Procedia Engineering 193 ( 2017 ) 35 41
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Evaluation of Concrete Resistance to Freeze-thaw B
2. Materials and methods
The tests and analyses were carried out on two concretes with varied structure and frost durability. The concretes were produced with the following constituents: • cement CEM I 42.5 R (concrete A), CEM II/B-V 32.5 (concrete B), • natural sand 0 - 2 mm, • coarse aggregate - granite 4 - 8, 8 - 16 mm, proportion 45:55 (concrete A), - basalt 2 - 8, 8 - 16 mm proportion 40:60 (concrete B), • superplasticizer (SPL). Table 1 compiles the constituents and selected properties of concrete mixes being tested. The scope of tests included determining the compressive strength f’ cm , water absorption n w and the degree of freeze-thaw resistance on 10x10x10 cm cubes. The specimens were cured in water for seven days before being left to air dry for 21 days. Table 1. Composition and selected properties of concrete mixes. Constituent Content, kg/m 3 (%m.c)
Concrete A Concrete B Cement 360 400
Water 169 159
Sand 599 670
Coarse aggregate 1216
1117 Superplasticizer (0.58) (1.00)
W/C 0.47 0.39
gb 2346
2542 38 Jerzy Wawrzeńczyk and Agnieszka Molendowska / Procedia Engineering 193 ( 2017 ) 35 – 41
The test for the resistance to internal cracking F150 ( ǻm, ǻR) according to PN-88/B-06250 [12] was carried out through direct freezing and thawing of the cubes by an ordinary method. Prior to starting freeze-thaw cycles, six (concrete B) or five (concrete A) specimens were saturated in water for seven days. Then, they were subjected to cyclic freezing at –18±2ºC for four hours and thawing in water at +18±2ºC for four hours. The number of freeze- thaw cycles used was 150. The six reference specimens for compressive strength tests were stored at +18±2ºC during the entire period of freeze-thaw durability testing. The testing procedures involved evaluation of the specimens by visual inspection, measurements of the mass of cubes and determination of the relative decrease in strength ¨R of the specimens subjected to freezing relative to the reference specimens after the last freezing. Concrete is regarded as resistant to frost if the mass loss is 5% or less and the compressive strength decrease is 20% or less.
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