A calcium sulphate-based product including gypsum and a shrinkage resistance additive. The shrinkage resistance additive is a metal nitrate, hydroxide, acetate or sulphate and is preferably provided in an amount greater than 4 wt % (based on the amount of additive and gypsum). The additive may be a nitrate of an alkali metal (e.g. potassium), an alkaline earth metal (e.g. magnesium or calcium), a transition metal (e.g. iron or zinc) or aluminium.

A cementitious mixture for a 3D printer, with improved performance, is described, and its relative use, more specifically for the production of finished products having a complex geometry using a 3D printing apparatus.

A cementitious mixture for a 3D printer, with improved performance, is described, and its relative use, more specifically for the production of finished products having a complex geometry using a 3D printing apparatus.

Method and composition for producing aggregates from cement and concrete, including residual or returned concrete. Exemplary methods involve the use of an aggregate-forming inducer that provides a surface anchoring site for cement paste to bond/adhere, such as shredded news print, cardboard, or mixtures thereof, and also including fiber materials such as polymers, glass, and other material fibers. The aggregate-forming inducer is mixed with fresh concrete until aggregates are formed.

Method and composition for producing aggregates from cement and concrete, including residual or returned concrete. Exemplary methods involve the use of an aggregate-forming inducer that provides a surface anchoring site for cement paste to bond/adhere, such as shredded news print, cardboard, or mixtures thereof, and also including fiber materials such as polymers, glass, and other material fibers. The aggregate-forming inducer is mixed with fresh concrete until aggregates are formed.

Disclosed are a mixed shrinkage reducing agent for concrete and a preparation method thereof. The mixed shrinkage reducing agent for concrete includes the following components in parts by weight: 35-45 of alkali modified diatomite, 15-22 of magnesium oxide, 13-20 of vermiculite, 8-11 of borax, 3-9 of sodium hexametaphosphate, and 7-13 of citric acid modified starch. The mixed shrinkage reducing agent for concrete according to the present application is used as an admixture to be mixed into cement for preparing concrete.

A precast concrete structure formed of a cementitious mixture is provided, the cementitious mixture comprising a mixture of: (a) cement, (b) silica fume, (c) supplemental material (limestone and/or slag), (d) masonry sand, (e) water and ice (f) plasticizers and (g) workability admixtures. The result is an improved concrete for use in the formation of long span bridge elements that are simple and safe to manufacture and having improved properties. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

A precast concrete structure formed of a cementitious mixture is provided, the cementitious mixture comprising a mixture of: (a) cement, (b) silica fume, (c) supplemental material (limestone and/or slag), (d) masonry sand, (e) water and ice (f) plasticizers and (g) workability admixtures. The result is an improved concrete for use in the formation of long span bridge elements that are simple and safe to manufacture and having improved properties. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

A precast concrete beam is provided in construction of a long span bridge structure. The beam is formed of a plurality of aligned modular elements each formed of prestressed UHPC mix as a unitary body. The UHPC mix includes discontinuous fibers distributed randomly throughout a concrete matrix. Each modular element is aligned modular and connected by an epoxy grout to adhering adjacent element joints. Finally, post-tensioning of the entire beam reinforces and affixes the plurality of aligned modular elements into a single long span beam.

A precast concrete beam is provided in construction of a long span bridge structure. The beam is formed of a plurality of aligned modular elements each formed of prestressed UHPC mix as a unitary body. The UHPC mix includes discontinuous fibers distributed randomly throughout a concrete matrix. Each modular element is aligned modular and connected by an epoxy grout to adhering adjacent element joints. Finally, post-tensioning of the entire beam reinforces and affixes the plurality of aligned modular elements into a single long span beam.