SLUMP LOSS IN READY MIX CONCRETE

SLUMP LOSS IN READY MIX CONCRETE

ABSTRACT

Concrete is a popular construction material owing to its ease of fabrication, versatility and low cost. Modern construction techniques often require higher construction rates making the use of ready-mix concrete (RMC) essential. RMC is manufactured in a mechanized factory with a set mix design and then delivered to a worksite by a transit mixer. This leads to a precise mixture being delivered throughout the construction project, higher supply volumes and, in general, better quality due to the automation involved. However, a major issue facing RMC in India is the inability to retain slump during the long transportation routes and delays on site. Consequently, the concrete of several trucks are rejected or water is added disregarding the need to maintain a certain water/cement ratio. Since the loss in the slump is normally large, especially in hotter climates, the future of RMC will be restricted if this issue is not studied and remedied. The paper presents a study performed in site conditions to relate the slump of concrete to factors such as travel distance and time, ambient temperature, and concrete characteristics. The observations are based on the measurements taken while RMC was being supplied to various sites in Chennai. The results show that the slump loss in concrete can be directly related to travel time and travel distance. Conclusions are drawn regarding the critical aspects and remedial measures are suggested.