SYNTHESIS AND CHARACTERIZATION OF SOME POLYAROMATIC COMPOUNDS AND THEIR APPLICATION ON CEMENTITIOUS MATERIALS

Abstract

Chemical admixtures are organic compounds including retarders, accelerators and superplasticizers; their role is mainly acting during the initial mixing of cement, mortar or concrete with water in the preparation of the fresh pastes. Superplastizers are added to the fresh cement pastes to improve the physico-chemical and mechanical properties of cement and concrete pastes; their effect is to increase the flowing characteristics of the fresh pastes by reducing the standard water of consistency (decrease the initial W/C ratio and increasing the workability during the preparation of the fresh cement pastes. In this investigation, three novel organic aromatic compounds were prepared, and from the results obtained regarding chemical analysis, molecular and structural characteristics, it was formed that one of these superplasticizers proved to be the more effective one this is sodium 5,5`-diformayl-2,2`-dioxido-1,1`-binaphthyl-4,4`-disulfonate (SDD) which represents the novel superplasticizer achieved. There fore, this superplasticizes (SDD) was used in this study with different doses of 0.25,0.50,0.75 and 1.00% by mass of cement and the physic-mechanical and chemical characteristics of the hardened cement pastes were studied at different ages of hydration namely, 1,3,7,28 90 and 180 days. The results obtained indicated that the compressive strength of the hardened cement pastes increase with increasing additions of SDD up to 0.50% and 0.75% by mass of cement, whereas the strength decreases at 1.00% addition of SDD. Evidently, at low SDD additions the strength increases due to electrostatic repulsion as a result of adsorption of SDD around cement grains leading to similar charges of cement grains. At higher SDD addition (at 1.00% ) the decrease in strength values is mainly due to steric effect, a result which is related to the higher conjugation system and the planner structure of SDD.