Consider the concrete slab. It has wreaked havoc in modern gardens. Concrete is a faithless material: it has the crispness of fresh snow when first laid, but deteriorates thereafter. Snow symbolizes virginal purity. Stained concrete symbolizes the ersatz horror of the 'concrete jungle'. Out of sight is the only proper place for concrete in gardens. Stone, by contrast, symbolizes strength, unity and eternity. During the animistic era, stones were worshipped, with meteorites held in the highest regard. The Black Stone of Kaaba, kissed by pilgrims who visit the Great Mosque in Mecca, is believed to have fallen from heaven as a white stone and turned black on encountering the sins of man.
Stone has other advantages:
stone is better from a sustainability point of view, because its production does not waste energy. Concrete consumes large amounts of energy in (1) crushing the stone (2) making the cement (3) transporting the pre-cast concrete, or the cement and aggregate, to the place it will be used
Despite the above advantages of stone, cement and concrete have their uses in gardens:
If using concrete as a paving material there is much to be said for using a very weak mix - ie with a low proportion of cement:aggregate. The cement then acts as a weak binder and the appearance of the paving surface is dominated by the stone aggregate. Typical cement:aggregate proportions are:
Sir Frederick Gibberd, the famous landscape architect/architect/planner, had a great interest in concrete mixes and a visit to what is now known as the Gibberd Garden is an excellent way of learning about the use of weak-mix concrete in gardens.