Wojciech Kubissa

Ecological Concrete Based on Blast-Furnace Cement with Incorporated Coarse Recycled Concrete Aggregate and Fly Ash Addition

This article deals with an experimental study concerning the development of concrete mixtures with significant ecological benefits. The studied concrete mixtures were based on blast-furnace cement, with an additional application of supplementary cementitious materials—fly ash, metakaolin, and silica fume and fluidized fly ash. Coarse aggregate in the form of crushed concrete was applied for all studied concrete mixtures. The experimental program was primarily focused on the assessment of the durability properties of the studied mixtures in terms of mechanical tests, absorption tests, chloride migration coefficient tests, water penetration tests, and accelerated carbonation depth tests. The results obtained showed good potential for waste materials in durable concrete production. The studied mixtures, with incorporated supplementary cementitious materials, exceeded the level of high performance concrete (HPC) in terms of mechanical properties. Such modification of the binding system also significantly contributed to an increase in durability properties; however, mixtures with the fluidized fly ash application exhibited reduced resistance to carbonation.

High Performance Concrete with SCM and Recycled Aggregate

In the article the possibility of utilization of two waste materials: Recycled Concrete Aggregate (RCA) fraction 4-16 mm and Class F fly ash (from coal burning power plant) in high perfor-mance concrete (HPC) was presented. Concrete with RCA were made with varying amount of cement and Suplementary Cementing Materials (SCM). The specimens of concrete were tested to compare mechanical properties as well as some properties related to the durability of concrete. Compression strength values up to 71.40 MPa were achieved and good values of properties determinig durability of reinforced concrete structures.

Determining Concrete Composition on Recycled Aggregates

The problem of recycling of construction wastes is important and at the same time difficult to deal with. One of the possible ways of using the construction wastes coming from the demolition of concrete constructions is to re-use them in the production of construction concretes as recycled concrete aggregates RCA. Determining the concrete composition with the use of RCA demands conditioning its different from the natural aggregates NA physical and mechanical properties. In the procedure of projecting the concrete composition with three equations theory the assumption of consistency class of concrete mixture is demanded. Having accepted it, the water demand of aggregates and cement is determined. In case of natural aggregates NA the formulas of Sternes and Bolomeys are used in which aggregates water demand is conditioned from its kind and granulation and also from concrete mixture consistency. In case of RCA, there is lack of such data and each time it is necessary to determine the water demand empirically after performing a trial batch. There also exists a necessity to determine the relation between RCA water demand and its other properties which are easy to be determined in laboratory conditions and in short time. Such a property can be measured with the crushing rate wrm resistance of aggregates to crushing. Crushing rate wrm was used to qualify the recycled aggregates from recycling with the point of their potential of being re-used in constructive concrete production. It was determined a relation between crushing rate wrmand the coefficient ARCA taking place in the modified strength equation of Bolomey and thus it became possible to use the method of three equations to project the concrete composition on recycled aggregates.

Application of Granulated Cable Plastic Waste for Soil Stabilization

Paper deals with the assessment of practical utilization of granulated cable plastic waste (GCPW) for the production of stabilized soil layers in transport engineering. The main goal of the experimental work was the evaluation of the influence of GCPW on mechanical properties of soil stabilization based on the fluidized fly ash. Mechanical properties were investigated using standard procedures in soil mechanics. GCPW was dosed as a partial replacement of fluidized fly ash up to 30 %. It was concluded, that the studied level of replacement performs critical level, additional increasing of GCPW would lead to a decline of required mechanical properties. Besides, replacement by studied waste material caused lower values of the bulk density.

Influence of Mix Proportions on Water Absorption of RCA Concretes

The subject of the work is to develop probabilistic models defining the water absorption of concretes made with the use of recycled aggregate (RCA). For the study 16 series of concrete mixtures were made with a 50 mass% share of recycled aggregate in the whole amount of coarse aggregate. The analysis of test results aimed at formulating a relationship between water absorption value and selected parameters of the composition of concretes. The objective was to find a model giving the best fit between calculated values and test results. Formulated models were then used in probabilistic modeling absorption using a Monte Carlo simulation. The results indicate a good agreement of the mean values of water absorption and possibility of good fitting of the standard deviation if an additional summand is introduced into the model.

Comparative Investigations of some Properties of Lightweight Cement Concretes Containing Siliceous Fly Ash

In the article the possibility of lightweight cement concrete manufacturing has been presented with use of binder in which part of cement was replaced with siliceous fly ash Class F. It was used lightweight aggregate Pollytag and Keramzyt. Total amount of binder was 400 kg/m3 with w/b=0.5. Mechanical properties has been tested as well as properties affecting durability of concrete. Replacing part of cement with fly ash improved concrete resistance on chloride ion migration, reduced compressive and tensile strength of concrete and increased carbonation depth.