Studying effects of chemical admixtures on the workability retention of zeolitic Portland cement mortar

AzariJafari, Hessam; Kazemian, Ali; Ahmadi, Babak; Berenjian, Javad; Shekarchi, Mohammad

doi:10.1016/j.conbuildmat.2014.09.020

Cited by 39 publications

(9 citation statements)

References 32 publications

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“…Many studies demonstrated that the conformation of polymers could be altered in the presence of some salts [ 29 , 30 ]. Once cement particles contacted with water, the cement particles would rapidly release CH solution into pore solution [ 31 ], the conformation of these polymers could be obviously affected by Ca 2+ [ 32 ]. The size distribution of these polymers was obtained with DLS so as to reveal the conformation behavior of PCE and PAA in the presence and absence of CH.…”

Section: Resultsmentioning

confidence: 99%

Effect of Polyacrylic Acid on Rheology of Cement Paste Plasticized by Polycarboxylate Superplasticizer

Peng

Tan

et al. 2018

Materials

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Viscosity-enhancing agents (VEA) have been widely employed in high flowability cement-based materials, so as to ensure that no bleeding and segregation would occur. However, in most cases, interaction between VEA and superplasticizer would be unavoidable. In this study, the effect of polyacrylic acid (PAA), known as one of the most commonly used VEAs, on rheology performance of cement paste containing polycarboxylate superplasticizer (PCE), was studied. The initial fluidity was assessed with mini slump, and rheological behavior of cement paste was evaluated with rotor rheometer. Adsorption amount was examined with total organic carbon (TOC) analyzer, and the zeta potential was also tested. The interaction between PAA and PCE in the presence of calcium ion (Ca2+) was analyzed with conductivity, X-ray photoelectron spectroscope (XPS), and dynamic light scattering (DLS). The results illustrate that PAA can adsorb onto the surface of cement particles to plasticize cement paste, being similar to PCE. In the presence of Ca2+, PAA can be curled and crosslinked, as a result of the combination between carboxyl groups (COO−) and Ca2+, thereby affecting the adsorption performance and conformation behavior. It is interesting that negative impact of PAA on dispersion efficiency of PCE can be demonstrated; one reason is the reduced adsorption amount of PCE by PAA competitively adsorbing onto the cement surface, and another possible reason is the invalided PCE by adsorption of PAA. Additionally, molecular weight of PAA should be considered if being used as VEA in PCE system.

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Section: Resultsmentioning

confidence: 99%

Effect of Polyacrylic Acid on Rheology of Cement Paste Plasticized by Polycarboxylate Superplasticizer

Peng

Tan

et al. 2018

Materials

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“…In liquid phase, phosphates were quickly ionized and released the anions of [PO 4 ] 3− or [P 6 O 18 ] 6− , with negative charge. On the one hand, because of electrostatic attraction resulting from the positive zeta potential of cement particles at the very beginning [55], the ionized phosphate could quickly adsorb onto the cement surface. On the other hand, the released Ca 2+ into solution that was caused by cement hydration could be precipitated with [PO 4 ] 3− or be combined with [P 6 O 18 ] 6-, which results in adsorption.…”

Section: Thickness Of Adsorption Layermentioning

confidence: 99%

“…It On the other hand, TSP could be precipitated with Ca 2+ in solution at a very low concentration since the solubility product constant (Ksp) of the calcium phosphate (TCP, Ca 3 (PO 4 ) 2 ) and hydroxyapatite (AH, Ca 10 (PO 4 ) 6 (OH) 2 ) is 2.07 × 10 −29 and 2.35 × 10 −59 at the room temperature [57]. It was well known that the pH value of cement suspension could exceed 12 immediately after the cement were mixed with water [55]. The concentration of Ca 2+ was calculated to be about 0.001-0.005 mol/L; if the concentration of [PO 4 ] 3was more than 1.0 × 10 −10 mol/L, the precipitation would take place.…”

Section: Composition Of Adsorption Layermentioning

confidence: 99%

Effect of Sodium Hexametaphosphate and Trisodium Phosphate on Dispersion of Polycarboxylate Superplasticizer

