Portland cement-free binder formulations, methods of making, and use of such cement-free binder formulations in building materials. The Portland cement-free binder formulations of the invention at least include a geopolymer material, preferably slag, present in an amount from about 90-98 wt. % of the binder formulation, an activator agent in an amount greater than 0 wt. % to less than 10 wt. %, and a slag accelerating agent in an amount from greater than 0 wt. % to less than 10 wt. % of the binder formulation. The activator agent may be hydrated lime, while the slag accelerating agent may be calcium dihydroxide and a calcium salt. The binder formulations of the invention may be premixed hydrated lime activated geopolymer-based binders for addition with the one or more additional compounds to render a building material composition.

There is provided the use of carrageenan as a viscosity-modifying admixture in a flowable cementitious suspension; a viscosity-modifying admixture for a flowable cementitious suspension, the viscosity-modifying admixture comprising carrageenan; a method of modifying the viscosity of a flowable cementitious suspension, the method comprising adding carrageenan as a viscosity-modifying admixture to the flowable cementitious suspension. There is also provided a dry cementitious composition comprising carrageenan as a viscosity-modifying admixture and a flowable cementitious suspension comprising carrageenan as a viscosity-modifying admixture. The flowable cementitious suspension typically comprises the dry cementitious composition as well as water. The flowable cementitious suspension can be a self-leveling flowable cementitious suspension, such as grout or mortar for self-leveling flooring, crack injection, or and anchorage sealing, or a self-consolidating flowable cementitious suspension, such as a flowable concrete.

Portland cement-free geopolymer based compositions for building materials, methods of making, and use thereof. The Portland cement-free geopolymer based compositions at least include a first pozzolanic binder material, preferably slag, in an amount from about 10-35 wt. % of the composition, and a second pozzolanic binder material, preferably pulverized fly ash, in an amount greater than 0 wt. % to 30 wt. % of the composition. The compositions further include a first alkali activator in an amount greater than 0 wt. % to 2 wt. %, a second alkali activator in an amount greater than 0 wt. % to 5 wt. %, a filler material comprising medium-fine sand in an amount from 10 wt. % to 60 wt. %; and one or more additional additives, wherein wt. % is based on a total weight of the composition. The first alkali activator may be potassium hydroxide powder, while the second alkali activator may be a sodium-based alkali activator.