Combined effects of biochar and MgO expansive additive on the autogenous shrinkage, internal relative humidity and compressive strength of cement pastes

Comparison of Fly Ash, Pva Fiber, Mgo and Shrinkage-Reducing Admixture on the Frost Resistance of Face Slab Concrete via Pore Structural and Fractal Analysis

“…3shows that the reduction effects of MgO on compressive strength are more noticeable at 7 and 28 days, when decreases of 7.1-10.4 % can be observed. The reduction effects of MgO on mechanical properties have been also reported by other authors12,26,58 . As Mo et al12 have concluded, the larger MgO dosage added, the greater the decrease in compressive strength of concrete, particularly at the ages of 7 and 28 days.…”

“…Besides, the refinements of the pore structures could be observed in Table 3, which could be attributed to the densification effect of MgO. Similarly, a series of MIP studies conducted by Mo et al 12,62 demonstrated that the cement paste containing 6 wt% MgO with different reactivities (35, 65 and 135 s) exhibited slightly finer pores in comparison to the pastes without MgO, while the refinement effect became weaker as the reactivity of MgO deceased. Moreover, the minor refinement of pore structure by SRA can be found in Table 3.…”

“…The reactivity of MgO is tested using the citric acid neutralization method described in details in Refs. 12,35 . The main physical properties and chemical compositions of cement, fly ash and MgO are shown in Table 1.…”

“…The high crack resistance is a typical feature of the well-designed face slab concrete. Some materials, such as fly ash 10 , fibers 1,2,11 and MgO expansive agent 12,13 are commonly used to improve the crack resistance of face slab concrete. Besides, the shrinkage-reducing admixtures (SRA) are widely reported to effectively decrease the shrinkage of concrete [14][15][16] .…”

A Review of Non-Soil Biochar Applications

“…Small sized particles (diameters below 2 µm) improved early strength and water tightness compared to big size macroporous biochar particles. Mo et al [285] combined biochar and MgO to mitigate the autogenous shrinkage of cement materials, and similar results were achieved by Muthukrishnan et al [286] by simply using low-ash pyrolyzed rice husks. Gupta et al [287] explored the addition of pre-soaked biochar particles that were produced at 500 • C, and they showed a reduction of sorptivity and a depth of water penetration of up to 60%.…”