Minimizing variation due to construction aggregate moisture probes

Abstract

Described are a method and system for minimizing errors in the manufacture or management of aggregate-containing construction materials such as concrete. Aggregates used for making concrete are stored or weighed in dry bulk bin type hoppers, and conveyed from these hoppers into mixer drums which batching or mix the concrete. The hoppers or conveyor belts may contain sensor probes for measuring moisture levels in the aggregate. These sensor probes require calibration from time to time, but time and expense are required for proper calibration, leading to habitually erroneous moisture level data used in the industry on a daily basis. The present inventors believe that the smallest inaccuracies in aggregate moisture level readings can have profound effects on the properties of the resultant concrete product. To confront this long suffered problem, the present inventors surprisingly discovered that the inaccuracy of these aggregate moisture sensors, as used for evaluating the aggregate as a dry bulk material, can be detected and even addressed through the use of slump monitoring systems to evaluate the concrete slurry mix prepared from the aggregates.

We claim: 
     
         1 . A method for monitoring concrete ingredients comprising:
 (A) comparing currently monitored slump changes of a slurried concrete mixture, achieved after adding a unit volume or mass of material per unit volume of concrete, with slump changes predicted for the slurried concrete mixture based on previously monitored slump changes of a slurried concrete mixture, achieved after adding a unit volume or mass of material per unit volume of concrete; and   (B) initiating at least one or more of the following actions, when the difference between expected and currently monitored slump changes meets or exceeds a predetermined threshold value:
 (i) sending a signal or alarm, to a concrete plant at which the concrete ingredients were batched from, indicating that the predetermined threshold value was met or exceeded; 
 (ii) sending a signal or alarm, to a construction site at which a concrete mixture prepared from the ingredients batched is scheduled to be delivered, indicating that the predetermined threshold value was met or exceeded; 
 (iii) sending a signal or alarm, to a computer processor unit that is monitoring the slump of a concrete mixture prepared from the ingredients batched, indicating that the predetermined threshold value was met or exceeded; or 
 (iv) performing a combination of any of steps (i) through (iii). 
   
     
     
         2 . The method of  claim 1  wherein the material is water, one or more chemical admixtures or a combination thereof. 
     
     
         3 . The method of  claim 1  wherein the initiation of the alarm is also based on (i) information, contained in an electronic ticket, regarding the design of the concrete mixture as provided by a computer processor unit at the concrete plant to the slump monitoring computer processor unit of the concrete delivery truck, (ii) currently measured plastic properties of the concrete, (iii) ambient temperature or relative humidity, or (iv) a combination thereof. 
     
     
         4 . The method of  claim 1  wherein, in step (B)(i), the signal is sent to a concrete plant computer processor unit used for batching the concrete mixture, whereby an adjustment is made in the amount of chemical admixture for making a subsequent load of concrete, an adjustment is made in the amount of water used for making a subsequent load of concrete, or adjustments are made in the amounts of both chemical admixture and water used for making a subsequent load of concrete. 
     
     
         5 . The method of  claim 1  wherein, in step (B)(ii), the signal is sent to a hand-held to mobile device located at the construction site at which the concrete mixture prepared from the materials batched, the signal enabling a construction site foreman to understand whether chemical admixtures, water, or mixture thereof can be added into the concrete mixture. 
     
     
         6 . The method of  claim 1  wherein, in step (B)(iii), the signal is sent to a computer processor unit which is continually monitoring the concrete mixture in-transit during delivery of the concrete mixture from a concrete plant to a pour event at a construction site, the concrete monitoring computer processor unit being programmed to receive the signal and to adjust the amount of water, the amount of chemical admixture, or the amounts of both water and chemical admixture into the concrete mixture being delivered to the construction site. 
     
     
         7 . The method of  claim 1  wherein, step (B)(i), the signal is sent to a concrete plant at which the materials were batch from, to notify that the mix design should be redesigned based on the change in a material. 
     
     
         8 . A system having a computer processor unit programed to monitor concrete slump and to perform the method of  claim 1 .