Abstract
According to the climatic characteristics of seasonal frozen area in northeast China, the concrete strength tests, surface resistivity, rapid chloride permeability, and freeze‐thaw test under salt solution were carried out to study the influences of mineral admixtures and air content on the conventional properties and salt freeze‐thaw resistance of concretes. Then, the correlation analysis of surface resistivity with strength and rapid chloride permeability were further investigated. Subsequently, the changes of cumulative mass loss and relative dynamic elastic modulus varying with salt freeze‐thaw cycles were analyzed to study the influences of mineral admixtures and air content on salt freeze‐thaw resistance of concrete. The test results showed that fly ash (FA) was not conducive to improve the strength and salt freeze‐thaw resistance of concrete. However, blast furnace slag (BFS) and silica fume (SF) could improve the compressive and flexural strength of concrete, in which SF can improve its strength more significantly. Increasing the air content of concrete will lead to the reduction of its compressive strength, and the flexural strength first increased and then decreased. Nevertheless, the addition of air‐entrainment agent (AEA) has the best effect on improving the salt freeze‐thaw resistance of concrete. Moreover, surface resistivity of concrete has a good exponential function relationship with strength and a good power function relationship with rapid chloride permeability. Therefore, it is of great significance for engineering quality control and quickly and nondestructive testing.
Highlights
Due to the high strength, considerable durability, and promising economy, concrete has been one of the most widely used building materials in civil engineering since the 20th century [1,2,3,4,5,6]
A large number of cases have shown that the durability of concrete with rosy frost resistance will be greatly reduced when serving in this salt freeze-thaw condition. e presence of salt solutions eventually results in premature spalling of the concrete surface [21, 22], which gives rise to additional maintenance costs every year [23, 24]
In order to analyse the influences of fly ash (FA), blast furnace slag (BFS), silica fume (SF), and air-entrainment agent (AEA) on the salt freeze-thaw resistance of cement concretes, different dosages of AEA and several mineral admixtures were studied. e dosage of FA or BFS should be controlled within 30% by the total mass of cementitious materials, respectively [54,55,56]
Summary
Due to the high strength, considerable durability, and promising economy, concrete has been one of the most widely used building materials in civil engineering since the 20th century [1,2,3,4,5,6]. When using the conventional method to design the mix proportion of air-entrained concrete with multimineral admixtures, a large number of trial mixes are required to select the desired combination of materials that meets special performance, which would be costly, time-consuming, and sometimes uneconomical and wasteful [44, 45] From these considerations, a simple genetic algorithm was applied to optimize the mix proportion design of this multiconstituent concrete in this paper. In this paper, aiming at improving the resistance of concrete to salt-frost erosion, the mix proportion of air-entrained concrete with multimineral admixtures was designed based on the genetic algorithm, in which the fitness functions of salt freeze-thaw resistance indices were adopted. The influences of mineral admixtures on the mechanical and physical properties as well as surface resistivity of concrete were studied, and the quantitative relationship between strength as well as rapid chloride permeability and surface resistivity of concrete were established
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