DateLaboratory Testing of Portland Cement Concrete Patch Material ...

placed into a 6-inch high, 6-inch diameter cylindrical mold. At regular intervals, theresistance of the mortar to penetration by a standard needle was measured. As the resistanceapproached 500 psi, the measurement intervals were shortened. Once the mortar was able toresist a pressure of 500 psi, the initial time of set had been reached and the testing wascomplete. Proprietary rapid setting concrete patch materials typically reach the initial time ofset in 15 to 25 minutes.Figure 4. Time of Set TestingA needle, attached to the hydraulic loading device, penetrates themortar at regular intervals until it meets a resistance of 500 psi. Thetime at which the mortar resists 500 psi is its initial time of set.The time of set test results, presented in Figure 5 on the following page, show that all of thesamples took much longer to achieve an initial set than proprietary concrete patch materials.The Mn/DOT 3U18 control took nearly 3 hours to achieve an initial set. Both Denkaproducts at the higher dosage rate of 50.56 lb/yd 3 (30 kg/m 3 ) slightly lowered the initialtime of set of the Mn/DOT 3U18 patch material, but all of the other products increased theinitial time of set, with the lightweight fine aggregate products adding over 30 minutes to theset time. Thus, all of the samples surpassed the 15-minute minimum; and since there is nomaximum time of set constraint, none of the samples were eliminated from Phase II basedon the time of set test results.13