Mortar Incorporating Supplementary Cementitious Materials: Strength, Isothermal Calorimetry and Acids Attack

WOS:000377429900004International audienceSupplementary cementitious materials (SCMs) prove to be effective to meet most of the requirements of durable concrete and leads to a significant reduction in CO2 emissions. This research studies the effect different SCMs (natural pozzolan (PN) /limestone fine (FC) at various replacement levels) on the physical and mechano-chemical resistance of blended mortar. The paper primarily deals with the characteristics of these materials, including heat of hydration, strength and effects of aggressive chemical environments (using sulphuric acid and nitric acid). Over 6 mixes were made and compared to the control mix. Tests were conducted at different ages up to 360 days. The experimental results in general showed that Algerian mineral admixtures (PN/FC) were less vulnerable to nitric and sulphuric acid attack and improved the properties of mortars, but at different rates depending on the quantity of binder

The intercropping cowpea-maize improves soil phosphorus availability and maize yields in an alkaline soil

Aim: This study assessed whether growing cowpea can increase phosphorus (P) availability in the rhizosphere and improve the yield of legume-cereal systems. In alkaline Mediterranean soils with P deficiency, it is assumed that legumes increase inorganic P availability.Methods: A field experiment was conducted at the Staoueli experimental station, in Algiers province, Algeria, to compare the growth, grain yield, P availability, and P uptake by plants with sole-cropped cowpea (Vigna unguiculata L. cv. Moh Ouali) and maize (Zea mays L. cv. ILT), intercropped cowpea-maize, and fallow. Results: P availability in the rhizosphere was increased in both sole cropping and intercropping systems compared with fallow. It was highest in intercropping. The increase in P availability was associated with (i) significant pH changes of the rhizosphere of cowpea in sole cropping and intercropping systems, with the rhizosphere acidification significantly higher in intercropping (−0.73 units) than in sole cropping (−0.42 units); (ii) significant increase in the rhizosphere pH of intercropped maize (+0.49 units) compared to fallow; (iii) increased soil respiration (C-CO2 from microbial and root activity) in intercropping compared with sole cropping and fallow; and (iv) higher efficiency in utilization of the rhizobial symbiosis in intercropping than in sole-cropped cowpea. Conclusion With cowpea-maize intercropping, cowpea increased the P uptake, by increasing the P availability by rhizosphere pH changes in an alkaline soil. Overall, this study showed that intercropping cowpea improved the plant biomass and grain yield of maize in this soil