RU2525150C2 - Method for determination of mean density of polystyrene filler granules for polystyrene concrete - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: invention relates to construction materials, in particular, to methods for determination of mean density of grains of coarse and fine filler for concrete and mortar mixes, specifically - to a method for determination of mean density of foamed granulated polystyrene filler granules for polystyrene concrete. The method for determination of mean density of foamed granulated polystyrene filler granules for polystyrene concrete in water consists in the following: as reference containing inter-grain medium one uses 15-25°C water modified with an air-removing organic-silicon additive with concentration equal to 0.001-0.01% of the water weight. A sample of polystyrene granules (preliminarily dried and cooled) is placed into a preliminarily weighed graduated metal cylindrical vessel with volume V_v. Then one performs compaction by way of slight tapping of the vessel bottom against a solid surface for 5-10 s for the top granules to lie within one and the same horizontal plane and be aligned with the vessel rim edges. Then the vessel with compacted granules is weighed, covered with a sieve with mesh size at least 0.3 mm less than the granules minimum size, weighed again, filled with water modified with an air-removing organic-silicon additive within the inter-grain space volume (V_a); 5 min after filling up with water, one measures the total weight (∑M) of the experimental measurement device inclusive of the weight of the graduated metal vessel (m_v), the weight of the sieve (m_s), that of polystyrene granules (m_g) and that of water spent (m_w).

EFFECT: higher precision of parameter measurement.

2 cl, 1 dwg, 1 tbl

Description

The invention relates to building materials, in particular to methods for determining the average density of grains of coarse and fine aggregate for concrete and mortar mixtures, and more particularly, to a method for determining the average density of granules of granular polystyrene foam granular aggregate (PVG) for polystyrene concrete.

A known method for determining the average density of grains of coarse aggregate in a cement paste.

The essence of the method is as follows.

A 3.5 l sample is taken from the dried sample, mixed on a pre-moistened baking sheet with a sample of cement in the amount of 1.7 kg and quartz sand in the amount of 3.4 kg. Water is gradually poured into the resulting mixture until an inactive concrete mixture is obtained with a hardness of 5-10 s. The amount of water consumed is measured.

The mixed mixture is kept for 15 minutes and then completely placed in a pre-weighed vessel with a capacity of 5 l. The mixture in the vessel is compacted by vibration for 30-60 s on a vibrating platform.

A vessel with a compacted mixture is weighed and the mass of the mixture in the vessel is determined with an error of up to 10 g and the volume of the mixture in the vessel with an error of up to 10 ml.

The average density of the grains of coarse aggregate is determined by dividing the mass of the dried sample by its volume.

A known method for determining the average density of grains of sand in a cement paste.

The essence of the method is as follows.

A sample of 0.9 l was taken from a dried sample to a constant mass of sand and mixed on a pre-moistened baking sheet with a sample of cement of 1 kg. Water is gradually poured into the resulting mixture until a plastic mortar mixture is obtained with a mobility of 6-8 cm. The amount of water consumed is measured. The mixed mixture is kept for 15 minutes and then placed in a 1 liter pre-weighed measuring vessel.

The mixture in the vessel vibrates for 5-10 s until complete compaction, characterized by abundant release of cement glue on the surface of the mixture. Then the vessel is weighed and calculate the average density of the prepared mixture in a compacted state.

The average density of fine aggregate grains is determined by dividing the weight of the dried sample by its volume.

A disadvantage of the known technical solutions is the impossibility of obtaining uniformity of the polystyrene concrete molding mixture due to the significant difference in the densities of the cement paste and polystyrene aggregate, which are respectively at the level of 1800-1900 kg / m ³ and 18-23 kg / m ³ . With this ratio of cement paste and aggregate, vibration compaction leads to a sharp stratification of the mixture with a mixture mobility of 6-8 cm.The lightweight polystyrene aggregate floats up, and the cement paste mainly concentrates in the lower part, which can lead to distortion of the results of final determinations of average density.

