Study Of Main Mechanical Properties And Durability Of Red Mud Concrete Pavement

The use of red mud-based concrete in pavement structure can effectively address the scarcity of road engineering material and the environmental harm caused by the accumulation of red mud.Moreover,it can facilitate the resource utilization of red mud and presents a novel solution for road engineering materials development.The soundness and reliability of red mud-based concrete in practical applications are contingent upon its fundamental performance,while its durability dictates the lifespan of the material.Therefore,investigating the effect of red mud on both the core attributes and long-term resilience of concrete forms the groundwork for the extensive exploitation of red mud.This paper investigates the i MPact of various factors,including red mud content,water-cement ratio and mineral admixtures on the core characteristics and longevity of red mud-based pavement concrete.Additionally,the study delves into the micro-level analysis of the wear and tear caused by freeze-thaw cycles and sulfate attacks on the durability of red mud-based concrete.The key findings of this research are as follows:(1)The compressive strength of concrete made with red mud exhibits an initial increase followed by a decrease as red mud content increases.Specifically,the addition of about 4%red mud(replacing approximately 25% of cement),results in the highest mechanical properties.However,the mechanical properties of the concrete deteriorate with increasing water-cement ratio.Furthermore,the presence of slag powder has a more notable i MPact on the mechanical properties than that of desulfurization gypsum.(2)In the freeze-thaw cycle test,the quality of the specimens initially improves due to water absorption,but subsequently deteriorates due to mass loss during the cycles.initially increases and then decreases when the red mud content is around 3% or the water-cement ratio is approximately 0.43.When the cycle is up to 100 times,the corresponding mass loss and strength reduction increase with the increase of red mud content,and increase with the increase of water-cement ratio.The addition of 6% slag powder and 2% desulfurization gypsum results in the smallest mass loss rate and compressive strength loss rate,indicating that the freeze-thaw resistance of red mud-based concrete is superior when slag powder is added co MPared to when desulfurization gypsum is used.(3)red mud based concrete due to sodium sulfate corrosion was observed to follow a Ushaped trend,with initial improvement followed by degradation.However,the appearance of the specimens remained stable throughout the corrosion process,indicating a superior overall performance in sulfate resistance.The results also indicated that when the test was conducted up to 120 days,the mass loss rate and compressive strength corrosion resistance coefficient of the sample increased with the amount of red mud added,water cement ratio,and the amount of slag powder replacing desulfurization gypsum.Thus,it can be inferred that factors such as reducing the amount of red mud,lowering the water cement ratio,or increasing the proportion of slag powder can enhance the sulfate corrosion resistance of red mud based concrete.The damage caused to red mud-based concrete by the erosion of sodium sulfate solution is predominantly due to chemical erosion.Specifically,when the concrete matrix is immersed in Na2SO4 solution,there is an ion exchange reaction between the solution and the hydrated gel product.This results in the disintegration and destruction of the hydrated gel product,leading to a decline in the cementation and adsorption of the aggregates and ultimately causing structural damage to the matrix.