Effect of alkali dosage and silicate modulus on carbonation of alkali-activated slag mortars

Shi, Zhenguo; Shi, Caijun; Wan, Shu; Li, Ning; Zhang, Zuhua

doi:10.1016/j.cemconres.2018.07.005

Cited by 170 publications

(107 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By incorporating soda-lime glass, the releasing alkali still can provide or keep a high pore solution alkalinity. This observation agrees with the study of Shi, which presented that the increasing alkali dosage and silicate modulus both result in a high carbonation resistance [24]. On the other hand, a small average pore size was observed by applying the additional Si source [12], which can also provide a positive effect on the resistance to CO 2 penetration.…”

Section: The Influence Of Waste Glass Addition On the Carbonation Ressupporting

confidence: 92%

“…As well known, the selection of binder composition and activator of alkali activated concrete can cause huge influences on the concrete durability performance. It has been reported that the higher silicate modulus of activator provides a higher resistance to carbonation of alkali activated slag [24]. However, compared to the water glass, the influence of waste glass as binder in alkali activated slag-fly ash system on mechanical and durability performance by using different activators is still not clear.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Waste glass as binder in alkali activated slag–fly ash mortars

2019

View full text Add to dashboard Cite

This paper illustrates the application of waste glass powder as part of the binder in slag-fly ash systems activated by NaOH and NaOH/Na 2 CO 3 activators. To evaluate the reaction kinetics, reaction products, mechanical properties, and durability performance of glass powder modified alkali activated slag-fly ash systems, calorimetry test, X-ray diffraction, FTIR, strength test, drying shrinkage tests, and carbonation test were conducted. From the isothermal calorimeter results, glass powder shows a higher reactivity compared to fly ash but still lower than slag. The reaction products of glass power modified samples exhibit an enhancement of polymerization degree of Si-O-T, observed in FTIR. As a consequence, higher drying shrinkage exists in glass modified mortars. The mechanical performance of different samples is mostly controlled by the Ca/Si of dry mixtures and activator type. After the slag-fly ash binder system was modified by the waste glass, a significant enhancement of resistance to carbonation was identified, especially for NaOH/Na 2 CO 3 activated mortars, which show an increase of 300% on the carbonation resistance ability compared to the reference sample. The Na/(Si ? Al) ratio of dry mixtures exhibits a positive correlation with carbonation resistance.

show abstract

Section: The Influence Of Waste Glass Addition On the Carbonation Ressupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Waste glass as binder in alkali activated slag–fly ash mortars

2019

View full text Add to dashboard Cite

show abstract

“…First, the diffusive peak at 2θ = 29.07 • is associated with C-A-S-H, which is regarded as C-S-H wherein Al 3+ is located within its silicate chains, more especially at the tetrahedral bridging sites [35]. Shi et al [21] pointed out that this peak could be attributed to the generation of tobermorite like C-A-S-H phase (PDF #00-033-0306), while other studies [36][37][38] reported that the C-A-S-H phase can be detected directly owing to its semi-crystalline characteristics [36]. Second, hydrotalcite (Mg 6 Al 2 (CO 3 )(OH) 16 •4H 2 O, PDF #00-014-0191), a type of hydration product penetrating octahedral aluminum, can be identified at peaks of approximately 11.6, 23.3, 34.9, and 39.8 • .…”

Section: Xrd Analysismentioning

confidence: 99%

“…In particular, hydrotalcite has a layer structure similar to brucite, where the interlayer region contains CO 2− 3 ions and water molecules [39]. Third, the peak on the left side of the C-A-S-H phase can be attributed to the poorly crystalline C-S-H(I) (C-S-H with low Ca/Si ratio, PDF #00-034-0002) [21,40]. The poorly crystalline C-S-H(I) is more ordered than the C-S-H phase [40].…”

Section: Xrd Analysismentioning

confidence: 99%

Reinforcing Mechanism of Reduced Graphene Oxide on Flexural Strength of Geopolymers: A Synergetic Analysis of Hydration and Chemical Composition

Long

Luo

et al. 2019

Nanomaterials

View full text Add to dashboard Cite

With the development of nanotechnology, reduced graphene oxide (rGO) has been used to improve the flexural strength of geopolymers. However, the reinforcing mechanism of rGO nanosheets on the flexural strength of geopolymers remains unclear. Here, this reinforcing mechanism was investigated from the perspectives of hydration and chemical composition. The effect of the reduction degree on rGO-reinforced geopolymers was also studied using isothermal calorimetry (IC), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) tests. Results show that the hydration degree and flexural strength of geopolymers effectively increase due to rGO addition. After alkali reduction at a temperature of 60 °C, rGO nanosheets have maximum reinforcement on the flexural strength of geopolymers with an increment of 51.2%. It is attributed to the promotion of slag hydration, as well as the simultaneous formation of calcium silicate hydrate with low Ca/Si ratio (C-S-H(I)) and calcium aluminosilicate hydrate (C-A-S-H) phases due to the inhibiting effect of rGO nanosheets on Al substitution on the end-of-chain silicates of C-S-H and C-A-S-H gels. In addition, different reduction degrees have almost no effect on the chemical composition of rGO-reinforced geopolymers, while excessive reduction impairs the improving effect of rGO nanosheets on the hydration process and flexural strength of geopolymers due to significant structural defects.

show abstract

“…Many critical aspects related to durability such as carbonation, chloride penetration and attack by sulphates, are related to water absorption capacity and permeability, which in turn are influenced by multiple factors such as precursors, activators, maturity, aggregate-paste interface and test methods (especially the conditioning aspects by pre-drying that can cause the appearance of microcracks) [13,15]. Several authors have investigated the carbonation process of the AAS mortars under accelerated carbonation conditions [16][17][18][19][20], chloride penetration [21][22][23] and electrochemical behaviour of steel in alkali-activated slag mortars [24,25]. Their main conclusions established that the formation and stability of the passivating film depend on the nature and dosage of the binder, and the environmental conditions as well.…”

mentioning

confidence: 99%

Corrosion resistance of steel reinforcements embedded in alkali activated ground granulated SiMn slag mortars

Navarro

Alcocel

Sánchez

et al. 2020

Construction and Building Materials

View full text Add to dashboard Cite

The corrosion process of steel reinforcements embedded in alkali activated SiMn slag mortars was investigated. NaOH and waterglass were used as alkali activators of SiMn slag. The steel reinforced mortars were subjected to two aggressive environments: carbonation and chloride ingress. Carbonation progressed quicker for the binder activated with NaOH, decreasing the rate with the concentration. However, during the corrosion of the steels embedded in the mortars, both activators showed a similar behaviour. Mortars prepared with waterglass exhibited higher chloride migration coefficients, which decreased as the activator concentration increased. In a chloride contaminated ambient, steel embedded in mortars prepared with NaOH offered lower corrosion rate levels and it increased with the activator concentration.

show abstract

Effect of alkali dosage and silicate modulus on carbonation of alkali-activated slag mortars

Cited by 170 publications

References 40 publications

Waste glass as binder in alkali activated slag–fly ash mortars

Waste glass as binder in alkali activated slag–fly ash mortars

Reinforcing Mechanism of Reduced Graphene Oxide on Flexural Strength of Geopolymers: A Synergetic Analysis of Hydration and Chemical Composition

Corrosion resistance of steel reinforcements embedded in alkali activated ground granulated SiMn slag mortars

Contact Info

Product

Resources

About