Laboratory work №4 Theme lessons: Determination of an average sample raw materials
The purpose of lessons: learn how to select a sample of the raw material, cement, and its main components.
The plan of lessons
1. Introduction to the procedure of GOST 30515.
2. Introduction to the method of GOST 16381 - 77. Building materials and products insulating. Classification and general technical requirements.
Running time of work – 3 hours
Brief theoretical information
To determine the properties of the raw materials or products of the average sample is taken the party. The correct selection of an average sample largely affects the accuracy of the performance properties of the tested materials.
Average sample called a relatively small amount of material, which in their chemical composition and physical properties fully consistent with the party of the material.
The average sample is taken immediately before testing shipments of raw materials or finished products.
batch size is determined by the corresponding GOST or TU. If the batch size is not specified by GOST, the material for the party taking the number of homogeneous material that has entered the production or warehouse pas at a time. If the test of a material is carried out directly in the quarry, the average sample taken at all workings, intersecting the useful thickness.
In selecting an average sample lump materials (limestone, marl, slag and t. P.) Should be kept in mind that the large pieces on the properties and chemical composition may vary from small pieces and dust full recommended to select all fractions to approximately the same ratio in which they are in this batch of material. When transporting lumpy and granular bulk materials into small pieces and dust accumulate at the bottom of the car, barge or container. The average sample in this case should be taken in the form of individual portions at different depths.
An average sample of fine-grained materials (cement, sand, etc.) are selected by means of special samplers, probes (Figure 1).
The selection of an average sample of liquid and semi-liquid materials (sludge, suspensions, emulsions, and so on. N.) Produced using booties, glass tubes or special samplers. For example, special cups (Figure 2) is used to select sample slurry or slip.
1
2
Figure 1 - Sampler for fine-grained materials |
a) is closed; b) open Figure 2 - Mug for sampling of sludge and slurry |
Na mug lowered certain depth and pulling up a rope attached to the top cover. The lid is raised, opening the feed opening, and a mug filled with slurry or slip. With the weakening of the rope cover under its own weight nada down, closing the opening. With such devices average sample slurries or other suspension can be taken with any container depth.
For testing generally requires a relatively small amount of material is significantly lower than it is contained in the selected sample medium, so the original average sample cut, bringing it to the desired value. Along with the reduction in the average sample material is ground by crushing or grinding.
The lowest average amount of ground sample taken for testing, the lab called the average sample. This sample is stored in a special container, usually keeps the material on changes in its composition and moisture. Part of the samples intended for testing or analysis and the other part is used for backup and retesting or arbitration analysis.
Reducing average sample lumpy and granular materials are produced by scooping, quartering or using special separating machines.
With the reduction of the average of the sample by quartering the material is thoroughly mixed and poured on a flat surface in the form of a cone. Then align the board or shovel so as to obtain a truncated cone which top is divided in two mutually perpendicular lines into four equal parts. Two opposite parts are discarded, and the remaining two again subjected quartering. This operation is continued until the average sample until it reaches the required value.
scooping method consists in the fact that small-largest average sample of the bulk material is distributed Race layer on a steel or plywood sheet and give it the shape of a square or straight-sided polygon. Then a square or rectangle divided line nine, fifteen or twenty squares. Each square (or every second square) with a spatula or sovochkom taken certain portion of the material. Selected portions pour together and mixed well.
Scooping method of cutting a small-largest average sample. Typically, an average sample cut first quartering or by dividing apparatus, and then, when it reaches the small quantities used scooping method.
The use of special devices, dividers can significantly accelerate the process of reducing the average sample. There are many different designs of separating apparatus. One of such devices (see Figure 3) is a hopper with several divisions of equal volume.
Figure 3 - Separating machine
The hopper is loaded gradually average sample, which is distributed evenly over its branches. Part of the samples of one or two compartments are further reduction and the remainder discarded, etc.
Finished articles average sample depending on the batch is taken as a certain number of products as follows. Party goods, such as diatomite bricks are placed in cells with an approximate size of 1x1 and a height of 1.8-2.0 m (250 pcs.). Because each cell is taken a certain number of bricks (usually cells seats five bricks).
Selected average sample of finished products pass an external examination. After that, a minimum number of products selected for the respective tests. The remaining product is attached to the consignment.