In addition, the known method is busy, inconvenient, and time-consuming (GOST 9758-86, clause 7.4.1 and clause 7.5).

The closest in technical essence and achieved effect is the determination of the average density of coarse aggregate grains by the hydrostatic method (according to GOST 9758-86) by the mass difference of a special container with a sample before and after it is saturated with water when weighed in water and in air.

The average grain density of the coarse aggregate of each fraction is calculated as the arithmetic average of the results of two parallel determinations, each of which is produced on a new portion of aggregate.

A disadvantage of the known technical solution is the relative complexity of the hardware design, in particular, weights for hydrostatically weighing aggregate granules and a special container for filling with water, as well as the inefficiency of using a special container that is not suitable for working with extremely light particles of polystyrene aggregate, whose density is two orders of magnitude lower than the density coarse aggregate used in heavy concrete (GOST 9758 p. 4 determination of the average density of coarse grains aggregate).

The technical problem is to create a convenient, efficient, low-cost and relatively quick way to determine the average density of polystyrene aggregate granules for polystyrene concrete.

This goal is achieved in that the sample of polystyrene granules 4, pre-dried at a temperature of not more than 60 ° C and cooled to a temperature of 15-25 ° C, is placed in a pre-weighed measured metal cylindrical vessel 3 (see Fig. 1) with a volume of V _s , they are compacted by lightly tapping the bottom of the vessel on a solid base 5 for 5-10 s so that the granules lie in the same plane horizontally and coincide with the edges of the upper edge of the vessel, then the vessel with compacted granules is weighed, covered with a 2 mesh sieve cells is not less than 0.3 mm smaller than the smallest granule size and is weighed again, filled through funnel 1 with water in the intergranular space (V _c ) and 5 minutes after filling with water (or water modified with an air-removing organosilicon additive of type 139-282 s concentration of 0.001-0.01% of the mass of water), measure the total mass (∑M) of the experimental measuring device, including the mass of the measured metal vessel (m _s ), the mass of the sieve (m _st ), the mass of polystyrene granules (m _g ) and the mass consumed water (m _in ).

The average density of polystyrene aggregate granules for polystyrene concrete is determined by the formula

, $${\rho }_{P\mathrm{AT}G}=\frac{\Sigma M-\left(m_{\mathrm{from}}+m_{\mathrm{from}t}+m_{\mathrm{at}}\right)}{V_{\mathrm{from}}-V_{\mathrm{at}}}$$

,

where ρ _PVG is the average density of PVG granules, g / cm ³ ;

∑M is the total mass of the measuring vessel together with the mass of sieves, PVG granules and consumed water in a volume of V _c , g;

m _{with the} mass of the measuring vessel, g;

m _article is the mass of the sieve, g;

m _in - the mass of consumed water, g;

V _in - the amount of consumed modified filling water, cm ³ ;

V _{with the} volume of the measuring vessel, cm ³ .

The materials and apparatus used for the known and proposed methods for determining the average density of granules of PVG polystyrene aggregate granules for polystyrene concrete and the results of comparative tests are shown in the table.

Used materials and equipment According to the prototype (GOST 9758-86 p. 4) According to the proposed method one 2 1. Water according to GOST 23732-79 1. Water according to GOST 23732-79, modified with an air-removing additive 2. A special container with a lid to saturate the filler according to GOST 9758-86 2. Measured metal cylindrical vessel with a capacity of 2 l (see Fig. 1) 3. Scales for hydrostatic weighing in accordance with GOST 24104-80 3. Electronic scales with a mechanism for zeroing the readings of the previous weighing 4. Scales for static weighing in accordance with GOST 23676-79 4. A sieve with openings with a diameter of at least 0.3 mm smaller than the smallest granule size 5. Sieve with holes 5, 10, 20, 40 mm 5. Drying cabinet in accordance with OST 16.0.801.397-87 6. Drying cabinet in accordance with OST 16.0.801.397-87 The disadvantages of the method The advantages of the method 1. The presence of a relatively complex special container with a lid for saturation of polystyrene aggregate granules of complex design. The apparatus is equipped with through holes along the entire lateral surface with a diameter of 4 mm with a pitch of 3 mm, which limits its use for determining granules of polystyrene aggregate with a diameter of less than 4 mm 1. The simplicity of the hardware design, its accessibility and relative ease of use in the presence of electrostatic properties of adhesion of PVG particles to various surfaces 2. The presence of the operation of removing water from the container for 10 minutes to re-weigh the container 2. There are no operations to remove water from the measuring vessel 3

