The relationship between the creep factor of concrete and hardened cement paste and the E-modulus of aggregate and evaluation of the effects of some modifiers on the creep factor of the hardened cement paste was determined. The influence of the SP on the creep factor of hardened cement paste is ambiguous: SP may increase, decrease, or not change the creep factor. The possible deviation of creep factor of hardened cement paste with the SP in certain cases can be up to 4 times. The average statistical increase in the creep factor of hardened cement paste may be 7 to 35%. The creep factor of regular concrete is equal 0.43 - 0.9 value of the creep factor of hardened cement paste. Superplasticizers may increase the creep of concrete up to 30% and in some cases - up to 3 times. Silica fume, metakaolin, white ash, including when used with the superplasticizers, may reduce the creep of concrete from 15 to 50%. An equation was suggested to calculate the E-modulus of concrete with the volume of hardened cement paste of 0.27 - 0.35 as a function of E-modulus of hardened cement paste and E-modulus of the aggregates.
Based on the analysis of the effect of various superplasticizers on the compressive and tensile strengths of concrete hardened under different conditions for three months, it was concluded that to estimate the effectiveness of superplasticizers it is not enough to compare the relative strength indicators of concrete only (f90/f28; ft = f(f); f = f(W/C)) without taking into account the effect of the superplasticizer on the water content in the concrete mix and the cement content. The assessment methodology is given. It is shown that provided the required design parameters for durability are ensured, analysis of only data on the increase in compressive and tensile strengths in time can lead to erroneous conclusions. A reliable assessment should be made taking into account the influence of the superplasticizer on the composition and cost of the concrete mix, shrinkage, creep and E-modulus of concrete.
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