Strength of the concrete modified with MasterGlenium SKY 608 polycarboxylate admixture of rigid pavement on different types of cement was investigated. For concrete mixtures preparation, two types of cement were used: ПЦ II/А-Ш-500 (CEM II/A-S 42.5) and pozzolanic cement ПЦЦ IV/А-500 Р (CEM IV/A(P) 42.5 R-SR). Amount of modifier ranged from 0.8 to 1.4% by mass of cement. Slump of all concrete mixtures was 6-7 cm. The aim of the research was to select a rational amount of the polycarboxylate admixture, taking into account early and grade compressive strength of concretes for rigid pavement repair. It was found that the MasterGlenium SKY 608 admixture significantly reduces W/C of mixtures in comparison with unmodified three-component concretes while maintaining the flowability of the mixture. The biggest reduction in the W/C of concrete mixtures is achieved with the addition of the polycarboxylate type admixture in an amount of 1.2% by weight of cement. In this case, the W/C of concrete mixtures based on pozzolanic Portland cement ПЦЦ IV/А-500 Р

Abstract. The effect of partial cement replacement with high-activity metakaolin on the strength, frost resistance, shrinkage and abrasion resistance of concrete modified with polycarboxylate admixture MasterGlenium SKY 608. Portland cement CEM II/A-S 42.5 (ПЦ II/А-Ш-500) with partial metakaolin replacement 15 kg (3.75 %) and 30 kg (7.5 %) was used for concrete preparation. The amount of superplasticizer in all studied compositions was 1.2% of cement weight. Slump of concrete mixtures was 6…7 cm. It was found that with increasing amount of metakaolin W/C ratio of mixtures increased slightly. The early compressive and flexural strength (at the age of 2 days) of the composition without metakaolin was higher than similar indicators with partial cement replacement with the active mineral admixture. It is worth noting the positive effect of increasing the metakaolin amount on early strength, because the composition with 30 kg metakaolin had strengths higher at 2 days of in difference to the composition with 15 kg metakaolin. It is necessary to note high frost resistance of all obtained concretes. Its grade of frost resistance reached F200 (evaluated according to the method for road concrete), which is equivalent to the grade F600 for structural concrete. Abrasion resistance was in the low range (0.30-0.31 g/cm2), total shrinkage does not exceed 0.28 mm/m, which in combination with high frost resistance has a positive effect on the durability of concrete mixtures for rigid pavements repair.