![]() ![]() This will be further discussed in the following sections. The positive effect of creep may be related to the modification of the hydration product and/or the densification of microstructures under moderate compressive loads. In this work, the load was applied after 3 days with a loading level of 40%. It is believed that the effect of creep on the mechanical properties of concrete strongly depends on several conditions, including loading levels, loading age, and loading direction. However, the results published by Liniers showed that tensile strength drop occurs after a compressive load above 40% of the compressive strength since micro-cracking takes place under such load. The increase in compressive strength was also reported for loaded conventional concrete at a loading level of 40%, and alkali-activated slag concrete at loading levels of 35% and 50%. ![]() The compressive strength and splitting tensile strength of the creep specimens were increased by 24.0–25.3% and 16.9–23.1%, respectively. The loaded specimens revealed higher mechanical properties than the unloaded specimens. The mechanical properties of MPC concrete specimens, which had been loaded for 550 days, and of unloaded specimens are shown in Figure 7. Struvite in MPC concrete generally showed a smooth texture and high crystallization grade, which can be considered positive for an enhancement of creep deformation. The gradual preferential re-orientation of C-A-S-H nano-crystallites induced by sustained stress could account for the creep development, while portlandite and ettringite with a limited degree of texture formation would contribute less to the creep of cement-based materials. The water-facilitated and time-dependent natures of the texture development of crosslinked C-A-S-H provide new insights into the mechanism of creep in cement-based materials. This may be due to the fact that the major binding phase of Portland cement is calcium silicate hydrate (C-S-H) gel, while the principal hydration products of MPC are crystalline struvite. However, the creep strain of OPC concrete with the same strength level generally reaches around −500 με, which is more than twice the value of MPC concrete. The final creep strains of MPC concretes stabilized between −200 and −240 με after 550 days. When free water is lost, capillary pressure increases and shrinkage occurs therefore, the more free water there is, the greater the drying shrinkage is. Excess water in concrete exists in the form of free water. The w/b ratio of MPC concrete in this study was only 0.17, which was much lower than that of Portland cement concrete with the same strength grade. ![]() M2 had a slightly higher shrinkage strain than M1 or M2 due to its higher cement content. ![]() The final temperature-corrected shrinkage of MPC concrete reached −140 to −170 με, which corresponded to one-third of that of Portland cement. After 65 days, the shrinkage strain continuously fluctuated (probably due to changes in relative humidity) and tended to be stable until the end of the test. It was estimated that the shrinkage strain was mainly due to the decreased content of free water as a result of its participation in reaction in the early stage and migration or evaporation in the late stage. The shrinkage strains showed a continuous increase at the beginning of the test and reached −120 to −135 με after around 65 days. I do not have a tabbing for the short acoustic break between verses 1 & 2.Figure 5 shows the temperature-corrected shrinkage strains of unloaded specimens. Use a single finger on the high E string and slide it down the string when changing frets. It's done with an acoustic through most of the song, but the last time it's electric. Here is the easily recognizable guitar melody. ![]()
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