high early concrete mix is one of the types of high performance concretes which attains a higher compressive strength at an early age than conventional concrete. This type of concrete is used mainly in fast-track paving, precast elements and construction works in colder areas where it facilitates the rapid pace of construction.
How does high early concrete mix develop its higher strength?
Several factors determine the age at which concrete develops its high strength, including the type of cement, the water/cement ratio and the presence or absence of accelerators. In addition to those, special concreting practices and admixtures can also increase the early strength of concrete.
The most common methods for developing high-early concrete mixes are the use of relatively high cement and accelerator contents to accelerate the rate of strength development. These measures have been successful in some applications, but may have detrimental effects on the long-term performance of concrete.
Reducing the hydration of cement in the newly mixed concrete by reducing the water to cement material (w/cm) ratios, ranging from 0.20 to 0.45 by mass has been demonstrated to produce high-early-strength concrete. This process can be accelerated by adding an aditivishment such as a calcium chloride accelerator.
Effect of replacing cement with fly ash and Adding metallic fibres on early strength gain
A study was conducted to investigate the effect of a non-chloride hardening accelerator, added in different proportions, on the tensile strengths of cubes tested at 7 and 28 days for a water binder ratio of 0.45 as shown in Figure 3. Conclusion: The results showed that concrete mixes with non-chloride hardening accelerator showed higher tensile strength values than reference mixes.