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INVESTIGATION ON EXPLOITATION STABILITY OF HYDRO-TECHNICAL CONCRETS WITH POLYMER COMPOSITE.

CONCRETEPOLYMERS

Boyka Doychinova Nikolova Belcheva

Institute of Soil Science, Sofia, Bulgariaemail: [email protected]

ABSTRACT

In a model experiment it was established that the addition of water-soluble

thermo-reactive resin containing epoxy and phenol-formaldehyde composite tothe concrete mixture improves its frost and corrosion resistance; decreases waterabsorption and permeability, which results in increasing the exploitation durabilityof the hydro- equipments constructed with the purposes and for the conditions ofthe irrigation agriculture.

Key words:Hydro-technical, Polymer composite, Concrete- polymers.

INTRODUCTION

Creating of new recipes about complex concrete composites with use in thehydro-technical and hydro-ameliorative constructions is an effective engineeringapproach and solution for the purposes and conditions of irrigation agriculture inour country. Through well quantified introduction of suitable polymer additives isreceived a concrete- polymer product , respectively a cement-polymer and theyhave a proper application in accordance with the determined geophysical andgeochemical conditions, and also in compliance with the project parameters ofthe hydro- equipment and the quality characteristic of transported by it irrigationwater.The orientation is to use water soluble thermo- reactive resins: epoxy andphenol- formaldehyde.

In this manuscript are reflected some results from series of investigations onbasic indexes about hydro-concrete polymers with use in the irrigationagriculture. Bulgarian produce of complex resins were studied. The chemicalreactions of their production are discussed in details.

BALWOIS 2008-Ohrid, Republic of Macedonia-27, 31 May 2008 1/6


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According the practical, applicable conditions, compared with the results from thelaboratory model experiment was chosen the recipe of the composition. As asignificant moment, however, has to be accentuated on proving of thepossibilities about the use of phenol-formaldehyde resin as a type of polymeradditive.For this purpose was carried out a huge investigation work about optimization ofthe recipe composition in two directions:- Choice of thermo reactive resin modification;- Optimization of recipe composition: resin and hardener, with technologicalpossibilities the resin to harden in the temperature interval of -15 C to 55 C inshort technological time, at durable adhesion to a wet base;- Optimization of composition work: resin- hardener-filler and evaluation of the

quality indexes.

MATERIAL. INVESTIGATION . ANALYSIS

Based on the results from the specialized laboratory research work, as well as inthe natural conditions and considering the technique economical reasoning fromthe introduction of the new product according the project decision of the problem,additional investigations were carried out with the aim to establish the exploitationdurability in years. By definition, as a base index at creation of the recipecompositions, is accepted the property degree of saturation, which necessitatesthe clarification of the following:

The chemistry, physic-chemical properties and structure of the investigatedpolymer products (resins), which can determine 20-25% of the saturation degreein comparison with the participating in the total resin composition additionalsubstances, such as cement plus hardener in the production of the polymer-cement with recommended application as working putty-mixture for localrepair works on corroded surfaces.The chemistry, physic-chemical properties and structure of the investigatedcomposition of cement plus filler plus water solution of the thermo-reactivepolymer resin (TRPR) determine 40 to 50% of the saturation in the compositionof the concrete mixture- cement : sand : gravel = 1 : 2 : 2 at water to cement ratio= 0.45, and at hardener/ TRPR = 0.05 (5% of hardener in the mixture).

The received concrete-polymer successively is experimented at construction ofhydro-equipments in zones with dangerous and unstable geophysical characte-



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The approach at determining of the property water saturation (Ws) was realizedin experimental set up, in which was included a vacuum pump, with which wasintroduced a water flow through the experimental body to the visualdetermination the end of the process (lack of air bubbles in the water cork at theopposite side). The total number of the experimental bodies was six control andsix samples. The following results were obtained:- Water saturation of samples was - Ws mean=1.42%- Water saturation of controls was- Ws mean = 4.01%The results of the investigation showed 2.79 times higher saturation at the control

samples in comparison with that of the experimentally produced samples withTRPR addition.Capillary water take upTo determine the capillary water take up (Wcw) were used prismatic matrix forms(5/5/2cm) at technological regime standard and test samples stay under water for5x24h time.The following results were received:Test Samples - Wcw mean= 0.81%Standard samples- Wcw mean= 1.3%The results from the experiments showed, that the capillary water take up is 1.5times higher than at the standard samples in comparison with that of the test

