DE2622465C3 - Hydraulically hardening compounds reinforced with artificial mineral fibers such as glass fibers - Google Patents

Description

The invention relates to artificial mineral fibers, such as. B. glass fiber reinforced, hydraulically hardening masses, which can be converted into fiber composite materials with low shrinkage and tear, high abrasion resistance, high impact strength, tensile and flexural strength with favorable long-term behavior, v-, the matrix of the masses except for binders, additives and water surcharges with a grain diameter of up to 4 mm.

In this context, aggregates are grain mixtures of natural or artificial origin dense or porous structure, which are usually inert, but also pozzolanic or hydraulic May have properties.

Recently, hydraulically hardening compounds reinforced with artificial mineral fibers have been gaining in popularity in importance, with the numerous advantages of the fiber composites created from these masses may be assumed to be known.

If artificial mineral fibers are used, the matrix of such masses usually consists of binders t, o and water. In special cases, additives and additives fine as cement, such as B. fly ash or Rock powder up to 20% by volume, based on the volume of the built-in mass, is added.

Up to now it was assumed that it was not possible to b5 and it would also not be advisable to use larger aggregates such as sand or light sand To add quantities, since these surcharges with the same consistency the water requirement and thus the water / Increase binder ratio. This in turn has a significant mechanical deterioration Properties such as flexural strength and impact strength result.

In addition, aggregates in the matrix make it more difficult to fully embed the fibers and increase it In addition, there is a risk of mechanical damage to the sensitive artificial mineral fibers Manufacture of the fiber composite material.

On the other hand, a matrix with little or no surcharge leads to certain disadvantages that have hitherto been found had to accept. It shows, for example, a high degree of shrinkage and a tendency to form cracks. The abrasion resistance is unsatisfactory. The desired high ductility of the fiber composite material does not persist over long periods of time if stored in a damp place. At the same time can be used for longer periods of time the tensile and flexural strength can be reduced by excessive growth of the fibers.

The present invention is based on the task of adding surcharges despite the difficulties involved such as sand or light sand, possibly together with air pores in larger quantities to be built into the matrix in order to achieve the known improvements of the technical properties, such as a significant reduction in shrinkage and swelling and thus to fully utilize a reduction in the tendency of the hydrated three-dimensional shaped bodies to tear.

The solution to this problem is according to the invention that the with artificial mineral fibers such. B. Glass fiber reinforced, hydraulically hardening compositions of the type mentioned at the outset are that additives in an amount of above 20Vol .-%, based on the volume of the built-in mass, are present that the increased water requirement of the supplement Matrix is compensated by a content of liquefiers and / or superplasticizers and that the through the Surcharges achieved in places prevented adhesion between fibers and matrix through bundling the fibers are supported.

This enables a full embedding of the artificial mineral fibers without compromising mechanical ones Use to damage sensitive fibers.

According to a preferred embodiment of the present invention, the compositions according to the invention are characterized in that the aggregates and / or the air pores in an amount of above 30% by volume, based on the volume of the fully installed mass.

According to a further preferred embodiment, the compositions according to the invention are characterized in that that there is swelling cement as a binding agent, which reduces the tendency to tear caused by aggregates already emaciated and thus less dwindling matrix is further reduced.

According to a further preferred embodiment, the desired high ductility is achieved over a longer period of time Periods of time are further improved by the fact that the fibers are sparingly water-soluble and / or in some areas have water-insoluble coatings, the coating at the same time having the mechanical resistance of fibers increased. These coatings prevent the products of hydration of the cement paste from getting anywhere grow up on the glass. As a result, the high density of the moldings is largely retained.

Mixtures with a higher proportion of additives produce relatively fewer hydration products than in the known mortars used for this purpose. This also has a beneficial effect on the Behavior of the molded body.

The matrix of the compositions according to the invention with cement as a binder is characterized by a low matrix Alkalinity off. The use of artificial mineral fibers that are not alkali-resistant will affect the the course of the chemical attack over time.

To the prior art, DE-OS 23 14352 should also be mentioned, which refers to a reinforced mixture which is characterized in that it comprises a castable matrix compound from the group a pourable concrete matrix mass and a pourable simple mortar matrix mass, wherein the pourable concrete matrix mass and the pourable simple mortar matrix mass hydraulic cement, Water, a variety of discontinuous reinforcing thread, a pozzolan-type material,:> o and contains an aggregate; all ingredients are within certain range limits.

The object of the present invention has to do with the nature of the reinforced mixture according to DE-OS 23 14352 no points of contact, to-;: s times with this known prior art mechanically sensitive fibers such as glass fibers with mechanically insensitive fibers such as steel fibers as an analog juxtaposition are.

The essence of the present invention will now be based on two exemplary embodiments, the preferred embodiments represent, further explained.

example 1

In the fiber spraying method, test specimens 6x30mm of learth thickness were produced from glass fiber concrete with a fiber content of 5% by volume using a Portland cement 550 and an alkali-resistant glass fiber with different aggregate content. The aggregate had a maximum grain of 2 mm. All mixtures were prepared by adding a flux - a sulfonated PoIykondensat - at about the same consistency overall v> introduced. The Probekorper moistened 7 days, and then rel in a climatic chamber at 20 ⁰ C and 50%. Humidity stored. The composition of the test specimens and the shrinkage measured between 7 and 180 days are given in Table 1 below.

