Recent advance of chemical admixtures in concrete

Liu, Jinliang; Yu, Cheng; Shu, Xin; Ran, Qianping; Yang, Yichao

doi:10.1016/j.cemconres.2019.105834

Cited by 104 publications

(51 citation statements)

References 117 publications

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“…Despite the fact that polymeric admixtures can influence the rheological behaviour of cementitious matrices significantly and may tailor their hydration kinetics over a wide range (Jolicoeur and Simard 1998;Cheung et al 2011;Liu et al 2019), research on the application of such additives with regards to 3D printing is mainly governed by empirical approaches for applicable mix designs. To reduce water drainage (Perrot et al 2018) most widely used polymeric admixtures for tailoring 3D printable cementitious materials are the family of viscosity modifying agents (VMA).…”

Section: Polymeric Admixtures In 3d Printable Cementitious Matricesmentioning

confidence: 99%

The effects of nano- and micro-sized additives on 3D printable cementitious and alkali-activated composites: a review

et al. 2021

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Additive manufacturing (AM), also referred as 3D printing, is a technology that enables building automated three-dimensional objects in a layer-by-layer manner. AM of cement-based and alkali-activated composites has gathered attention over the last decade and is one of the most rapidly developing civil engineering fields. Development of proper mixture compositions which are suitable in fresh and hardened state is one of the key challenges of AM technology in construction. As the behaviour of cement-based materials (CBM) and alkali-activated materials (AAM) is determined by chemical and physical processes at the nano-level, incorporation of nano- and micro-sized admixtures has great influence on the performance of printable composites. These modifications are attributed to the unique reactivity of nanoparticles associated with their small size and large surface area. This review paper summarizes recent developments in the application of nano- and micro-particles on 3D printable cementitious composites and how they influence the performance of 3D-printed construction materials. The research progress on nano-engineered CBM and AAM is reviewed from the view of fresh and hardened properties. Moreover, comparison between nano- and micro-sized admixtures including nanosilica, graphene-based materials, and clay nanoparticles as well as chemical admixtures such as viscosity-modifying admixtures and superplasticizers is presented. Finally, the existing problems in current research and future perspectives are summarized. This review provides useful recommendations toward the significant influence of nano- and micro-sized admixtures on the performance of 3D printable CBMs.

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Section: Polymeric Admixtures In 3d Printable Cementitious Matricesmentioning

confidence: 99%

The effects of nano- and micro-sized additives on 3D printable cementitious and alkali-activated composites: a review

et al. 2021

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“…[11][12][13] PCEs play an important role in modern concrete production due to their superior dispersing performance. [14][15][16] Over the past 40 years, PCEs have evolved from the very first generation, the so-called MPEG-type PCEs, to a large family with broad chemical and structural diversity. [11,12] It is believed that an improved understanding of the synthesisstructure-property-performance relationships of PCEs is crucial for the molecular design and optimization of such functional polymers.…”

mentioning

confidence: 99%

Phase Behavior of Partially Charged Polyelectrolyte Solutions with Salt: A Theoretical Study

Qiu

Wang

2021

Macro Theory & Simulations

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Weakly (or partially) charged polyelectrolytes represent an important subset of the polyelectrolyte family. For instance, polycarboxylate-based superplasticizers, or PCEs, are comb-shaped polyelectrolytes possessing anionic backbones grafted with neutral side chains. PCEs play an important role in modern concrete production. However, their behavior in salt solutions remain poorly understood. The present work builds upon a recently developed liquid-state theory for fully charged polyelectrolyte solutions and extends it to describe the phase behavior and salt partitioning of PCEs in a 2:1 salt solution. Previous studies have shown that there can be an additional short-range attraction, often referred to as the "calcium-binding" interaction between calcium ions and the negatively-charged carboxylate groups of PCEs. Such a calcium-binding interaction and how its strength affects the phase behavior are investigated. It is found that increasing the calcium-binding strength expands the phase-separated region and increases the critical extra salt concentration, and it also leads to a wider phase-separated region for salting-out and salting-in phenomena. The structural parameters of PCEs also affect the phase behavior. Increasing the side-chain length shrinks the phase-separated region, while increasing the acid-to-ether ratio expands the phase-separated region. Those results may find applications in molecular design of weakly charged polyelectrolytes like PCEs.

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“…A cast-in-place concrete floor slab was cast in one time and had dimensions of 12 × 8 x 0.12 m 3 and no curing methods were used. No cracks were observed and the used gel-type SAP showed potential to mitigate earlyage cracking.. SAPs were also applied in the China Zun tower [160]. It was found that the SAPs reduced shrinkage by 46% and that the later age compressive strength was not affected when 0.56 m% of SAP was added to the mixture.…”

Section: Practical Applications Of Saps In the Construction Industrymentioning

confidence: 99%

5 Superabsorbent polymers as a solution for various problems in construction engineering

Snoeck¹

2021

Superabsorbent Polymers

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One of the most-used man-made materials is concrete, a mixture of cement, sand, aggregates, water, and admixtures. It can be seen everywhere: in tunnels, bridges, and high-rise buildings. Ever since concrete was rediscovered two centuries ago, it has been studied in detail in order to optimize the material and to solve its inherent problems. Most people know that concrete is gray, hard, and strong, and expect it to last decades and even centuries. Unfortunately, this is not always the case. Concrete is a material which can cope with high compressive forces but when it is subjected to tensile forces, it may crack. This cracking is based on several environmental and loading conditions, but the fact that concrete is prone to crack is a big issue. When cracking occurs and potentially harmful substances enter the interior of concrete, the concrete matrix may be damaged and even be destroyed. That is the reason why a lot of maintenance and repair works are due in order to increase the durability and lifetime of structures in civil engineering. One way of dealing with these issues is the modification of the material itself, making it less prone to cracking and the durability-related consequences. An example is the use of reinforcements, coping with the tensile forces when concrete cracks. Cracks are not harmful but intruding substances may trigger the corrosion of the iron rebars leading to structural failure, which is again unwanted. In consequence, along the history, different materials were investigated and added to concrete to solve the previous adverted problems. So, why not try adding the white powder superabsorbent polymers in the cementitious material in order to solve these issues?

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Recent advance of chemical admixtures in concrete

Cited by 104 publications

References 117 publications

The effects of nano- and micro-sized additives on 3D printable cementitious and alkali-activated composites: a review

The effects of nano- and micro-sized additives on 3D printable cementitious and alkali-activated composites: a review

Phase Behavior of Partially Charged Polyelectrolyte Solutions with Salt: A Theoretical Study

5 Superabsorbent polymers as a solution for various problems in construction engineering

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