Effects of retempering methods on the compressive strength and water permeability of concrete

Retempering of concrete is a common practice in ready-mixed concrete industries for adjustingthe workability that might adversely affect strength and durability properties in hot climates. in thispaper, the effects of retempering with melamine sulphonate naphthalene-based superplasticizer (rs),water (rw) and withhold water (rww) on the compressive strength and water permeability (wp) ofconcrete, are experimentally investigated. the results of this study indicated that the compressive strengthof concrete retempered with superplasticizer and withhold water, enhanced by increasing the delayin casting, while retempering with water, resulted in a substantial decrease. moreover, it was foundthat rs improved the water permeability of retempered concrete much more than rww, whereas rwdiversely increased this parameter. althoughrwwimposed a slight slump loss,rwwand rs are generallyproposed for the retempering of concrete, due to the suitable strength and permeability results.