Gypsum-Dependent Effect of NaCl on Strength Enhancement of CaO-Activated Slag Binders

Sim, Sungwon; Lee, Hwan; Jeon, Dongho; Song, Haemin; Yum, Woo Sung; Kim, Do-Hoon; Suh, Jung-Il; Oh, Jae Eun

doi:10.3390/app8122515

Cited by 5 publications

(4 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the effect of sole GY was likely sufficient in promoting soil aggregation and subsequent leaching of soluble salts and Na + from the soil, possibly boosted by the increased solubility of GY (~2-3 fold) in the presence of NaCl, meaning that relatively more Ca 2+ could infiltrate the soluble form. This is in agreement with Gupta and Gupta [27], who stated that the solubility of gypsum in alkali soils is considerably higher than in normal soils, and is also increased if it is applied in conjunction with manures; and also coincides with Sim et al [28], who found that NaCl largely increases the solubility of gypsum. In addition, Ahmad et al [7] found that the increased addition of gypsum can improve the retention of Ca 2+ + Mg 2+ and enhance leaching even for loamy sand and sandy loam soils.…”

Section: Resultssupporting

confidence: 92%

Combined Application of Organic Amendments and Gypsum to Reclaim Saline–Alkali Soil

Foronda

Colinet

2022

Agriculture

View full text Add to dashboard Cite

Saline–alkali soils have high sodicity, high pH, and high levels of soluble salts, as well as carbonates. This study aimed to evaluate the effect of cattle manure and chicken manure combined with gypsum at three levels on reclaiming a saline–alkali soil, through a soil column experiment. Combined treatments were more effective than those of sole gypsum in reducing the initial exchangeable sodium percentage (ESP) below 5%. Electrical conductivity (ECe) was lowered below 1.6 dS m−1 by all treatments, except the control. The higher effectiveness of manures combined with gypsum can be explained by their synergistic effect on Na+ displacement and subsequent soil structure improvement, leading to an enhancement in the leaching process, and then the salinity/sodicity reduction. Soluble salts and Na+ were considerably reduced in all treatments at the first leaching. Soil ESP and ECe threshold values from the US Salinity Lab classification were reached by any treatment, except the control. The addition of cattle manure or chicken manure might enhance the reclamation effect of gypsum with leaching for some saline–alkali soils.

show abstract

Section: Resultssupporting

confidence: 92%

Combined Application of Organic Amendments and Gypsum to Reclaim Saline–Alkali Soil

Foronda

Colinet

2022

Agriculture

View full text Add to dashboard Cite

show abstract

“…6 however were quite the same showing a presence of: i) calcium silicate hydrate (CSH) derived from the pozzolanic reaction between the zeolite and calcium hydroxide; ii) zeolite (mordenite) and portlandite that did not fully react; iii) calcite in weak intensities, while its presence increased in samples containing CaSO 4 .2H 2 O; it was produced by the reaction of lime with CO 2 during the mixing period (carbonation of lime); and iv) ettringite in the X-ray diffractograms of samples containing CaSO 4 .2H 2 O; this ettringite was formed after hardening of the zeolitelime paste, not having noticed any swelling or cracks visible to the naked eye on the surface of the samples; its effect was therefore beneficial; indeed, its presence increased the compressive strength (Fig. 5); in a previous study, it was observed that the peak intensities of ettringite in the pastes increased with the dosage of chemical activator; at the same time, the strength increased with dosage of chemical activator; it is postulated that a significant increase in ettringite content due to activator dosage has a key influence on the observed compressive strength [31]; ettringite is known as a strength enhancing material by filling pores [23].…”

Section: Resultsmentioning

confidence: 94%

“…Adding NaCl showed either no effect or negative effect on increasing compressive strength. The most likely contributor to this effect was the decreased solubility of Ca(OH) 2 [23]. The addition of chlorides decreases the solubility of Ca(OH) 2 but increases its dissolution rate significantly.…”

