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New epoxy with self-repairing properties of environmental-friendly building structure adhesives

Liu Mengmeng, Zhang Lu, Lee Chienhung

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 1

39--48

EN

With the rapid increase in newly constructed buildings, the number of old buildings that need reinforcement and repair also increases due to aging, accidental damage, or modernization refurbishment. Likewise, the demand of the building adhesive keeps growing with the expansion of its application scope. However, because of the recognition of many demerits of the existing epoxy building adhesives (e.g., low bonding strength, high frangibility, and low elasticity modulus), the need for a new environment-friendly building structure adhesive has been growing steadily. In this paper, the potential of nano-scaled rubber (VP-501: diameter of ~70 nm) was investigated with respect to its capacity to enhance the capacity of the epoxy resin with respect to the static tensile, fracture toughness, and dynamic mechanical properties. Further, its effects on the thermal stability and glass-transition temperature change were also examined with the content of toughening agent. Our discussion was extended further to describe the mechanism under which the toughness and heat resistance of the modified epoxy resin are improved.

2

Experimental study on the working and mechanical properties of high performance cementitious structural grouts

Zhang Lu, Liu Mengmeng

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 4

487--498

EN

By using the experimental study method, the working properties and mechanical properties of grouting materials were determined by changing the cement-sand ratio, water-cement ratio, and cement admixtures. The main factors affecting the properties of grouting materials and the mutual influence rules of various factors are analysed and determined, and the best value range is obtained. Finally, the compressive strength of 28-day ordinary Portland cement structure grouting is optimised to 50-80 MPa. Based on the grouting ratio of ordinary Portland cement, an experimental study on the early strength structure paste of sulphate aluminate cement was carried out. The paste with one day strength as high as 70 MPa and good compatibility was prepared, and the early strength change law of the optimum ratio was deduced.

3

Dynamic non-linear Mohr-Coulomb strength criterion for hybrid basalt-polypropylene fibre-reinforced concrete under impact loading

Fu Qiang, Xu Wenrui, Huang Daguan, He Jiaqi, Zhang Lu, Kou Hailei, Niu Ditao

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

95--113

EN

Variations in the dynamic triaxial strength of hybrid basalt–polypropylene fibre-reinforced concrete (HBPRC) with strain rate and confining pressure were investigated, and a dynamic non-linear Mohr–Coulomb (M–C) strength criterion for HBPRC was established. The results showed that the dynamic strength of HBPRC increased non-linearly with the strain rate and confining pressure; however, the strain rate effect decreased with an increase in the confining pressure. The restraint effect of the basalt fibre and polypropylene fibre on the cracks enhanced the strain rate effect of the dynamic strength of concrete. The cohesion of HBPRC increased with the strain rate and confining pressure but decreased with an increase in the amount of fibre monofilaments. However, the internal friction angle showed a reverse trend. The established dynamic non-linear M–C strength criterion reflected the relationship of the dynamic strength of HBPRC with the confining pressure and strain rate, as well as the effect of fibre content on dynamic strength. The less average standard deviation and the tangential relationship between the strength envelope and the Mohr’s circle of stress demonstrated the applicability of the established dynamic non-linear M–C strength criterion.