Restriction of Cl^- and SO₄ ^2- Ions Transport in Alkali Activated Slag Cement Concrete in Seawater

Abstract

The relevance of alkali activated slag cement (AASC) concretes for structures operated in seawater is due to their enhanced resistance in aggressive environments. The application of high consistency fresh concretes is accompanied by negative changes in their structure with higher penetration of aggressive environments. Thus, the methods to prevent corrosion of steel reinforcement in plasticized AASC concrete are actual for investigations. It is shown, that modification of plasticized AASC concrete (consistency class S4) by the complex «alumina cement - portland cement - clinoptilolite - trisodium phosphate (Na3PO4·12H2O)» restrict the transport of aggressive Cl- and SO4 2- ions. The results of DTA, XRD, electron microscopy, microzond analysis show that mentioned complex limits transport of the mentioned aggressive ions due to their binding by AFm phases in hydration products, exchange with OH- ions in the structure of clinoptilolite, formation of hydrated products of apatite group Ca5(PO4)3(OH, Cl). This was confirmed by qualitative reaction on Cl- and SO4 2- ions in concrete structure, as well as by assessing of surface and mass loss of steel bars embedded in AASC concrete after 9 months in seawater. It was ensured the advanced crystallization with densification of microstructure, which increases corrosion resistance of artificial stone.

A Study of Innovative Alkali-Activated Binders for Soil Stabilisation in the Context of Engineering Sustainability and Circular Economy

“…GGBS is now a widely used by-product and an established commercially supplied low-cost supplementary cement material (SCM) in blended Portland cements for concrete. GGBS AAC systems for concrete have been shown to have good durability, for instance against sulphate or acid attack, and other chemically aggressive environments [44,48,49]; for ground improvement GGBS has been used in blends with calcium-based soil stabilisers to counteract effects of sulphate-induced heave [50]. There is therefore good potential for the use of GGBS in AAC if the right AAC system is chosen.…”

Mitigation of Corrosion Initiated by Cl− and SO42−-ions in Blast Furnace Cement Concrete Mixed with Sea Water

“…The AFm phases can be represented by monocarboaluminate, hemicarboaluminate, stratlingite, hydroxy-AFm and monosulfoaluminate [55]. The presence of the nitratecontaining AFm phase, as well as those containing Cl − and SO 4 2− -ions, has also been demonstrated in [56,57].…”

The Synthesis and Performance of a Novel Lignin Modified Salt-Resistant Branched High-Performance Water Reducer

“…This study is still in its early stages, and there is no relevant research yet. The available salt-resistant water reducer literature is mostly about the resistance of erosion of concrete by sulfate and chloride salts after being added [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], rather than to improve its fluidity during construction.…”