US-12617725-B2 - Method for making carbonated precast concrete products with enhanced durability

US12617725B2US 12617725 B2US12617725 B2US 12617725B2US-12617725-B2

Abstract

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.

Inventors

Hucheng QI
Mehrdad MAHOUTIAN
Karmen HOGE

Assignees

CARBICRETE INC

Dates

Publication Date: 20260505
Application Date: 20221128

Claims (16)

1 . A method of making a carbonated precast concrete product, comprising: obtaining an intermediate having a core and an external layer disposed on a surface of the core, the core having a first composition and the external layer having a second composition different than the first composition, the intermediate being demolded, wherein faces of the intermediate are exposed to ambient air, and wherein a binder of the second composition of the external layer is selected from the group consisting of ground granulated blast-furnace slag (GGBFS), steel slag, and stainless steel slags; conditioning the intermediate to obtain a conditioned intermediate thereby reducing a water-to-binder ratio of at least the external layer, including reducing the water-to-binder ratio by evaporating a portion of water contained in the external layer; after the conditioning of the intermediate, at least partially compensating for an excessive reduction of the water-to-binder ratio of the external layer by causing a weight gain in the external layer by applying an aqueous medium on an outer surface of the external layer of the conditioned intermediate to increase the water-to-binder ratio of the external layer to obtain a moisturized intermediate, the excessive reduction of the water-to-binder ratio resulting in a moisture content at the outer surface being about 50% of a moisture content at the core of the conditioned intermediate, the external layer extending from the outer surface of the conditioned intermediate towards the surface of the core; and curing the moisturized intermediate with carbon dioxide to obtain the carbonated precast concrete product.
2 . The method of claim 1 , wherein the at least partially compensating for the reduction of the water-to-binder ratio by causing the weight gain includes causing the weight gain of the external layer of at least 10 g/m 2 .
3 . The method of claim 2 , wherein the causing of the weight gain of the external layer of at least 10 g/m 2 includes causing the weight gain of 50 g/m 2 to 350 g/m 2 .
4 . The method of claim 1 , wherein the at least partially compensating for the reduction of the water-to-binder ratio by causing the weight gain in the external layer with the aqueous medium includes applying one or more of water, a water-based solution, and a water-based slurry to the external layer.
5 . The method of claim 1 , wherein the obtaining of the intermediate having the core and the external layer includes obtaining the intermediate with the external layer having a water-to-binder ratio greater than a water-to-binder ratio of the core.
6 . The method of claim 1 , wherein the obtaining of the intermediate having the core and the external layer includes obtaining the intermediate with the external layer having a binder content greater than a binder content of the core.
7 . The method of claim 1 , wherein the obtaining of the intermediate having the core and the external layer includes obtaining the intermediate in which second composition of the external layer is devoid of a water repellent admixture.
8 . The method of claim 1 , wherein the obtaining of the intermediate having the core and the external layer includes obtaining the intermediate in which the second composition of the external layer is devoid of a cementitious binder.
9 . A method of making a carbonated precast concrete product, comprising: applying an external layer on a core to obtain an intermediate, the core and the external layer differing in their respective compositions, the intermediate being demolded, faces of the intermediate being exposed to ambient air, wherein a binder of the external layer is selected from the group consisting of ground granulated blast-furnace slag, steel slag, and stainless steel slags; conditioning the intermediate to obtain a conditioned intermediate thereby reducing a water-to-binder ratio of at least the external layer, including reducing the water-to-binder ratio by evaporating a portion of water contained in the external layer; after the conditioning of the intermediate, at least partially compensating for an excessive reduction of the water-to-binder ratio of the external layer by causing a weight gain in the external layer by applying an aqueous medium on an outer surface of the external layer of the conditioned intermediate to increase the water-to-binder ratio of the external layer to obtain a moisturized intermediate, the excessive reduction of the water-to-binder ratio resulting in a moisture content at the outer surface being about 50% of a moisture content at the core of the conditioned intermediate, the external layer extending from the outer surface of the conditioned intermediate towards the core; and curing the moisturized intermediate with carbon dioxide to obtain the carbonated precast concrete product.
