Admixtures

Admixtures

Ready Mix Concrete is generally transported to different construction sites and delivered with the help of revolving type transits mixers. These sites are located at long distances and the concrete delivered is workable, plastic and flowable. Experience shows that slump loss takes place with certain types of cement and to prevent this superpplasticiser are used.

Ready Mix Concrete's often use admixtures formulated for special purposes lik e:

(a) Improvement of screeds, renders, mortars and concrete for increased water resistance and less risk - from aggressive materials,

( b) Integral water proofers,

 (c) Foamed - for light weight insulation. void filling and semi structural support,

(d) Water repelling for semi-dry block concrete,

(e) Microsillica for use in high performance concrete. The introduction of microsillica was observed to improve the pore solution chemistry of HPC. For higher replacement of cement by silica fumes, the concentration of both K+ and OH-ions are substantially removed. However, up to 20% replacement will not cause a drop in pH below that of saturated CaOH solution, which is approx.12.5. Even at 30%

replacement,  pH does not drop below 11.5, which is considered to be a threshold value for maintaining a good passivity of embedded steel.