The utilization of black liquor, produced by the pulp and paper industry in Egypt, as a workability aid and set retarder admixture has been investigated. This approach may help eliminate the environmentally polluting black liquor waste. It also provides a low cost by-product, which can be widely used in the construction industry. The properties of black liquor and its performance on concrete at two different ratios of water to cement have been studied. The results revealed that black liquor from rice straw pulp increases concrete workability, improves compaction, and reduces honeycombing. Moreover, it retards the initial and final set time and enhances uniform compaction. The effect of incorporating small portions of silica fume has been investigated. The ageing effect of this material over a period of one year, to determine its safe storage period, has been studied. Finally, this admixture was found to comply with the relevant Egyptian standards.

Euphorbia retusa (family Euphorbiaceae) is an annual plant in the desert of Egypt with a 20 to 60 cm high. The aerial part of the plant containing latex is used in many biological activities. This study aimed to determine the phytochemical constituents, antioxidant, antimicrobial properties and allelopathic activities of aerial parts of E. retusa collected from Wadi Arabah, North Eastern Desert, Egypt. Standard methods were used for the qualitative and quantitative of tannins, saponins, flavonoids, alkaloid, phenolics, steroids, terpenoids, and glycosides. The antioxidant activity was measured based on the reduction of DPPH.Antimicrobial activity was evaluated against pathogenic bacteria, as well as the allelopathic potential against Chenopodium murale was assayed. E. retusa attained the highest values of saponins, tannins, and phenolics compared. In the DPPH test system, the IC50 value of the antioxidant inhibition for E. retusa was 802.74µg mL-1. The data obtained indicated that, the sensitivity of the seedling growth to the extract was higher than the germination of the test species. In addition, the root growth of C. murale was more affected than the shoot system to the inhibitory allelopathic activity induced by E. retusa. At higher concentration (40 g L-1) the germination of the tested seed was highly inhibited by 51.77%, while the shoot and root were reduced by 60.98% and 74.55%, respectively. However, the opposite response was observed at the lower concentration (2.5 g L-1).In conclusion, theextract of E. retusa plant has phytotoxic properties and thus contains phytotoxic substances

The objective of this study was to analyze the phytochemicals and to determine the antioxidant, antibacterial and allelopathic potential of three wild Mesembryanthemum species (M. crystallinum L., M. forsskaolii Hochst. Ex Boiss and M. nodiflorum L.). The phytochemical composition of the methanolic extract of studied species revealed the considerable quantities that might be responsible for their powerful antioxidant activity. The IC50 values were 386.51, 592.97, and 752.23µg/ml for M. nodiflorum, M. crystallinum and M. forsskaolii extracts respectively. The antibacterial activity index was calculated for each extract in comparison with the standard antibiotics. M. nodiflorum showed higher potency than ampicillin and penicillin G against against Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis. The allelopathic potential showed that the studied Mesembryanthemum species expressed a significant phytotoxic activity against Chenopodium murale weed in a dose dependent manner. M. nodiflorum sample showed the most phytotoxic effect among the studied species.