*3.7. Density*

Measured as mass per unit volume, density is the quantity of a substance. All samples were weighed after curing for 28 days at room temperature, and their masses were split by the mold's 100 mm × 100 mm × 100 mm dimensions. The impact of adding fiber to geopolymer concrete's density is seen in Figure 13.

According to the findings, 2421 kg/m3 was the density of the addition of 2% plastic fiber. In direct proportion to the addition of more nylon66 fibers, the geopolymer's density rose. This result is illustrated by the range 2315–2421 kg/m3 after fiber was added. The results show that the density of GPC and NFRGC increase 4% at 2% fiber added.

The change in density value with the addition of fiber in geopolymer concrete does not reveal any discernible trend in which the density rises and then somehow falls with the addition of a particular fiber. If the substitute fibers have nearly equal specific gravities, the density of any fiber-reinforced concrete often does not change considerably.

This tendency according to past investigations is the reverse of what we discovered. Fiber has increased based on weight rather than volume in this case. The GPC is influenced by the weight of nylon66 fibers itself. More fiber is added, which boosts the NFRGC's performance. We employed the dry test, with a total density of GPC of 2400 kg/m3, in this experiment. The sample illustrates that the increase in the fiber addition reduces the shrinkage that can cause the weight loss.
