Self compacting concrete (SCC) is a new kind of concrete that combines a high flowability and a high segregation resistance obtained by a large amount of fine particles or the presence of a viscosity modifying agent and the use of superplasticizers. As self compacting concrete does not need external compaction, the pore structure, and more specifically the amount of capillary pores, is not influenced by the compaction method. These capillary pores play a very important role in the transport of water and gases in concrete and are of major importance for the understanding of degradation mechanisms. In order to verify the correlation between the transport properties and the capillary pores, tests were carried out. Water and gas permeability, capillary absorption, carbonation and chloride penetration tests were performed on 11 self compacting concrete mixtures and 1 traditional concrete mixture. The selection of the mixtures is made in order to consider some important parameters like the cement/powder and water/cement ratio, the amount of water, the amount of powder and the type of filler(limestone filler with two different grading curves). The amount of capillary pores was calculated by the method of Powers. The calculated values were compared with the test results and gave very good correlations.

Among the harmful substances carried into reinforced concrete by water, none is potentially more damaging than chloride ions, which destroy the passivity layer on steel in alkaline environment leading to corrosion processes of reinforcement and loss of durability. In this work we present direct potetiometric measurements of chloride ions in the pore water of mortar samples by using Ag/AgCl indicator electrodes. The long-term stability of electrodes in highly alkaline environment of cementitious materials and selectivity to chloride ions were improved with the deposition of polymer membrane consisting of polyvinyl chloride matrix and chloride ionophore. The chloride ingress experiments were performed on cylindrical mortar samples with over 50 sensors embedded into the solid body of the sample. The ingress of dissolved chloride ions into the mortar sample was monitored for more than six months. The concentration profiles of chlorides at different places in the sample were determined and used for the evaluation of diffusion processes of chlorides through the pores of the microporous matrix.

This study evaluated the viability of electric heating sheets for the curing of concrete housing foundations in severe, low-temperature environment. The heating sheets tested use PTC (positive temperature coefficient resistor) ceramic elements. The heating temperature is automatically adjusted by these elements in response to adjacent air temperature. The experiment was carried out in two series. The first phase was carried out at -10°C in a thermostatic chamber. The second phase involved on-site testing. Under severe, low-temperature conditions, of up to -11°C outside air temperature, it was found that curing was possible at about +15°C through the use of heating sheets. Compressive strength was found to be sufficient. The heating sheet is considered to be extremely useful for curing concrete in cold regions.

Self consolidating concrete (SCC) is defined as a concrete with high flowability and good cohesiveness which is compacted under its own weight without the need of any vibration effort. For a successful SCC, higher amounts of binders are used together with the new generation of superplasticizers to achieve the necessary fresh properties. Recent investigations show that the use of mineral admixtures such as fly ash improves the workability properties of SCC. Replacing part of the binder with fly ash not only causes a reduction in the dosage of cement and superplasticizer but also improves the durability properties of SCC. Within the scope of this research, SCC with high volumes of high-lime and low-lime fly ash replacements was produced. Properties of SCC in the fresh and hardened states with both fly ash types are investigated. The fresh properties of the concretes were observed through slump flow and diameter, V-funnel time, L-box, GTM sieve stability, setting times and the rheological parameters relative yield stress and relative plastic viscosity. The strength properties included the compressive strength at 28, and 90 days. It was observed that the geometry and surface characteristics of the fly ash affected the workability properties of SCC mixtures. As a result, it was possible to produce SCC incorporating fly ash replacement volumes of up to 70% with sufficient strength.

A new type of admixtures for cement-based materials presented in this work is based on silane-modified acrylic polymers prepared by emulsion polymerization of acrylic monomers and organofunctional silane precursor. The acrylic polymer chain was functionalized with organofunctional silane molecules to build an organic-inorganic polymer structure with terminal siloxane groups. The advantage of this type of polymers over already known polymer modifiers for concrete and mortars is the ability to act as a coupling agent between different phases in the cementitious system. The presence of siloxane groups enables strong chemical interaction among mineral phases of inorganic matrix (cement, aggregate) and direct chemical bonding of organic polymer chain to inorganic phases of the cement based material. The influence of silane-modified acrylic latex admixture on the properties of cement paste and mortar was evaluated and compared to unmodified acrylic latex. Mortars modified with this type of hybrid inorganic-organic polymers showed improved physical-mechanical properties like higher mechanical strength, better adhesion to the substrate, lower shrinkage, better thermal conduction and better resistance to different sources of corrosion.