Water retention test mode ￠ 100 × 25mm
The masonry cement mortar water retention rate tester is the mortar water retention rate is the quality of the water retained in the mortar after water absorption treatment, and is expressed by the mass percentage of the original water amount.

1. The principle of water retention test mode
Use the freshly mixed mortar with the specified fluidity range to perform water absorption treatment according to the specified method. The water retention rate of the mortar is the quality of the water retained in the mortar after water absorption treatment, and is expressed by the mass percentage of the original water amount.

2. Instrument for measuring the water retention rate of masonry cement mortar
2.1 Rigid test mode, round, inner diameter 100 mm ± 1 mm, internal effective depth 25 mm ± 1 mm;
2.2 Rigid bottom plate, round, without holes, diameter 100 mm ± 5 mm, thickness 5 mm ± 1 mm;
2.3 Dry filter paper, slow quantitative filter paper, diameter is 110 mm ± 1 mm;
2.4 Metal filter, mesh size 45 μm;
2.5 Metal scraper;
2.6 Electronic balance, weighing 2 kg, 0.1 g sensing capacity;
2.7 Iron mound, with a mass of 2 kg.

Measuring method of water retention of masonry cement

1. The principle of water retention test mode
Use the freshly mixed mortar with the specified fluidity range to perform water absorption treatment according to the specified method. The water retention rate of the mortar is the quality of the water retained in the mortar after water absorption treatment, and is expressed by the mass percentage of the original water amount.

2. Instruments
2.1 Rigid test mode, round, inner diameter 100 mm ± 1 mm, internal effective depth 25 mm ± 1 mm;
2.2 Rigid bottom plate, round, without holes, diameter 100 mm ± 5 mm, thickness 5 mm ± 1 mm;
2.3 Dry filter paper, slow quantitative filter paper, diameter is 110 mm ± 1 mm;
2.4 Metal filter, mesh size 45 μm;
2.5 Metal scraper;
2.6 Electronic balance, weighing 2 kg, 0.1 g sensing capacity;
2.7 Iron mound, with a mass of 2 kg.

3. Masonry cement mortar water retention tester Cement water retention tester Operation steps of mortar water retention

3.1 Weigh the empty dry test mold to the nearest 0.1 g; weigh 8 unused filter papers to the nearest 0.1 g.
3.2 Weigh 450g ± 2g cement, 1350g ± 5g ISO standard sand, measure 225mL ± 1mL water, prepare mortar according to GB / T 17671, and measure the fluidity of mortar according to GB / T2419, adjust the water volume to flow with cement mortar The level is within the range of 180mm ~ 190mm.
3.3 When the fluidity of the mortar is in the range of 180mm ~ 190mm, remix the remaining mortar in the mixing pot at a low speed for 15 s, then fill the test mortar with a spatula and smooth the surface.
3.4 Weigh the trial mold filled with mortar to the nearest 0.1 g. Cover the surface of the mortar with a filter screen, cement mortar water retention tester and put 8 pieces of weighed filter paper on the top of the filter screen, put a rigid bottom plate on the filter paper, turn the test model 180 ° upside down on the cheek The iron mound with a mass of 2 kg is placed on the bottom plate of the trial mold. Remove the iron mound after 5min ± 5s, put it back upside down again, remove the rigid bottom plate, filter paper and filter screen, and weigh the filter paper to the nearest 0.1 g.

4. Calculation of cement water retention
First calculate the water amount (Z) in the mortar before absorbing water according to formula (1):
Z = [Y × (W-U)] / (1350 + 450 + Y) …………………………………… (1)
In the formula: U--the mass of the empty mold, g;
W—the quality of the trial mold filled with mortar, g;
Y—The amount of water used to prepare the mortar with a fluidity value of 180 mm to 190 mm, g.
Calculate the water retention rate (R) according to formula (2)
R = [Z- (X-V)] × 100 / Z ………………………………………… (2)
In the formula: V—the mass of 8 filter papers before water absorption, g;
X—the mass of 8 filter papers after water absorption, g;
Z—the amount of water in the mortar before water absorption, g.
Calculate the average value of the water retention rates of the two trials to the nearest whole number. If the deviation between the two test values ​​and the average value is greater than 2%, repeat the test, and then use a batch of freshly mixed mortar for two sets of tests.