The present disclosure is directed to chemical additives for geopolymer cements that can improve the rheological properties of geopolymer cements. These chemical additives include sulfates and selenates of a specific formula as well as hydroxycarboxylic acid salts of Li, Na, and K including but not limited to glycolic, lactic, citric, mandelic tartaric, and malic acids. The chemical additives for geopolymer cements disclosed herein can facilitate the uniform mixing, increase the time mixtures can be transported, and improve the ability to place and finish concrete and mortars made with the geopolymer cements.

The present invention relates to a cement additive and a method for producing same, wherein carcinogens, including heavy metals such as hexavalent chromium and the like, generated from cement are removed while maintaining the strength and characteristic physical properties of cement. Moreover, the cement additive according to the present invention can provide cement that does not become oxidized by heat into hexavalent chromium.

Disclosed is an acid-modified flour and a method of making the acid-modified flour. The acid-modified flour is desirably prepared using a dry milling process. A starting flour is combined with a strong acid to form a mixture. The mixture is heated. A neutralizer is added to increase the pH of the mixture. If desired, the mixture can be dried and any agglomerates can be removed. The acid-modified flour can be used as a binder in a slurry for preparing one or more gypsum layers in a gypsum board.

Disclosed are a grouting material for modifying mudstone, a preparation method and an application thereof, belonging to the technical field of material science and geotechnical engineering. The grouting material for modifying mudstone includes the following raw materials: cement, water, superfine micronized powder, water reducer, silane, fiber, diatomite, urea-formaldehyde resin and waterborne polyurethane. The preparation method of the grouting material for modifying mudstone includes steps of: (1) weighing the raw materials in parts by weight, mixing water of 40% of a total amount of water with water reducer, superfine micronized powder, fiber and diatomite, stirring to obtain a material A; (2) adding silane, urea-formaldehyde resin, waterborne polyurethane and residual water into the material A, obtaining a material B after continuous stirring; and (3) adding cement into the material B, and uniformly stirring to obtain the grouting material for modifying mudstone.

Embodiments of the present disclosure relate to char bricks and methods of making char bricks. A composition (e.g., a char brick) includes about 0% to about 10% sand, about 30% to about 70% pyrolysis char (PC), and about 30% to about 60% cement. The PC has a particle size distribution from about 50 μm to about 500 μm. A method of making the composition includes mixing dry ingredients into a dry mixture, mixing the dry mixture with water to create a wet mixture; molding the wet mixture into a composition; and curing the composition. The dry ingredients include sand, pyrolysis char (PC), and cement. The PC has a particle size distribution from about 50 μm to about 500 μm.

A fiber reinforced polymer rebar composition and a method of forming the rebar composition is described. The method includes the steps of feeding a first fiber and a second fiber simultaneously through a preforming guide into a resin impregnator, pulling the fibers through the liquid polymeric resin in the resin impregnator to form a resin-soaked hybrid fiber, and passing the resin-soaked hybrid fiber through a heated stationary die where the resin of the resin-soaked hybrid fiber undergoes polymerization and cross-linking.

A limestone calcined clay cement construction composition comprises a) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases, and having a Blaine surface area of at least 3800 cm.sup.2/g, in an amount of 180 to 400 kg per m.sup.3 of the freshly mixed construction composition; b) a supplementary cementitious material having a Dv90 of less than 200 μm, in a total amount of 50 to 100 parts by weight, relative to 100 parts by weight of cementitious binder a), the supplementary cementitious material comprising (b-1) a calcined clay material and (b-2) a carbonate rock powder in a weight ratio of (b-1) to (b-2) in the range of 0.5 to 2; c) optionally, an extraneous aluminate source; d) a sulfate source; and e) a polyol in an amount of 0.3 to 2.5 wt.-%, relative to the amount of cementitious binder a). The composition contains available aluminate, calculated as Al(OH).sub.4.sup.−, from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder a), in a total amount of at least 0.08 mol, if the amount of cementitious binder a) is in the range of 180 to less than 220 kg per m.sup.3 of the freshly mixed composition, at least 0.06 mol, if the amount of cementitious binder a) is in the range of 220 to less than 280 kg per m.sup.3 of the freshly mixed composition, and at least 0.05 mol, if the amount of cementitious binder a) is 280 kg or more per m.sup.3 of the freshly mixed composition; and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0. The construction composition further comprises f) an ettringite formation controller comprising (i) glyoxylic acid, a glyoxylic acid salt and/or a glyoxylic acid derivative; and (ii) at least one of (ii-a) a borate source and (ii-b) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g.Math.L.sup.−1 or more, organic carbonates, and mixtures thereof; and g) a co-retarder selected from (g-1) α-hydroxy monocarboxylic acids and salts thereof, (g-2) phosphonic acids and salts thereof, (g-3) polycarboxylic acids and salts thereof, and mixtures thereof. The limestone calcined clay cement construction composition is a reduced carbon footprint composition and exhibits high early strength, high final strength, sufficient open time and high durability. Ingredients of the construction composition are abundantly available.

The invention provides a method of containing PFAS within a low permeability cementitious product, the method comprising: forming a cementitious slurry, the cementitious slurry comprising: cement; water; aggregate; and allowing the cementitious slurry to cure and thereby form a cementitious product; wherein one or more of the water and the aggregate is contaminated with PFAS; and further wherein the method comprises adding one or more of: siliceous pozzolans; plasticizer(s); and crystalline growth water-proofing compound(s), in an amount sufficient to produce a cementitious product comprising low water permeability, the low water permeability substantially preventing leaching of PFAS.

The invention comprises a cementitious material comprising a natural pozzolan selected from hyaloclastite, sideromelane or tachylite, wherein the natural pozzolan has a volume-based mean particle size of less than or equal to 40 μm. The cementitious material also comprising an aqueous alkaline activating solution suitable for forming a geopolymer. A method making a cementitious material is also disclosed.

A magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified, and a preparation method thereof are provided. In the preparation method, a basic magnesium sulfate cement is adopted as a cementing agent and a fly ash is adopted as a mineral admixture to prepare a slurry; foaming is conducted through a physical foaming process in a foaming machine to obtain a foam; and the foam is mixed with the slurry, and a resulting mixture is poured and cured, and then subjected to a surface hydrophobic modification through vapor deposition to obtain the sound-absorbing material. The sound-absorbing material has a density of 251 kg/m.sup.3 to 306 kg/m.sup.3, a noise reduction coefficient (NRC) of 0.65 to 0.7, a compressive strength of 1.8 MPa to 2.2 MPa, and a water contact angle of 129° to 151°.