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A finite element implementation of delayed ettringite formation in concrete structures
Published in Günther Meschke, Bernhard Pichler, Jan G. Rots, Computational Modelling of Concrete Structures, 2018
M. Malbois, B. Nedjar, L. Divet, S. Lavaud, J.-M. Torrenti
Delayed ettringite formation (DEF) in concrete can have significant impact on the long term behaviour of massive concrete structures. Ettringite is a crystal that has been chraracterised in the 1970s by Moore & Taylor (1970) and its formation controls the concrete hardening, and the material workability at young age as well. Under a particular set of conditions, ettringite formation could be delayed and could lead to degradations of the material. The swelling induced by the development of delayed ettringite generates cracking and so can affect the durability of the concrete structures. The economic impact of DEF can then be potentially significant due to maintenance and repairing, or even destruction fees. It is then of major importance to build numerical tools that can simulate this expanding kinematics and its consequences on the structural serviceability.
Effect of aggregate mineralogical composition on DEF in concrete
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
M. Malbois, F. Benboudjema, J.M. Torrenti, L. Divet, S. Lavaud
Delayed ettringite formation (DEF) in concrete can have a significant impact on the long-term behavior of massive concrete structure. Ettringite is a crystal characterized in 1970 by Moore and Taylor (Moore et al., 1970) and its formation controls the concrete hardening but also the material workability at young age. Under a particular set of conditions, ettringite formation could be delayed and could lead degradations of the material. The swelling induced by the development of delayed ettringite generates internal and external cracking and so affect the durability of the concrete structures (Al Shamaa et al., 2014). Finally, the economic impact of DEF is significant due to the maintenance and repairing, or even destruction fees.
Concrete
Published in A. Bahurudeen, P.V.P. Moorthi, Testing of Construction Materials, 2020
In many cases, durability problems are generally due to an increase in volume that leads to cracking. Sulphate salts of sodium, magnesium, calcium and ammonium are harmful in nature; they cause expansion of concrete and subsequently lead to cracking. When external sulphate ions ingress into concrete, they react with calcium hydroxide and the concrete is converted into gypsum. Afterwards, this gypsum further reacts with the available C3A and forms ettringite. The ettringite is expansive in nature and leads to cracking in concrete.
A chemo-mechanical coupling model for concrete lining subjected to external sulfate attack
Published in European Journal of Environmental and Civil Engineering, 2021
Huiming Hou, Dawei Hu, Hui Zhou, Jingjing Lu, Fan Zhang
External sulfate attack on concrete usually induces expansion due to the formation of ettringite. Previous experimental results (Yu et al., 2013) showed that expansion from the formation of ettringite was associated with the calcium alumino monosulfate within calcium silicate hydrate. At first, sulfate ions penetrating into concrete are absorbed by calcium silicate hydrate, which decreases the concentration of sulfate in pore solution. When the aluminates phase in the cement is exhausted, the concentration of sulfate ions in pore solution starts to increase. Then, the sulfate concentration is supersaturated with respect to the ettringite to induce the crystal growth. The ettringite crystal grows in a confined space and exerts expansive pressure on the wall of the pore, which results in expansion and cracking. The cracks induced by the formation of ettringite will reduce the mechanical properties of concrete.
An investigation of sulfate effects on compaction characteristics and strength development of cement-treated sulfate bearing clay subgrade
Published in Road Materials and Pavement Design, 2021
A. Kampala, P. Jitsangiam, K. Pimraksa, P. Chindaprasirt
As mentioned, sulfate-induced heave is a well-known adverse effect from the cement stabilisation process when applied to sulfate rich soil conditions. Previous research demonstrated that when natural sulfate rich soil is stabilised by calcium-based materials (e.g. cement and lime), a series of active reactions occur to form an expansive sulfate-mineral-based compound, ettringite (Hunter, 1988). Ettringite is a sulfate hydrate compound containing 26 molecules of water. It can withstand a large volume increase when subjected to hydration, leading to a significant heave effect (Puppala et al., 2014; Binod et al., 2017). Furthermore, the sulfate concentration, termed the ‘threshold level of sulfate’, at which heave occurs must be considered. A range of 2,000–10,000 ppm as the threshold level of sulfate has been reported (Dermatas, 1995; Hunter, 1988; Petry & Little, 1992). Sulfate concentrations of 3,000–7,000 ppm can be treated with lime stabilisation, but some caution must be taken Harris et al. (2003).
Experimental assessment of cement hydration and leaching characteristics for waste-to-energy bottom ash mixed with concrete
Published in Journal of the Air & Waste Management Association, 2021
Jinwoo An, Boo Hyun Nam, Byoung Hooi Cho, Jongwan Eun
Moreover, ettringite (Ca6Al2(SO4)3(OH)12 · 26H2O) and gypsum (CaSO4∙2H2O) were found. The presence of ettringite in hydrated WTE BA could be explained by the balance between aluminate and sulfate in the anhydrous WTE BA (see Equation (4)). During BA-water interactions, supersaturated mixture with respect to relatively high calcium, sulfate ions, and a low concentration of aluminate ions may lead to the quick formation of large crystals of ettringite which might be considered fail set (An, Kim, and Nam 2017). The existence of gypsum in hydrated WTE BA is due to the hydration of basanite (CaSO4·½ H2O) which is known as plaster of paris in anhydrous WTE BA (see Equation (5) and Figure 4).