**4. Fresh Concrete Properties**

#### *4.1. Workability*

There are two parallel points of view on the workability of WG-containing concrete. A review of past studies on the impact of WG aggregates on the mixes of workability

is summarized in Table 5. It can be noticed that various research investigations have shown that the mixing of WG increases workability. They connected this beneficial impact of WG on the workability to the weaker cohesive between the cement mortar and the smooth surfaces of waste glass [48–52]. The smooth surface and low absorption capacity of WG are also important factors in increasing workability [53,54]. For example, Ali and Al-Tersawy [55] substitute fine aggregate in self-compacting concrete (SCC) mixes with recycled WG at levels of 10% to 50% by volume. Constant content of water–cement ratio and various superplasticizer doses have been used. They stated that slump flow increased by 2%, 5%, 8%, 11%, and 85%, with the incorporating of 10%, 20%, 30%, 40% and 50% of WG, respectively. In addition, Liu, Wei, Zou, Zhou and Jian [56] substitute fine aggregate in ultra-high-performance concrete (UHPC) mixes with recycled liquid crystal display (CRT) glass at levels of 25% to 100% by volume. Constant content of water–cement ratio and various superplasticizer (SP) doses have been used. Moreover, they stated that flowability increased by 11, 14, 16, and 12 mm, compared to the control sample, incorporating 25%, 50%, 75%, and 100% WG, respectively. Enhancing the workability by including WG is a benefit of utilizing this recycled material [57–60]. There is potential to utilize glass to create HPC in which high workability is necessary. In addition, WG can be used to boost workability rather than employing admixtures such as HRWR or superplasticizers [61–64].

Contrastingly, some studies have stated that including waste glass into the mixes lowered workability. Nevertheless, such a decrease has been associated with sharp edges, higher glass particle aspect ratio, and angular form, with obstruction of the movement of particles and cement mortar [65–71]. For example, Wang [72] substitutes fine aggregate in liquid crystal display glass concrete (LCDGC) mixes with recycled LCD at levels of 20% to 80% by volume. Various contents of w/c ratio (0.38–0.55) and various superplasticizer doses have been used. The author stated that slump flow decreased by 4%, 7%, 19%, and 26%, incorporating 20%, 40%, 60%, and 80% of WG, respectively, for w/c of 0.44. In addition, Arabi, Meftah, Amara, Kebaïli and Berredjem [73] substitute coarse aggregate in SCC mixes with recycled windshield glass at levels of 25% to 10% by volume. Various contents of w/c ratio (0.60–0.69) and various superplasticizer doses have been used. They stated that slump flow decreased by 3%, 8%, 9%, and 11%, incorporating 20%, 40%, 60%, and 80% of WG, respectively. According to Rashad [61], the optimal content of glass waste to achieve good workability is 20%.


**Table 5.** Summary of the results of past studies on the workability of waste-glass concrete.


**Table 5.** *Cont.*

Where: SCGC is self-compacting glass concrete; SCC is self-compacting concrete; HPGC is high performance recycled liquid crystal glasses concrete; UHPC is ultra-high performance concrete; LCDGC is liquid crystal display glass concrete; LCD is liquid crystal display; CRT is cathode ray tube; WG is waste glass; PVC is polyvinyl chloride; SP is superplasticizer; HRWRA is a high-range water-reducing agent; WR is water-reducing; AE is air-entraining; SF is silica fume; F.A. is fly ash; GBFS is granulated blast furnace slag; MK is metakaolin; SH is sodium hydroxide solution; SS is sodium silicate solution; F.A is fine aggregate; C.A is coarse aggregate; vol. is replacing by volume; wt. is replacing by weight.
