Performance assessment of repair material for deteriorated concrete slabs using chemically bonded cement

Kim, Hak-Young; Han, Da-Hee; Kim, Kyoungmin; Romero, Pedro

doi:10.1016/j.conbuildmat.2019.117468

Cited by 35 publications

(15 citation statements)

References 31 publications

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“…These advantages have opened new applications on the basis of the near-neutral pH property of struvite-K cements, including the immobilization of certain radioactive wastes, − particularly reactive metals and other problematic waste streams that are not compatible with conventional Portland cement encapsulation. Other applications include fiber–cement composites − (e.g., glass fiber and mineral wools, which may react in conventional cements), internal concrete repair/bonding, − and the stabilization of contaminated soils. , Aside from the cementitious properties, there is also interest in the chemistry of struvite-K (alongside struvite and Na-struvite) to facilitate phosphate removal from wastewaters, − as part of global efforts toward sustainable stewardship of phosphate resources.…”

Section: Introductionmentioning

confidence: 99%

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

et al. 2020

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Struvite-K (MgKPO4·6H2O) is a magnesium potassium phosphate mineral with naturally cementitious properties, which is finding increasing usage as an inorganic cement for niche applications including nuclear waste management and rapid road repair. Struvite-K is also of interest in sustainable phosphate recovery from wastewater and, as such, a detailed knowledge of the crystal chemistry and high-temperature behavior is required to support further laboratory investigations and industrial applications. In this study, the local chemical environments of synthetic struvite-K were investigated using high-field solid-state 25Mg and 39K MAS NMR techniques, alongside 31P MAS NMR and thermal analysis. A single resonance was present in each of the 25Mg and 39K MAS NMR spectra, reported here for the first time alongside the experimental and calculated isotropic chemical shifts, which were comparable to the available data for isostructural struvite (MgNH4PO4·6H2O). An in situ high-temperature XRD analysis of struvite-K revealed the presence of a crystalline–amorphous–crystalline transition that occurred between 30 and 350 °C, following the single dehydration step of struvite-K. Between 50 and 300 °C, struvite-K dehydration yielded a transient disordered (amorphous) phase identified here for the first time, denoted δ-MgKPO4. At 350 °C, recrystallization was observed, yielding β-MgKPO4, commensurate with an endothermic DTA event. A subsequent phase transition to γ-MgKPO4 was observed on further heating, which reversed on cooling, resulting in the α-MgKPO4 structure stabilized at room temperature. This behavior was dissimilar from that of struvite exposed to high temperature, where NH4 liberation occurs at temperatures >50 °C, indicating that struvite-K could potentially withstand high temperatures via a transition to MgKPO4.

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Section: Introductionmentioning

confidence: 99%

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

et al. 2020

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“…Kim et al [ 61 ] carried out pull-out bond strength tests to study the bond performance of cement-based repair materials containing magnesium potassium phosphate for concrete slab repair. Feng et al [ 62 ] conducted split-pull bond strength tests and slant shear bond strength tests to measure the tensile strength and the cohesion and friction components between ultra-high performance concrete (UHPC) repair mortar and normal concrete (NC) substrate.…”

Section: Interface Between Cement-based Repair Materials and Concrete...mentioning

confidence: 99%

Cement-Based Repair Materials and the Interface with Concrete Substrates: Characterization, Evaluation and Improvement

Song

Líu

et al. 2022

Polymers

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Surface damages usually occur in concrete structures. In order to restore the functions and prolong the service life of concrete structures, their surface damages should be repaired in time. This paper reviews the main requirements for repair materials for concrete structures and the most used inorganic repair materials, such as cement-based materials, alkali-activated materials and polymer modified inorganic repair materials. Moreover, techniques to characterize and even improve the interfaces between these repair materials and concrete substrate are summarized. Cement-based material has the advantages of good mechanical properties and consistency with concrete substrate while having the problems of high shrinkage and low flexibility. Polymer modified materials were found as having lower shrinkage and higher flexural strength. Increasing the roughness or humidity of the surface, adding fibers and applying interfacial agents can improve the bond strength between cement-based repair materials and concrete substrates. All of these repair materials and techniques can help to build a good interfacial bonding, and mechanisms of how they improve the interface are discussed in this article. These are of great importance in guaranteeing the effectiveness of the repair of the concrete surface and to guide the research and development of new repair materials.

