Polymer-modified hybrid micro-fiber cementitious composite material

Patent metadata

Field	Value
Publication number	US-2020157006-A1
Application number	US-201916680511-A
Country	US
Kind code	A1
Filing date	Nov 12, 2019
Priority date	Nov 20, 2018
Publication date	May 21, 2020
Grant date	—

Abstract

A polymer-modified hybrid-fibers cementitious composition has a one-day compressive strength of at least approximately 17 MPa, a 28-day tensile strength of at least approximately 3.8 MPa, an ultimate tensile strain of approximately 3% to approximately 9%, and a 7-day bond strength of at least approximately 2.3 MPa. A binder of ordinary Portland cement, fly ash, and silica fume is provided. Other components include limestone powder, sand, superplasticizer, and water. The composition further includes one or more of styrene butadiene rubber or ethylene-vinyl acetate copolymer in an amount ranging between approximately 2% and approximately 8% by mass of binder. Fiber additives include steel fibers in an amount ranging between approximately 0.3% and approximately 3.0% by volume of the cementitious composition and polymer fibers in an amount less than approximately 1.0% by volume of the cementitious composition. Chamfers made of the composition are positioned at beam-column joints.

First claim

1 . A polymer-modified, hybrid fibers cementitious composition having a one-day compressive strength of at least approximately 17 MPa, a 28-day tensile strength of at least approximately 3.8 MPa, an ultimate tensile strain ranging from approximately 3% to approximately 9%, and a 7-day bond strength of at least approximately 2.3 MPa, the composition comprising:
a binder including ordinary Portland cement, fly ash, and silica fume; limestone powder; sand; superplasticizer; and water;
the composition further including polymer additives comprising one or more of styrene butadiene rubber or ethylene-vinyl acetate copolymer in an amount ranging between approximately 2% and approximately 8% by mass of binder, and fiber additives comprising steel fibers in an amount ranging between approximately 0.3% and approximately 3.0% by volume of the cementitious composition and polymer fibers in an amount ranging between approximately 0.8% and approximately 1.0% by volume of the cementitious composition.

2 . The polymer-modified, hybrid fibers cementitious composition as recited in claim 1 , wherein the fly ash is approximately 25% to approximately 35% by mass of the binder.

3 . The polymer-modified, hybrid fibers cementitious composition as recited in claim 1 , wherein the silica fume is approximately 5% by mass or less of the binder.

4 . The polymer-modified, hybrid fibers cementitious composition as recited in claim 1 , wherein the steel fibers have a diameter of at least approximately 160 microns.

5 . The polymer-modified, hybrid fibers cementitious composition as recited in claim 1 , wherein the polymer fibers have a diameter of approximately 0.025 mm or less.

6 . The polymer-modified, hybrid fibers cementitious composition as recited in claim 1 , wherein the superplasticizer is a polycarboxylate-based superplasticizer.

7 . The polymer-modified, hybrid fibers cementitious composition as recited in claim 1 , wherein the steel fibers are copper-coated steel fibers.

8 . The polymer-modified, hybrid fibers cementitious composition as recited in claim 1 , wherein the steel fibers have an average length greater than approximately 13 mm.

9 . A repaired concrete structure, comprising:
a concrete beam-column joint; and a chamfer positioned on the beam-column joint, the chamfer filling an approximately right-angled intersection between a beam and a column, creating an approximately diagonal surface extending between the beam and the column, the chamfer comprising a hardened repair mortar, the repair mortar comprising a binder including ordinary Portland, cement, fly ash, and silica fume, and further including sand, polymer additives, and fiber additives comprising steel fibers and polymer fibers.

10 . The repaired concrete structure of claim 9 , wherein a ratio of a chamfer dimension to a least dimension of the column and the beam ranges from approximately 0.5 to approximately 1.0.

11 . The repaired concrete structure of claim 9 , further comprising a second chamfer, wherein the chamfer and the second chamfer are positioned below the beam.

12 . The repaired concrete structure as recited in claim 9 , wherein the fly ash is in approximately 25% to approximately 35% by mass of the binder.

13 . The repaired concrete structure as recited in claim 9 , wherein the silica fume is approximately 5% by mass or less of the binder.

14 . The repaired concrete structure as recited in claim 9 , wherein the steel fibers have a diameter of at least approximately 160 microns.

15 . The repaired concrete structure as recited in claim 9 , wherein the polymer fibers have a diameter of approximately 0.025 mm or less.

16 . The repaired concrete structure as recited in claim 9 , wherein the superplasticizer is a polycarboxylate-based superplasticizer.

17 . The repaired concrete structure as recited in claim 9 , wherein the steel fibers are copper-coated steel fibers.

18 . The repaired concrete structure as recited in claim 9 , wherein the steel fibers have an average length greater than approximately 13 mm.

Assignees

• Nano & Advanced Materials Inst Ltd

Inventors

• Fang Shuai
• Lam Yuet Kee
• Sham Man Lung
• Zhu Honggang

Classifications

• C04B14/28

  of calcium · CPC title

• C04B2111/723

  Repairing reinforced concrete · CPC title

• C04B20/1033

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• E04B1/21

  Connections specially adapted therefor · CPC title

• E04G23/0218

  Increasing or restoring the load-bearing capacity of building construction elements (E04G23/0203 and E04G23/0266 take precedence) · CPC title