A method for making a carbonated precast concrete product includes: obtaining a mixture including at least one binder material, an aggregate, and water; molding the mixture into a molded intermediate; demolding the molded intermediate to obtain a demolded intermediate, the demolded intermediate having a first water-to-binder ratio; conditioning the demolded intermediate to provide a conditioned article having a second water-to-binder ratio less than the first water-to-binder ratio of the demolded intermediate; moisturizing at least one surface of the conditioned article with an aqueous medium, thereby causing a weight gain of the conditioned article and providing a moisturized product, a first portion of the moisturized product having a third water-to-binder ratio greater than a fourth water-to-binder ratio of a remainder of the moisturized product; and curing the moisturized product with carbon dioxide to obtain the carbonated precast concrete product.

A method for making a carbonated precast concrete product includes: obtaining a mixture including at least one binder material, an aggregate, and water; molding the mixture into a molded intermediate; demolding the molded intermediate to obtain a demolded intermediate, the demolded intermediate having a first water-to-binder ratio; conditioning the demolded intermediate to provide a conditioned article having a second water-to-binder ratio less than the first water-to-binder ratio of the demolded intermediate; moisturizing at least one surface of the conditioned article with an aqueous medium, thereby causing a weight gain of the conditioned article and providing a moisturized product, a first portion of the moisturized product having a third water-to-binder ratio greater than a fourth water-to-binder ratio of a remainder of the moisturized product; and curing the moisturized product with carbon dioxide to obtain the carbonated precast concrete product.

A method for making a carbonated precast concrete product includes: obtaining a mixture including at least one binder material, an aggregate, and water; molding the mixture into a molded intermediate; demolding the molded intermediate to obtain a demolded intermediate, the demolded intermediate having a first water-to-binder ratio; conditioning the demolded intermediate to provide a conditioned article having a second water-to-binder ratio less than the first water-to-binder ratio of the demolded intermediate; moisturizing at least one surface of the conditioned article with an aqueous medium, thereby causing a weight gain of the conditioned article and providing a moisturized product, a first portion of the moisturized product having a third water-to-binder ratio greater than a fourth water-to-binder ratio of a remainder of the moisturized product; and curing the moisturized product with carbon dioxide to obtain the carbonated precast concrete product.

Provided is a concrete hardener composition. The concrete hardener composition includes a sodium silicate compound, an acid compound and a balance amount of solvent. The sodium silicate compound includes sodium silicate or a mixture of sodium silicate and sodium methylsilicate. The acid compound includes acetic acid, glycolic acid, ethylenediaminetetraacetic acid, tartaric acid, nitric acid, boric acid or a combination thereof. The solvent includes water or a mixed solution of water and polyol. Based on the total weight of the concrete hardener composition, the content of silicon is between 5 wt % and 15 wt %, and the content of the acid compound is between 2 wt % and 30 wt %.

Provided is a concrete hardener composition. The concrete hardener composition includes a sodium silicate compound, an acid compound and a balance amount of solvent. The sodium silicate compound includes sodium silicate or a mixture of sodium silicate and sodium methylsilicate. The acid compound includes acetic acid, glycolic acid, ethylenediaminetetraacetic acid, tartaric acid, nitric acid, boric acid or a combination thereof. The solvent includes water or a mixed solution of water and polyol. Based on the total weight of the concrete hardener composition, the content of silicon is between 5 wt % and 15 wt %, and the content of the acid compound is between 2 wt % and 30 wt %.

The present application provides for water capsules, preparation methods of water capsules, a preparation method for lightweight concrete and a structure of lightweight concrete. Each of the water capsules comprises an alkali-sensitive shell and water inside; the water capsules are used to mix with a cementitious matrix, the water capsules can survive during concrete mixing and transportation processes but then gradually rupture in hardened concrete; the water released during the hardening of the concrete is beneficial for the hydration of the concrete. The water capsules and their preparation method, the preparation method for and structure of the lightweight concrete of the present application are of unique design and strong practicability.

Provided is a concrete hardener composition. The concrete hardener composition includes a sodium silicate compound, an acid compound and a balance amount of solvent. The sodium silicate compound includes sodium silicate or a mixture of sodium silicate and sodium methylsilicate. The acid compound includes acetic acid, glycolic acid, ethylenediaminetetraacetic acid, tartaric acid, nitric acid, boric acid or a combination thereof. The solvent includes water or a mixed solution of water and polyol. Based on the total weight of the concrete hardener composition, the content of silicon is between 5 wt % and 15 wt %, and the content of the acid compound is between 2 wt % and 30 wt %.

Provided is a concrete hardener composition. The concrete hardener composition includes a sodium silicate compound, an acid compound and a balance amount of solvent. The sodium silicate compound includes sodium silicate or a mixture of sodium silicate and sodium methylsilicate. The acid compound includes acetic acid, glycolic acid, ethylenediaminetetraacetic acid, tartaric acid, nitric acid, boric acid or a combination thereof. The solvent includes water or a mixed solution of water and polyol. Based on the total weight of the concrete hardener composition, the content of silicon is between 5 wt % and 15 wt %, and the content of the acid compound is between 2 wt % and 30 wt %.

Disclosed are surface retarder composition and method for etching cementitious materials which achieve a desirable light acid etch look without using muriatic (hydrochloric) acid or sand blasting, removing the human health and environmental concerns. Formulations in accordance with embodiments disclosed herein are easier to remove from formwork or molds after demolding than conventional retarder paints. Surface retarders prevent the hydration of cement particles, which allows the uncured layer of paste next to the form to be removed such as by washing with water or other fluids, or by brushing, revealing aggregates. Also disclosed are molded cement and concrete materials or articles exhibiting such light etch.

A porous fiber preform enclosed within a mold may be melt infiltrated by pouring a molten material through an inlet of the mold, the porous fiber preform comprising ceramic fibers. A ceramic matrix composite component comprising the ceramic fibers may be formed by solidifying the molten material that is in the mold and in the porous fiber preform.