Piotr Woyciechowski

Influence of mineral additives on concrete carbonation

ABSTRACT The aim of the paper was to show the important aspect of treating waste additives as the main way to achieve sustainable development in the concrete technology. The author considers the effects of minimizing the use of cement replacing it with waste additives, on the concrete durability. The depth of carbonation is adopted as the possible measure of durability. Results of accelerated and natural tests of carbonation progress for concrete with normal and fluidal fly ash, silica fume and blast furnace slag are shown, influence on carbonation of the additive type, its content in concrete and its role (cement or aggregate substitution) is discussed. The important impact of early water curing on depth of carbonation is stated also.

Model of Concrete Carbonation as Limited Process – Experimental Investigations of Fluidal Ash Concrete

The aim of the paper is to develop a theoretical model predicting carbonation depth of concrete made with fluidal ash replacement of cement. Experimentally determined model describes the depth of carbonation depending on time of exposition, w/s ratio and early-age curing conditions. A new mathematical formulation of carbonation depth as a hyperbolic function of time assumes that carbonation process is limitable in depth due to process of fulfilling concrete pores with carbonation products. The depth of carbonation in concretes made with portland cement and various quantities of fluidal ash (30%, 15%, 0% of cement mass replacement) was measured in environment with high CO 2 concentration (1%). The test results are shown and used to derive equations for prediction of carbonation depth in such concretes.

Influence of Acidic Environments on Cement and Polymer-Cement Concretes Degradation

Cement concrete is hardly considered as the acid resistant material however it should be possible to compare the ability of various cement based composites to resist the sever and chemically aggressive environments. The paper presents assessment of the resistance of cement concretes (of two types of mineral binders) as well as polymer-cement concretes (PCC) to hydrochloric acid. Due to the lack of proper standard procedures the tests were conducted according to the DBME own procedure: concrete specimens were exposed to acids of various concentrations and for various exposure times. The criteria for evaluation the concrete ability to resist the chemical attack were changes of mass, compressive and flexural strength. As PCC is considered to be a composite of better chemical tolerance it was treated as a kind of the reference material (chosen PCC characterized with similar compressive strength level as the previously introduced cement concretes). Approach used in the presented research enabled to compare different composites of similar compressive strength, the basic property to be taken into account in the design of the concrete and reinforced concrete structures.

The Influence of Dosing Method and Material Characteristics of Superabsorbent Polymers (SAP) on the Effectiveness of the Concrete Internal Curing

This paper examines the influence of dosing method and material characteristic of superabsorbent polymers (SAP) used for internal curing, on the selected concrete properties. A new method of introducing SAP into the concrete mix and its impact on the shrinkage and compressive strength of concrete was studied. It was shown that the method of dosing SAP to the concrete mix and the differences in the properties of the tested SAPs have a significant impact on the course of changes of selected properties of the tested concrete composites. In order to compare tested series with each other and with other published results on the subject, a new method of including SAP mass content in the concrete mix, as a percentage of absorbed mixing water, was presented. The effectiveness of internal curing using different types of SAP under different dosing methods was presented as a percentage difference in tested concrete properties between modified series and reference series.

Influence of Method of Preparation of PC Mortar with Waste Perlite Powder on Its Rheological Properties

The aim of this research is to determine the influence of waste perlite powder quantity on rheological properties of polymer–cement mortar mixture. Influence of dosing sequence of waste perlite powder on mortar mixture properties was especially taken into consideration. In the research, eight mortar mixtures were prepared using different quantities of perlite powder in mortar and by using different dosing sequence of mixture components. During the research, the influence of waste perlite powder on consistency and workability of mortar mixture was evaluated. By analyzing the various dosage sequences of the ingredients, the problem of difficult homogenization of the mortar and excessive dusting of the waste perlite powder were investigated. The obtained results show that changing the dosing moment of the key component – waste perlite powder – can influence technological properties of polymer–cement mortars.

Chemical Resistance of Vinyl-Ester Concrete with Waste Mineral Dust Remaining After Preparation of Aggregate for Asphalt Mixture

The aim of the research was to test the ability of vinyl-ester concrete containing waste powder to resist chemical attacks of sulfuric acid and sodium hydroxide. Tested composites contained mineral dust remaining after preparation of aggregates for mineral-asphalt composites. It was experimentally confirmed that from the point of view of chemical composition, granulometry, specific surface area, and density, the waste dust appeared to be a good substitute for commercial quartz powder used in polymer concrete. The evaluation of chemical resistance of polymer concrete with waste dust was done in terms of mass loss and change in compressive strength of composite after its exposition to aggressive media. The tests were performed according to the modified method described in guidelines for the precast elements production. Analysis of test results showed that even the high substitution of quartz powder with waste mineral dust (up to ~85%) in vinyl-ester concrete is possible and such composite presents high mechanical properties (though in some cases it requires using larger amounts of polymer) – not much worse than in case of non-modified composites.