Method for rapidly detecting activity index of fly ash

Abstract

The invention discloses a method for rapidly detecting activity index of fly ash. The method specifically comprises: preparing to-be-detected fly ash into a fly ash-Ca(OH)2-H2O hydration sample, curing under a constant-temperature water bath curing condition, drying and grinding the hydration sample reaching a fixed age into powder, screening, firing at a high temperature, calculating the binding water rate of the hydration sample by using the mass difference of the hydration powder before and after firing, and finally obtaining the activity index according to the function relationship between the binding water rate and the activity index at different ages. According to the invention, the content of chemical binding water generated by a fly ash-Ca(OH)2-H2O reaction system is used for representing the activity index of fly ash, so that the detection time of the activity index is shortened to 3 days or below from original 28 days, the detection efficiency is improved by about 90%, and the detection efficiency of the activity index of the fly ash is greatly improved; and the method has better detection timeliness than the traditional detection method based on the strength index, and is high in accuracy and suitable for popularization and application.

Description

technical field

[0001] The invention belongs to the technical field of detection of concrete raw materials, in particular to a rapid detection method of fly ash activity index. Background technique

[0002] Mineral admixtures such as fly ash are widely used in commercial concrete, and participate in the cement hydration process, which has a significant impact on the workability, strength development, durability and volume stability of concrete. Therefore, to ensure that fly ash Quality compliance with relevant technical indicators is of great significance to improve the overall quality of concrete.

[0003] The fly ash activity index can intuitively show the quality of the fly ash itself, but at present, the detection method of the fly ash activity index in the concrete mixing plant mainly relies on "Pozzolanic mixed materials used in cement" (GB / T2847- 2005) according to the strength index method specified in the standard "Cement Mortar Strength Test Method" (GB / T17671-199...

Examples

Embodiment 1

[0056] A kind of rapid detection method of fly ash activity index, comprises the following steps:

[0057] 1) Fly ash-Ca(OH) 2 -H 2 O hydration sample preparation: Dry the fly ash to be tested (105°C) to constant weight and cool to room temperature, weigh 5g of fly ash sample and the same mass of calcium oxide, then weigh 0.1g of active activator and 0.5 g calcium stearate, put them into a clean 200ml beaker together, measure 50ml of distilled water with a measuring cylinder and pour it into the beaker, and put it into an ultrasonic disperser to fully disperse the substances;

[0058] 2) Fly ash-Ca(OH) 2 -H 2 O Hydration sample curing: seal the beaker and put it in a water bath (80°C) for 8h and 72h respectively, and take out the beaker every 8-12h and stir (1min) and put it back quickly to avoid the hydration sample in the beaker from sinking Bottom agglomeration affects the progress of the secondary hydration reaction;

[0059] 3) Grinding and sieving: After curing to t...

Embodiment 2

[0072] The detection method described in Example 2 is roughly the same as that in Example 1, except that the temperature of the constant temperature water bath is adjusted to 90°C for constant temperature water bath maintenance. The analysis results of the fly ash activity index obtained in this example were compared with the activity index R based on the intensity index method, and the results are shown in Table 3.

[0073] Table 3 Example 2 and the traditional activity index detection results based on the intensity index method

[0074]

[0075]

[0076] It can be seen from Table 3 that under the condition of 90°C constant temperature water bath curing, the 8h activity index of Example 2 is 1-2% higher than that of Example 1, and the 72h activity index is roughly the same, and compared with the activity index R obtained by the traditional strength index method , comparable detection results can be achieved.

[0077] The above results show that as the temperature of th...

technical field

[0001] The invention belongs to the technical field of detection of concrete raw materials, in particular to a rapid detection method of fly ash activity index. Background technique

[0002] Mineral admixtures such as fly ash are widely used in commercial concrete, and participate in the cement hydration process, which has a significant impact on the workability, strength development, durability and volume stability of concrete. Therefore, to ensure that fly ash Quality compliance with relevant technical indicators is of great significance to improve the overall quality of concrete.

[0003] The fly ash activity index can intuitively show the quality of the fly ash itself, but at present, the detection method of the fly ash activity index in the concrete mixing plant mainly relies on "Pozzolanic mixed materials used in cement" (GB / T2847- 2005) according to the strength index method specified in the standard "Cement Mortar Strength Test Method" (GB / T17671-199...

Examples

Embodiment 1

[0056] A kind of rapid detection method of fly ash activity index, comprises the following steps:

[0057] 1) Fly ash-Ca(OH) 2 -H 2 O hydration sample preparation: Dry the fly ash to be tested (105°C) to constant weight and cool to room temperature, weigh 5g of fly ash sample and the same mass of calcium oxide, then weigh 0.1g of active activator and 0.5 g calcium stearate, put them into a clean 200ml beaker together, measure 50ml of distilled water with a measuring cylinder and pour it into the beaker, and put it into an ultrasonic disperser to fully disperse the substances;

[0058] 2) Fly ash-Ca(OH) 2 -H 2 O Hydration sample curing: seal the beaker and put it in a water bath (80°C) for 8h and 72h respectively, and take out the beaker every 8-12h and stir (1min) and put it back quickly to avoid the hydration sample in the beaker from sinking Bottom agglomeration affects the progress of the secondary hydration reaction;

[0059] 3) Grinding and sieving: After curing to t...

Embodiment 2

[0072] The detection method described in Example 2 is roughly the same as that in Example 1, except that the temperature of the constant temperature water bath is adjusted to 90°C for constant temperature water bath maintenance. The analysis results of the fly ash activity index obtained in this example were compared with the activity index R based on the intensity index method, and the results are shown in Table 3.

[0073] Table 3 Example 2 and the traditional activity index detection results based on the intensity index method

[0074]

[0075]

[0076] It can be seen from Table 3 that under the condition of 90°C constant temperature water bath curing, the 8h activity index of Example 2 is 1-2% higher than that of Example 1, and the 72h activity index is roughly the same, and compared with the activity index R obtained by the traditional strength index method , comparable detection results can be achieved.

[0077] The above results show that as the temperature of th...

Images