Cementitious product treatment processes

Processes for reducing deformation of concrete are provided herein. In some instances, the processes may include applying a moisture control membrane layer to control moisture loss of the concrete, applying an intermediate layer to the moisture control membrane layer, and applying a finish layer to the moisture control membrane layer to create a substantially level upper surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. 13/841,850, filed on Mar. 15, 2013, titled “APPARATUSES FOR MIXING, PUMPING, AND DELIVERING SELF-LEVELING MIXTURES,” which is hereby incorporated by reference in its entirety including all references cited therein.

FIELD OF THE INVENTION

The present technology relates generally to processes for reducing deformation of cementitious products during drying. More specifically, but not by way of limitation, the present technology may be used to reduce or eliminate deformation of products such as concrete or mortar.

BACKGROUND

Cementitious products such as concrete slabs are typically poured into a prepared form or foundation. Generally, these concrete slabs, such as slabs on ground or slabs on metal deck, dry or cure in a top-down manner, meaning that the uppermost portion of the slab will dry before the bottommost portion of the slab. This drying behavior typically causes slabs to exhibit some degree of deformation, such as warping, due to formation of a moisture gradient through the thickness (e.g., depth) of the slab. As a slab dries, an exposed top surface undergoes drying shrinkage while concrete in the lower portion of the slab does not shrink, or does not shrink in a corresponding manner. This differential shrinkage may result in a raising of the slab edges at joints and cracks. Commonly referred to as slab “curling,” this distortion often requires remedial work, such as grinding and/or the application of a leveling course, to re-profile the concrete slab surface in preparation for the finish flooring.

SUMMARY OF THE PRESENT TECHNOLOGY

According to some embodiments, the present technology may be directed to a method for reducing deformation of concrete by: applying a moisture control membrane layer to control moisture loss of the concrete; applying an intermediate layer to the moisture control membrane layer; and applying a finish layer to the moisture control membrane layer to create a substantially flat and smooth upper surface.

According to some embodiments, the present technology may be directed to a method of applying a moisture control membrane layer to concrete to slow a drying rate of the concrete and prevent formation of a moisture gradient through the concrete.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

It will be understood that like or analogous elements and/or components, referred to herein, may be identified throughout the drawings with like reference characters. It will be further understood that several of the figures are merely schematic representations of the present technology. As such, some of the components may have been distorted from their actual scale for pictorial clarity.

The present technology may be utilized to address slab curling, warping, or other deformations common in poured concrete. As mentioned above, concrete, such as slabs on ground or slabs on metal deck, typically dries from the top, down. These slabs tend to exhibit some level of warping due to the formation of a moisture gradient through the depth of the slab. As slabs dry for the exposed top surface, concrete in the upper portion of the slab undergoes drying shrinkage while concrete in the lower portion of the slab does not shrink. This differential shrinkage results in raising of the slab edges at joints and cracks. Commonly referred to as slab “curling,” this distortion often requires remedial work, such as grinding and a leveling course, to re-profile the concrete slab surface in preparation for the finish flooring.

The present technology may include application of one or more layers of a moisture control membrane or intermediate layer shortly after slab placement to slow the drying rate of the concrete and reduce the formation of a moisture gradient through the slab depth. The application of the moisture control membrane/layers thus minimizes slab curling or other deleterious effects caused by the aforementioned non-uniform slab drying.

Referring now toFIGS. 1 and 2collectively, which illustrate a treated slab10and a process200for producing the treated slab10, it is noteworthy that the processes described herein may equally be applied to other cementitious products such as mortar, grout, and so forth, to prevent deformation caused by uneven drying.

FIG. 1illustrates a cross-sectional view of a section of a treated slab10, which has been subject to a process of the present technology.FIG. 2illustrates a flowchart of an exemplary process200for creating the treated slab10ofFIG. 1. The following description will reference bothFIGS. 1 and 2concurrently.

