DD288144A5 - METHOD FOR PRODUCING A TRANSPORTABLE ANHYDRITE MORTAR - Google Patents

Abstract

The method of making an anhydrous bovine transportable is used to retard initial hardening and serves to prevent the setting of the mortar over a longer period of time. The Anhydritmoertel held for several hours while preserving the Abbindevermoegens is ready mixed in a heatable Mischgefaesz of natural or synthetic anhydrite, aggregates, water and plasticizers and maintained during mixing and transport at a temperature above 35C and well below 60C. For energetic reasons, a temperature of 35 to 40C is sufficient.

Description

Field of application of the invention

The process serves to produce a mortar based on natural or synthetic anhydrite which has been delayed in its initial hardening and can thus be transported over a relatively long distance.

Characteristic of the known state of the art

Ready mixed screed mortar on the basis of natural or synthetic anhydrite has a processing time of about 30 minutes after the addition of water, that is, it is available for the promotion and distribution at the installation for a limited time. If the screed mortar does not come to rest after this time, no hardening process is achieved. This happens, for example, during the transport of mixed mortar in rotating transport containers, while in contrast, cement-bound mortar can be kept workable over several hours. Also, the so-called dry premix is not a successful solution. Experience has shown that so-called dry sands only sand qualities with a certain intrinsic moisture available. Furthermore, have central mortar mixing plants no technological requirements for sand drying, the usual storage of sand is still under the open sky, so that a really dry sand is not available. "Dry" premixes have been tried by various construction companies in recent years, with the result that the always present low residual water content in the sand led to a conversion of the binder.

Although apparently dry and free-flowing products are present after transport, considerable amounts of binder have already been converted into calcium sulfate dihydrate so that no setting ability is left or enormous decreases in the strength behavior occur.

In DRP 510,699 a process for the preparation of liquid to be obtained Brannt-Gipsmörtelmischungen is given, which are obtained in a temperature range well above 60 ° C to near 100 ⁰ C liquid over a period of several hours, but a temperature drop below 60 ⁰ C is to be avoided , with the! Note that from 5O ⁰ C used a hardening, which runs very rapidly in the temperature range of 38 to 45 ⁰ C. This temperature range is energy-consuming, not unproblematic in terms of industrial safety and is not applicable due to another reaction mechanism for anhydrite binders.

Object of the invention

The aim of the invention is to avoid the setting of the Anhydritmörtels over a longer period.

Explanation of the essence of the invention

It was the object to develop a process by which an anhydrite mortar can be prepared and kept flowing for several hours while preserving the setting capacity.

The object is achieved in that an anhydrite mortar of natural anhydrite, additives, water and other additives, such as plasticizers, is mixed ready in a heatable mixing vessel, wherein according to the invention, the temperature is 35 to 40 ° C. It has been found that the temperature according to the invention above 35 ⁰ C and 6O ⁰ C are significantly below should. During transport, the mass is protected by suitable devices from cooling and transported at 35 to 40 ° C. After casting, leave the mass of its natural cooling and curing in place.

embodiments

Example 1 (Laboratory test)

In a laboratory mixture, 2 liters of water, 6.5 kg of anhydrite binder, 6.5 kg of sand and 65 ml of plasticizers were mixed and simultaneously kept warm with a heating coil, which was controlled by a thermostat, at 35 ° C. for 24 hours. With a laboratory stirrer at the same time every 2 h, the mixture was stirred for I min.

After mixing the fresh mortar and after 24h held by the liquid mortar test specimens were prepared.

The following parameters were obtained: fresh mortar

Compressive strength 28d: 35.9MPa Flexural strength 28d: 11.2MPa mortar held at 35 ° C for 24 hours Compressive strength 28d: 25.4 MPa Flexural strength 28d: 7.5MPa

Example 2 100 liters of water, 300 kg of anhydrite binder, brand FA-E of the VEB Leuna-Werke "Walter Ulbricht" were used in a 10OO-liter mixer. Gypsum works Niedersachswerfen, 300kg sand and 31 plasticizer "Viskomin" (manufacturer VEB Stickstoffwerk Piesteritz) mixed

and heated to 4O ⁰ C by a heating coil located in the mixing vessel. The heating process can be done by using

Hot water can be abbreviated. In a transporting vessel provided with a heating coil were several mixtures

driven together to the installation site. The Transportgofäß was also isolated against heat loss. A revolution or

Stirring during transport can be carried out, but is in principle not required for liquid maintenance, but

prevents only Sedimontationserscheinungen ago. On site, the contents of the transport vessel by means of a

Mortar pump brought to the place of installation, distributed and left to self-cooling and curing. The following parameters were measured: fresh mortar Compressive strength 28d: 31,6 MPa Bending tensile strength 28d: 9.6 MPa Mortar, held for 2 h at 35 to 40 ° C and transported Compressive strength 28d: 29.4MPa Bending tensile strength 28d: 9.5 MPa

Claims (2)

1. A process for the preparation of a transportable Anhydritmörtels, wherein in a heatable mixing vessel of Anhydritmörtel of natural or synthetic anhydrite, additives, water and other additives, such as plasticizers, is ready mixed, characterized in that the finished mortar during mixing and during transport is kept at a temperature above 35 ⁰ C and well below 6O ⁰ C. 2. The method according to claim 1, characterized in that dio temperature is 35 to 4O ⁰ C.