Abstract
The interfacial transition zone (ITZ) is a weak part of concrete, which is the main reason that the mechanical properties of concrete are far lower than those of hardened cement paste and aggregate itself. In order to improve the mechanical properties of concrete ITZ, the effects of cement varieties, water-binder ratio, mineral admixtures and aggregate types on the strength of hardened cement paste-aggregate ITZ were studied by orthogonal test. A linear regression model between interfacial bonding splitting tensile strength and splitting tensile strength of hardened cement paste was proposed. The results show that the water-binder ratio has the greatest impact on the mechanical properties of ITZ, followed by aggregate. The interfacial bonding splitting tensile strength of five kinds of aggregate and cement paste is in the order of marble > coral > granite > basalt > quartzite. The optimal interface test combination is as follows: water-binder ratio 0.25, aggregate is marble, P•O52.5 cement, slag content 15%, fly ash content 20% and silica fume content 10%. The optimal cement slurry combination is: water-cement ratio 0.25, basic magnesium sulfate cement, slag content 15%, fly ash content 20% and silica fume content 10%. The linear regression model between interfacial bond splitting tensile strength and hardened cement paste splitting tensile strength is established by dividing aggregate, which is of great significance to study the law of interfacial strength.
Highlights
Concrete is a kind of building material with uneven, extremely complex and obvious differences in the composition of various internal components
Wang found that the addition of fly ash would reduce the thickness of interface transition zone (ITZ), so the interfacial bonding splitting tensile strength was higher than that of concrete without fly ash [9]
In order to establish the relationship between the interfacial bonding splitting tensile strength and the strength of cement paste, the cement paste mixture ratio with the same proportion of cementitious materials as the interface test specimen is designed, and a new orthogonal table is formed
Summary
Concrete is a kind of building material with uneven, extremely complex and obvious differences in the composition of various internal components. The strength test methods of ITZ include direct method and indirect method [3]. Zhou et al found that the interfacial bonding strength of concrete decreased with the increase of water-cement ratio [8]. Due to the difficulty in testing the strength characteristics of ITZ, there are few macro-mechanical data of ITZ. Wenliang Han et al.: Experimental Study on Interface Strength Between Hardened Cement Paste-Aggregate to establish the ITZ interface mechanical properties database of common concrete, orthogonal design was used to systematically study the influence of cement varieties, water-binder ratio, types and contents of admixtures and aggregate types on ITZ strength, so as to determine the key factors of interface strength, and establish the relationship between interface strength and hardened cement paste strength
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