Mechanical Strength of Trass as Supplementary Cementing Material

The suitability of trass in Indonesia as a supplementary cementing material was investigated and studied. Mechanical properties of pozzolanic–lime obtained from trass reacting with lime were evaluated according to procedure ASTM C-593. Compressive strength of mortar was measured at ages of 2, 3, 7, 14 and 28 days. In addition to the compressive strength, pozzolanic reaction of trass and lime was also evaluated by Thermal Activity Measurement (TAM) Air Calorimeter. Results showed that increasing of fineness until 9000 Blaine resulted strength of 60 kg cm–2 at age of 2 days. Further increase in compressive strength of 90 kg cm–2 at the age of 2 days was obtained by the addition of 2.71 wt. % Na2SO4. Results of TAM Air Calorimeter of pozzolanic reaction showed that heat released followed a linear and exponential correlations for increasing fineness and addition of Na2SO4, respectively.