Influence of alkaline and alkali-free accelerators on strength, hydration and microstructure characteristics of ultra-high performance concrete

Luo, Biao; Luo, Zhengdong; Wang, Dehui; Shen, Chengpeng; Xia, Minmin

doi:10.1016/j.jmrt.2021.09.133

Cited by 18 publications

(7 citation statements)

References 42 publications

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“…The actuation of the setting accelerator in the enhancement of resistance at short curing ages was in agreement with the references consulted [31,32].…”

Section: Influence Of Percentage Of Setting Accelerator On Flexural A...supporting

confidence: 86%

Preliminary Study of the Fresh and Hard Properties of UHPC That Is Used to Produce 3D Printed Mortar

et al. 2022

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Three-dimensional printed concrete (3DPC) is a relatively recent technology that may be very important in changing the traditional construction industry. The principal advantages of its use are more rapid construction, lower production costs, and less residues, among others. The choice of raw materials to obtain adequate behavior is more critical than for traditional concrete. In the present paper a mixture of cement, silica fume, superplasticizer, setting accelerator, filler materials, and aggregates was studied to obtain a 3DPC with high resistance at short curing times. When the optimal mixture was found, metallic fibers were introduced to enhance the mechanical properties. The fresh and hard properties of the concrete were analyzed, measuring the setting time, workability, and flexural and compressive strength. The results obtained demonstrated that the incorporation of fibers (2% in volume) enhanced the flexural and compressive strength by around 163 and 142%, respectively, compared with the mixture without fibers, at 9 h of curing. At 28 days of curing, the improvement was 79.2 and 34.7% for flexural and compressive strength, respectively.

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“…The actuation of the setting accelerator in the enhancement of resistance at short curing ages was in agreement with the references consulted [31,32].…”

Section: Influence Of Percentage Of Setting Accelerator On Flexural A...supporting

confidence: 86%

Preliminary Study of the Fresh and Hard Properties of UHPC That Is Used to Produce 3D Printed Mortar

et al. 2022

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“…Thus, complex admixtures based on alkali metal salts and PCE provide optimization of properties and acceleration of hardening of mixtures of different compositions [15,16]. The introduction of alkaline aluminate Na[Al(OH) 4 ] in combination with PCE makes it possible to obtain high-strength concrete, which is characterized by increased durability in aggressive environments [17,18]. The disadvantage of such cementitious systems is that there may be some decline in their strength with the age of hardening.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Effect of layered double hydroxides Ca-Al LDHs and polycarboxylate ethers on the hardening of Portland limestone cement

Kropyvnytska

Sanytsky

Kaminskyi³

et al. 2022

EEJET

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The use of layered double hydroxides (LDHs) is a new direction in chemistry of cement. The influence of calcium/aluminum double hydroxides (Ca-Al LDHs) and polycarboxylate ethers (PCE) on the strength development of Portland limestone cement has been investigated. It has been shown that Ca-Al LDHs form in cement slurry with the introduction of alkaline aluminate accelerator Na[Al(OH)4]. It was determined that this contributes to a significant increase in the early strength of cement stone. However, this reduces the setting time of hardening, and there is a decrease in strength with age. At an early stage of structuring in cement paste with the addition of Na[Al(OH)4], metastable high-water hydrate phases of Ca-Al LDHs of type C4AH19 ([Ca2Al(OH)6]2(ОН)2·12H2O) are formed, which, due to the conversion phenomenon, transform to cubic C3AH6. Such processes are accompanied by an increase in overall porosity and decreases in the strength of cement stone. Stabilization of the Ca-Al LDH structure is achieved by introducing anions [NO3]- into the interlayer space with the formation of Ca-Al-NO3 LDHs through the use of sol-gel technology. X-ray phase analysis, IR spectroscopy, and electron microscopy proved the fact of synthesis of AFm-phases of type [Ca2Al(OH)6]2(NO3)2.6H2О. When modifying such hydrates with polycarboxylate ethers, a nanocomposite Ca-Al-NO3 LDHs-РСЕ is formed. It was found that when the Ca-Al-NO3 LDHs-РСЕ nanocomposite was introduced to СЕМ ІІ/A-LL 42,5 R, the strength over the period of 8...24 hours increases by 2.0–1.5 times, and, after 2 and 28 days, 58 and 144 % of the standard strength is achieved (Rс28=62.5 MPa). The obtained nanomodified Portland limestone cement refers to extra rapid-hardening and high-strength cement, which makes it possible to solve the task of carrying out work on the rapid restoration of reinforced concrete structures' elements

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“…The question of rapid soil stabilization arises with larger treatment quantities (hundreds of tons). Adding accelerators to traditional binders for soil stabilization has recently attracted much attention in civil engineering and the construction industry (Meng et al, 2017;Luo et al, 2021;Kantesaria et al, 2021;Zhang et al, 2021;Zhao and Khoshnazar, 2021;Wang et al, 2022b). Combinations of admixtures significantly improve the physical and mechanical properties of clayey soil.…”

Section: Introductionmentioning

confidence: 99%

Hardening Accelerators (X-Seed 100 BASF, PCC, LKD and SALT) as Strength-Enhancing Admixture Solutions for Soil Stabilization

Lindh

Lemenkova

2023

Slovak Journal of Civil Engineering

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This study is aimed at evaluating the strength of stabilised soil collected from the Port of Norvik, Stockholm, Sweden, where 350,000 m3 of clay had to be stabilized. The tests were performed in the laboratory of the Swedish Geotechnical Institute (SGI). The soil was stabilised by binder mixtures using Portland cement clinker (PCC) and lime and lime kiln dust (LKD). Accelerators (X-seed 100 BASF, PCC, LKD and salt) were added to the soil samples for quicker stabilization. The strength of the stabilised soil was assessed using resonance frequency measurements of seismic P-waves by an ICP accelerometer in order to estimate the shear strength of the soil and to evaluate the effects from the accelerators, binder ratios, and the curing temperature on the gains in stabilization and strength. Various proportions of the binders were tested, i.e.: 50/50 cement/lime and 50/50 PCC/lime. The temperature was measured using a calorimeter in double experiments. The results showed that the accelerators improve the strength in the stabilized specimens and enhance the soil performance for engineering construction work.

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Influence of alkaline and alkali-free accelerators on strength, hydration and microstructure characteristics of ultra-high performance concrete

Cited by 18 publications

References 42 publications

Preliminary Study of the Fresh and Hard Properties of UHPC That Is Used to Produce 3D Printed Mortar

Preliminary Study of the Fresh and Hard Properties of UHPC That Is Used to Produce 3D Printed Mortar

Effect of layered double hydroxides Ca-Al LDHs and polycarboxylate ethers on the hardening of Portland limestone cement

Hardening Accelerators (X-Seed 100 BASF, PCC, LKD and SALT) as Strength-Enhancing Admixture Solutions for Soil Stabilization

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