Influence of superabsorbent polymers on hydration of cement pastes with low water-to-binder ratio

Abstract

Internal curing with superabsorbent polymers (SAP) is a method for promoting hydration of cement and limiting self-desiccation, shrinkage and cracking in highperformance, and ultra high-performance concrete with low water-to-binder ratio. SAP are introduced in the dry state during mixing and form water-filled inclusions by absorbing pore solution. The absorbed solution is later released to the cement paste during hydration of the cement. In this paper, cement pastes with low water-tobinder ratios incorporating superplasticizer and different dosages of SAP and corresponding additional water were prepared. Reference cement pastes without SAP but with the same amount of water and superplasticizer were also mixed. Isothermal calorimetry was used to measure hydration heat flow. Water entrainment by means of SAP increased the degree of hydration at later hydration times in a manner similar to increasing the water-to-binder ratio. Addition of SAP also delayed the main calorimetric hydration peak compared to the reference pastes, however, in a less prominent manner than the increase in water-tocement ratio.

Sorption kinetics of superabsorbent polymers (SAPs) in fresh Portland cement-based pastes visualized and quantified by neutron radiography and correlated to the progress of cement hydration

“…Justs et al [10] as well as Reinhardt and Assmann [11] employed isothermal calorimetry in order to characterize the impact of SAP on the hydration kinetics of cement pastes. The white Portland cement paste investigated in [10] had a basic W/C of 0.25, and the addition of SAP resulted in a slight delay in and a diminished extent of hydration within the first 30 h when compared to the SAP-free reference paste.…”

“…The white Portland cement paste investigated in [10] had a basic W/C of 0.25, and the addition of SAP resulted in a slight delay in and a diminished extent of hydration within the first 30 h when compared to the SAP-free reference paste. In the long term, the degree of hydration of the SAP-containing paste conformed to that of the SAP-free paste with the same total amount of water in the sealed system.…”

“…In the long term, the degree of hydration of the SAP-containing paste conformed to that of the SAP-free paste with the same total amount of water in the sealed system. In [11] the authors utilized normal Portland Cement and Concrete Research 75 (2015) [1][2][3][4][5][6][7][8][9][10][11][12][13] cement and W/C between 0.30 and 0.50 but did not report in detail on the first few hours of cement hydration. However, they found as well that in the long run the degree of hydration depends only on the overall amount of water present in the system, irrespective of whether a part of it was entrapped in SAP at an early age.…”

Impact of different types of plasticizing admixtures on the rheological properties and hydration of blended cements

“…They can also react with hydration products of the cement. It is reported that some of them can lower the initial hydration rate by reacting with C 3 A preferentially, while others delay the hydration reaction of C 3 S component [17,18]. Among the plasticisers lignosulfonate-based works like retarders.…”

Influence of Plasticizer Amount on Rheological and Hydration Properties of CEM II Type Portland Cements

“…Blended cement is a wellknown component of concrete. CEM II blended Portland cements, in comparison with ordinary CEM I Portland cements have ecologic advantages, since the use of admixtures reduces fuel costs and CO 2 emissions into the atmosphere during Portland cement production and somewhat solve waste utilization problems [1,2,3,4]. That'-is why it is expected that the future world production of CEM II blended Portland cement will be continuously increasing.…”