Evaluation of Super-Water Reducers for Highway Applications

摘要

'Super-Water Reducers' were characterized and evaluated as potential candidates for production of low water-to-cement ratio, high strength concretes for highway construction applications. Admixtures were composed of either naphthalene or melamine sulfonated formaldehyde condensates. A mini-slump procedure was used to assess dosage requirements and behavior of workability with time of cement pastes. Required dosage was found to be a function of tricalcium aluminate content, alkali content, and fineness of the cement. Concretes exhibited high rates of slump loss when super-water reducers were used. Slump loss was found to be a function of cement and admixture composition, dosage of admixture, time of addition of admixture, concrete paste contents, and temperature. Based on results of this testing, the use of these admixtures in central mix paving operations is not recommended. Incorporation of super-water reducers into conventional concretes was found to alter the entrained air system. Use of higher initial plastic air contents of 7-8 percent is recommended. The most promising area of application of these products appears to be in production of dense, high cement content concrete using mobile concrete mixer/transporters.