Slump Retention Research Articles

Ecofriendly Concrete with High Volume of Lagoon Ash

A high volume of lagoon (pond) ash produced as a waste from the thermal power station in India is used as a replacement of cement (55–65%) in concrete. The test specimens were prepared with and without superplasticizer. No air-entraining agent was used. At constant slump, the required amount of water reduced with the addition of lagoon ash. The slump retention property of the concrete with superplasticizer and lagoon ash was studied. A substantial increase in the setting time (initial and final) was observed. The development of early strength (1,3 days) was low. The 28-day strength for concrete with lagoon ash, without the addition of superlasticizer, was in the range of 16.4–24.3 MPa for 65 and 55% cement replacement, respectively. The change in strength of concrete was observed over a period of 365 days in the present study. The investigation shows a scope to utilize lagoon ash in concrete. An attempt was made to use lagoon ash in the concrete mix, referred as dry lean concrete, used as base course for ...

Influence of dispersant structure and mixing speed on concrete slump retention

The relationship between rate of dispersant depletion from the aqueous phase and concrete slump retention was investigated by varying polycarboxylate dispersant structure and mixing speed. The influence of dispersant structure on the rate of slump loss was determined by testing two polycarboxylate-polyether dispersants that differed in charge density. The influence of mixing rate on slump loss was determined by changing mixer rotation speed. The rate of dispersant depletion was influenced by dispersant structure and mixing speed. A higher rate of dispersant depletion was observed at higher mixing speed and with a polymer of higher charge density. In comparing the different mixing procedures, a good correlation was found between slump value and the number of drum revolutions, while a poor correlation was found between slump value and time. Concrete slump retention was influenced by the rate of dispersant depletion and the rate of dispersant depletion was influenced by dispersant structure and mixing speed.

95/06006 Slump retention of fly ash concrete with and without chemical admixture

95/06006 Slump retention of fly ash concrete with and without chemical admixture