Long-term compressive strength

The compressive strength vs hardening time development for concrete with NITCAL^® is generally speaking higher for very early strength due to faster setting (i.e. parallel displacement of hardening curve). The 16 h and 1 day strengths are about equal, while compressive strengths from 3 days and more are higher than the reference concrete. An example is shown after 220 days of water storage at 20°C. Note that a 2 % NITCAL^® addition to the HSC concrete with w/(c+s) = 0.45 and 4 % SF increases the 220 days compressive strength from 83 to 98 MPa. For the same concrete, the increase after 1/3, 2/3, 1, 7, 28 and 220 days was 181, 16, 6, 13, 18 and 18 %. The relative increase in compressive strength in a OPC concrete with 2 % NITCAL^® was 107, 9, -4, 0, 4 and 2 % at the same ages.

The reason for the long-term strength increase is not known at present, but it may be due to morphology/composition changes in the binder. The effect seems to be more pronounced for typical high strength cements characterised by higher belite and lower alkali content than usual.

Compressive strength at 220 days up to 2% CN dosages. The curves flattens aout above this maximum recommended dosage.

Use of NITCAL^® reduces time before concrete decks may be surface smoothed.