Air entrainment in fresh concrete and its effects on hardened concrete-a review

Shah, Hammad Ahmed; Yuan, Qiang; Zuo, Shenghao

doi:10.1016/j.conbuildmat.2020.121835

Cited by 91 publications

(31 citation statements)

References 115 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This relation between air content and density can be justified as material containing larger pore sizes, and more porosity will have higher air content; hence, fresh density will be lower. The presence of the higher air content in concrete increases the workability of concrete, but declines the density and strength of concrete [ 48 ]. The influence of NGPs on the air content of concrete and the percentage reduction of air content concerning different dosages of NGPs are reported in Figure 5 .…”

Section: Resultsmentioning

confidence: 99%

Performance Evaluation of Cementitious Composites Incorporating Nano Graphite Platelets as Additive Carbon Material

et al. 2021

View full text Add to dashboard Cite

Nano graphite platelets (NGPs) belong to the carbon family and have a huge impact on the construction industry. NGPs are used as multi-functional fillers and have the potential to develop reinforcing within cementitious composites. In this paper, NGPs were incorporated in cementitious composites to investigate the effects of NGPs on the fresh, mechanical, durability, and microstructural properties of concrete. Five mixes were prepared with intrusion of NGPs (0%, 0.5%, 1.5%, 3%, and 5% by weight of cement). The properties studied involved workability, air content, hardened density, compressive strength, tensile strength, flexural strength, sorptivity, ultrasonic pulse velocity (UPV), water absorption, and external sulfate attack. The workability and percent air content decrease by 22.5% and 33.8%, respectively, for concrete with 5% NGPs compared to the control mix. The specimens containing 5% of NGPs revealed the hardened density, compressive, tensile, and flexural strength to increase by 11.4%, 38.5%, 31.6%, and 44.34%, respectively, compared to the control mix. The results revealed that the incorporation of 5%NGPs in cementitious composites reduces the sorptivity and water absorption by 32.2% and 73.9%, respectively, whereas, it increases the UPV value by 7.5% compared to the control mix. Furthermore, the incorporation of NGPs provided better resistance against external sulfate attacks. SEM–EDX spectroscopy was carried out to investigate its microstructural analysis.

show abstract

Section: Resultsmentioning

confidence: 99%

Performance Evaluation of Cementitious Composites Incorporating Nano Graphite Platelets as Additive Carbon Material

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Chemical additives are materials used in the production of concrete aiming to improve properties of interest. They are generally used in quantities of up to 5% of the OPC mass [ 166 ]. The main types of chemical additives are air-incorporated additives, tack modifying additives, water-reducing additives, and shrinkage-mitigating additives, especially used in UHPC.…”

Section: Classic Components Used For Hpc and Uhpc Productionmentioning

confidence: 99%

“…As the name suggests, air-incorporated additives add air bubbles to concrete voids, improving the plasticity and workability of the material, but potentially compromising compressive strength. They are used in situations where concrete is subjected to ice and thaw, acting as a kind of reservoir where water can migrate, since when freezing the water expands, which could cause the concrete to crack [ 166 , 167 , 168 ].…”

Section: Classic Components Used For Hpc and Uhpc Productionmentioning

confidence: 99%

Materials for Production of High and Ultra-High Performance Concrete: Review and Perspective of Possible Novel Materials

Marvila¹,

Azevedo²,

Matos

et al. 2021

Materials

106

View full text Add to dashboard Cite

This review article proposes the identification and basic concepts of materials that might be used for the production of high-performance concrete (HPC) and ultra-high-performance concrete (UHPC). Although other reviews have addressed this topic, the present work differs by presenting relevant aspects on possible materials applied in the production of HPC and UHPC. The main innovation of this review article is to identify the perspectives for new materials that can be considered in the production of novel special concretes. After consulting different bibliographic databases, some information related to ordinary Portland cement (OPC), mineral additions, aggregates, and chemical additives used for the production of HPC and UHPC were highlighted. Relevant information on the application of synthetic and natural fibers is also highlighted in association with a cement matrix of HPC and UHPC, forming composites with properties superior to conventional concrete used in civil construction. The article also presents some relevant characteristics for the application of HPC and UHPC produced with alkali-activated cement, an alternative binder to OPC produced through the reaction between two essential components: precursors and activators. Some information about the main types of precursors, subdivided into materials rich in aluminosilicates and rich in calcium, were also highlighted. Finally, suggestions for future work related to the application of HPC and UHPC are highlighted, guiding future research on this topic.

show abstract

“…(a) (b) The critical influence of air voids can be further demonstrated by creating a poorly vibrated mixture by decreasing the vibration time (R7-REF-EXP-V30). Vibration is very effective expelling air from fresh cementitious mixture [56]. Inversely, by decreasing vibration time from 60 to 30 s during the casting process, more air bubbles could be substantially maintained in the mixture; thus, the hardened specimens may possess higher air void fraction.…”

Section: Impact Of Air Void Defects On Compressive Behaviormentioning

confidence: 99%

Mechanical Properties of Lightweight Cementitious Cellular Composites Incorporating Micro-Encapsulated Phase Change Material

Šavija

2021

Materials

View full text Add to dashboard Cite

This work focuses on combining digitally architected cellular structures with cementitious mortar incorporating micro-encapsulated phase change material (mPCM) to fabricated lightweight cementitious cellular composites (LCCCs). Voronoi structures with different randomness are designed for the LCCCs. Aided by the indirect 3D printing technique, the LCCCs were prepared with a reference mortar (REF) and a mortar incorporating mPCM. The compressive behavior of the LCCCs was studied at the age of 28 days, by experimental and numerical methods. It was found that the highly randomized Voronoi structure and the mPCM have minor negative influence on the compressive properties of the LCCCs. The mPCM incorporated LCCCs have high relative compressive strength compared to conventional foam concrete. Furthermore, the critical role of air voids defects on the compressive behavior was identified. The highly randomized porous Voronoi structure, high mPCM content and good compressive strength ensure the LCCCs’ great potential as a novel thermal insulation construction material.

show abstract

Air entrainment in fresh concrete and its effects on hardened concrete-a review

Cited by 91 publications

References 115 publications

Performance Evaluation of Cementitious Composites Incorporating Nano Graphite Platelets as Additive Carbon Material

Performance Evaluation of Cementitious Composites Incorporating Nano Graphite Platelets as Additive Carbon Material

Materials for Production of High and Ultra-High Performance Concrete: Review and Perspective of Possible Novel Materials

Mechanical Properties of Lightweight Cementitious Cellular Composites Incorporating Micro-Encapsulated Phase Change Material

Contact Info

Product

Resources

About