For the purpose of defining maximal chemical durability of the formed material at the optimal content of the polymer the kinetics of polymer concrete decomposition in acid media has been investigated.
The data got at the investigation of the air content dependence on the polymer-cement ratio in the mortar modified by ВДВХМК-65Е-ВДК (Fig.1) testify that in the area conforming to 7-10% content of the polymer from the cement mass the decrease of air entrainments and increase of the forming closed pores number, the result of which is receiving the polymer-cement frame possessing maximal chemical durability.
The possibility of cement systems lifetime increase in aggressive media owing to their modification by chemically resistant water dispersion has been established in principle.
For the purpose of establishing modified concretes´ corrosion resistance the tests in various aggressive media: nitric, sulfuric and hydrochloric acids and also solutions of sodium chloride and sulfate, were carried out. The corrosion resistance was estimated on the modified materials´ strength properties loss, when cured in 10% aggressive medium.
Due to the carried out experiments it is established that on the intensity degree of the effect on the modified mortars´ physical and mechanical properties the investigated aggressive media represent the following comparative range: hydrochloric acid > sulfuric acid > nitric acid > sodium sulfate > sodium chloride > benzine. In salt solutions the modified materials´ durability increases considerably compared to the non-modified ones.
The mathematical treatment of the experimental data inclusive of the works performed by the research workers of A.F. Polak´s school, Ivanov F.M., Rozental N.K. and others allowed the author to suggest a calculation formula for the modified concretes´ and mortars´ durability definition depending on the aggressive agents in the exploitation medium:
, (1)
where h - is the aggressive substance concentration in the exploitation medium; L - the thickness of the construction being subjected to the exploitation medium´s aggressive effect, (cm); L0 - the laboratory sample thickness (4 cm); A0 - the constant defined experimentally by the errors sum-of-squares minimization on the formula (А0 <0):
, (2)
where Si - is the sample strength [kg/cm2] after being cured in the aggressive medium for the time ti; m - the number of measurements carried out for every sample; S0 - the sample strength initial value [kg/cm2]; h - the mortar concentration (0<h <1).
The established functional dependence and corrosion resistance of the modified mortars and concretes in acidic and salt aggressive media allow forecasting a material´s lifetime and, consequently, structural units´ durability as a whole at the anticorrosion protection design stage already.
The work was submitted to international scientific conference «Prospects for the development of university science», Dagomys (Sochi), 20-23 September 2008, came to the editorial office on 11.08.2008.