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 A beam for use in construction of a long span bridge structure comprising: a reinforcing member having a geometric configuration selected from a group consisting of: a “U” tub beam with composite deck system; a decked I-beam; and an adjacent box beam; said geometric configuration formed of a UHPC mix having: an initial compressive strength, f′.sub.ci=10.0 ksi; a compressive strength at service, f′.sub.c=17.4 ksi; a modulus of elasticity of concrete, E.sub.c=6500 ksi; a residual rupture stress, f.sub.rr=0.75 ksi; and a concrete unit weight, w.sub.c=0.155 kcf; and
said UHPC mix further comprises a plurality of discontinuous fibers distributed randomly throughout a concrete matrix, said plurality of discontinuous fibers formed of a material selected from the group consisting of: steel; polypropylene; nylon; polyvinyl alcohol; polyolefin; polyethylene; polyester; acrylic; aramid; carbon; silica glass; basalt glass; glass fiber-reinforced polymer; and basalt fiber-reinforced polymer.

Cured cements, cement slurries, and methods of making cured cement and methods of using cement slurries are provided. The method of making a cured cement comprising: synthesizing nanomaterials via chemical vapor deposition on at least one of cement particles or cement additive particles to form nanomaterial particles, adding the nanomaterial particles to a cement slurry to form a modified cement slurry, and curing the modified cement slurry to form a cured cement, in which the nanomaterials are interconnected and form a conductive web within the cured cement.

The present invention concerns a Portland cement-free porous rigid mineral substrate made of alkali-activated pozzolans, a method for preparing the same, and use of said substrate to optimize plant germination and growth.

PCE-type copolymers in powder form can be obtained by spry-drying and are easily re-dispersed in water. The fineness and the anti-caking properties of said PCE-type copolymers in powder form, as well as their water reduction potential and influence on slump life are improved. A production process of said PCE-type copolymers in powder form is by a spray-drying method, and PCE-type copolymers can be used for the improvement of mineral binder compositions and especially dry mortars.

A nanocarbon material includes agglomerate nanostructures made of aggregates of: (i) graphene nanostructures having at least partially crumpled morphology, and (ii) clusters of at least one carbon material. The carbon material may have a graphitic structure. At least a portion of the graphitic structure may be at least partially hollow and have at least one winged protrusion. Optionally, the nanocarbon material may be part of a composition that includes a dispersion medium or a cementitious material. Methods of making such a composition are also disclosed.

The present invention provides fiber cement articles, such as roof tiles having improved impact and hail resistance and methods for making them. The fiber cement articles comprise cement, an optional filler, reinforcing fibers, such as poly(vinyl alcohol) fibers or a mixture of cellulosic and synthetic fibers, one or more core-shell aqueous emulsion polymers having a crosslinked rubbery core with a calculated glass transition temperature (calculated Tg) of from −20 to −140° C., and an at least partially grafted acrylic or vinyl shell polymer having a calculated Tg of from 20 to 170° C., and having a Z-average primary particle size of from 55 to 800 nm, or, preferably, from 140 to 650 nm. The solids weight ratio of the crosslinked rubbery core to the shell of the core-shell aqueous emulsion polymer may range from 85:20 to 97:3.

For measuring the stress history in a simple form, which is widely applicable to various types of structural materials which the elastic modulus is different from each other, a large number of calcite particles is embedded as a stress sensor in a cement-based composite material that can be elastically deformed after receiving an external.

A twin-crystal density of the calcite particles is measured after an external force is applied to the composite material, to convert the twin-crystal density to a strain by an approximate formula set in terms of a strain ε (%) generated in the composite material and a twin-crystal density Dtw (lines/mm) of the calcite particles, and further to convert this strain to a stress by the elastic modulus of the composite material, whereby to estimate the history of stress and strain. The approximate formula between strain and twin-crystal density is independent of the modulus of the composite material and is used in a common form.

Provided herein are fiber reinforced cementitious materials and mixtures with increased crack resistance. The cementitious materials and mixtures include a cement and at least one carbon fiber. Also provide is a fiber reinforced cementitious mortar that includes the fiber reinforced cementitious material to which at least one of water, an aggregate material or a chemical admixture is added.

A concrete composition having an optimized formulation and suitable for 3-D printing is provided. The composition may include a hydraulic cement composition, aggregate, cement and/or aggregate by-product dust, one or more rheology modifiers, a plasticizer, fibers, and a sufficient amount of water to effect setting of the composition. Optionally the concrete composition may include a setting agent. A method for 3D printing multiple layers of the concrete composition is also provided.