The Effect of Using Commercial Red and Black Iron Oxides as a Concrete Admixtures on its Physiochemical and Mechanical Properties

Study discuss the effect of using commercial red and black iron oxides (RIO and BIO) as a concrete admixtures in percentages do not exceeded 2.5% of each oxide from the amount of cement, this study tested the effect of every portion from each oxide at different ages on the compressive strength as well as the workability represented as a values of slump. We conclude that the optimum portion of RIO is 2.5%, but for BIO is 1%, while the proposed uses of RIO in concrete technology are retarder through slump increment reach to 50%, coloring material and mineral admixture through Compressive Strength increment (7-365 days) 5.5-12.8%. On the other hand BIO will propose as, coloring material and mineral admixture through Compressive Strength increment (7-365 days) 22.2-30.8%. SEM-images are clearly show the formation of Calcium hydroxide phase at 7-days while at 1-year the CSH phase is a predominate one, in both cases of RIO and BIO. XRD-pattern is supported the results outcomes through SEM-images

Effect of Alkali Concentration on Physico -Chemical and Mechanical Properties of Slag Based Geopolymer Cement.

In this article we studied the effects of sodium hydroxide pellets (SH) and sodium silicate liquid (SSL) as an activator on the physico chemical and mechanical Properties of ground granulated blast furnace slag (GGBFS) geopolymer pastes. Various mixes are prepared using different liquid/solid ratios (L/S) by weight. The hydration characteristics of the various mixes have been tested through determination of total porosity, compressive strength, bulk density, chemically combined water, and XRD analysis at different time intervals from 2 days up to 90 days under relative humidity 100%. The results elucidated that as the quantity of alkali activator increases up to (15% SSL, and 15% SH), the compressive strength increases up to 90 days. The combined water content of all mixes increases up to 90 days. Also the bulk density raises and the total porosity minimizes, this is due to the addition of the pozzolanic materials. All mixes showed good stability of its compressive strength values in 5 % MgSO4 solution. The data showed that mix S6 (100% GGBFS) activated by (15% SSL, and 15% SH) is the most appropriate binding material (geopolymer cement) that has good properties so it can be used as alternative binding materials to the ordinary Portland cement

Effect of Calcium Chloride on the Hydration Characteristics of Ground Clay Bricks Cement Pastes

Effect of CaCl2 on the hydration characteristics of the different cement pastes using ordinary Portland cement (OPC) and blended Portland cement with ground clay bricks (GCB) was studied. Various mixes were prepared using a water/solid ratio (W/S) of 0.25 (by weight). Three percentages of CaCl2 (0.25, 0.5 and 0.75%) are used; the CaCl2 used was dissolved in the mixing water. The hydration characteristics were tested via the determination of the combined water content, phase composition, compressive strength, total porosity (P%) and X-ray diffraction analysis (XRD) at different time intervals up to 180 days. The results showed that calcium chloride accelerates cement hydration in all systems studied. Ten % GCB in the presence of 0.50 % CaCl2 is the optimum ratio which has the higher compressive strength. Key words: Blended Portland cement; calcium chloride; ground clay bricks; hydration cemen

Inertization of lead by using blended cement pastes

Inertization of lead nitrate Pb(NO3)2, a representative of soluble lead compound, with five cements pastes based on either ordinary Portland cement (OPC) or blended Portland cement with granulated blast-furnace slag (GBFS) or metakaolin (MK) was studied. Various mixes were prepared by using a water/solid ratio (W/S) of 0.28 (by weight). Two ratios of Pb ions (1.0% and 2.0% of the solid binder) was used by adding to the mixing water. Hydration characteristics of the different cement pastes were investigated via the examination of chemically combined water content, compressive strength, X-ray diffraction analysis and thermal analysis (DTA/TGA). Leaching of lead ions from various hardened cement pastes was examined. The results showed that lead nitrate retards cement hydration through the formation of plumbate salt CaPbO3. The obtained results of leaching showed a high degree of immobilization of Pb ions in the various cement pastes. Moreover, partial replacement of Portland cement by MK is more efficient than granulated blast-furnace slag GBFS