Analysis On The Influence Mechanism Of Curing System On Mechanical Properties Of Reactive Powder Concrete

RPC has high strength and durability.It can be applied to large and super large structures.RPC has ultra-high toughness.And its application to the structure can reduce the use of steel bars.It avoids causing the problems of steel corrosion.With the deepening of research,it is found that RPC has the strength decrease phenomenon.It is seriously harmful to the structure subjected to long-term load.Therefore,this paper aims to study the effect and mechanism of delay period and curing temperature on the long-term compressive strength decrease rate of RPC.This paper tested the 7 d,28 d and 90 d compressive strength of RPC at delay period of 18 h,24 h and 30 h,when the curing temperature is 90?.This experiment tested the 7d,28 d and 90 d compressive strength of RPC in 50?,70? and 90? curing temperature,when the delay period was 24 h.The highest value of 7 d and 28 d compressive strength measured by the test were taken as the reference value.And the difference was compared with the value of 90 d to determine the decrease rate.Combined with the amount of non-evaporable water,X-ray diffraction(X-ray diffraction,hereinafter referred to as XRD),the scanning electron microscope(scanning electron microscope,hereinafter referred to as SEM)and energy disperse spectroscopy(energy disperse spectroscopy,hereinafter referred to as EDS)of hydration products.The experiment investigated the effect of delay period and curing temperature on RPC of compressive strength and long-term strength decrease rate.The results showed that,by changing the length of the delay period,the amount and microstructure of the hydration products inside the RPC will also change,thereby changing the compressive strength and long-term strength decrease rate of the RPC.The suitable delay period is beneficial to the improvement of compressive strength and strength stability of RPC.When the delay period was 30 h,the compressive strength of RPC was higher,and the long-term strength decrease rate was smaller.Steam curing at different temperatures,the internal microstructure and mechanical properties of RPC are significantly different.The higher the curing temperature is,the denser the structure ofhydration products inside RPC,and the higher the compressive strength is.The change of RPC's long-term strength decrease rate was not a simple linear relationship with the change of curing temperature.With the increase of temperature,the long-term strength decrease rate firstly increased and then decreased within the scope of this test.Considering the change law of compressive strength and long-term strength decrease rate,steam curing at 90? is the best curing temperature of RPC.This paper explores the influence and mechanism of the curing system on the mechanical properties of RPC.It can optimize the long-term mechanical properties of RPC.It can not only provide new ideas for solving practical engineering problems,but also have reference for future research.