Boral Material Technologies Inc.

Handy Chemicals Ltd.

Ioan Spiratos

Russell Hill

Carmel R Jolicoeur

Thi Cong To

Monique Page

Mario Dupuis

A method of producing cementitious mixtures containing fly ash as one of the cementitious components, under air entrainment conditions. The method involves forming a mixture comprising water, cement, fly ash, optionally other cementitious materials, aggregate, conventional chemical admixtures, and an air entrainment agent and agitating the mixture to entrain air therein. Additionally, at least one sacrificial agent is also included in the mixture. The sacrificial agent is a material or mixture of materials that is not required to act as an air entrainment agent but interacts preferentially with components of the fly ash that otherwise neutralize, repress or depress the activity of the air entrainment agent. The invention includes cementitious mixtures and hardened concretes resulting from the method and fly ash treated with sacrificial agent, or air entrainment agent/sacrificial agent combinations, and processes for selecting suitable sacrificial agents.

Sacrificial agents for fly ash concrete

A process of producing an aqueous solution of a sulfonated melamine-formaldehyde resin. The process comprises condensing melamine and formaldehyde or a precursor of formaldehyde (e.g. paraformaldehyde) in an aqueous mixture having a pH in the range of 8-10 to form a reaction mixture containing a condensation product of melamine and formaldehyde. The condensation product is then reacted in an aqueous mixture having a pH of 8-10, preferably 8-9, with a sulfonating agent to produce a mixture containing a sulfonated condensation product. Finally, polymerizing the said sulfonated condensation product in an aqueous mixture having a pH of 5-7 to form a resin solution. In the process, at least one of the sulfonation step and the polymerizing step is carried out under superatmospheric pressure (generally 5 to 70 p.s.i.) and at an elevated temperature of, in the case of the sulfonating step, 100.degree.-130.degree. C. for a time of 1 to 5 hours or of, in the case of the polymerizing step, 105-150.degree. C. for a time of 15 minutes to three hours. Modifications of the basic process involve carrying out the sulfonation of the formaldehyde before the condensation of the melamine and formaldehyde or reacting all of the melamine, formaldehyde or precursor and the sulfonating agent all together under superatmospheric pressure. The resulting aqueous solution, or the dried resin extracted therefrom, has low salt content and is suitable as a superplasticizer for concrete mixes.

Processes for manufacture of sulfonated melamine-formaldehyde resins

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Ioan Spiratos