Abrasion-Resistant and Temperature Control of Lining Concrete for Large-Sized Spillway Tunnels

With regard to the high anti-scouring and abrasion-resistant performance requirements and great temperature control difficulties of lining concrete for large-sized spillway tunnels, in this study, a performance test was conducted on anti-scouring and abrasion-resistant concrete. The finite element method was used to analyze the temperature change rules of sidewall C(90)50 (design strength of concrete is 50 MPa at 90 days) lining concrete for the spillway tunnel. Further, a new cooling measure was proposed for adopting "early-throughput, high-flow and short-duration". As indicated by the results of this study, fly ash could reduce water consumption and micro-cracks via its "morphological effect". Silica fume could improve the early strength of cement concrete and make up for the strength loss caused by fly ash. Polyvinyl alcohol (PVA) fiber could enhance concrete durability. The doping of these three additives reinforced the strength and abrasion resistance of concrete. The results showed that the temperature of the lining concrete presented a change trend of "rapid increase first, followed by a slow decrease". The peak temperature was reached roughly 2 days after casting. In addition, properly increasing throughput flow or decreasing throughput temperature in the early stage of casting could significantly reduce the highest temperature and maximum temperature difference of concrete. Based on the results from the numerical simulation of temperature control effect, it was proposed to adopt "early-throughput, high-flow, and short-duration" for temperature control and cracking prevention. Specifically, within 2 days after casting, cooling water at roughly 12 degrees C was guided in at a flow of approximately 3.5 m(3)/h. Within 3-7 days after casting, river water at around 17 degrees C was guided in at a flow rate of approximately 1.8 m(3)/h. After 7 days, the cooling effect can be well achieved by only using the surface flowing water for curing. According to the field monitoring data, the changes in measured temperature were basically consistent with those from numerical simulations, and detection on the temperature of the sidewall lining concrete showed that a qualification rate of >91% was satisfactorily obtained by using the proposed approach.