Abstract

Previous studies have shown that the obsidian pozzolana of the Sabaloka area processes a high pozzolana index. Therefore, it was chosen to study the effect of its curing condition and use of additives on the compressive strength of lime pozzolana mortar. The investigation revealed that the strength of pozzolana mortar is affected positively or increases with the curing condition (humidity, time, and temperature); also the strength increases with the addition of torona (2, 5 and 10%) which the higher the strength reveals the higher the percentage of additives (10%). This is probably due to carbonation. The indirect curing gave higher strength than that of direct curing when we compared the carry fine fractions, respectively for indirect and direct curing. Regarding carbonation, the possibility of absorption of CO2 from the atmosphere is greatly increased by the indirectly cured lime/pozzolana cubes because atmospheric CO2 rates with lime to produce caco3 which is accompanied by a gain in strength. The strength of pozzolana/lime mortar affected by the earing time. Long time of curing (120 days) gave the strength compared to the early strength 7 and 14 days; the same behaviour also for less finer (90 to 63 μ)  gave 16 N/cm2 for 120 days as compared to only 11 N/cm2 for 7 days.

Key words: Pozzolana, curing condition, humidity, time, tempreture, torona, strength, carbonation.