ASTM C403/C403M:08 pdf free download – Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance.
Note 4—To tacilitaic determination of when the required pcnctration has been attained, a sliding marker may be attached to the needle shaft. 14w examplc, a paper clip or masking tape may be placed on the shaft so that it coincides with the scribe mark. ibe marker should not interfere with the penetration of the needle into the mortar. ‘The position of the marker should be checked prior to making a penetration.
9.3 For conventional concrete mixtures at laboratory temperatures of 68 to 77 “F 120 to 25 “CI. make the initial test after an elapsed time of 3 to 4 h after initial contact between cement arid water. Subsequent tests should be made at ½- to I-h intervals. For concrete mixtures containing accelerators, or at temperatures higher than laboratory. it is advisable to make the initial test after an elapsed time of I to 2 h and subsequent tests at ‘h-h intervals. For concrete mixtures containing retarders. or at temperatures lower than laboratory, the initial test may be deferred until an elapsed time of 4 to 6 h. In all cases, time intervals between subsequent tests may be adjusted as necessary. depending upon the rate of setting, to obtain the required nuniher of penetrations.
9.4 Make at least six penetrations for each time-of-setting test, with time intervals of such duration as to provide a satisfactory curve of penetration resistance versus elapsed time (ote 5). Continue testing until one at least penetration resistance reading equals or exceeds 44)00 psi 127.6 MPaj.
Nim 5—A satisfactory curve is one which represents the overall development of penetration resistance and includes points before and after the times of initial and final setting to improve the accuracy of the required interpolation. For nonnal setting mixtures, test points are usually at equally spaced time intervals. Premature penetration testing will result in too many data points earlier than the initial setting time. This may decrease the accuracy of the estimated setting time by biasing the best fit line when regression analysis i.s used to analyze the penetration resistance
9.5 Plotting Test Resulr.s—One of the following alternative procedures may be used to plot the test results and obtain times of setting (Note 6). Appendix Xl illustrates the application of these procedures.
NonE 6—The plot of penetration resistance versus elapsed time provides information on the rate of setting. The plot may be used to select the time for subsequent penetration tests and it can assist in identifying spurious test results. Therefore, it is recommended that the data be plotted as they are being accumulated.
9.5.1 Use the following plotting procedure to determine he times of setting by hand-titling a smooth curve through the data. Prepare a graph of penetration resistance, as the ordinate, versus elapsed time, as the abscissa, using a scale such that 5(X) psi 13.5 MPaI and I h are each represented by a distance of at least ½ in. 115 mml. Plot the values of penetration resistance as a function of elapsed time.
9.5.2 Use the following plotting procedure to determine the times of setting by linear regression analysis of the logarithms of the data by using a suitable calculator. Using log-log graph paper. prepare a graph of penetration resistance, as the ordi. nate. versus elapsed time in minutes. as the abscissa. The limits of penetration resistance on the ordinate should extend from 10 psi [0.1 MPaJ to 10000 psi [100 MPaI. and the limits of elapsed time on the abscissa should extend from 10 to 1000 mm.