Post Date:22,Aug,2022

1. Sand: focus on checking the sand’s fineness modulus, particle gradation, mud content, mud block content, moisture content, sundries, etc. The sand should be visually inspected for indicators such as mud content and mud block content, and the quality of the sand should be preliminarily judged by the method of “seeing, pinching, rubbing and throwing”.

(1) “Look”, grab a handful of sand and spread it in the palm of your hand, and look at the uniformity of the distribution of coarse and fine sand particles. The more uniform the distribution of particles at all levels, the better the quality;

(2) “Pinch”, the water content of sand is pinched by hand, and the tightness of the sand mass is observed after pinching. The tighter the sand mass, the higher the water content, and vice versa;

(3) “Scrub”, grab a handful of sand in the palm of your hand, rub with both palms, clapping your hands lightly, and see the mud layer adhering to the palm of your hand. ;

(4) “Throw”, after the sand is pinched, throw it in the palm of the hand. If the sand mass is not loose, it can be judged that the sand is fine, contains mud or has high water content.

2. Crushed stone: focus on checking the stone specifications, particle gradation, mud content, mud block content, needle-like particle content, debris, etc., mainly relying on the intuitive method of “seeing and grinding”.

(1) “Looking” refers to the maximum particle size of the crushed stone and the uniformity of the distribution of crushed stone particles with different particle sizes. It can be preliminarily judged whether the gradation of the crushed stone is good or bad, and the distribution of needle-like particles can be estimated. The degree of influence of crushed stone on the workability and strength of concrete;

The degree of mud content can be analyzed by looking at the thickness of the dust particles attached to the surface of the gravel; the degree of grain distribution on the surface of the clean gravel can be analyzed by combining with “grinding” (two gravels against each other) to analyze the hardness of the gravel. .

Check whether there are shale and yellow skin particles in the stone, if there are more shale particles, it is not available. There are two kinds of yellow skin particles. There is rust on the surface but no mud. This kind of particle is available and will not affect the bond between the stone and the mortar.

When there is yellow mud on the surface of the particle, this particle is the worst particle, it will greatly affect the bond between the stone and the mortar, and the compressive strength of the concrete will be reduced when there are more such particles.

3. Admixtures: concrete admixtures, through visual observation of the color, it can be roughly judged whether it is naphthalene (brown), aliphatic (blood red) or polycarboxylic acid (colorless or light yellow), of course, there are also naphthalene and fat The product (reddish brown) after compounding can also be judged from the smell of the water reducing agent.

4. Admixtures: The sensory quality of fly ash is mainly judged by the simple method of “seeing, pinching and washing”. “Looking” means looking at the particle shape of the fly ash. If the particle is spherical, it proves that the fly ash is the original air duct ash, otherwise it is ground ash.

(1) “Pinch”, pinch with thumb and index finger, feel the degree of lubrication between the two fingers, the more lubricated, the finer the fly ash is, and vice versa, the thicker (fineness) is.

(2) “Washing”, grab a handful of fly ash with your hand and then rinse it with tap water. If the residue attached to the palm of the hand is easily washed away, it can be judged that the loss on ignition of the fly ash is small, otherwise the residue is relatively small. If it is difficult to wash, it means that the loss on ignition of fly ash is high.

The appearance color of fly ash can also indirectly reflect the quality of fly ash. The color is black and the carbon content is high, and the water demand is greater. If there is an abnormal situation, the mixing ratio test should be carried out in time to check the influence on the water consumption, working performance, setting time and strength.

The appearance color of slag powder is white powder, and the color of slag powder is gray or black, indicating that the slag powder may be mixed with steel slag powder or fly ash with low activity.