Технические
науки/Отраслевое машиностроение
УДК
666.97.052
Candidate of technical sciences Nurmukhanova A.Z., Candidate of physical and mathematical sciences Mukhtarova M.N., Nurseytova A.K.,
Konakbaev B.O.,
Ermaganbetova S. D.
Kazakh National University named after Al-Farabi, City
of Almaty
Republic of Kazakhstan
Evaluation of technical condition of
stationary concrete made equipment
Due
to the high growth rate of construction, the use of modern high-performance
machines and mechanisms, improvement of the technology and organization of
construction processes, introduction of new advanced forms of work organization
with automated systems and computing machinery using, the construction has
become one of the leading industries.
As
is known, concrete and mortar are the one of the main types of building
materials. They are prepared centralized as at large factories, as well at the
construction site.
At
the enterprises all processes are fully automated with the exception of
determining the moisture of aggregates. Beside the fact of reducing the
preparation complexity of the concrete mixture the quality of the concrete
dramatically improves, as it increases homogeneity.
In
Kazakhstan various plants for concrete mixing are being certified. Stationary
plants are divided into three categories according to the performance: high,
medium and low power. Stationary high productivity plants process 23 000000 m3
per year of concrete mix, and the performance of medium and small plants is
37,000 and 29,000 m3 per year of concrete mix.
To
provide concrete mixes facilities the mobile or stationary concrete mixing
plants are used.
Concrete
plant and facilities may be cyclic (periodic) and continuous. The cycle
consists of the three operations: loading of raw materials in the concrete
mixers, mixing and unloading of raw materials in the concrete mixer, mixing and
ready mix unloading. This scheme allows changing the dosage quickly and issuing
within the concrete mix change with different parameters: mobility, brand, etc.
On
factories and facilities of continuous dosing process, unloading, mixing and
dispensing of ready mix proceed without interruption. Such installations should
be appropriately placed where a large number of concrete with the same process
parameters are need to be received.
To
obtain concrete or mortar of specified composition correctly the measure of the
amount of the components prior to entering the mixer has to be set. A
predetermined amount of components can be measured in volume, weight or volume
of a correcting weight (for lightweight aggregates). Deviation from a
predetermined number of doses of the content or another material refers to a
percentage. According to GOST 7473-85, permissible error dosage for binders,
water and additives is + 2% and + 2.5% for aggregates.
Batchers
serve for storage of materials and therefore they have relatively greatest
heights relative to dimensions in plan. Batchers have different shapes, as they
are used in a various conditions. By the form and terms the batchers are round,
rectangular and slotted. Simple batchers are one solid geometry; usually
complex ones consist of two bodies. The upper part of the complex batchers is
called body, lower part is called bottom. Round batchers have the form of a
truncated body and truncated bodies with cylinder, rectangular batchers have
the form of a truncated pyramid or prism with its combination. A batcher’s
discharge port is on its axis or it is shifted to the side. More complex forms
of round or rectangular batchers are rare.
Recently,
some enterprises apply equipment for a vibrated method of preparation of the
concrete mix. During the vibratory mixing the cement paste has conditions
similar to those that arise in vibratory grind with grinding bodies that cause astringent body to be activated, water is evenly distributed
in the cement and achieved some of its dispersion. Vibratory mixing is
particularly effective for hard mixes with low VTS which are difficult to
prepare in a conventional mixer. Vibratory mixed concrete is stronger in
comparison to concrete prepared in serials. In addition, the increase of
strength depends on the homogeneity of the mixtures. Due to the lack of serial
vibratory grinds for the improvement of the concrete mixtures mixing, an
additional device that transmits vibratory pulses to the stirred mixture is
used.
To
ensure a layered expiration of material under normal angles of inclination of
the bottom wall (5 ... 10 greater than the angle of repose of the material) the
vibrators are applied. Vibrators affect the material through the bottom wall of
the batchers, inform to the material its fluidity and provide layering
expiration.
Batcher
valves prevent self-productive rash of material from the outlet of the batcher
or silo, and provide adjustable unloading material. The main requirement for
the seal structure is reliability and ease of management. The gate should not
be opened under the influence of material falling pieces during loading into an
empty tank and the pressure of the material at full load. The most widely used
batcher gates are made in the form of valves, gate valves, trays, sectors,
chain curtains. Closures are also different in feeders design. They ensure
uniform supply of material from the batchers into processing machines or means
of continuous transport.
As
can be seen from the above material, equipment for making concrete mixed
mixture is sufficient as on the device as well on the methods of service and
exploitation, and in some cases requires innovative approach to maintain and
repair it.
Literature:
1.
Nurmukhanova A.Z. Evaluation of the
technical condition of the equipment stationary concrete preparatory works.
//Proceedings of the X Anniversary International Scientific Conference
"Science and Education - a leading factor in the strategy" Kazakhstan
- 2030 ". Issue 2 -Karagandy, 2007. - P.454 – 456.
2.
Erehinsky V.V. Efficiency and
quality of construction. Gorkiy: Volga - Vyatka book. publishing house, 1981.
-223 p.
3.
Kessel L.A. Cost-effectiveness of
new technologies and methods for its determination. – М.: GosINTI, 1976 y.