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“…Based on the above results, this study chose the ultimate shear bond stress, the slip value corresponding to the ultimate shear bond stress, and the interfacial fracture energy as eigenvalues, and proposed a simplified bond–slip constitutive relationship model, as shown in Equations (3)–(7) [ 2 ].

τ u = ατ u 1 τ u 2 τ u 3 τ u 4 τ u 5 τ u 6 S u = βS u 1 S u 2 S u 3 S u 4 S u 5 S u 6 G f = γG f 1 G f 2 G f 3 G f 4 G f 5 G f 6

where τ c is the calculated shear bond stress; τ u is the ultimate shear bond stress; S u is the slip value corresponding to the ultimate shear bond stress; G f is the interfacial fracture energy; S f is the ultimate slip value; α , β , and γ are fitting coefficients; τ u 1 , S u 1 , and G f 1 are influence coefficients of fiber volume fraction on τ u , S u , and G f , respectively; τ u 2 , S u 2 , and G f 2 are influence coefficients of borax content on τ u , S u , and G f , respectively; τ u 3 , S u 3 , and G f 3 are influence coefficients of M / P on τ u , S u , and G f , respectively; τ u 4 , S u 4 , and G f 4 are influence coefficients of W / S on τ u , S u , and G f , respectively; τ u 5 , S u 5 , and G f 5 are influence coefficients of S / B on τ u , S u , and G f , respectively; τ u 6 , S u 6 , and G f 6 are influence coefficients of fly ash content on τ u , S u , and G f , respectively.…”

Section: Bond–slip Model Of Mpc-ecc With Ordinary Concretementioning

confidence: 99%

“…Magnesium Phosphate cement (MPC), a kind of inorganic cementitious material, is made of dead-burned magnesium oxide, acid phosphate, and a certain amount of borax as a retarder [ 1 ]. MPC has several advantages [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ], such as high early strength, excellent durability, superior adhesive strength, low permeability, rapid hardening, and good compatibility with ordinary concrete. MPC gains strength over a short duration as compared to several hours with OPC [ 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Bond Properties of Magnesium Phosphate Cement-Based Engineered Cementitious Composite with Ordinary Concrete

et al. 2022

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A magnesium phosphate cement-based engineered cementitious composite (MPC-ECC) was developed using polyvinyl alcohol (PVA) fibers and fly ash. In this study, the bond behavior of MPC-ECC with ordinary concrete was evaluated through single and double shear bond strength tests. The effects of the water to solid mass ratio (W/S), the sand to binder mass ratio (S/B), the molar ratio of MgO to KH2PO4 (M/P), the fly ash content (F), the borax dosage (B), the volume fraction of PVA fibers (Vf), and curing age on the bond behavior of MPC-ECC with ordinary concrete were examined. The results showed that as the W/S increased, the single and double shear bond strengths were gradually reduced. As the S/B increased, the double shear bond strength increased; the single shear bond strength first decreased up to an S/B of 0.1 and then increased. With the increase of M/P, the single and double shear bond strengths increased. With the increase of F, the single shear bond strength first increased up to an F of 30% and then decreased; the double shear bond strength decreased. With the increase of B, the single and double shear bond strengths increased first and then decreased, and their strength reached its maximum at a B of 6%. The increase of Vf improved the single and double shear bond strengths. The research results can provide some technical guidance for repairing concrete structures with MPC-ECC.

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Performance assessment of repair material for deteriorated concrete slabs using chemically bonded cement

Cited by 35 publications

References 31 publications

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

Cement-Based Repair Materials and the Interface with Concrete Substrates: Characterization, Evaluation and Improvement

Bond Properties of Magnesium Phosphate Cement-Based Engineered Cementitious Composite with Ordinary Concrete

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Performance assessment of repair material for deteriorated concrete slabs using chemically bonded cement

Cited by 35 publications

References 31 publications

Characterization of and Structural Insight into Struvite-K, MgKPO4·6H2O, an Analogue of Struvite

Characterization of and Structural Insight into Struvite-K, MgKPO4·6H2O, an Analogue of Struvite

Cement-Based Repair Materials and the Interface with Concrete Substrates: Characterization, Evaluation and Improvement

Bond Properties of Magnesium Phosphate Cement-Based Engineered Cementitious Composite with Ordinary Concrete

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Product

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Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite