Possibilities of Cement Content Reduction in Concretes With Admixture of Superplasticiser Snf

The problem of the possibility of cement saving in concretes with admixture of sodium salt of formaldehydic polycondensates of sulphonic‐napthalene acids (SNF) is presented. Executed investigations show a strong plastifying performance of this admixture as well as an elongation of setting time of Portland cements. On adding 1,5 % of admixture it is possible to obtain a substantial saving of cement with simultaneous reduction of water amount (constant W/C ratio), without a change of consistency of concrete mixture apparent density, compressive strength, absorption and water penetration of concrete. For the estimation of economic effectiveness of superplasticiser SNF it is proposed to introduce an index of cement saving Sc and an index of cement utilisation in concretes Iec .