The amount of water used in mixing concrete to make it fluid enough for placement usually is well in excess of the cement compounds’ hydration requirements. This extra water, often referred to as “water of convenience,” evaporates over time leaving voids or pores in the concrete that contribute to drying shrinkage cracking. By using a rapid hardening concrete admixture, most of the water used in the mix is used up in the hydration process, resulting in dense concrete with much lower levels of drying shrinkage cracks.
Fast setting concrete allows formwork to be stripped and re-used, cutting construction and curing times. It also enables contractors to meet tight schedules and deadlines. In fact, the value of time saved can be greater than the cost of the premium for rapid-hardening hydraulic cement.
rapid hardening concrete admixture increases the strength of concrete to a level that is similar to normal Portland Cement (OPC) concrete after only three days of curing. It is ideal for use in applications such as road and rail renovation where a high early strength is required.
It can be added to the concrete at batching or to a mixed batch on site, in either slurry or dry form, depending on the equipment being used. It can be combined with a retarder to extend the workable time or a set accelerator for even faster results. It is compatible with most mineral admixtures, including natural pozzolans and fly ash and silica fume, as well as with conventional portland cements. It is also effective in marine and deicing salt environments, protecting reinforcement from chloride-induced corrosion.