If the finished products are subjected to physical and chemical testing or chemical analysis on the part of the average sample specimens chip pieces, which are then milled to the required particle size. For example, in chemical analysis lightweight refractory material chips from the pieces of all products inspected for appearance, or to all samples after test compressive strength.
Equipment, tools and technical means: natural raw materials; shaker; a set of screens; jaw crusher; Ball Mill.
The order of performance of works in the audience:
1. Master students familiarize with the procedures of GOST 30515.
2. Graduate familiarize with the procedures of GOST 16381 - 77. Building materials and products insulating. Classification and general technical requirements.
3. After completing the necessary information undergraduates determine the average sample of raw materials
Working process
When tested on a large-sized insulation products strength, high density, heat conductivity, resistance to frost, humidity, etc. are usually cut out, drilled or cut out samples of certain sizes and shapes. The shape and dimensions of the samples depends on the type of material and the heat-insulating nature of the test.
Testing of products from cellular concrete produced on samples cut out of the selected test plates or panels. Usually test compressive strength, frost resistance, water absorption and to produce an average density or size 10x10x10 cm 7x7x7 samples. The samples were cut out in a number of three pieces for each type of test different portions of the article. Sawing samples should be carried out so that the surface of the product was not a sample surface. This is because in the manufacture of contact with the ground in cellular concrete compacted form and at a distance of 7-10 mm from the surface properties differ from the properties of the inner layers of product.
Determination of the average density to produce mineral wool products integer, and for determining the tensile strength of them (parallel to grain) sample was cut for three size mm 260x50.
The magnitude of the seal plates to determine the load size 100x100 mm samples are cut to three selected pieces from each test plate diagonally.
Humidity boards and binder content in the product is determined pas samples in the form of cylinders with a diameter of 10 mm, which drilled the mirror drill in the amount of 12 pieces from different places products.
Test of rigid and semi-rigid materials for insulating heat conduction to produce samples of discs of 250 mm diameter and 10 mm thick.
All the small-size insulating materials in the form of bricks, blocks and small test panels mainly in the entire product and bulk (perlite, vermiculite, etc.) and loose (lump rock wool, asbestos fluff, etc.) by selecting and testing average sample.
Control questions
1. What is the average sample?
2. How otbirat average sample fine materials?
3. How otbirat average sample of liquid and semi-liquid materials?
Safety requirements
Laboratory premises in which work is performed to determine the chemical composition of cement and cement production materials should be equipped with ventilation systems in accordance with GOST 12.4.021.
When operation of electric installations and electric appliances used in the process analysis must be performed by electrical safety regulations in accordance with GOST 12.1.019.
When working with acids and alkalis, observe the safety regulations in force in chemical laboratories.
When operating the units with sources of ionizing radiation (X-ray apparatus) should be guided by the requirements of the radiation safety standards NRB-76/87 and the basic sanitary rules OSP-72/87.
When working with flammable and explosive substances must be complied with safety requirements according to GOST 12.1.010.
When working with hazardous and noxious substances is necessary to use protective equipment according to GOST 12.4.004, personal protective equipment (respirators in accordance with GOST 12.4.011 GOST 12.4.028 or rubber gloves according to GOST 12.4.103, clothing according to GOST 27654 and GOST 29058).
List of used literature:
Main literature
Жакипбаев Б.Е., Альжанова А.Ж. Композиционные силикатные материалы. Учебник для магистрантов. Изд-во ЮКГУ, 2016. – 186 с.
Bibol Ye. Zhakipbayev Composite silicate materials. Textbook for master students. SKSU published, 2016. – 180 P.
Худякова Т.М., Жакипбаев Б.Е. Технология вяжущих и композиционных материалов. Учебник для магистрантов. Изд-во ЮКГУ, 2015. – 226 с.
Additional literature
Горлов Ю.П. и др. Технология теплоизоляционных материалов. – М.: 1980. - 399 с.
Горлов Ю.П. Технология теплоизоляционных и акустических материалов и изделий. – М.: 1989. - 384 с.
Горлов Ю.П. Лабораторный практикум по технологии теплоизоляционных материалов. – М.: ВШ. 1982. – 239 с.
А.Г.Комар Строительные материалы и изделия. – М.: 1988. - 527 с.
Китайцев В.А. Технология теплоизоляционных материалов. – М: 1970. – 382 с.