Workability And Mechanical Properties Of Mortars Containing A Bioadmixture Manufactured With Extracellular Substances

A bio-admixture was used in mortar and its influence on the properties of fresh and hardened mortars was investigated. Various concentrations of bioadmixture (0.5; 1.5; 2.5%) were added to mortars containing CEM I or CEM V cements. In mortars, water-cement ratio was kept constant (W/C = 0.5). The initial slump and slump loss for various mortar mixtures were determined. The compressive and flexion strengths were observed after 28 days water curing. The first experimental results show that the admixture acts as a plasticizer on mortars because it increases their workability, whatever the admixture rate for CEM V, while only mortars with 1.5% and 2.5% of admixture were significantly greater than the un-admixtured mortar with CEM I. In addition, for the CEM I based mortar, the sample containing 2.5% of bioadmixture has a lower compressive strength than that of the mortar without bioadmixture; while for a bioadmixture rate in the range of 0.5-2%, compressive strength are comparable. Flexural strengths of CEM I with 2 and 2.5% of bioadmixture based mortars are comparable. For CEM V based mortars, compressive strength is the same for rates of 1, 1.5 and 2% of bioadmixture and superior than that of the un-admixtured mortar, which has a compressive strength similar to mortars with 0.5 and 2.5% of bioadmixture. Finally, the bioadmixture has no effect on the flexural strength of the CEM V based mortar, except for mortar containing 1% of bioadmixture.