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Method for adjusting concrete rheology based upon nominal dose-response profile

  • US 9,789,629 B2
  • Filed: 10/11/2012
  • Issued: 10/17/2017
  • Est. Priority Date: 06/23/2010
  • Status: Active Grant
First Claim
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1. A method for controlling rheology of a hydratable cementitious composition in a rotatable mixer drum on a concrete delivery vehicle having an automated system for monitoring and adjusting concrete rheology, wherein the improvement comprises:

  • providing a truck comprising a rotatable mixer in the form of a drum for mixing and measuring rheology of a hydratable cementitious composition and further comprising a computer processor unit (“

    CPU”

    ) programmed to monitor and to adjust rheology of hydratable cementitous composition contained within said mixing drum; and

    (a) entering into said CPU a target rheology value (“

    TRV”

    ) and load size for a hydratable cementitious composition containing or intended to contain a particular rheology-modifying agent or combination of rheology-modifying agents within said truck mixing drum; and

    (b) obtaining a current rheology value (“

    CRV”

    ) of hydratable cementitious composition contained within said truck mixing drum based on input from a hydraulic sensor or electric sensor for measuring the energy required for rotating the mixing drum, a rotational speed sensor for measuring the speed of mixing drum rotation; and

    temperature sensor for measuring the temperature of the concrete mixin the mixing drum;

    (c) comparing through use of said CPU the current rheology value obtained in step (b) against a nominal dose response (“

    NDR”

    ) profile stored in CPU-accessible memory and wherein said NDR is based on at least one data set wherein various dose amounts of a particular rheology-modifying agent or combination of rheology-modifying agents and their correlative effect on rheology value selected from slump, slump flow, or yield stress is retrievably stored, and determining the nominal dose of said particular rheology-modifying agent or combination of rheology-modifying agents required to change the obtained CRV to the TRV specified in step “

    (a)”

    ;

    (d) dosing the hydratable cementitious composition contained in said truck mixing drum with a percentage of said particular rheology-modifying agent or combination of rheology-modifying agents that is selected or pre-selected from 5% to 99% based on the nominal dose determined in step (c) required for changing said obtained CRV to said TRV as specified in step (a);

    (e) obtaining a subsequent CRV of the hydratable cementitious composition contained in said truck mixing drum after the percentage of the nominal dose of the particular rheology-modifying agent or combination of rheology-modifying agents selected or preselected in step (d) is added into and uniformly mixed with said hydratable cementitious composition;

    comparing the dose selected or preselected in step (d) to the dose according to the NDR profile for the same change in the rheology value from step (b) to step (e), and determining the scaling factor (“

    SF”

    ) by which to adjust the dose from the NDR profile, where SF is defined as the actual dose from step (d) divided by the nominal dose to achieve the same change in rheology value indicated by the NDR profile; and

    (f) mixing into the hydratable cementitious composition the particular rheology-modifying agent or combination of rheology-modifying agents in an amount calculated in terms of SF multiplied by the dose from the NDR profile indicated to convert the current CRV measured in step (e) to the TRV specified in step (a); and

    wherein steps (a) through (f) are done by said CPU.

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