CS267725B1 - Building material on cement base - Google Patents

Abstract

For the production of cement-concrete mixtures and mortars, a building material containing an additive of 0.5 to 2.5 "f-mass of poly-condensate of 2-naphthalenesulfonic acid with formaldehyde with 5 to 8 aromatic nuclei and terminal methylols with lower chain alcohols of chain length is intended. C1 to C4, wherein the weight of the additive refers to the weight of the cement contained in the mass.

Description

The invention relates to a cement-based building material, in particular cementitious concrete mixtures and mortars.

The properties of fresh mix and hardened material under operating conditions at the destination are decisive for the technology of production of comentoboton mixtures. The rheological parameters of the produced mixture must comply with the construction technology used, its solidification and hardening must correspond to the relevant conditions of maturation and treatment of the mixture. Equally important is the achievement of the required initial and final strengths. The properties of cement concrete mixtures are a function of the properties of the raw materials used, ie the individual components. The basic role is played by the quality and quantity of cement and aggregates and the water content used to prepare the mixture. However, with these basic components, the properties of the mixture can be changed only to a limited extent, which is far from meeting the needs of modern construction. Therefore, other components called chemical additives are increasingly used to modify the properties of concrete mixtures. The most commonly used are additives with plasticizing and liquefying effects and additives influencing the setting speed of mortars and cement concrete mixtures. The additives used to improve the rheological properties of mortars and concrete mixtures are mostly of the above and high molecular weight substances of natural or synthetic character. The first group is alkali metal and earth lignin sulfonates. Their use is most common in the production of elements and structures with hardening of concrete at normal temperatures. The disadvantage of these natural substances is the fluctuating content of undesirable admixtures, which adversely affect the beginning and end of the hardening of the concrete mixture. Due to this property, these substances cannot be used in the technology of accelerated hardening of concrete. Despite various measures, it has not yet been possible to achieve the standard parameters of modifiers based on such a chemical basis. In contrast, additives of synthetic origin are of standard quality. These include the above and high molecular weight nitrogen-containing heterocyclic compounds, such as melamine, pyrimidone or linear compounds, such as urea with formaldehyde, which are modified by sulfation and sulfitation to improve the effects. their sodium salts. The most commonly used include sulfonated melamine formaldehyde condensates, sulfonated naphthalene formaldehyde condensates, sulfonated phenol formaldehyde condensates and modified lignosulfonates. However, even these additives have some shortcomings. The swelling effects often decrease significantly with increasing time after mixing into the mixture. Other undesirable side effects are aeration of the mass and slowing down of hardening of the concrete. The reduction of short-term strengths limits the use of these admixtures for production with accelerated concrete hardening technology, especially in the production of precast products. Their use on a larger scale is also limited by other unfavorable properties, such as precipitation of admixture components during freezing, or polycondensation of components during storage, which negatively affects the resulting properties of concrete.

These disadvantages are eliminated in the case of the building material according to the invention, the essence of which consists in the fact that this material contains an additive of 0.5 to 2.5% by weight of 2-naphthalenesulfonic polycondensate. new acids with formaldehyde, with 5 to 8 aromatic nuclei, with terminal methylols etherified with lower alcohols of chain length C1 to C4, the dose of additive being based on the weight of cement in the mass. _x

This additive, when added to the cement concrete mixture, has high flow effects over the entire dosage range with an efficiency of 15 to 30%. It shows very low aeration, max.2 <compared to the comparative cement concrete mixture, which does not affect the strength even when using the technology of accelerated setting of concrete. The reduction in liquefying effects over time is small. Measured by lowering the cone after 30 minutes, it is less than 20 mm and even after 60 minutes from mixing the mixture reaches a value of about 80 f: original, which is an order of magnitude higher than the similar effect of existing ingredients. The admixture in question also causes a high increase in the initial strength of the concrete, both during normal curing and in the technology of accelerating the setting of the concrete. As tests have shown, this additive can also be applied for concreting at low temperatures, resp. for concretes curing at temperatures around - 5 ° C. The additive is thus manifested in the cement concrete mixture by a combined action with highly positive effects. · · Ή ;, / · /

CS 267 725 Bl

The invention will now be described in more detail with reference to the effects of the additive by means of examples of its use and the results of the tests carried out.

Individual measurements monitoring the effect of the admixture on a certain parameter of the cement-concrete mixture were always performed for the comparative concrete mixture hereinafter referred to as BBS, containing no admixture, and samples containing sulfonated phenol-formaldehyde condensates as admixture A, admixture B sulphonates, additive D - sulphonated naphthalene formaldehyde condensates and

set E according to the invention. Results performed measurements are clearly arranged in tables. Example 1 A basic cement concrete mixture with the composition was prepared cement SPC 325 3 300 kg / m aggregates of granulometers i 850 kg / m ³ 0 to 4 mm 4 to 8 mm 350 kg / m ³ 8 to 22 mm 650 kg / m ³ Water with a basic dose of about 220 li was dosed in such a way that that the processability of the mixture was given value K = 700 * 20 mm seat cones. To samples of the mixture the above ingredients were dosed in an amount of 1.0; 1.5 and 2.0 wt ., relative to per batch of cement. Water loss during dosing The orchard was leveled with aggregate as well that sum used sl the mesh of the mixture was always 1 m. The following data were obtained: Mixture dose ingredients water 1 / m aqueous aeration efficiency in souč. ý, Je PBS 0 221 0.63. 1.8 - A 1.0 202 0.58 2.1 8.5 198 0.57 2.0 10.4 2.0 192 0.55 2.3 13.1 B 1.0 195 0.56 1.8 11.8 1.5 190 0.54 1.9 14.0 2.0 180 0.51 . 1.9 18.6 C 1.0 198 0.57 2.4 10.4 1.5 195 0.56 2.2 11.8 2.0 190 0.54 2.3 14.0 D · 1.0 196 0.56 3.9. 11.3 1.5 189 0.54 4.5 14.5 2.0 180 0.51 5.6 18.6 E 1.0 185 0.53 2.6 16.3 1.5 174 0.50 2.9 21.3 2.0 167 0.48 3.5 24.4

