Alkali silica reactivity (ASR) resistant aggregate concrete

Abstract

Improved methods are provided for producing exposed aggregate concrete resistant to alkali silica reactivity. A concrete mixture is poured over a subgrade into a formwork. In a first embodiment, the concrete mixture includes a combination of lithium nitrate solution and concrete. In an alternative embodiment, the concrete mixture is a combination of concrete, aggregate and a lithium nitrate. Once the concrete mixture has been poured, the upper surface is floated or screed. Where aggregate has not been integrally mixed into the concrete mixture, the aggregate is surface seeded by broadcasting the aggregate upon the ASR resistant concrete surface. Thereafter, the concrete surface is troweled to embed the aggregate in the upper surface and provide a homogenous uniform surface. The aggregate is then exposed utilizing chemical retardants or mechanical apparatus.

1 . A method of creating a surface seeded exposed aggregate concrete resistant to alkali silica reactivity, the method comprising:
 (a) preparing a subgrade or formwork for concrete placement;   (b) preparing an integral alkali silica reactivity resistant concrete mixture by mixing a lithium nitrate solution with concrete in a ratio of two (2)-eight (8) gallons of 5-50% lithium nitrate solution with each cubic yard of concrete;   (c) pouring the alkali silica reactivity resistant concrete mixture upon the subgrade or within the formwork to create an exposed concrete surface;   (d) floating, screeding or troweling the concrete surface utilizing bull floats, screeds or trowels so that the concrete surface is consolidated and uniform, while in a plastic state;   (e) broadcasting an aggregate reactive to concrete upon the concrete surface;   (f) mixing the aggregate into the concrete surface by troweling or floating the aggregate into the concrete surface; and   (h) exposing the aggregate within the concrete surface by either (1) applying a concrete surface retardant, allowing the retardant to retard hardening of a layer of the concrete, and washing away the surface retardant with water, or (2) mechanically exposing the aggregates utilizing abrasive mechanical apparatus to remove a surface layer of the concrete surface.   
     
     
         2 . A method of creating a surface seeded exposed aggregate concrete resistant to alkali silica reactivity of  claim 1  wherein the step of preparing an integral alkali silica reactivity resistant concrete mixture includes mixing a ratio of two (2)-five (5) gallons of about 30% lithium nitrate solution with each cubic yard of concrete. 
     
     
         3 . A method of creating a surface seeded exposed aggregate concrete resistant to alkali silica reactivity of  claim 1  wherein the step of preparing an integral alkali silica reactivity resistant concrete mixture includes mixing more than three (3) gallons of about 30% lithium nitrate solution with each cubic yard of concrete. 
     
     
         4 . A method of creating a surface seeded exposed aggregate concrete resistant to alkali silica reactivity of  claim 1  wherein the aggregate includes seashells, stone, or glass. 
     
     
         5 . A method of creating a surface seeded exposed aggregate concrete resistant to alkali silica reactivity of  claim 3  wherein the aggregate includes seashells, stone, or glass. 
     
     
         6 . A method of creating an integrally mixed exposed aggregate concrete resistant to alkali silica reactivity, the method comprising:
 (a) preparing a subgrade or formwork for concrete placement;   (b) preparing an integral alkali silica reactivity resistant aggregate seeded concrete mixture by mixing: 1) a lithium nitrate solution, 2) an aggregate reactive to concrete, and 3) concrete, and wherein the ratio of lithium nitrate solution to concrete is two (2)-eight (8) gallons of 5-50% lithium nitrate solution with each cubic yard of concrete;   (c) pouring the concrete mixture upon the subgrade or within the formwork to create a concrete surface;   (d) floating, screeding or troweling the concrete surface utilizing bull floats, screeds or trowels so that the concrete surface is consolidated and uniform, while in a plastic state; and   (e) exposing the aggregate within the concrete surface by either (1) applying a concrete surface retardant to the concrete surface, allowing the retardant to retard hardening of the layer of the concrete, and washing away the surface retardant with water, or (2) mechanically exposing the aggregates utilizing abrasive mechanical apparatus to remove a surface layer of the concrete surface.   
     
     
         7 . A method of creating an integrally mixed exposed aggregate concrete resistant to alkali silica reactivity of  claim 6  wherein the step of preparing an integral alkali silica reactivity resistant concrete mixture includes mixing a ratio of two (2)-five (5) gallons of about 30% lithium nitrate solution with each cubic yard of concrete. 
     
     
         8 . A method of creating an integrally mixed exposed aggregate concrete resistant to alkali silica reactivity of  claim 6  wherein the step of preparing an integral alkali silica reactivity resistant concrete mixture includes mixing more than three (3) gallons of about 30% lithium nitrate solution with each cubic yard of concrete. 
     
     
         9 . A method of creating an integrally mixed exposed aggregate concrete resistant to alkali silica reactivity of  claim 6  wherein the aggregate includes seashells, stone, or glass. 
     
     
         10 . A method of creating an integrally mixed exposed aggregate concrete resistant to alkali silica reactivity of  claim 8  wherein the aggregate includes seashells, stone, or glass.