Zhang

Liu

et al. 2019

Materials

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Enhancement in dispersion of polycarboxylate superplasticizer (PCE) could be obtained by incorporating retarders in normal concrete. The generally believed reason was that the consumption of free water and polymer at the beginning was reduced by retarding cement hydration. This theory could not convincingly explain why sodium hexametaphosphate (SHMP) was able to promote the dispersion capacity of PCE, while trisodium phosphate (TSP) could not, despite that both TSP and SHMP could obviously retard the cement hydration. The adsorption behavior of PCE and phosphate was investigated and the mechanism was analyzed in order to gain deeper understanding. The results showed that TSP and SHMP delayed the cement hydration, impeded adsorption process of PCE, and increased thickness of adsorption layer. It was interesting that TSP reduced the dispersion, but SHMP enhanced. The reason for this contradiction was due to the difference in composition of adsorption layer. In the PCE-TSP system, this layer was composed of the precipitates (formed by TSP and Ca 2+ ) and the invalided PCE (caused by these precipitates in the immediate vicinity of the cement grains); the invalided PCE was due to the decrease of PCE dispersion. In the PCE-SHMP system, "Inner-phosphate (multi-layers) + Outer-PCE (single layer)" structure was formed to make the PCE work more effective, hence enhancing the dispersion. These results were expected to be useful for the design of highly efficient dispersants. dispersion capacity [26][27][28][29][30]. Based on this, the retarder might hinder the adsorption process of PCE and it was referred to as competitive adsorption [31][32][33][34][35], thereby reducing the dispersion. In addition, the thickness of the adsorption layer should also be accepted as a factor influencing the dispersion of PCE [36,37]. In spite of the decline in adsorption amount of PCE in the presence of retarder, as reported in previous study, the adsorption layer was obviously thickened to enhance the dispersion [37]. On the basis of discussion above, the conclusion could be made that the dispersion capacity of the PCE-retarder system should be associated with the retarding effect of retarder, adsorption behavior of PCE, and the thickness of the adsorption layer.Poly-phosphates, such as sodium tripolyphosphate and sodium hexametaphosphate (SHMP), have been widely used to promote the dispersion ability and dispersion retention ability of the superplasticizer system in real engineering practice. However, mono-phosphates, such as trisodium phosphate (TSP) and sodium hydrogen phosphate, cannot play the same roles as poly-phosphate in commercially available PCE products. If the retardation was the main reason for the enhancement, poly-phosphate and mono-phosphate would both have a similar effect on dispersion of PCE system, because both TPS and SHMP could retard the cement hydration [38]. Therefore, the reason why the poly-phosphate could effectively enhance the dispersion, whilst the mono-phosphate failed cannot be simply explained by the retard...

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“…In addition, the effect of zeolite on reduction of the risk of ASR damage was investigated. The efficacy of zeolite as a SCM in reducing bleeding and segregation potential and improving compressive strength and durability of concrete are well‐documented before 34‐47 . Natural zeolite has been used as a SCM in the concrete industry in China, Germany, Russia, Slovenia, Cuba, Serbia, and Spain 41 .…”

Section: Introductionmentioning

confidence: 99%

Tackling the issues of self‐compacting concrete containing high volume of waste glass aggregate by zeolite

Khalooee

Ahmadi²,

Askarinejad³

et al. 2020

Structural Concrete

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The use of waste glass in concrete can bring significant economic and environmental benefits due to reduction of landfills and demand for natural aggregates. This paper presents a comprehensive investigation on the feasibility of using high volume of waste glass as fine aggregate in self‐compacting concrete (SCC). A detailed investigation on fresh behavior of mixtures was performed by evaluating filling ability, stability, passing ability, and viscosity of SCC mixtures. Compressive strength and electrical resistivity experiments and scanning electron microscope analysis were also performed to investigate the strength and durability of the concrete mixtures. Furthermore, alkali silica reaction (ASR) potential of different size ranges of the used glass was assessed. The obtained results revealed that excessive bleeding and segregation and deleterious ASR expansion are possible challenges of incorporating fine glass aggregates in SCC. Interestingly, there was no evidence that glass has a considerable impact on the mechanical performance of concrete whereas it increased the electrical resistivity of concrete. Utilizing high volume of waste glass in SCC up to 600 kg/m3 became feasible when a part of portland cement was substituted with zeolite.

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Studying effects of chemical admixtures on the workability retention of zeolitic Portland cement mortar

Cited by 39 publications

References 32 publications

Effect of Polyacrylic Acid on Rheology of Cement Paste Plasticized by Polycarboxylate Superplasticizer

Effect of Polyacrylic Acid on Rheology of Cement Paste Plasticized by Polycarboxylate Superplasticizer

Effect of Sodium Hexametaphosphate and Trisodium Phosphate on Dispersion of Polycarboxylate Superplasticizer

Tackling the issues of self‐compacting concrete containing high volume of waste glass aggregate by zeolite

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