Triethanolamine (TEA) and Triisopropanolamine (TIPA) are used in small amounts as grinding aids in the cement grinding process. TIPA is particularly known to enhance mechanical strength of mortars at 7 and 28 days while TEA does not. A mechanism based on the formation of a soluble TIPA-iron hydroxide complex which could increase the degree of hydration of the cement and so could improve the mechanical properties, has been proposed for the TIPA. The aim of this work is to explain why addition of TIPA or TEA which have close molecular structure lead to different results on the mechanical properties of mortars. The physico-chemical evolution of a cement's hydration was first followed by coupling isothermal calorimetry and ionic concentrations measurements. Then, mechanical compressive tests were carried out on mortars (limestone aggregate). Tetracalcium aluminoferrite (C4AF) hydration is modified in presence of both additive because of the formation of a soluble complex between trialkanolamine and iron III. An adsorption of TEA on the Portlandite surface is significant during the silicate phase hydration, while TIPA does not adsorb. In the case of TEA, the molecule affinity for the Portlandite surface is stronger than that of the formation of the soluble complex. These results could explain differences obtained on mechanical compressive tests of mortars characterising by an increase of the mechanical strength in presence of TIPA.

The development of concrete, which need not be vibrated, and which consolidates under its own weight, is a challenge to the building industry. In order to achieve this behavior, fresh concrete must show high fluidity and good cohesiveness. For the purpose of evaluating these properties, some concretes were prepared with a water to cement ratio of 0.45 by alternatively adding two different kinds of acrylic-based superplasticizer to the mixture at a dosage of about 1 % by weight of cement. Either fly ash or limestone powder or rubble powder (that is a powder obtainded from the recycling process of rubble from building demolition) were used as mineral admixture, in order to ensure adequate theological properties to the self-compacting concretes in the absence of viscosity modifying agents. Preliminary rheological tests were carried out on pastes in which cement was partially replaced by these fine materials. The fresh concrete properties were evaluated through both the slump flow and the L-box tests. The segregation resistance was also determined. Compressive strength was also measured on hardened concretes after 1, 3, 7 and 28 days of wet curing.

An equation was formulated for estimating the plastic viscosity of cement paste containing an air-entraining admixture, which is a commonly used chemical admixture for concrete. Air-entraining admixtures slightly increase the plastic viscosity of neat cement paste. The viscosity equation was derived by incorporating this effect, to minimize the difference between the estimation and measurement. The ratio of the plastic viscosity estimated from the proposed viscosity equation to the measured plastic viscosity was found to be approximately 1, the anticipated value. Viscosity equations for mortar and concrete also formulated based on an existing viscosity equation were found to be valid even when the plastic viscosity of the matrix changed.

The effects of calcium nitrite based corrosion inhibitor (CNI) and fly ash on the corrosion of high performance concrete subjected to a simulated marine environment were investigated. Small-scale concrete slabs containing steel reinforcement were cast with a cover depth of 20 mm and with a construction joint intersecting the steel reinforcing at right angles. The slabs were subjected to a simulated marine environment with two cycles of wetting and drying per day. Corrosion activity of the reinforcing bars was evaluated using the linear polarization resistance technique and free water-soluble chloride content at the rebar level was determined at the end of the testing period. Testing in areas away from the construction joint and away from corrosion induced cracking revealed that the water to cementitious materials ratio (w/cm) has a significant effect on the ingress of chlorides. Thus, chloride content obtained for 0.29 and 0.37 w/c were less than one third that of 0.45w/c concrete. Furthermore, a reduction in the amount of chlorides at the rebar level was clearly demonstrated when fly ash was used in 0.45w/c concrete.

The paper summarizes the results on flowing and cohesive superplasticized mixtures studied and placed in the 1970's and 1980's with properties very close to those of Self-Compacting Concretes (SCCs) presently considered to be the most advanced cementitious material. Case histories (from Hong Kong, New York, and Trieste, Italy) concerning placing of superplasticized self-levelling concrete without any vibration at all, published in the 1980's, are re-examined to compare them with the present SCCs. In particular, the paper deals with the ingredients of these mixtures (superplasticizer, cement, fly ash, ground limestone, silica fume, etc.) by examining their specific role in determining the main properties of these concretes, such as fluidity, on the one hand, and resistance to segregation, on the other. Some interesting new materials, such as ground fly ash or powder from recycled aggregates, appear to be very promising for manufacturing SCC in agreement with the requirements needed for sustainable progress.