one 2 3. The need to use scales for hydrostatic weighing 3. Instead of scales for hydrostatic weighing, electronic scales with a built-in zeroing mechanism use the previous weighing 4. Unsuitability and inefficiency of using a special container for working with especially lightweight particles of polystyrene aggregate grade PVG, the density of which is two orders of magnitude lower than the density of coarse aggregate in heavy concrete 4. The ability to obtain reliable results of determining the average density of PVG granules through the use of water, a modified air-removing additive, eliminating pinching of air bubbles. The relative measurement error of the proposed method is 10-15% lower compared to the known technical solution with significantly reduced time costs. 5. The inconvenience of working with the container when using light PVG particles having the properties of electrostatic attraction to the surface of the container 5. The efficiency of the analysis. The duration of one determination from the moment of loading the dried granules of PVG in a measured cylindrical vessel is 10-15 minutes 6. Possible distortion of the analysis results due to pinching of water in the intergranular space 7. The relative duration of the analysis. The duration of one determination from the moment of loading the dried granules of PVG in a special container is 45-60 minutes

An analysis of the tabular data shows that the application of the proposed method for determining the average density of granules of PVG polystyrene aggregate leads to a significant simplification of the hardware design, reduction of 2-3 times or more time spent on determining and improving the accuracy of parameter measurement. The relative measurement error of the proposed method is 10-15% lower compared to the known method.

Claims (2)

1. A method for determining the average density of polystyrene aggregate granules in water for polystyrene concrete, including the preparation, testing and processing of test results, characterized in that water is used as a reference containing intergranular medium at a temperature of 15-25 ° C, modified by an air-removing additive to a concentration in water at a level of 0.001-0.01%, while a sample of polystyrene granules, previously dried at a temperature of not more than 60 ° C and cooled to a temperature of 15-25 ° C, is placed in a preliminary a weighed measured metal cylindrical vessel with a volume of V _s is compacted by lightly tapping the bottom of the vessel on a hard surface for 5-10 s so that the upper granules lie in the same plane horizontally and coincide with the edges of the upper edge of the vessel, then the vessel with compacted granules is weighed, cover with a sieve with a mesh size of at least 0.3 mm smaller than the smallest granule size and weigh it again, fill it with water, a modified air-removing additive in the intergranular space (V _in ), and h 5 min after full filling with water, measure the total mass (∑M) of the experimental measuring device, including the mass of the measuring metal vessel (m _s ), the mass of the sieve (m _st ), the mass of polystyrene granules (m _g ) and the mass of water consumed (m _in ) . 2. The method for determining the average density of polystyrene aggregate granules for polystyrene concrete according to claim 1, characterized in that the average density of polystyrene aggregate granules is determined by dividing the mass of dried weighed polystyrene granules by their volume by the formula
$${\rho }_{P\mathrm{AT}G}=\frac{\Sigma M-\left(m_{\mathrm{from}}+m_{\mathrm{from}t}+m_{\mathrm{at}}\right)}{V_{\mathrm{from}}-V_{\mathrm{at}}}$$

,
where ρ _PVG - PVG granules of average density, g / cm ^3;
∑M is the total mass of the measuring vessel together with the mass of sieves, PVG granules and consumed water in a volume of V _c , g;
m _{with the} mass of the measuring vessel, g;
m _article is the mass of the sieve, g;
m _in - the mass of consumed water, g;
V _in - the amount of consumed modified filling water, cm ³ ;
V _{with the} volume of the measuring vessel, cm ³ ;