The treated slab10may be created by implementing a first step205of pouring a slab100. The slab100may be poured on a foundation such as soil, although the slab100may be poured over any foundation that would be known to one of ordinary skill in the art.

In some instances, after the slab100is poured, an upper surface105of the slab may be conditioned in step210to improve adherence between the slab100and a moisture control membrane110. Exemplary processes for conditioning the slab100may include, but are not limited to machine floating and/or bullfloating the upper surface of the slab100. In some instances, conditioning may include pan floating the surface105of the slab100to leave the surface open. Pan floating may create mechanical irregularities on the upper surface105of the slab100that facilitate an enhanced bond between the slab100and the moisture control membrane110.

After conditioning the slab100, bleedwater must be allowed to evaporate from the slab100, as the presence of bleedwater salts on the slab100will reduce the bond between the slab100and the moisture control membrane110. Once the bleedwater has evaporated, the surface of the slab100must be pan floated to reincorporate the bleedwater salts back into the concrete. Once the concrete has taken a firm set, a moisture control membrane110is applied via any desired means, such as painting, rolling, floating, and spraying—just to name a few.

Before the moisture control membrane110is applied, the installer may determine in step215whether primer is required. If primer is required, primer is applied in step220.

The process moves to step225where the installer determines if the slab100is ready for the moisture control membrane110. Generally, the step225is performed after the slab100has been allowed to dry for a period of time. It is noteworthy that the slab100may be allowed to cure until it becomes difficult or impossible to disturb (e.g., mark) the upper surface105of the slab100, via a mechanical means, such as a brush. Indeed, an exemplary method for testing the readiness of the slab100for application of the moisture control membrane110includes application of firm pressure to the upper surface105of the slab100using a blunt object. If the blunt object fails to disturb the upper surface105of the slab100, the moisture control membrane110may be applied.

To reduce deformation of the slab100, which may cause curling or warping of the slab100, a moisture control membrane110is be applied to the slab100to control moisture loss in step230. Stated otherwise, the moisture control membrane110may slow a drying rate of the slab100and prevent formation of a moisture gradient through the slab100.

In some instances, the moisture control membrane110may comprise a layer of a highly cross-linked epoxy that is applied to the slab100in a fluid form. Exemplary moisture control membrane products may include Ardex MC Rapid™, Ardex MC Ultra™, Ardex MC Plus™, Ardex MC MRP™ manufactured by ARDEX Engineered Cements of Aliquippa, Pa., or other similar moisture control products of similar permeability. Advantageously, the moisture control membrane110is applied to the slab100within twenty four hours of pouring the slab100.

The moisture control membrane110may be rolled or otherwise applied to the slab100. According to some embodiments, an intermediate layer115may be applied to the moisture control membrane110in step235. The intermediate layer115may include, for example, a layer of aggregate, such as sand, which is broadcast or spread across the moisture control membrane110while the membrane is still fresh (e.g., green). After allowing the moisture control membrane110to dry, excess amounts of the intermediate layer115may be removed by sweeping, vacuuming, blowing, or other suitable methods.

When both the moisture control membrane110and the intermediate layer115have been applied to the slab100, it is preferable that the vapor permeability of the treated slab10be approximately less than 0.2 perms, with vapor permeability being defined by the American Society for Testing and Materials (ASTM), Standard E96.

After removal of excess intermediate layer115, a finish layer120must be applied to the intermediate layer115in step240. In some instances, the finish layer120may comprise a self-leveling mixture, such as ARDEX SD-T™, Ardex K 15™ Premium Self Leveling Underlayment, and/or Ardex V 1200™ Self Leveling Underlayment although other suitable finish layer products may also likewise be utilized in accordance with the present technology.

Exemplary methods and apparatuses for applying a finish layer120, such as those listed above are found in co-pending U.S. patent application Ser. No. 13/841,850, filed on Mar. 15, 2013, which is hereby incorporated by reference herein in its entirety.