Very High-Strength Rapid-Hardening Concrete

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Title: Very High-Strength Rapid-Hardening Concrete

Author(s): V.R. Falikman, Y.V. Sorokin, and O.O. Kalashnikov

Publication: Special Publication

Volume: 228

Issue:

Appears on pages(s): 85-96

Keywords: binders; durability; hardening; interblending; intergrinding; mineral additive; physical properties; shrinkage; structure; superplasticizers; very high-strength concrete

Date: 6/1/2005

Abstract:
Mix design and technology of very high strength rapid-hardening concrete (VHSC) on the base of composite cements produced by «intergrinding» (IG) and «interblending» (IB) have been developed, and their characteristic properties have been studied. The use of mechanical-chemical activation of binders in combination with both new generation superplasticizers based on polycarboxilates and traditional ones and efficient dispersed fine mineral additives (silica fume, metakaoline, etc) allows to obtain VHSC. The strength ranged from 50-80 MPa after 24 hours and 125-140 MPa after 28 days of normal curing for self-leveling concrete mixtures (slump value 22-25 cm). Intensive concrete hardening starts after either 10 hours (IG) or 15 hours (IB) from mixing time. With the increase of hardening temperature ranging from 40 to 500C, the induction period decreases by 2-2,5 times, and strength of concrete exceeds 50 MPa in 8-10 hours after mixing (IG and IB, respectively). Volumetric water absorption of coarse aggregate concrete produced with water/binder ratio of 0.24-0.28 amounts to 2.2-3.3%, and that of fine-grained concrete, with water/binder ratio of 0.32-0.39, to 3-3.4%. Waterproofness of such concrete exceeds W20 (water tightness relating to Russian standard testing of cube specimen 150 mm in diameter and 50 mm in height under 2 MPa pressure during 6 hours), and their freezing-thawing resistance surpasses 600 cycles. Physical and mechanical properties (initial modulus of elasticity, tensile strength) are in line with the normal indices for corresponding concrete classes. Shrinking deformations of heavy weight concrete after 28 days of normal curing are 10x10-2 – 17x10-2 mm/m and those of fine-grained concrete are 29x 10-2 – 48x10-2 mm/m.