First crack strength

Mix details Fiber content and treatment First crack strength, Of (psi) First crack toughness, T (Ib-in.) I5 Co ho 30 Toughness index, Tjci (lb-in.)2 Equivalent flexural strength, CTb (psi) "... 

ASTM C 1018. 2002. Standard Test Method for Flexural Toughness and First-Crack Strength of Fibre Reinforced Concrete. American Society for Testing and Materials, Annual Book of ASTM Standards. 

Johnston, C. D., Gray, R. J. (1986) Flexural toughness and first crack strength of fibre reinforced concrete, using ASTM Standard C1018, in Proc. RILEM Symp. Developments in Fibre Reinforced Cement and Concrete, R. N. Swamy, R. L.Wagstaffee, D. R,Oakley eds, Sheffield paper 5.1. 

ASTMC 1018-97 (1997) Test method for flexural toughness and first-crack strength of fiber-reinforced concrete (using beam with third-point loading). 

The aim of the experiments was to investigate a simple test which could supply adequate information about the behaviour of SFRC. The basic concept was to use the ASTM approach of describing the matrix properties through the first crack strength (at LOP) and the fibre reinforcing effect through a toughness index. In addition crack distribution should be evaluated. 

S. Mindess, L. Chen and D.R. Morgan, Determination of the first-crack strength and flexural toughness of steel fibre reinforced concrete , J. Advanced Cement Based Materials. 1,1994, 201-208. 

Strength criterion to enable strain hardening with a modest amount of fibres. Eqs 12.9-12.12 outline the quantification of this criterion, which requires that the first crack strength will not exceed the maximum bridging stress of the crack in the characteristic stress-crack opening function. 

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