Drying shrinkage of alkali-activated slag concrete with natural/recycled aggregates

Each year a large amount of construction and demolition waste (CDW) is generated in the European Union. For sustainability development the CDW is recycled and re-used. To promote the use of CDW, recycled aggregates from CDW were incorporated in alkali-activated concrete (AAC), which mainly consisted of secondary materials or industrial by...

Mitigating the autogenous shrinkage of alkali-activated slag by internal curing

Alkali activated slag (AAS) has shown promising potential to replace ordinary Portland cement as a binder material. Synthesized from industrial by-products, AAS can show high strength, thermal resistance and good durability. However, AAS has been reported to exhibit high autogenous shrinkage. Autogenous shrinkage is a critical issue for building...

Effect of CA bacteria on the carbonation process of γ-C2S

Carbonation has been proven to be a promising way to improve the mechanism properties and durability of steel slag products. CA bacteria can promote the hydration of CO2. In this study, one kind of alkali-resistant CA bacteria was chosen to investigate its effects on the carbonation process of γ-C2S. Results showed that bacteria could increase...

Utilization of biomass fly ash in alkali-activated materials

This paper investigated the feasibility of using biomass fly ash (BFA) to prepare alkaliactivated slag and fly ash paste. The reference mixture was alkali-activated slag and coal fly ash (CFA) paste with a slag-to-coal fly ash ratio of 50/50. In other mixtures, coal fly ash was replaced at 40% and 100% with BFA, respectively. The results showed...

Acoustic radiation due to scattering of T-S wave by the mean-flow distortion induced by steady local suction

Substantial sound waves can be generated by boundary-layer instability modes when the latter are scattered by a rapid mean-flow distortion. This is a rather generic mechanism and operates when an oncoming T-S wave is scattered by a steady local suction slot. This paper focuses on this problem by extending a recently developed Local Scattering...

Detached coherent structures in channel revisited: Comparison with homogeneous shear turbulence

Coherent structures in statistically-stationary homogeneous shear turbulence (HST) are compared with those of the detached family in channels. Similarly to attached ones, detached Qs in channels form streamwise trains of side-by-side groups of a Q2 and a Q4. This is also true in HST. Contrary to attached structures, but similarly to those in HST...

The effect of processing parameters on the formation of epoxy/UF resin microcapsules

Epoxy E-51/UF resin microcapsules were prepared by traditional two-stepped in situ polymerization method and processing parameters affecting the final microcapsules’ shape and size were carefully studied in the aim to obtain microcapsule with ideally spherical shape and uniform size. It’s found the polycarboxylate surfactant of SMA (styrene...

Preparation of mono-sized epoxy/MF microcapsulesin the appearance of polyvinyl alcohol as co-emulsifier

For epoxy microcapsules embedded in concrete as mechanic-triggered self-healing adhesive, globular shape with uniform size is the basic requirement to ensure the solid shell broken and the liquid core released at a designed stress. In this paper, monodispersed melamine–formaldehyde (MF) resin-walled epoxy E-51 microcapsules were successfully...

Inorganic powder encapsulated in brittle polymer particles for self-healing cement-based materials

Many types of healing agents have been investigated. These agents are processed in different ways, such as adhesive polymer in capsules or hollow fibre glasses, bacteria in porous aggregates and geo-materials directly incorporated in the cementbased materials. In this study, sodium silicate powder is encapsulated in polystyrene particles ...

The smart releasing behavior of a microcapsule based on chemical self-healing system caused by chemical trigger activation

A novel chemical self-healing system based on microcapsule technology for cementitious composites is established in Guangdong Key Laboratory of Durability for Coastal Civil Engineering, Shenzhen University. The key issue of this system is how to release the healing material and how to activate the healing mechanism. In this paper, the study is...

Preparation and characterization of poly (urea-formaldehyde) walled dicyclopentadiene microcapsules

Poly (urea-formaldehyde) (PUF) shelled dicyclopentadiene (DCPD) microcapsules were prepared by in-situ polymerization technology for self-healing concrete applications. It’s found, during the process, sodium dodecyl benzene sulfonate (SDBS) behaves better in emulsification of DCPD than other surfactant of sodium lauryl sulfate (SLS) and styrene...

A study on the steel corrosion protection of a microcapsule based self-healing cementitious system by means of electrochemical impedance spectroscopy

Based on microcapsule technology, a new type of self-healing system for cementitious composites is established. The performance of the system was characterized by means of electrochemical impedance spectroscopy of steel bars immersed in a simulated concrete environment. The results demonstrate strong inhibition of chloride-induced corrosion when...

Self-encapsulation of epoxy resin by a controlled interface curing process in epoxy/water emulsion

The microcapsules of epoxy E-51 resin encapsulated by cured itself were prepared by interfacial curing reaction, in which ethylenediamine (EDA) was employed as curing agent and sulfonated copolymer of styrene and maleic anhydride (SMA) as emulsifying agent. It’s found the morphology of microcapsules strongly depend on reaction time and EDA...