Mix the sand and cement together, in a three to one ratio in the wheelbarrow. Use goggles and a mask to keep the cement out of your eyes and lungs. In a separate container, mix the liquid coloring, the acrylic fortifier and a small amount of water together. Pour into the concrete mix and start stirring. Cautiously add more water, a little at a time, until the concrete is the consistency of very soft cookie dough, or toothpaste. Once liquid is added to the dry materials, constant stirring is necessary until you are done making leaves. Unless you rent or own one of those small electric mixers, you need a partner strong enough to keep the concrete moving from this point on.