The invention relates to geopolymer compositions, geopolymers and methods for their production and use. The geopolymers may be used as aggregates, and those aggregates may be used in concrete manufacture. The geopolymer composition comprises fly ash or a fly ash substitute, an aluminum phyllosilicate, an alkaline component and water, wherein the water is present at an amount of about 6% to about 10% by weight of the composition. The geopolymers are made by forming a geopolymer composition as described above, compacting the mixture by applying pressure of about 50 to about 90 kgf/cm2; and curing the compacted mixture to form the geopolymer.