Determining the Mineral Admixture and Fiber on Mechanics and Fracture Properties of Concrete under Sulfate Attack

Abstract

The concrete structure in the coastal area suffers from the combined erosion of sulfate and dry–wet cycles. In this study, in order to modify ordinary concrete, fly ash, slag powder, silica fume and polyester fiber are added separately. The crack resistance of concrete was studied through mechanical performance test and three-point bending fracture test of notched beam under sulfate dry–wet cycles. The load-crack opening displacement (P-CMOD) curve characteristics, fracture toughness and fracture energy of modified concrete after corrosion are calculated and analyzed. Results reveal that the P-CMOD curve of modified concrete after corrosion has gone through four stages of damage: initial bending section, proportional elastic section, stable expansion section and softening section. With the increase of dry–wet cycles, the overall corrosion resistance and toughening coefficient of modified concrete increases first and then decreases. Adding 25% fly ash can significantly enhance the fracture toughness of concrete in the initial stage. The addition of polyester fiber and slag is beneficial to the improvement of the instability toughness and fracture energy of the concrete in the later stage.

Hydration and pore structure characteristics of concrete incorporating internal curing materials in a dry and large-temperature-difference environment

“…The water-cement ratio near PCs is relatively large, which can promote the mass production of ettringite. Further, the PCs itself is a sphere with an inner hollow shell, which provides enough space for the growth of ettringite [26], so the ettringite grows densely near the pore wall, filling the holes formed by the PCs after releasing water to a certain extent.…”

Early-Age Mechanical Characteristics and Microstructure of Concrete Containing Mineral Admixtures under the Environment of Low Humidity and Large Temperature Variation

“…The interface transition zone is the weakest and most sensitive area inside the concrete, and the breakdown of concrete often starts here [ 10 ]. In the early stage of curing, the hydration degree of cement was low in concrete, so the bonding between the cement paste and the coarse aggregate was weak.…”

“…In recent years, an effective method of adding mineral admixtures was adopted by scholars to improve the performance of concrete [ 9 , 10 , 11 ]. According to the research of Lee [ 12 ] and Johari [ 13 ], mineral admixtures (fly ash and slag) can fill voids in concrete and react with cement hydration products to form calcium silicate hydrate, increasing the compaction of concrete, optimizing the pore structure, and improving the ability to resist cracking.…”

The Counterbalance of the Adverse Effect of Abrasion on the Properties of Concrete Incorporating Nano-SiO2 and Polypropylene Fiber Based on Pore Structure Fractal Characteristics

“…Incorporating different materials to improve the abrasion resistance of concrete is the most effective and widely used method in engineering [2][3][4][5][6]. Combined with the form and process of concrete being damaged by abrasion, the materials currently used are mainly through the following three ways: (1) Improve the strength of concrete cement paddle by adding mineral admixtures to form a harder cement shell to resist the damage of highspeed sand-containing water flow, such as silica fume concrete, high-strength concrete, HF concrete, and a series of concrete materials [7].…”