samples, produced with TRPR addition.Water permeabilityTo determine the water permeability (WP) of the concrete polymers were testedsamples with cylindrical form d:h=70:20mm (diameter to height ratio= 70:20mm).The method of Stalkin - Solnceva - Popova - Natov - Valcheva - Nazurski wasused. A technological regime: P in the beginning = 0.1MPa for technological timeof 24h, as after visual evaluation of the opposite side of the sample wetting, thepressure is increased with 0.1MPa. The experiment is terminated at establishingof wetting.The experimental results proved, that at control samples the wetting appearedafter 5x24h, i.e. at working pressure P= 0.5MPa The samples with TRPR additive

at these conditions of time and regime were resistant. The samples with TRPRadditives at these conditions for time and regime showed a good resistance.When the samples were cut, it was seen an equal distribution through the area ofthe control samples and a pulsating line with a height of 10mmon the active side,i.e. water reached half of the total height of the samples with TRPR additive.

At detailed observation of all received and reported up results, it was established,that the addition of the thermo reactive, water-soluble composite to



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the cement-sand or concrete mixture (cement : Sand : gravel = 1:2:2.46 andwater : cement =0.45) is an effective technological decision, which grants highstrength and anti filtration characteristics for the constructed hydro-equipment.This fact is especially significant for the purposes of the irrigation agriculture,where exist all preconditions for corrosive degradation (amortization) at thehydro-ameliorative and hydro technical equipments.

DISCUSSION . ANALYSES

The results from the experimental work proved, that the TRPR additive basically

decides the problem with the porous structure of the concrete. It is known, that athardening the concrete forms a structure, which includes a system of capillaryand pores that predetermines the worsening of the discussed up exploitationcharacteristics. It was proved, that the possibility of the capillary to absorb, con -duct and evaporate water depends on their dimensions, in which according thephysical laws, is formed different in strength pressure of the saturated watervapors. It was established experimentally, that the capillary with a radius of 50 to1000Ao (5x10-7 to 1x10-5cm) accumulated water from the air condensates incollimating effect, due to which the capillary even under pressure, do nottransport water. At the experimental samples with polymer composite additive theporosity was measured with mercury pores meter type CE, and was obtained

data about total pores volume and the distribution of the capillaries bydimensions- Table 3 and figures 1 and 2. After discussion of the received integraland differential curves the following conclusions can be made:1. The total volume of the pores of the experimental samples with TRPRadditive was established that the present capillaries are with total equivalentradius Re= 250 Ao, or 1.8 times lower than that of the etalon samples (withoutadditive), which have total equivalent radius Re = 450Ao.2. The compact structure of the concrete-polymer samples influences favorablythe exploitation properties and it make possible the enlarging of their area of usein the practice. It is necessary, though, to admit that at contact with aggressiveand neutral water in the structure of the experimental samples with TRPR

additive, at hardening, formation of low basic calcium hydro- silicates highlydispersal and with big specific surface is possible, which leads to additionalstructure compaction. It can be supposed with a high probability also theformation of massive associates between the components of the composition, asthe total volume of pores reach the equivalent radius of 300Ao (lower than that ofthe standard samples with ) and the experimental samples made of cement



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plus TRPR-additive having equivalent radius Re = 240Ao in comparison with theequivalent radius of the standard samples, which is Re =450Ao.

CONCLUSION

The experiments in this aspect are not as yet finished, but the data definitely canorientate the engineer- projectors to a suitable recipe composition, according thedetermined requirements and conditions for each hydro- equipment and itsspecific use.

The scientific-applicable activity for creation and introduction of new constructionmaterials and respective technological decisions aims at increasing theexploitation durability of the hydro- equipments, used in the irrigation agriculture,limiting the negative processes due to corrosion, overgrowing by plants and lossof useful irrigation water, due to filtration.

REFERENCES

Fraser , P., (1981), The Science of the Total Environment., 18, pp. 103-116Nikolova-Belcheva, B. L. Tzachevska, (1998), Polymer materials in Agriculture

Economics and management in agricultural, 7, pp. 44-48Nikolova-Belcheva, B. (2001), On the irrigation Agriculture State in Bulgaria,

International conference and Seminar "BALKANERECO'02"S.,Nikolova-Belcheva, B. (2001), Polyurethane Stuffs and Possibilities of Their

Application in the Agriculture International Conference and Seminar"BALKANEIRECO'02"S.,


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