Table 1: Composition and shrinkage of the test specimens Made of glass fiber reinforced concrete with 5% by volume glass fibers

mixture

No.

Mixing ratio- flow-

nis in weight average

share

Cement: surcharge:

Water% by weight ')

Aggregate vibration content the

Vol-% ² ) mm / m The shrinkage of mixes No. 3 and 4 with more than 20% by volume of aggregates is significantly lower than that of mix No. 1.

Mixtures No. 1 and 3 became after 28 days, 1 and 2 years, with constant water storage the flexural strengths and flexural impact strengths are determined on 10 test specimens of the same type Average values are compiled in Table 2.

, ο Table 2: Flexural tensile strength and flexural impact strength of glass fiber concrete with 5% by volume glass fibers

characteristic

Mixture No. 1 3

Flexural strength in kp / cm ¹

28 days 385 360

1 year 260 335

2 years 235 310 Bending impact strength in cm

kp / cm ²

28 days 23 21

1 year 13 19

2 years 8 16

Mixture No. 3 according to the invention is the previous one Common mixture No. 1 not only in terms of shrinkage, but also in terms of strength properties and the ductility over long periods of time when stored in a moist environment is clearly superior.

Example 2

In a compulsory mixer, pourable mixtures of Portland cement 550 with and without Sand produced as an aggregate using 3% by volume of 25 mm long alkali-resistant glass fiber chips and then further processed to test specimens 6 X 30 cm with a thickness of 1 cm. The sand had a maximum grain of 3 mm. The consistency of the mixtures was increased by adding a superplasticizer sulfonated polycondensate - brought to roughly the same consistency.

The test specimens were moist for 7 days and then in the climatic room at 50% rel. Humidity stored. The composition of the test specimen and the shrinkage measured between 7 and 180 days are entered in Table 3 below.

Table 3: Composition and shrinkage of glass fiber concrete with 3% by volume of glass fiber chips

Mixing ratio in parts by weight

Zem. : Surcharge :
No. Wass.

Superplasticizer

Aggregate vibration content the

% By weight ')% by volume ² ) mm / m

0.5
1.0
3.0

0.4 0.4 0.4 0.4

0 2

3.2 4th

0
20th
34
60

3.2
2.1
1.4
1.0

0.5

0.4 0.4 0.4

2.9

0 19 32

3.3 2.3 1.2

) Based on cement.
² ) Based on the test specimen.

') Relating to cement.

² ) Based on the test specimen.

Mixture No. 3 according to the invention is the two mixtures with lower aggregate contents Considering the shrinkage clearly lay out.

Mixtures nos. 1 and 3 became after 28 days, 1 and 2 years with constant water storage the flexural strengths and impact strengths were determined on 10 test specimens of the same type Average values are shown in Table 4.

Table 4: Flexural tensile strength and impact strength of glass fiber concrete with 3% by volume of glass fiber chips

characteristic

Mixture No. 1 3

The matrix without fibers of the mixtures No. 1 and No. 3 was additionally tested for flexural strength after 28 days of water storage and mixed storage, 7 days of water and 21 days of air with 50% rel. Humidity, checked. The result contains Plate 5.

Flexural strength kp / cm ²

28 days 180 160

1 year 135 140

2 years 115 145

Bending impact strength in cm
kp / cm ²

28 days 15 16

1 year 10 12

2 years 6 10

Mixture No. 3 according to the invention is the one so far

executed mixture no. 1 also with regard to strength and ductility over longer periods of time superior to moist storage.

Table 5: Flexural tensile strength of the matrix of mixture no. 1 and 3 with different storage

Matrix of mix no.

1 3

Flexural strength
kp / cm ²

water
Water / air

70-100 60-90 20-40 40-80

The flexural tensile strength of the matrix of mixture according to the invention no. 3 increases when it dries out significantly less than the flexural strength of the matrix due to shrinkage stresses Mixture No. 1.

Mixture no. 3 according to the invention is less prone to cracking and is therefore of the previous embodiment considerably superior.

Claims (4)

Patent claims: 1. Hydraulically hardening compounds reinforced with artificial mineral fibers such as glass fibers, those in fiber composites with low shrinkage and tear, high abrasion resistance, high Impact strength, tensile strength and flexural strength can be transferred with favorable long-term behavior, with the matrix of the masses except binders, additives and water aggregates with a grain diameter contains up to 4 mm, characterized in that that surcharges in an amount of above 20 vol .-%, based on the volume of the built-in mass, are present that the increased water requirement of the supplement Matrix is compensated by a content of liquefiers and / or superplasticizers and that the Adhesion between fibers and matrix that was prevented in places by the aggregates is supported by a bundling of fibers. 2. With artificial mineral fibers reinforced, hydraulically setting compositions according to claim 1, characterized characterized in that aggregates and / or air pores in an amount of more than 30% by volume, based on the volume of the fully installed mass, are present. 3. Hydraulically hardening compositions reinforced by artificial mineral fibers according to claims 1 and 2, characterized in that swelling cement is present as the binding agent. 4. Hydraulically hardening compounds reinforced by artificial mineral fibers after at least one of claims 1 to 3, characterized in that the mineral fibers are partially heavy water-soluble and / or water-insoluble coatings j5 \ exhibit.