DD157028A1 - METHOD FOR THE CONTROLLED TREATMENT OF HEAT TREATMENT IN CONCRETE FINISHED COMPONENTS - Google Patents

Abstract

The invention relates to a method for the controlled course of the heat treatment in concrete finished parts in the time domain of Durchwaermephase. The invention aims to increase the quality of concrete precast elements with minimal consumption of energy and cement. According to the invention, the supply of heat energy is periodically controlled, whereby an analogue course of the temperature in the range of the set max. and min. Temperature for the heat treatment is achieved. This has the consequence that at the time of the temperature decreases due to the thermal conductivity of the concrete a more even redistribution of the heat field achieved and the moisture migration is reduced within the concrete.

Description

Method for the controlled course of the heat treatment in concrete finished parts

Applicatio ndungsgebiet e rfi invention

The invention relates to a method for the controlled course of the heat treatment in prefabricated concrete elements for housing construction in the time domain of the warm-through phase.

C harakter is lic of known technical solutions

In the manufacturing process and in the supply of precast concrete and reinforced concrete components, various demands are placed on the strength of the concrete.

Modern binders harden slowly under normal humidity and temperature conditions. »This causes the concrete to reach the so-called stripping strength only after a few days. The natural hardening of the concrete therefore inevitably leads to a large number of forms and to the enlargement of production areas in the production of finished products.

In order to shorten the duration of the production process and improve the ITutzung of forms, equipment and the production area below and thus influence dio production efficiency _t v / you end sur acceleration of Srhärtungsvorganges Wanabehandlungsver- go to "

Here, the heat treatment .der Beton- and reinforced concrete precast by evaporation in chambers Ъэі normal atmospheric pressure or with steam-air mixtures and temperatures on average from 60 to 100 ⁰ O, by Hochuruckbeaampfung in autoclaves by means of saturated water vapor and at temperatures of 175-190 ⁰ O as well as by heating in closed forms пгіѣ delivery of v / arms to the concrete performed by the enclosing area of S'orffl *

As further methods, the Elcktroergic rank with flow of electric current directly through the concrete element, the concrete reheating by means of infrared radiation, and the inductive concrete heating within an electromagnetic field are ended.

All heat treatment methods make it possible to reduce the hardening time because at elevated temperatures the hydration and hydrolysis of the cement is shortened, the formation of a supersaturated solution and formation of a coagulating structure under the influence of molecular adhesive forces accelerates the more intensive formation of a larger amount of smaller crystallization centers is achieved «,

In this case, the high temperature must be associated with a necessary for a normal hydration of the cement moisture of the concrete *

The heat treatment under elevated temperatures and under favorable humidity conditions leads to premature termination of the hydration and to its faster course in the initial phase, which results from the inadequate penetration of the water into the depth of the grain and from the rapidly compressing coating around the hydrated formation of the protein Thus, an unwanted coarsely crystalline structure is formed, as a result of which the contact areas between Sen crystals decrease, vms leads to a reduction of the final strength.

Further structural disturbances of the concrete are due to the rapid development of internal pressure in the concrete during heating due to significant differences in the coefficients of thermal expansion of water and air in comparison to the solid bonds and the associated partial softening gradient within the finished part.

A disadvantage of the said method is that when the temperature rises and within the Boirchwärmephase the moisture migrates from the outer heated layers in the colder inner layers of the concrete and during the cooling phase after completion of the soaking process, the Feuch-. action from the warmer inner layers to the cooling outer surface layer. This leads to StrukturstörungeH by increases in the Gesamtporenimimes, creating directed capillary _t which adversely affect the properties of the concrete, 'such as frost resistance, impermeability, etc. "

Object of the invention

By the invention, a method is to be created in which the Kachteile sum state of the art are eliminated by improving the quality with minimal consumption of energy and cement *

Presentation of the VTesgns of the Er.find ung

The object of the invention is to provide a method for the controlled flow of the heat treatment in concrete precast elements for housing in the time range of heat so ZVL ßaS reduces the moisture migration within the'Betons and a more uniform redistribution of the heat field is made possible.

According to the invention, this object is achieved in that, by means of a periodically controlled supply of the thermal energy, an analogue flow of the temperature for the heating

in the case of precast concrete elements, whereby the moisture migration within the concrete is reduced and a more uniform distribution of the heat field is achieved at the times when the temperature of the concrete melts due to the thermal conductivity of the concrete .

The invention will be explained in more detail below with reference to an exemplary embodiment ^1. "

The accompanying drawing shows:

Pig · 1 = Cycle of the heat treatment according to the isothermi-Bchen regime with constant temperature control

Pig * 2 = Cylusus of heat treatment according to the isothermal regime with periodically controlled supply of heat energy

The entire cycle of warm treatment is divided into the following phases;

Ky = preliminary storage to the beginning of V / arm treatment

Ay a warming up of the concrete elements "to sum projek-

, tFejnperaturwert'Kjj

  D = heating of the concrete elements up to the specified lateral flow ЛЬ = cooling.dea.- concrete elements

The periodically controlled supply of "thermal energy, Fig. 2, takes place only for the fixed side dsr heat-up phase D for the Betorielcmente" Aufwänaphase Au and the Ablnihlphase Ab at periodically controlled supply dor ffarmsehergie, Fig « 2 _t corresponds to those at constant temperature control according to Pig " 1*

At the end of the presentation K ^ the actual heat treatment cycle begins with warming-up of the concrete elements by full supply of Y / thermal energy for the first time reaching the specified NFEX. Temperature K _D1 . After that, the complete throttling of the fi'ärmeeinzuführung и1, m2, иЗ, ..... mn until the specified min. Temperature K ^ g with the subsequent full supply n1, d2, n3, 'nn, to z \ ir max.

Temperature Kj ₃₁ . This periodic progression between temperature decrease m1, m2, m3,..., Mn and temperature increase El, n2, n3,... Nn within the values Kj ₃₁ and ICgg is repeated during the entire warming-up phase D.

The duration of the throttling of the heat energy and thus of the temperature reductions at the times m1, m2, m3,, mn is given by the thermal conductivity of the concrete, a uniform redistribution of the energy field within the concrete and a reduction of the moisture content.

As a result, in the treatment of concrete precast concrete elements to achieve the planned strength at Gleichera Zesenteinsatz the time course for the DurotoSrmphase D shortened or at the same time for the Durchv / Märmphase B cement use compared to the "VTarmbehandlungsverfahren nit constant Temperaturregeluiig shown in FIG. 1 reduced can.

The definition of the parameters for the heat treatment, such as time delay for DurehvjKrmen D, setting the max. Temperature Kj ₃₇ and min. Temperature Κ ^ -, ρ »depend on the type and dimensions of the concrete precast elements.

Claims (1)

Erflacm "gsanspri'.oh Method for the controlled course of the heat treatment of precast concrete elements in the phase dea ШгоЬѵ / märmvorgangea (D), characterized in that by a periodically controlled supply of the "energy еЗлі analogue Verlaiif the temperature (m1, n1, m2, n2 .... . on, nn) (within the set max "temperature Kj, -.) and minimum temperature (Krjp) is done for heat treatment in concrete prefabricated elements, thereby dampening Igke it stands tion reduced within the concrete and (at times the Tenjperatiirabsenkungen m1 , пі2, шЗ, in4 «> ♦«. ип) until reaching the minimum temperature (Kj) ₂ ) as a result of the thermal conductivity of the concrete a more even redistribution of the heat is achieved » To this 1 ssiie drawings