Section: Resultsmentioning

confidence: 99%

Study of chemical and thermal activations of zeolite-lime blend

et al. 2021

View full text Add to dashboard Cite

The advantages of using zeolites are lower costs and better durability, but it requires longer setting time and slower strength development. Chemical and thermal methods have been developed to overcome these disadvantages and to enhance the reactivity of natural zeolite. This paper addressed through a parametric experimental pozzolanic reactivity, the strength and setting time by varying the cure temperature and the amount and type of chemical activators. To this end, several mixtures of natural zeolite-lime pastes were made with two concentrations of chemical activators including 4% and 8% of NaOH, NaCl, and CaSO 4 .2H 2 O. The produced pastes were cured at 20, 40, and 80 °C. The blends were also analyzed by X-ray diffraction and infrared spectroscopy. The results showed that curing at high temperatures accelerated the pozzolanic reactivity and increased the compressive strength. The use of CaSO 4 .2H 2 O led to an increase in the consumption of Ca(OH) 2 and strength. Adding NaCl improved slightly the compressive strength at high curing temperatures. The addition of 8% NaOH at 40 °C significantly improved reactivity and strength. Setting time was accelerated by adding chemical activators to the blends. The raw zeolite had good pozzolanic activity, but the addition of CaSO 4 .2H 2 O enhanced it.

show abstract

“…In NaCl solutions, NaCl can accelerate the dissolution of gypsum to form ettringite and increase the heat of hydration [33][34][35]. Meanwhile, NaCl can significantly increase the compressive strength of cement [36]. In this work, the hydration process, compressive strength development and linear expansion rate of CSA cement will be detailed, by illustrating the testing methods of isothermal calorimetry, X-ray diffraction, and pore structure development in the presence of different contents of CaCO 3 and gypsum under fresh water and NaCl solutions.…”

Section: Introductionmentioning

confidence: 99%

Hydration and Mechanical Properties of Calcium Sulphoaluminate Cement Containing Calcium Carbonate and Gypsum under NaCl Solutions

et al. 2022

View full text Add to dashboard Cite

Hydration characteristics and mechanical properties of calcium sulphoaluminate (CSA) cement with different contents of CaCO3 and gypsum under NaCl solutions were studied, using the testing methods of isothermal calorimetry, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), linear shrinkage, and compressive strength. Results show that CaCO3 can promote hydration and reduce the hydration heat of CSA cement. The reaction between gypsum and C4A3S(_) releases a large quantity of heat in the initial hydration period; however, over 3 days of accumulation, the level of hydration heat is reduced. Under NaCl solutions, the aluminate phase has difficulty reacting with CaCO3 to form carbonate phase but combines with chloride ions to form Friedel’s salt. On the contrary, gypsum reduces aluminate phase, and the content of Friedel’s salt is also reduced. Furthermore, CaCO3 and gypsum both increase the total porosity of the CSA cement paste under NaCl solutions during the early curing phase, and over the long-term, pore structure is also optimized. CaCO3 and gypsum reduce the linear shrinkage of CSA cement paste under NaCl solutions. Overall, the compressive strength of CSA cement is reduced with the addition of CaCO3, and the trend will be sharper with the increase in CaCO3. However, when it comes to gypsum, the compressive strength is almost the same during early curing, but in the long-term, compressive strength improves. Essentially, the compressive strength of CSA cement mortar with CaCO3 and gypsum will improve under NaCl solutions.

show abstract

Gypsum-Dependent Effect of NaCl on Strength Enhancement of CaO-Activated Slag Binders

Cited by 5 publications

References 53 publications

Combined Application of Organic Amendments and Gypsum to Reclaim Saline–Alkali Soil

Combined Application of Organic Amendments and Gypsum to Reclaim Saline–Alkali Soil

Study of chemical and thermal activations of zeolite-lime blend

Hydration and Mechanical Properties of Calcium Sulphoaluminate Cement Containing Calcium Carbonate and Gypsum under NaCl Solutions

Contact Info

Product

Resources

About