Strength activity index and bulk resistivity index modifications that differentiate inert and reactive materials

Recent developments in reactivity testing of supplementary cementitious materials

“…Heat release, bound water, calcium hydroxide consumption, or strength measured in these tests have been correlated to various cement paste, mortar, or concrete properties. Reactivity increases as the value of the measured property increases and all tests are able to differentiate between inert and reactive materials [8][9][10][11][12][13][14][15][16][17][18][19][20].…”

“…Several studies have shown that bulk resistivity is able to differentiate between inert and reactive materials, as the latter show increased values of bulk resistivity, especially at later ages, higher temperatures, and greater SCM mass replacements [15,18,19]. The bulk resistivity index test involves the non-destructive measurement of bulk resistivity at 7 and 28 days, the value of which is normalized using the corresponding bulk resistivity of the control mortar (no SCM).…”

“…The bulk resistivity index test involves the non-destructive measurement of bulk resistivity at 7 and 28 days, the value of which is normalized using the corresponding bulk resistivity of the control mortar (no SCM). The test can differentiate between inert and reactive materials [15].…”

“…While correlations with later-age concrete strength have been demonstrated [20], this test is not aimed to estimate strength. Considering the numerous factors that affect strength, the variability of strength, and the issues with strength measures such as the strength activity index [15], it is the opinion of the author that reactivity tests do not have to be able to estimate strength. Mortar compressive strength and bulk resistivity index do not correlate, as resistivity is far more sensitive to reactivity than strength [15].…”

“…A discussion of these tests, including their flaws, is presented in [12] but they are not covered in this work. The scope of this work is limited to four recently developed reactivity tests -the R 3 test [13], the modified R 3 test [9], the lime strength test [14], and the bulk resistivity index test [15]. The ability of the tests to differentiate inert, pozzolanic, and latent hydraulic materials is assessed.…”