## 4 Conclusions  
In this study, foamed concrete blocks were developed by adding civil construction waste (CCW), which totally replaced the conventional fine aggregates (natural sand). Based on our analysis, the following conclusions could be made:  
* CCWs can be used integrally as aggregates in the production of foamed concrete blocks, thereby reducing civil construction companies' liabilities and reducing environmental impacts due to the irregular disposal of waste. In addition, by using this residue, the consumption of natural sand can be reduced. Sand is a finite aggregate and its extraction causes environmental damage, especially in rivers and lakes;
* The additives have little influence on the properties of foamed concrete blocks. Different additive proportions can be evaluated in future works to seek the optimization of the use of additives in concrete foam;
* For the specimens studied it is possible to obtain compressive strength of specimens higher than the minimum value of 1.4 MPa required by ASTM C869/C869M--11, but the values of compressive strength found are still low when compared with other studies on lightweight concrete that used other aggregate types. Therefore, studies should be conducted to try to increase the compressive strength of these materials, for example, studying the use of different curing processes to decrease the connectivity between the pores;  
Figure 11: **(a)** Thermal conductivity as a function of dry density, **(b)** water absorption as a function of air void, and **(c)** air void as a function of dry density.  
Figure 10: Compressive strength as a function of **(a)** dry density and **(b)** air void.  
* As expected, the dry density and saturated density decrease when the amount of foam in the structure of the blocks increases. However, the densities are still high for lightweight concrete. Increasing the amount of foam in the fabrication of the blocks and experimenting with other foam agents could be a solution to decrease the density of these materials;
* The air void and the water absorption are strongly influenced by the amount of foam added to the structure, i.e., as the amount of foam increases, the number of pores increases. To minimize the water absorption, the connectivity between the pores must be reduced. For this reason, the foam stability should be studied in more detail;
* Specimens developed with CP II-Z cement showed, on average, the highest compressive strength, the highest densities, the highest thermal conductivity, the lowest air void, and the least absorption of water. Specimens developed with CP II-Z cement showed, on average, the lowest compressive strength, the highest densities, the highest air void and absorption of water, and the lowest thermal conductivity. The cement with pozzolanic addition presented the best results. So, to further improve the results, other materials, under replacement of the cement, can be added in new studies;
* The thermal conductivity found for foamed concrete blocks is in accordance with what NBR 15220 determines, namely that the thermal conductivity must be below 2 W/(m.K). To minimize the thermal conductivity, studies of foamed concretes with the addition of thermal insulation materials (wood, Styrofoam, etc.) can be carried out.  
[PERSON] performed the tests, analyzed the results, and wrote the paper. [PERSON] and R.M.C.T. assisted in the characterization of CCW and analysis of the results. [PERSON], [PERSON], and F.T. planned the study and assisted in the analysis of the results and with writing the paper.  
The authors would like to thank Fundacao Meridional and CAPES for financial support.  
The authors declare no conflict of interest.