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Analysis test of water-cement ratio of concrete mixtures (frying method)
2024.12.30
Purpose and Scope
Determine the water-cement ratio of the concrete mix.
2 Instruments and Equipment
1 balance scale: weighing 2kg, sensitivity 1g
2 electric stoves: 2000W (for easy control, *** connected with a voltage regulator);
3炒盘：铁制，2-4个；
3 frying pans: iron, 2-4 pieces;
4 sieves: one with a pore size of 0.16mm and one with a pore size of 5mm.
5 small iron buckets: with a capacity of about 2 liters, two of them.
Mix and shovel 6.
3 Experimental Steps
Determination of fineness modulus ƒ: The same as the provisions related to the "Analysis Test of Water-Cement Ratio of Concrete Mixtures (Water Washing Method)" in 3.11.
Determine the water absorption rate of sand: in accordance with the relevant provisions of DL/T 5151-2001.
3. Use a 5mm sieve to quickly sieve about 2kg of mortar samples from the concrete mix to be analyzed, divided into two portions. Each sample is about 800g, placed on a frying pan of known mass (G0) for testing according to the following steps.
The total mass of the mortar sample and the pan is Gl, and the mass of the mortar sample is Gm = Gl - G0.
Place 5 frying pans containing mortar samples on an electric stove to dry the mortar. After cooling, weigh the frying pans and the total mass of dried mortar samples (G2).
Put the dried mortar sample in a small iron bucket, add water and stir to separate the cementitious material from the sand. After stirring, let it stand for about 10 seconds, and discard the suspended cementitious material through a 0.16mm sieve. Add water to the bucket again, repeat the above operation until most of the cementitious material is removed. Then place the sand on a 0.16mm sieve several times, wash it with water, then put it on a frying pan to dry, weigh the mass of the sand (G3) after cooling.
Experimental results processing
The quality of sand, cementitious materials, and water in the test sample are calculated according to formulas (3.12.4-1), (3.12.4-2), and formula.
The calculation (3.12.4-3) is: 0.12
WS=G3(1+ƒ)(1+a1） ( 3.12.4-1) translates to "WS equals G3 times the quantity of 1 plus ƒ times the quantity of 1 plus a1"
WW=(G1-G2)-G3(1+ƒ)a1 can be translated into English as:
WW equals the difference between G1 and G2, minus the product of G3, the sum of 1 and ƒ, and a1.
Wcm equals Gm minus Ws minus Ww
In the formula: Ws, Wcm, Ww - the mass of sand, cementitious material, and mixing water in the mortar sample, g;
The total mass of the sand sample before roasting and the roasting pan, in grams.
G2 - Mass of mortar sample after drying and total mass of pan after drying, in grams.
Gm - mortar sample mass, g;
G3 - Quality of sand after washing and drying, g;
The saturated surface dry absorption rate based on dry sand as a reference, %.
粉砂修正值。 translates to "Powder sand correction value."
The actual water-cement ratio is Ww/Wcm.
Take the average of two measurements as the experimental result.
Note: The test results processing is the same as that of the "Concrete Mix Water Cement Ratio Analysis Test (Water Washing Method)" on March 11th.
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