For this case we have to by definition:

Where:
d: It is the density
M: It's the mass
V: It is the volume
According to the data we have to:

On the other hand we have that 1 meter is equivalent to 100 centimeters. Thus the measurements of the walkway are:
600 cm long, 100 cm wide and 10 cm thick. Looking for the volume we have:

According to the formula we have:

Thus, the mass of the walkway is 1,800,000g
Answer:
1,800,000g