| dc.description.abstract | Concerns of poor construction practices and rapid execution of construction works cited as prime causes for collapse of structures in construction projects, which are still evident in Uganda coupled with many noticeable signs of early deterioration on buildings like; wall capillary water rises, floor dampness, cracks, associated with poor curing and the predominance of Portland Pozzolana Cement in Uganda triggered this study given the pivotal role of curing in both literature and good practice. In this experimental study, influence of three water curing methods (Burlap Covering, Sprinkling and Ponding), on 2 common normal concrete grades 25 and 30, produced using Cement IV and Cement IIB, which are predominant in the local construction sector were evaluated for Strength Development and Sorptivity relative to the same Cement I normal concrete grades. A total of 270 concrete cubes and 180 concrete discs samples discretized for 1, 3, 7, 14, and 28 day curing ages were molded and assessed during the study; each of these samples were appropriately treated prior to subjection to the two experimental procedures for Strength Development and Sorptivity evaluation guided by respective codes of practice.
The findings indicate that, curing has very strong influence on both compressive Strength Development and its Sorptivity, the extent of which varried with the curing methods. Incremental growth in Strength Development for all the cement types studied was observed with Ordinary Portland Cement having superior performance of up to 114% Strength Development for the 28- day ponded samples in C30 and a respective 34% Strength Development for its 1-Day aged samples, the least Strength Development of 13% was recorded by 1-day old Cement IV grade 25 samples. Both Initial and Secondary Sorptivity values decreased with increase in curing period for all the curing methods and cement types, with the 28-day ponded Cement IV grade 25 having the least initial sorptivity value of 0.006148 m/s0.5 while the 1 day sprinkled sample of the same cement and strength category having the highest initial sorptivity of 0.0518m/s0.5. The cumulative volumes of water absorbed used for the Sorptivity value computations remained relatively constant on the last 4 experimental days, that is, the 5th to 8th days resulting into very insignificant secondary sorptivity values, an observation attributed to the saturation of capillary pore spaces in the concrete matrix during the initial exposure period.
Weak negative relationship exists between Strength Development and Sorptivity, with all the computed Pearson’s correlation coefficient r-values ranging between -0.27 and -0.01 for all the cements and grades, thus not significant to predict the values of either variable interms of the other. | en_US |
