Effect of SAP on the Freeze-Thaw Resistance of Concrete:Tests According to Russian Standards

摘要

Russian standardized method for an estimation of concrete frost resistance is characterized by number of cycles of freezing and thawing of specimens under standard test conditions without essential strength decrease.The frost resistance tests were carried out in accordance with GOST 10060-2012 and GOST 26134-2016.Two SAP-types were selected for study.One basic and two accelerated freezing-and-thawing test methods were used.Cubic concrete specimens which were subjected to freezing-and-thawing tests had dimensions of 100 x 100 x 100 mm.Frost-resistance factor Kfr of concretes,i.e.the ratio of strength of key samples after a given number of alternate freezing and thawing cycles to the strength of control samples,was calculated for each sample after test cycles.Control value was estimated as 0.95.For tests in salt water,Kfr was even over 1 sometimes that indicates to the available reserve of durability.In contrast,the frost resistance of some samples does not exceed 200 cycles depending on the type of SAP.A different picture was observed when testing concrete in fresh water.In this case,the frost resistance of concrete with SAP was always higher than that of the control samples.It seems that SAP reduces the strength of concrete at the age of 28 days compared to the check sample without SAP by 10...13%;in the process of testing,concrete with SAP is gaining strength,resulting in an Kfr increase.Thus,the procedure prescribed by the Russian standard should be clarified in respect to testing of concretes with SAP.