# Long-Term Deformations and Mechanical Properties of Fine Recycled Aggregate Earth Concrete
## 3 Results
### Long-Term Deformations  
#### 3.1.1 Shrinkage  
Figure 3 shows the results of the mass loss, autogenous shrinkage and total shrinkage of NS and RS mixtures. Figure 3a presents the mass loss of both mixtures. The curves can be divided into three phases. A rapid mass loss is reported during the first days. Such a phase is controlled by the ambient conditions, and it continues as long as there is a supply of water from inside the specimen. Once the water migrating from the inside to the outside is not enough to meet that evaporative demand, the second phase starts and a lower rate of drying is observed in comparison to the first phase. The third phase is characterized by almost a constant low evaporation rate [32; 33]. The mass loss values show a higher water migration rate for RS earth concrete mixtures. This may be related to its microstructure considering the additional porous network of RS and the water added for the pre-saturation.  
Figure 2: The compressive test setup and AE sensors’ positions.  
The autogenous shrinkage decreases when RS replaces NS. This tendency is similar to the trend reported for normal concrete [34, 35]. This has been attributed to the internal curing effect of recycled aggregate. In fact, more water will flow out of the recycled concrete aggregate to compensate the water loss due to self-desiccation. Studies have found that a dry recycled concrete aggregate cannot effectively reduce the autogenous shrinkage [18]. The latter, even if additional water was added to the mixture, may be attributed to the absorption process that will take place by the recycled aggregate [36]. In the following study, the complete replacement of NS by RS following a pre-saturation of 80% reported a 54% decrease in the autogenous shrinkage of earth concrete. However, the drying shrinkage value of the RS mixture is higher, which may be attributed to the higher porosity of RS specimens in addition to the higher water absorption capacity [35, 36].  
Figure 4a shows the drying shrinkage (total shrinkage minus autogenous shrinkage) in parallel with the relative humidity and temperature. The temperature values did not show any great differences throughout the test, while the RH values did. As highlighted by arrows, a decrease in RH was accompanied by an increase in shrinkage rate.  
Figure 4b shows the drying shrinkage as function of mass loss. The complete replacement of NS by RS was reflected by an increase of drying shrinkage with a rate of 77% from 2313 \(\upmu\)m/m to 4095 \(\upmu\)m/m. The high mass loss values in the first phase were accompanied by low drying shrinkage rate as the migration of free water did not induce shrinkage [16, 17]. The loss of water due to hydration may also contribute to this phenomenon [37], in addition to micro cracks [28]. In phases two and three, the mass loss was reflected by drying  
Figure 4: (**a**) The drying shrinkage in parallel with RH and temperature and (**b**) correlation between drying shrinkage and mass loss.  
Figure 3: (**a**) The mass loss, (**b**) autogenous and total shrinkage of NS and RS earth concrete mixtures.  
shrinkage. It can be noticed that the rate of shrinkage in phase 2 is higher in the NS mixture, which may be due to different porosity network. Moreover, it has been observed that the three phases are longer in RS mixture, which may be attributed to the fact that the water migrated from RS specimen is not only the local water as for the NS specimen, but from the RS itself also due to pre-saturation [37].