An Evaluate on Factors Affecting Workability of Concrete With constant Water-Cement Ratio

Civil Engineering

Workability can be defined as the amount of useful internal work necessary to produce full compaction. Consistency, mobility and compactability define workability. Factors such as constituent materials and environmental conditions affect workability. Research works has been done on the factors while field work continues to be starved of knowledge of the effect of time after mixing on workability. To this end, this paper presents an investigation into the effect of time on the workability of different fresh concrete mixtures handled differently. To achieve this, a slump test, compacting factor test and the modified Vebeconsistometer test was carried out under ambient conditions of 29-300C temperature, 95% relative humidity and less windy condition with 250kg, 350kg, 415kg, 545kg and 560 kg of cement and max. aggregate size of 40mm at w/c ratio of 0.46. The results (curves) show that in 1hr times the loss of workability of the un-agitated mixes was remarkable while the agitated concrete still retains an appreciable workability after 1hr but tends to lose its workability totally in 2½hrs time. It showed that the % loss of workability of un-agitated MX1, MX2, MX3, MX4 and MX5 dropped by 75%, 70%,75%, 66.7% and 68.2% after 1hr against the 43.8%, 40%, 40%, 38% and 40.9% of the agitated concretes respectively by slump test. Also, the workability tends to increase as the cement-aggregate ratio increases. The three results showed a similar trend even if no relationship existed between them.

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.