CC BY
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Ш. К. Торпищев, М. К. Кудерин, М. Жусупов, А. Кузьменков
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1ехногенд1 еншдердщ непзшдеп бетондар Yшш ти1мд1 кешенд1 модификатор (тYрезгертушi)
С. ТораЙFыров атындаFы Павлодар мемлекетлк университетi, Павлодар к.
Материал 15.12.14 баспаFа tyctî.
Sh. K. Torpishev, M. K. Kuderin, M. Zhusupov, A. Kuzmenkov
Effective complex modifier for concretes on basis of technogenic products
S. Toraighyrov Pavlodar State University, Pavlodar.
Material received on 15.12.14.
Мацалада бетон цоспаларынан химиялыц устемелер эзiрлен2ен, бул цоспаларды бшк бiргелкi цозгалшыцтыц арцалылы квтерщт баянныц жэне узац арцылы устемелер алынганы кврсет^ен.
In this is paper described the use of the data on design of composition of complex modifying agent for concrete mixes. The agent promotes strength development and durability.
UDC 666.972.16(088.8)
Sh. K. Torpishev, M. K. Kuderin, R. N. Suleymenova, G. K. Abisheva
S. Toraighyrov Pavlodar State University, Pavlodar
EXPERIMENTAL AND THEORETICAL PRINCIPLES OF STRUCTURIZATION OF MIXED BINDING MATERIALS INVOLVING THE USE OF ALKALI CONTAINING FILLERS
The article considers the experimental and theoretical principles of structurization of mixed binding materials Involving the use of alkali containing fillers.
Keywords: mixed binding materials, alkali fillers, structurization, cement, construction industry.
The exposure of principles of formating the cement stone structure based on mixed cements is the obligatory clause for formating of binding with set constructive-technical peculiarities, moreover it is the scientific basis for using these binding industrial wastes as a raw material in construction industry.
The structure and durability of the cement stone or sandy cement stone are determined by:
- the sort [type] and quantity of the crystals of the hydrate compounds;
- the volume of gell content;
- the size and volume of pores content;
- the stability of generating phases and the speed of their excretion.
As it is known the main circumstance for generating hydraulic binding material of the silica- or alumo system is the synthesis of waterless monomerous alumo- or silica-oxygenous compounds that have Al2O3 and SiO2 as a structure formating basis. This process is possible in case of blocking these ions by such oxides that have high degree of ionity connection as the oxides of alkaline-earth metals. Moreover waterless compounds after hydrotation process must generate insoluble or less soluble water compounds. Particularly minerals of the protlandcement clinker have such features. Their transfer to the hydrate phases is connected with the polarizing influence of the water molecules and protonization of the oxide ion the ability of which is determined by the ionization degree of Ca - O connection. At the same time calcium ions transfer to the liquid phase in the ionic form, automatically increasing the quantity of the OH- ions in the solution.
The increase of the pH environment stipulates the formation of silica-oxygenous and alumooxygenous aquacomplexes and provide the conditions for their own existence in the system of hydrosilicates as the independent phases.
Thus hydratoformating of the cement clinker minerals is of the autocatalytic character with the obligatory generation of the alkaline environment and possible only in case of using high-basic systems.
During the hydrotation of the ions of the extra basic minerals transfer to the content of the formations in the same stechiometric correlation in which they are in the tough phase and that provokes the extra basicity of the hydrate new formations. Because f the extra basicity that products are methastable and tend to transfer into stable condition. The last aspect provokes the destructive process which reduces the cement durability.
Moreover the longitudal strength of the crystallic product of hydrotation of extra basic minerals varies [vary] from 770 to 830 MPa what is more lower than the longitudal strength of crystals of low basic Ca hydrosilicates (tobermorith, xonolith, foshazith). Their longitudal strength is 2000MPa. It is provoked by reduction of the high basic minerals, the share of stronger co-valent connections as -Al-O- Si-, -Si-O-Si- and increasing of the share of the weak ionic connections as -Ca-O-.
