Processes for improving the bond between hydrating cement-based materials and existing cement-based substrates

Abstract

Cement compositions and processes for improving the bond between new hydrating cement-based materials and the surface of "old" cement-based substrates are disclosed. A mechanically and chemically integral bond is created between the surfaces of the cement-based materials by moistening the old cement-based surface, exposing the moist surface to carbon or carbonate sources (such as with carbon dioxide) and then applying a new hydrating cement-based material thereon. The treatment of the surface of the cement-based substrate as described above creates an aqueous phase chemistry thereon which is compatible to the aqueous phase chemistry of the hydrating cement-based materials applied thereafter. The compatibility of the aqueous phase chemistries results in a mechanically and chemically integral bond formed between the surface of the old cement-based surface and the hydrating cement-based materials. The bond interface may be characterized by low calcium hydroxide concentrations, the presence of amorphous, noncrystalline material, a low water/cement ratio, greater than 90% of all voids being less than 0.15 mm. in diameter, and a low total air content of the interface. The present invention is particularly applicable to the repairing, resurfacing and topping of existing concrete highways, roads and surfaces.

Dependencies are inferred from the claim text.