Preparation And Properties Of Photocatalytic Concrete

Photocatalytic concrete,as an important green concrete,has been attracting much attention.Using photocatalytic technology in concrete materials,it has developed environmentally friendly and widely used building materials.Photocatalytic reactions under natural conditions such as light can improve air quality and living environment.In the case of water cement ratio of 0.43,the Nano titanium dioxide was mixed into cement by incorporation and then stirred to form photocatalytic concrete.The amount of Nano titanium dioxide doped was 0%,2%and 4%,and the amount of diatomite doped was 0%and 3%.Formulate a parallel experimental plan.The surface density,water absorption,softening coefficient,7d compressive strength,28d compressive strength and sulfate corrosion resistance of the concrete tested by several sets of 100mm×100mm×100mm specimens were prepared;The preparation of 100mm×100mmx400mm sample was tested by fast freezing method.Preparation of 150mm×15mm×10mm sample to test the photocatalytic properties of concrete at 0%to 8%of nanometer titanium dioxide content.By catalyzing the methylene blue solution,spectrophotometer was used to determine the change in the concentration of methylene blue solution and calculate the photocatalytic degradation rate to evaluate photocatalytic performance.The results showed that the water absorption of concrete decreased with the increase of the nanometer titanium dioxide,and the water absorption reached 4.70%when the nanometer titanium dioxide was 4%.When the same nanometer titanium dioxide is doped,the water absorption rate of 3%diatomite concrete is lower than that of non-doped concrete.With the increase of Nano titanium dioxide admixture,the softening coefficient of photocatalytic concrete has been increasing.When the amount of Nano titanium dioxide admixture is 4%,the softening coefficient reaches a maximum of 0.915,and the increase of 0%to 2%is large.When the amount of Nano titanium dioxide admixture is the same,the softening coefficient of concrete with 3%diatomite is higher than that without diatomite.In terms of mechanical properties,with the increase in the amount of nanometer titanium dioxide admixture,the compressive strength of the concrete 7d and 28d are first raised and then reduced.When the amount of nanometer titanium dioxide admixture is 2%,the 7d compressive strength of the concrete reaches a maximum of 32.8MPa.The 28d compressive strength also reached a maximum of 46.3MPa.When nanometer titanium dioxide is doped in the same amount,the compressive strength of 7d and 28d mixed with 3%diatomite concrete is higher than that of non-doped diatomite.In terms of durability,with the increase of nanometer titanium dioxide admixture,the mass loss rate and dynamic elastic modulus change rate of concrete are reduced first and then increased,that is,the frost resistance is improved first and then decreased;When the amount of nanometer titanium dioxide is 2%,the mass loss rate of concrete reaches a minimum value of 3.73%,and the dynamic elastic modulus change rate reaches a minimum value of 24.6%.With the increase of Nano titanium dioxide,the corrosion resistance of concrete to sulphate is first increased and then decreased.When the amount of Nano titanium dioxide is 2%,the corrosion resistance coefficient of concrete can reach 81.6%.When adding 3%diatomite,the frost resistance and sulfate corrosion resistance of concrete are better than those without diatomite.In terms of photocatalytic properties,with the increase in the amount of nanometer titanium dioxide from 0%to 8%,the degradation rate of methylene blue solution is basically the same,showing a tendency of first rising and then decreasing.At different times,the amount of Nano titanium dioxide doped reached the highest point of degradation rate at 5%,50.32%at 90min,70.16%at 180min,and 81.23%at 270min.The degradation rate was 17.63%at 90 min,35.64%at 180 min,and 48.52%at 270 min,reaching 35.04%,50.80%and 59.73%at peak,respectively.It also has a good photocatalytic effect.