Solid State Phenomena Vol. 315

Abstract: The rheological properties of concrete have a great impact on the workability, and the L-box test can obtain the relationship between the morphology and the yield value of the material under free flow conditions. However, as an elastoplastic fluid, the low water-cement ratio concrete can hardly flow freely without the admixture. The vibrating process is often used in the production to meet the requirements, but the rheological properties of the material under vibration are difficult to measure. A new vibration test method for the flowability of low water-cement ratio concrete is proposed in combination with the L-box idea. The flow morphology and flow velocity of two kind of low water-cement ratio concrete in the L-box are observed under the condition of controlling the vibration frequency. After that, theoretically analyzing the yield value of the material under vibration is applied. The results show that with the increase of vibration frequency, the average flow velocity of the material increases, but the trend is gradually slower. With the increase of vibration frequency, the yield value of low water-cement ratio concrete is much lower than before. This test method can be used in related engineering applications of vibrating compacted concrete.

Abstract: This work studied the effects of medium-length fibrous cellulose (MFC) on the morphology, mechanical and thermal properties of poly(lactic acid) (PLA)/propylene-ethylene copolymer (PEC) (90/10) blends. The morphological analysis of PLA/MFC composites observed MFC fibers inserted in the PLA matrix and MFC appeared agglomeration when added high MFC loading. The phase morphology showed the two-phase separation of PLA/PEC blends. The presence of PEC reduced the agglomeration of MFC fibers in polymer matrix. The tensile stress and strain curves found that the ultimate stress of PLA was the highest value and the addition of MFC increased Young’s modulus of PLA/MFC and PLA/PEC/MFC composites. The PEC presence improved the strain at breaking point of PLA/PEC blends. The thermal properties found that the incorporation of MFC did not improve the thermal stability of PLA/MFC and PLA/PEC/MFC composites due to the PLA had degradation temperature higher than MFC.