Shrinkage of Various Types of Portland Clinker-Based Cements With Respect to Their Hydration Degree

Abstract

The volume changes of cement based composites are significantly exhibited in the hardening process. Initial phases of the hardening are complemented by the expansion due to the heat evolution that is subsequently alternated by the shrinkage. Both could cause a crack initiation. It is evident that ultimate volume changes of cement based composites are a complex process, because the final shrinkage is determined by the binder used, exposition and also by the previous history. The paper focuses on the evaluation of the main types of cements based on the Portland clinker by using a conventional procedure for the determination of the shrinkage on the standard cements mortars. These mortars were exposed to drying after 1 and 3 days of curing, related to the actual degree of hydration, which was estimated on the basis of compressive strength development. The hydration process was additionally monitored using thermogravimetry on the accompanying paste specimens during one year. The performed experimental program confirmed the essential sense of the curing regime especially for blended cement systems, which exhibited very low values of the hydration degree at applied curing intervals. Despite the slightly higher values of shrinkage of blended cements, the obtained results signalize the crucial effect of prolonged curing for these types of binders. The conclusion highlighted the necessity of taking into consideration the hydration degree during cement testing by using the conventional contact method. Otherwise, the simple interpretation leads to an overestimation of the less-suitable material solution.

Influence of Surface Treatment of Fresh Concrete on its Resistance to Drying Shrinkage

“…The loss of the moisture has direct influence on the values of the shrinkage, respectively to drying shrinkage, because ultimate level of shrinkage is affected also by the mineralogy and properties of used cements (Davidova and Reiterman, 2020;Deboucha et al, 2017;Nili and Ehsani, 2015). The dimensions of the ring are rather small, which enables quicker testing of mortar susceptibility to cracking.…”

Assessment of Rational Design of Self-Compacting Concrete Incorporating Fly Ash and Limestone Powder in Terms of Long-Term Durability

“…The pozzolanic activity of FA can be enhanced using some chemical admixtures (NaOH, Na 2 SO4 and Na 2 CO 3 ) [ 23 ]. The positive influence of FA on durability was declared by a number of studies [ 24 , 25 ] and practical experiences [ 26 ], because of the slower reaction kinetics of FA hydration contributing to the gradual densifying. However, global interest is focused on its influence in presence with other SCM [ 27 , 28 ], especially with limestone filler [ 29 , 30 ].…”