Example 2

A basic cement concrete mixture with the composition was prepared

Cement PC 400 350 kg / m ³ Aggregates with a particle size of 0 to 4 mm 820 kg / m ³ 4 to 8 mm 320 kg / m ³ 8 to 16 sun 620 kg / m ³

CS 267 725 B1 '-3. 3 3 ·

Water into the snail was dosed in two doses of 200 l / m and 180 l / m. Additives according to the above designation in the amount of 1.5% by weight of cement are dosed into the samples of this mixture. The change in processability of the mixture as a function of time, i.e. at 0, 20 and 60 minutes after mixing of the mixture, was measured and at the same time the air content in the mixture was measured. .

Mixture water content l / m water coefficient workability / min / content air $ 0 30 60 SBS 200 0.57 25 10 2 1.6 AND 200 0.57 95 59 28 2.2 180 0.51 56 32 10 2.6 D 200 0.57 100 78 35 3.9 ^r 180 0.51 65 41 15 4.6 E 200 0.57 215 198 190 1.7 180 0.51 199 181 159 2.0

Příklad Example 3

A basic cement concrete mixture with the composition was prepared

Cement PC 400 400 kg / m ³ aggregates on granulometry up to 4 mra 800 kg / m ³ ' 4 to 3 mm 610 kg / m ³ 8 to 16 mm 220 kg / m ³ Water was dosed for workability K = 100 + 20 mm taper fit. The samples were shit

The following additives are metered in in an amount of 1.5% by weight of cement. Test specimens, a cube with an edge of 150 mm were then made of the individual mixtures and stored in a standard environment. Under normal maturation conditions, the strengths were measured after 1, 7 and 28 days.

Mixture content , water / \ / rn / water coefficient fortress 1 at pressure t / VSa / after days 28 SBS 235 0.59 9.6 25.2 37.9 AND 200 0.50 12.3 32.3 45.6 D 198 0.50 10.9 28.7 42.8 E 178 0.45 16.3 41.9 50.1

Example 4

Eyla prepared a basic cement concrete mixture with the composition

Cement PC 475 400 kg / m ³ aggregate with a granulome trii of 0 to 4 mm 780 kg / m ³ 4 to 8 mm 350 kg / m ³ With up to 16 mm 620 kg / m ³

Water was dosed to workability K = 100 + 20 mm of cone seating · Additives A, B, D, Σ, F in the amount of 1.5% by weight of cement were dosed into the mixture. Test specimens, cubes with an edge of 150 mm were produced from the mentioned mixtures and these specimens were subjected to the process of accelerated hardening of concrete in the following thermal insulation regime:

Leaving rise 20 to 85 ° C isotherm. heating 85 ° C cooling 1 h 2 h 2.5 h, '? ^0.5 viso- Deformation strengths were measured after 6 hours and compressive strength after 24 hours. For comparison were /

t

CS 267 725 B1 also measured the strengths during normal curing of a comparative concrete mix / PBS /

Mixture water content l / ni water sum. pmoxt 6 h r pressure / MPa / za 1 day 28 days PBS — normal. maturation 239 0.60 13.4 39.7 PBS concrete 237 0.59 12.3 21.5 38.5 AND 20S 0.52 10.1 23.8 40.7 B .202 0.51 13.1 24.5 41.9 Τ » 202 0.51 8.2 18.7 40.2 G 182 0.46 20.3 28.2 45.3

Example 5

A cement concrete mixture of the basic composition cement PC 400 aggregate with a granulometry of 0 to 4 mm to 16 mm was prepared

350 kg / m 2

900 kg / m 2

900 kg / nP

Water was dosed to workability K = 60 + 10 mm of cone seating. Additives A, B, D, Ev were metered into the mixture in an amount of 1.5% by weight of cement.

Test specimens were made from the individual mixtures as in the previous example. These bodies were stored for 24 h in a standard environment and then in a cooling box at a temperature of -5 ° C. Compressive strength tests were performed on the bodies thus treated after 1, 7 and 28 days.

Mixture water 1 / m ³ water sum · efficiency compressive strength / MPa / po 1 7 28 days DOG 219 0.63 - 5.4 10.6 18.8 AND 192 0.55 12.3 4.7 15.7 28.1 B 197 0.56 10.0 6.5 12.2 27.9 D 188 0.54 14.1 4.6 13.5 26.8 T? 171 0.49 21.9 8.8 20.7 41.2

CS 267 725 Bl -5-

Claims (1)

Cement-based building materials, in particular cement-concrete mixtures and mortars, characterized in that they contain 0.5 to 2.5% by weight, additives based on polycondensate of 2-naphthalenesulfonic acid with formaldehyde, with 5 to 8 aromatic nuclei and with terminal methylosis etherified lower alcohols with a chain length of C1 to C4, the dose of additive being based on the weight of cement contained in the mass.