The crystals' durability depends not only on their structure but also on their size. The reduction of the crystals diameters provokes the increasing of the perfection degree of their structure and reduction of the dangerous defects concentration: dislocations, pores, cracks. The better effect is reached when the crystals of a fibrous form are grown in the cement stone and their growth in one crystallographic direction which is parallel to the direction of the strongest connections creates the armor effect. In the conditions of equal degree of defection of the crystals the most durable of them those that have higher theoretical endurance, provoked by the chemical content and structure of the crystal lattice, i.e. in crystals of a low basic compounds.
Not the least role in formating endurable structure of the cement stone is played by plastic matrix which is represented by the tobermorith gell. In the appearing gell-crystallic structure of hardening the plastic matrix has the following functions:
- in the process of continuous formation it fills the pores in the stone;
- coops up the cracks;
- eliminates the defects;
- decreases capillary porousness and increases micropores quantity, i.e. it formates the physical structure of the stone;
- connects the crystals and joints transmitting enclosed load;
- reinforces elastoplastic features;
- decreases the fragility of the cement stone and all that provokes the decrease of various stresses in the specimen with the help of its plastical deformation.
The ratio of the crystallic and gell phases range in determined ranks, 10-30% of the crystals, better of fibrous form and [the latter] what is left the plastic matrix which may be oriented and armored by these crystals.
And eventually the most important role in increasing of effectiveness of binding systems is played by the regulation of new formations content. If we analize the geological data on genesis of metamorphic and sedimentary rocks and the basis of their rock formatting minerals, we will be able to see that in the area of weathering the highest mobility of all alkaline and earth alkaline elements have Ca, Na, Mg and K. In the same sequence the minerals' durability is changed. For example the potassium field spars are weathered much longer than calcareous sodium; albit is the most resistible among the last ones. The same sequence is held for plagioclazes: the calcium plagioclazes are destroyed first of all. Muscovite, paragonith - the alkaline hydrates - have the heightened durability to weathering in comparison with calcium hydrates.
Thus the obligatory conditions for increasing physic-mechanical properties of the cement stone are:
- [providing the] conditions for forming low basic hydro silicate silicates in the structure of the cement stone, mainly of alkaline or earth alkaline alumosilicate content;
- the presence of hydrogell in amount prevailing at the content of big crystals;
- generating of the crystals of a definite size and form in the gell-crystallic structure;
The reduction of the basicity of the new formations may be achieved by lowering
the basicity of the cement clinker. But because of this very reduction of the basicity the share of the ionic connections automatically reduces and that stipulates the increase of the phases' stability [resistance] to the hydrolytic destruction. It is because the polarity of the water molecules is not enough for breaking the connections during hydratoformation. This process may be intensified by increasing the ionic strength of the solution, i.e. increasing the OH- ions concentration by incorporating alkalines. The OH- ions role in that case is to intensify polarizing effect on ionic Ca - O connection and effect on catalytic action on breaking up the strong covalent -Si-O-Si-, -Al-O-Si- connections by the type of nuclephile SN2 substitution. At the same time all the needed conditions for formating alomo- and silica-oxygenous aquacomplexes that are the basis of the low basic hydrosilicates. The increase of the OH- ions concentration can be reached by incorporating the alkaline metals to the solution that provokes the alkaline reaction in water.
The presence of alkaline metals provokes great impact on the process of the structure formating [structurization] of the cement stone. The cations of alkaline metals keep the high pH level in the solution and take part in cationic-exchange reaction of more durable alkaline and mixed alkaline earth alumosilicate new formations. Moreover alkaline
metals decrease the degree of oversaturation of the master batch solution with CaO thus they regulate ratio of silica and CaO in liquid phase and that stipulates the decrease of basicity level of the new formations and forming of the crystals of a definite form and size. The increase of the pH environment provokes the conditions for the increase of the hydrogell quantity as a result of higher reactive abilities of the elements of the 1-st group of Mendeleyev's table comparing with the elements of the second group. Moreover involving the use of the alkalines gives opportunities for incorporating them as soluble silicates or aluminates of the extra hydrogell quantity.