10 . The method of claim 9 , wherein the at least partially compensating for the reduction of the water-to-binder ratio by causing the weight gain includes causing the weight gain of the external layer of at least 10 g/m 2 .
11 . The method of claim 10 , wherein the causing of the weight gain of the external layer of at least 10 g/m 2 includes causing the weight gain of 50 g/m 2 to 350 g/m 2 .
12 . The method of claim 9 , wherein the at least partially compensating for the reduction of the water-to-binder ratio by causing the weight gain in the external layer with the aqueous medium includes applying one or more of water, a water-based solution, and a water-based slurry to the external layer.
13 . The method of claim 9 , wherein a water-to-binder ratio of the external layer is greater than a water-to-binder ratio of the core.
14 . The method of claim 9 , wherein a binder content of the external layer is greater than a binder content of the core.
15 . The method of claim 9 , wherein the external layer is devoid of a water repellent admixture.
16 . The method of claim 9 , wherein the binder of the external layer is devoid of a cementitious binder.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application is a continuation of U.S. patent application Ser. No. 17/234,952 filed on Apr. 20, 2021 which claims priority to U.S. Patent Application No. 63/034,037 filed Jun. 3, 2020, both of which said applications are incorporated herein by reference in their entirety. TECHNICAL FIELD This disclosure relates generally to precast concrete products, such as but not limited to concrete pipes, traffic barriers, walls, boxes, culverts, tiles, pavers, hollow-core slabs, patio slabs, steps, curbs, retaining walls and concrete masonry units. More particularly, the present disclosure relates to carbonated precast concrete products and methods of making them. BACKGROUND Precast concrete has become widely adopted in the construction industry. Precast concrete is a construction product that is cast into a reusable mold or form under controlled factory conditions. It cures in a controlled curing environment in the factory. After curing, it is then transported to the building site. There is a wide range of structural and architectural applications for precast concrete. Some common examples include pavers, foundations, slabs, beams, floors, columns, walls, retaining walls, manholes, sewage pipes, blocks, modular boxes, bridge decks, and so on. Traditionally, Portland cement is used as the binder in the manufacturing of precast concrete products. However, the manufacturing of Portland cement is known to have undesirable environmental impacts. For every tonne of Portland cement produced, approximately one tonne of CO2 is released. The acquisition of Portland cement involves quarrying, emitting airborne pollutants and entails the use of large-scale kilns, requiring substantial amounts of energy. Cement-based precast products rely on the hydration of cement to obtain satisfactory strength. Heat and steam curing techniques have been widely adopted as the standard curing methods to accelerate early strength development in traditional cement-based precast concrete products. Curing precast concrete in a CO2-rich environment may offer a reduction of the environmental impacts of precast concrete. This is known as carbonated precast concrete. While such carbonated precast concrete has certain environmental advantages, there remains a need to improve other physical properties of carbonated precast concrete, such as its ability to better endure freeze-thaw cycles and abrasion. SUMMARY In one aspect, there is provided a method for making a carbonated precast concrete product comprising: 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. In some embodiments, the moisturizing of the at least one surface includes applying the aqueous medium using an application method selected from dipping the at least one surface partly or wholly in a water-containing liquid, spraying the aqueous medium to the at least one surface, or applying the aqueous medium to the at least one surface with a roller device. In some embodiments, the moisturizing of the at least one surface of the conditioned article includes moisturizing the at least one surface until the conditioned article achieves a weight gain of at least 10 g/m2. In some embodiments, the applying of the aqueous medium includes applying water, a water-based solution, and/or a water-based slurry on the at least one surface. In some embodiments, the applying of the aqueous medium includes applying the aqueous medium being at a temperature of from 15 to 25° C. In some embodiments, the conditioning of the demolded intermediate includes conditioning the demolded intermediate until between 20% to 70% by weight of an initial moisture content of the demolded intermediate is removed. In some embodiments, the obtaining of the mixture includes obtaining a dry part and a liquid part, the dry part having at least one aggregate material and at least one binder material, the liquid part having water, and mixing the dry part with the liquid part to obtain the mixture. In some embodiments, the method comprises mixing additives with the dry part and the liquid part. In some embodiments, the method comprises mixing micro-fibers wit