First-principles investigations of arsenate doping into the ettringite lattice

Hazardous wastes are commonly immobilized using cementitious materials. Ettringite (Ca₆Al₂(OH)₁₂(SO₄)₃∙26H₂O) is one of the main components of hydrated cement and is known to stabilize anionic species. Thus, it is a promising material for the stabilization of arsenate (As(V))...

Early age hydration of model slag cement: Interaction among C₃S, gypsum and slag with different Al₂O₃ contents

A deeper insight into SO₃/Al₂O₃ ratio including the contribution of alumina in slag at early age is required to ensure a properly sulfated slag cement. In this paper, to investigate the effect of gypsum and alumina of slag, emphasis was laid on the hydration characteristics of C₃S-gypsum-slag system...

Effect of chloride salts on sulfoaluminate cement hydration

The effect of including 5 % chloride salts (NaCl and CaCl2) on calcium sulfoaluminate cement hydration was studied. The rate of heat release, setting times and mechanical strength were determined in 2 d, 28 d and 90 d cement pastes. The hydration products formed at those ages were identified with XRD and SEM. Hydration reactions were hastened...

Pore solution chemistry of expansive heat cured cementitious systems

Heat cured cement mortars may result in linear expansion due to later age ettringite precipitation, popularly termed as delayed ettringite formation (DEF). However, later age ettringite precipitation may not result in expansion always. To differentiate the expansive and non-expansive nature of heat-cured cementitious systems, in this research...

Strength development and hydration progress of a cement-based solidifying agent used in cementtreated soil containing volcanic mineral components

This study investigates the relationship between the strength development and hydration progress of cement-based solidifying agents (CBSAs) in cement-treated soil with volcanic mineral components. A CBSA is a cement-based material used as a soil stabilizer. It is known that the strength development of cement-based materials is inhibited by...

Basic properties of cement paste mixed with calcium hydroxide-ettringite composite type expansive additive

In this study, we targeted a calcium hydroxide and ettringite composite-type expansive additive (EA) and obtained the basic characteristics of the EA mixed cement paste in order to create a method for calculating volume expansion based on the hydration reaction of the PCEA system. Expansion strain, setting time, and compressive strength were...

Basic properties of cement paste mixed with calcium hydroxide-ettringite composite type expansive additive

In this study, we targeted a calcium hydroxide and ettringite composite-type expansive additive (EA) and obtained the basic characteristics of the EA mixed cement paste in order to create a method for calculating volume expansion based on the hydration reaction of the PCEA system. Expansion strain, setting time, and compressive strength were...

Sulfate precipitation treatment for NOM-rich ion exchange brines

Ion exchange (IEX) resins can remove natural organic matter (NOM) from drinking water sources. However, the IEX system produces a waste brine rich of sodium, chloride, NOM and sulfate. The treatment of the waste brine aims to recover a clean solution rich of sodium chloride, that can be reused to regenerate IEX resin. Previous research showed...

Surface crack self healing behaviour of mortars with expansive additives (abstract)