Experimental Study On Properties Of Early Strength Self-compacting PVA-ECC

Engineered Cementitious Composite(ECC)is a new type of concrete material,which shows better mechanical and durability properties than that of common concrete.After nearly 20 years development,it has been applied in some practical engineering.It has been used to built bridge dack pavement and structural strengthening.But it is difficult to vibrate to make the structure compact due to the low flowability of ECC.This can lead to holes arise in sturcture,which affects the entirety of the structure.To overcome the shortcoming of ECC,a kind of new ECC with good working performance was invented and studied in this paper.Sulphoaluminate cement with early strength is used,which can meet the needs of rapid reinforcement.The working properties,compressive properties,flexural properties,tensile properties and micro-morphology of early strength self-compacting fiber reinforced cement-based composites are experimentally studied and analyzed.The specific contents are as follows:(1)Experimental study on working performance of fresh mix with early strength and self-compacting PVA-ECC were conducted.The influence of water-cement ratio,fiber content and fly ash content on fluidity was obtained by orthogonal test range and variance analysis.The fluidity increases with the increase of water-cement ratio and fly ash content,and decreases with the increase of fiber content.(2)Experimental study on compressive performance of early strength self-compacting PVA-ECC were conducted.The test results were obtained and analyzed by range and variance.The influence of water-cement ratio,fiber content and fly ash content on compressive strength was studied and analyzed.With the increase of water-cement ratio and fly ash content,the compressive strength gradually decreases,and when the fiber content is 0.5%,the compressive strength is the highest.(3)Experimental study on flexural properties of early strength self-compacting PVA-ECC was conducted.The flexural strength and load-displacement curves were obtained.The range and variance analysis of the flexural strength was carried out,and the effects of water-cement ratio,fiber content and fly ash content on the flexural strength were obtained.The toughness index analysis of the load-displacement curves was carried out,and the three factors on the flexural toughness of materials were studied and analyzed.With the increase of water-cement ratio and fly ash content,the flexural strength decreases gradually,and with the increase of fiber content,the flexural strength increases obviously.(4)Experimental study on uniaxial tensile properties of early strength self-compacting PVA-ECC was conducted.Tensile strength and tensile stress-strain curves were obtained,and failure modes of specimens with different fiber content were analyzed.When the fiber content is 1%,the strain hardening phenomenon is obvious.