Thermal Conductivity and Strength of Vermiculite Mortar

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  • TANAKA Masami
    Department of Applied Chemistry, College of Engineering, University of Osaka Prefecture
  • HATTORI Makoto
    Department of Applied Chemistry, College of Engineering, University of Osaka Prefecture
  • TSUBAKI Takayuki
    Department of Applied Chemistry, College of Engineering, University of Osaka Prefecture
  • OKI Mamoru
    Department of Applied Chemistry, College of Engineering, University of Osaka Prefecture
  • KAMIIKE Osamu
    Department of Applied Chemistry, College of Engineering, University of Osaka Prefecture

Bibliographic Information

Other Title
  • 蛭石モルタルの熱伝導率と強度
  • ホンポウサン ヒルイシ ニ カンスル ケンキュウ 2
  • Studies on Vermiculite from Japan, (II)
  • 本邦産蛭石に関する研究 (第2報)

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Description

The properties of vermiculite mortar made of the vermiculite from Fukushima, Japan, were discussed. The following tests were carried out on the insulating mortar samples cured in damp air: thermal conductivity, bulk density, compressive strength, tensile strength and modulus of rupture. By means of hand mixing, the expanded vermiculite (temperature of firing: 600°C) and commercial portland cement were mixed until the resultant mass had a uniform color; water (mixed with the neutralized solution of vinsol resin) was then added, and the batch was mixed for about 5 min to have a unifom consistency. From the data presented, the following results were obtained: (a) The bulk density of mortar decreased as the vermiculite content increased. (b) The lower-density mortars had lower strength but higher insulation value. (c) The effect of vermiculite content on thermal conductivity was greater in the range of 1:1-4 than in the range of 1:4-9 (cement: vermiculite); the rate of decrease in the conductivity with the increase of vermiculite content changed abruptly at about 1:4 mixture. (d) The effect of vermiculite content on strength was greater in the range of 1:0-1 mixtures than in the range of 1:2-4 mixtures; the curve in the range between 1:0-1 was steeper than in the range between 1:2-4. (e) For general construction purposes except the most unusual load conditions, the best mortar can be produced with a 1:4 mixture in accordance with Scholes and his coworkers' results for N. Carolina vermiculite. The properties of this mixture (by use of 475 litres of H2O per cu. m. of vemiculite and a mixing time of 5 min) after 28 days were as follows: Thermal conductivity, λt (kcal/m hr °C), at the mean temperature of t (°C): λt=0.0605+0.000191×t; bulk density: 0.902; compressive strength: 18kg/cm2; tensile strength: 7kg/cm2; modulus of rupture: 16kg/cm2 (f) The vermiculite mortars produced with 1:8-9 mixtures had higher insulation values than the loose-filled vermiculite (expanded at firing temperature of 700°C) pressed by 20 per cent. (g) Data on thermal conductivity, bulk density and strength of vermiculite mortars having various ratios of cement: vermiculite were given. (h) Expanded “Fukushima vermiculite” would be excellent as an aggregate for light-weight mortar with high insulation value.

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