite mortar of the same specific gravity even when vol.

[Brief explanation of the drawing]

The drawing is a chart showing the correlation between the material age and free shrinkage rate of various mortars.

Claims (1)

[Claims] 1. A method for producing pearlite mortar and concrete, which comprises mixing pearlite, pinestone-based soft pearlite with artificial lightweight aggregate of 35 o/vol or less with a grain size of 5 mm or less obtained by firing shale or clay.