THE AIR REQUIREMENT OF FROST RESISTANT CONCRETE
THE AIR REQUIREMENT OF FROST RESISTANT CONCRETE
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发表时间：
1950
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影响因子：
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通讯作者：
T. Powers;T. Willis
中科院分区：
文献类型：
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作者：
T. Powers;T. Willis
根据混凝土霜冻作用的液压假说，夹带空气的有效性取决于空隙间距。通过分析发现理论最大允许间距是焊膏特性、焊膏饱和度和冷却速率的函数。应用六种不同焊膏的实验数据，以每小时 20°F 的速度冷却，理论计算得出的间距系数范围为 0.01 至 0.026 英寸。或更多，取决于焊膏特性和空隙尺寸。硬化混凝土中的空隙的间距因子以及空气的总体积可以根据线性横向法获得的数据来计算。本文给出了必要的数学关系。某些抗冻混凝土的实际最大间距系数估计约为 0.01 英寸，这一结果被认为与理论计算得出的结果非常吻合。空气需求量是满足间距要求的量。一般来说，给定冷却速率所需的空气量取决于焊膏含量、空隙的具体表面以及最大允许间距系数。当空隙间距过大而无法防止饱和焊膏失效时，在水分含量低于饱和度时也会发生失效。在一定限度内，膏体越稠密，失效时的饱和度就越低。 /作者/
ACCORDING TO THE HYDRAULIC-PRESSURE HYPOTHESIS OF FROST ACTION ON CONCRETE, THE EFFECTIVENESS OF ENTRAINED AIR DEPENDS ON VOID SPACING. THE THEORETICAL MAXIMUM PERMISSIBLE SPACING IS FOUND ANALYTICALLY TO BE A FUNCTION OF PASTE PROPERTIES, DEGREE OF SATURATION OF THE PASTE, AND RATE OF COOLING. APPLIED TO EXPERIMENTAL DATA FROM SIX DIFFERENT PASTES, COOLED AT 20 F. PER HOUR, THE THEORETICAL CALCULATIONS GAVE SPACING FACTORS RANGING FROM 0.01 TO 0.026 IN. OR MORE, DEPENDING ON PASTE CHARACTERISTICS AND VOID SIZE. A SPACING FACTOR FOR THE VOIDS IN HARDENED CONCRETE, AS WELL AS THE TOTAL VOLUME OF AIR, CAN BE CALCULATED FROM DATA OBTAINABLE BY THE LINEAR TRANSVERSE METHOD. THE NECESSARY MATHEMATICAL RELATIONSHIPS ARE GIVEN IN THIS PAPER. THE ACTUAL MAXIMUM SPACING FACTOR FOR CERTAIN FROST RESISTANT CONCRETES WAS ESTIMATED TO BE ABOUT 0.01 IN., A RESULT CONSIDERED TO BE IN EXCELLENT AGREEMENT WITH THAT OBTAINED FROM THE THEORETICAL CALCULATIONS. THE AIR REQUIREMENT IS THAT AMOUNT THAT MEETS THE SPACING REQUIREMENTS. IN GENERAL, THE AIR REQUIREMENT FOR A GIVEN RATE OF COOLING DEPENDS UPON THE PASTE CONTENT, THE SPECIFIC SURFACE OF THE VOIDS, AND THE MAXIMUM PERMISSIBLE SPACING FACTOR. WHEN VOIDS ARE TOO WIDELY SPACED TO PREVENT FAILURE OF SATURATED PASTE, FAILURE WILL ALSO OCCUR AT MOISTURE CONTENTS BELOW SATURATION. WITHIN LIMITS, THE DENSER THE PASTE THE LOWER THE DEGREE OF SATURATION AT FAILURE. /AUTHOR/