Truck Mixing

UHPC can be successfully mixed in a common ready mix truck. We have had good experience mixing up to 4 cubic yards in a mixer with a spiral mixing rib (see pictures below). For truck mixing, it is recommended to use a high level of high range water reducer (HRWR) to facilitate successful mixing, i.e. Mix D in the section ‘Ingredients‘ above.

Mix Proportions for a Cubic Yard of UHPC

Cement (Portland Type I): 653 lbSlag Cement (GGBS 100): 653 lbSilica fume: 327 lbWater: 264 lb = 31.6 gallonsHRWR (3% Sika): 39.19 lb (550 oz)Steel fibers (2%): 265 lbFine sand 1: 395 lbFine sand 2: 1580 lbDefoaming agent: 0.5 lb

Mix Protocol

Dry mix: 5-10 minutesAdd water and HRWR over 2 minutesWait for turnover (fluidity), which usually occurs within 15 minutesMix another 10 minutes after turnover.Add fibers gradually over 2 minutesMix for 15 minutes then cast.

Material Suppliers

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Compressive Strength

7 day strength (including 2 day hot water curing): 24,970 ksi

Figure above: General view showing truck being loaded with dry mix components. Courtesy: Clare County Road Commission.

Figure above: Addition of steel fibers. Courtesy: Clare County Road Commission.

Figure above: Spiral mixing rib. Courtesy: Clare County Road Commission.

Figure above: Pouring UHPC after mixing. Courtesy: Clare County Road Commission.

Figure above: Measuring spread after mix. Courtesy: Clare County Road Commission.