The analysis of the investigations on binding systems based on bauxite pulps shows that the role of alkaline mixtures was ignored in one case, in another alkalines considered to be harmful component which was leading to aggravation of the constructive properties (appearing of the salt sediments at the surface of the concrete). But their content in bauxite pulps is great enough.
For instance the pulps of Volkhov Aluminum Plant contain 2.6 - 7.2 % of R2O; Tichvinsky Aluminum Plant 3.0 - 5.0 %. During the technological process of the alumina production the aluminates and the silicates interact with water simultaneously. And it provides actual and good contact between the original and new formations, particularly hydroalumosilicates of Ca and alkali, is almost inevitable. The hydroalumosilicate phases being a result of alumina production are investigated in detail in this research work. The deciphering of their content is also enclosed. Here is being shown the formating of the solid solutions of the variable content in the system 3CaO*Al2O3*6H2O - 3CaO*Al2O3*3SiO2. that is why we can suppose that in the mixed cement slime system the interaction between the CaO and Na hydroalumosilicates is not limited by the similar substitution of NaO by the CaO and it is quite probable that there will be formatted complicated alkaline hydrates with the help of reaction of addition[connection]. The alkaline hydrosilicates on their turn in the alkaline environment in presence of the Ca(OH)2 can actually generate hydrogarnets excreting alkali to the solution and can generate mixed hard soluble alkaline alkaline - earth hydroalumosilicates of the variable basicity. The possibility of these reactions undergoing [procedure] is determined by the fact that the components of the binding alumosilicate content must have hyaline, amorphous structure close to methastable which will provoke their interaction with alkalines.
Thus the bauxite slime in the mixed cement-slime system is in a need for being used incorporating amorphous silicate or alumosilicate components. This makes the preconditions generating the coagulative-crystallyzed structure containing:
- the gell constituent part;
- low basic Ca hydroalumosilicates;
- calcite;
- hydrocarbosilicates and the most important - mixed hydrosilicates, alumosilicates and alkaline hydroalumosilicates.
I.e. the alkaline phase of the bauxite slime should make a considerable influence on the process of structure formating [structurization] in the slime systems and mixed compositions based on protlandcement.
That very phase itself can:
- intensify destruction and hydrolytic glass dissolutions (if there any in the binding material);
- take part in of the interim products (alkalinehydrosilicates and hydroalumosilicates);
- take part in generating of alkaline hydroalumosilicates;
- synthesize the environment that stipulates generating and high durability of the low-basic Ca hydrosilicates.
The presence of alkaline metals' cations in the solution can reduce the degree of oversaturating of the liquid phase by the CaO which is generated during the hydrotation of the cement and thus regulate concentration ratio of alumina and Ca(OH)2. This should stipulate the reduction of the new formations' basicity and generation of the crystalls of the proper form and size.
Thus the reduction of the cement minerals' basicity with the simultaneous increase of the pH level of the solution and incorporation of the alkaline cations creates all needed conditions stipulating the increase of the effectiveness of the binding material.
Material received on 15.12.14.
Ш. К. Торпищев, М. К. Кудерин, Г. К. Абишева, Р. Н. Сулейменова
Олтщурамдас толтыргыштарымен туткырлы, езгертул1 араласкан курылымкурауыштарыныц басты тэж1рибел1-теориялары
С. ТораЙFыров атындаFы Павлодар мемлекетлк университет^ Павлодар к.
Материал 15.12.14 баспаFа TYCTi.
Ш. К. Торпищев, М. К. Кудерин, Г. К. Абишева, Р. Н. Сулейменова
Экспериментально-теоретические основы структурообразования смешанных вяжущих, модифицированных щелочесодержащими наполнителями
Павлодарский государственный университет имени С. Торайгырова, г. Павлодар.
Материал поступил в редакцию 15.12.14.
В статье рассматриваются экспериментально-теоретические основы структурообразования смешанных вяжущих, модифицированных щелочесодержащими наполнителями.
Макрлада сшт^рамдас толтыргыштарымен тутцырлы, взгертулi араласкан цурылымцурауыштарыныц басты тэжiрибелi-теориялары царастырылган.
