# Sustainable Development of Concrete through Aggregates and Innovative Materials: A Review
## 2 Recycled Materials
### Crushed Glass
For the same conditions, 28 days flexural strength and static modulus of elasticity of this concrete were decreased by 4.2%, 8.5%, 9.9%, 12.7% and 22.5%, and 1.8%, 4.6%, 7%, 9.2%, and 11%, respectively. Furthermore, these authors found through SEM images that the amount of voids and cracks of this concrete increases with the percentage content of the RGFA. [PERSON] and [PERSON] [50] measured the mechanical properties of concrete containing crushed glass aggregate that replaced the cement in proportions from 10 to 50%. For 10-40% crushed glass aggregate the compressive strength of concrete was close to 30 MPa after 28 days and 90 days of curing. For this same aggregate percentage and days of curing, the flexural strength of the concrete was above 5 MPa. Properties of glass powder-manufactured concrete were evaluated by [PERSON] et al. [51]. Figure 6 depicts the behavior of compressive and flexural strength of concrete samples with glass powder aggregate as function of proportion ratio of glass powder aggregate. These mechanical properties are adjusted to an exponential mathematical model with an R\({}^{2}\) value of 0.60 for flexural strength and R\({}^{2}\) value of 0.49 for compressive strength. The highest compressive strength and flexural strength were achieved with 30% replacement of glass powder aggregate in cubes of 40 mm \(\times\) 40 mm \(\times\) 160 mm. Both compressive and flexural strength were reduced for replacement percentage of glass powder higher than 30%. In addition, the volumetric weight in the control concrete sample decreased to 1914 kg/cm\({}^{3}\) from 1935 kg/cm\({}^{3}\) with 47% replacement of glass powder. There is a decrease in volumetric weight of the concrete leading to a lighter material. Therefore, it is recommended to find the optimum content of glass waste replacement. [PERSON] and [PERSON] [52] evaluated the effect of ground glass powder (GCP) used to replace the cement or aggregate on the mechanical properties of Portland cement concrete. In addition, they investigated the impact of combinations of glass powder with  
Figure 6: Flexural and compressive strength behavior of concrete samples with glass powder. Reprinted with permission from [51]. Copyright © 2013, Elsevier B.V.  
crushed glass aggregate or natural mineral aggregate on the properties of concrete samples. They employed 80% of crushed glass aggregate and 20% of GGP. The concrete samples were handled accordingly to the ASTM C192 standard test method. The 28 days compressive strength of the concrete containing 20% glass powder as cement replacement decreased 13.7% with respect that of the control sample (27.0 MPa). On the other hand, 28 days compressive strength of the concrete containing content of 20% glass aggregate increased 25.93% in comparison with control sample. [PERSON] and [PERSON] [53] reported the behavior of sustainable ultra-high-performance glass concrete (UHPGC) containing glass powder aggregate that was generated from recycled glass culets (see Figure 7). This glass powder aggregate was employed to replace cement and quartz powder in typical UHPC. This can help to reduce the CO\({}_{2}\) emissions, costs and carbon footprint of conventional UHPC as well as conserve natural resources. They used content of 10%, 20%, 30%, 40% and 50% of glass powder aggregate in conventional UHPC. The higher proportion ratio of glass powder aggregate causes greater workability of the UHPGC. This concrete type reduced its maximum heat flow and total heat. In addition, the UHPGC offers accelerated hydration kinetics for content of glass powder up to 20%.