A coating composition is used for coating or overlaying Portland cement concrete or metal. The composition includes a synthetic polymer latex, an amine-functional epoxy curing agent, an epoxy-functional or amine-functional silane, a liquid epoxy resin, and a filler having a fine particle size. The coating composition has superior crack resistance and low cost in comparison with epoxy/amine-type polymer concrete, and excellent strength development, chemical resistance, and rapid cure in thick films in comparison with latex-based cementitious compositions. The coating composition can be mixed from a pair of storage-stable components; a dry mix including the fine particle size filler and the epoxy resin, and optionally larger size aggregate, and a wet mix including the polymer latex, the silane, and the amine curing agent. The two components can be mixed on site to give a fluid coating composition having a long pot life and low viscosity, which rapidly develops strength, and ultimately develops high compressive strength, thermal shock resistance, and resistance to chemical attack, especially attack by aqueous acids.