Influence of sodium aluminate on cement hydration and concrete properties

Wang, Kejin; Shi, Jiyao; Wang, Yue

doi:10.1016/j.conbuildmat.2014.04.089

Cited by 85 publications

(26 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, increasing shrinkage with alkali content was expected due to chemical shrinkage affects, as addition of alkali introduced more OHin the matrix; thereby accelerating cementitious reactions, and in particular those associated with C 3 A and C 3 S [27,34]. This potential effect is particularly significant for the first 10 hours as shown in Figure 4.…”

Section: Resultsmentioning

confidence: 99%

Investigation of effects of Portland cement fineness and alkali content on concrete plastic shrinkage cracking

Yang

Zhong

Magee

et al. 2017

Construction and Building Materials

View full text Add to dashboard Cite

From a material viewpoint, modern concrete's frequent propensity to plastic shrinkage cracking can be attributable to a combination of low water-binder ratio use and ever-changing properties of binding materials. To obtain a better understanding of this phenomenon, this paper explores the effects of cement fineness and alkali content on the plastic shrinkage cracking of concrete manufactured with two water-binder ratios. Results indicate that within the range 275-385m 2 /kg, cement specific surface area is approximately directly and inversely proportional to hydration rate and evaporation rate respectively; a trend generally leading to higher plastic shrinkage and resulting areas of plastic cracking. Similar effects were observed for alkali contents which resulted in increased levels of plastic shrinkage. Furthermore, while decreasing crack tendency was noted as alkali content increased from 0.4 to 0.8% by mass of cement, further increases in alkali content caused significant decreases of compressive strength and slump; thereby lowering overall concrete performance. It is also found that plastic shrinkage cracking is closely related to the kinetics of plastic shrinkage. In summary, the experimental programme confirmed that cement with relatively low surface area (less than 340 m 2 /kg) and low alkali content (less than 0.8%) is preferred for modern concretes with minimal plastic cracking problems.

show abstract

Section: Resultsmentioning

confidence: 99%

Investigation of effects of Portland cement fineness and alkali content on concrete plastic shrinkage cracking

Yang

Zhong

Magee

et al. 2017

Construction and Building Materials

View full text Add to dashboard Cite

show abstract

“…However, it also shows that the total hydration heat and the hydration degree increased at the beginning of the hydration process and decreased in the later age as the dosage of AS enhanced. This depressed hydration ability may due to the increased quantity of AFt, which acts as a barrier on the surface of cement particles during the hydration of calcium silicate (Han et al 2014).…”

Section: Setting Timementioning

confidence: 99%

“…Accelerators can be divided into alkaline accelerators and alkali-free accelerators. Although alkaline accelerators have the advantage of more general range of application and smaller cost (Salvador et al 2016), it can impair later age compressive strength (Han et al 2014). Moreover, it could pose a threat to workers' health.…”

Section: Introductionmentioning

confidence: 99%

Influence of Aluminum Sulfate on Hydration and Properties of Cement Pastes

Chen

Sun

2018

ACT

View full text Add to dashboard Cite

This study evaluates the influence of aluminum sulfate (AS) on hydration and properties of cement pastes. The hydration behavior of cement paste contributed by AS was identified via isothermal calorimetry, X-ray diffraction (XRD), scanning electron microscope (SEM) and helium pycnometry. Setting time, compressive strength and pore structure of accelerated cement paste were also evaluated. Results indicate that the addition of AS can reduce setting time significantly and increase compressive strength of cement paste. Moreover, hydration process of accelerated cement paste can be divided into four stages according to absolute volume change measured by helium pycnometry, which are dissolution-crystallization stage, induction stage, rapid shrinkage stage and structure compacting stage. More nano-scale pores (pore diameter smaller than 10 nm) are generated in structure compacting stage, resulting in the "fake" absolute volume expansion. The rebound rate of shotcrete can be reduced with the increase of AS.

show abstract

“…This was explained after the transformation of some hydration products from the acicular crystal form (ettringite) to the hexagonal tabular crystal form (C4AH19, and C2AH8) at the final stages of hydration (28 days), which caused a sharp depletion in the compressive strength of the hydrated paste OPC-MK10, [40]. On the other hand, the lowest compressive strength measures were recorded in case of OPC-MK15.…”

Section: C3s C2s Clinker H O Calcium Silicate Hydrates C-s-h Ca Ohmentioning

confidence: 99%

Metakaolin as an Active Pozzolan for Cement That Improves Its Properties and Reduces Its Pollution Hazard

Ibrahim¹,

Hagrass²,

Boulos³

et al. 2018

JMMCE

View full text Add to dashboard Cite

Prepared metakaolin produced by calcination of a kaolin sample at 750˚C after soaking for 5 hrs was tested as an active pozzolan for locally produced cement. Blended pastes of partially replaced ordinary Portland cement with different metakaolin amounts 5%, 10% and 15% were prepared, then they were hydrated with water for various time intervals of 1, 3, 7, 14 and 28 days. At each time interval, the hydrated paste specimens were tested for compressive strength, hydration kinetics and followed up using differential scanning calorimetry, X-ray diffractometry analyses and scanning electron microscopy techniques. Results showed that the blended pastes OPC-MK10 recorded the highest compressive strength values at all the hydration times reaching 33. 10, 86.40, 101.20, 112, and 122 MPa with increasing the age of hydration as compared with the neat samples which recorded 31.70, 65.20, 72.6, 82 and 101.30 MPa respectively. Meanwhile, the OPC-MK10 blend showed a decrease in the free CaO content reaching 4.07%, 4.27%, 4.23%, 4.19%, and 4.11% CaO with increasing age of hydration compared with the neat samples which recorded 4.27%, 5.15%, 5.42%, 5.61%, and 5.96% CaO respectively. The DSC thermograms results for the hardened neat and OPC-Mk10 pastes at the 14 and 28 hydration days showed the formation of hydrated materials mainly calcium silicate hydrates, calcium sulphoaluminate hydrates and calcium aluminates hydrates. The X-ray diffractometry analyses of both hardened neat and OPC-MK10 showed that, the intensity of calcium hydroxide peaks of OPC-MK10 was lower than in case of neat OPC, while the peak of the hydration products of calcium silicate hydrates and calcium aluminates silicate hydrates of OPC-MK10 samples were of higher intensity than in case of neat OPC. Scanning electron microscopy micrographs indicated the formation of denser microstructure for the hardened OPC-MK10 paste as compared to neat OPC pastes after the 28 days age of hydration.

show abstract

Influence of sodium aluminate on cement hydration and concrete properties

Cited by 85 publications

References 12 publications

Investigation of effects of Portland cement fineness and alkali content on concrete plastic shrinkage cracking

Investigation of effects of Portland cement fineness and alkali content on concrete plastic shrinkage cracking

Influence of Aluminum Sulfate on Hydration and Properties of Cement Pastes

Metakaolin as an Active Pozzolan for Cement That Improves Its Properties and Reduces Its Pollution Hazard

Contact Info

Product

Resources

About