| Cement concrete pavement has many advantages, such as high strength, strongcarrying capacity as well as good durability, which is widely used in highway at alllevels. However, because of improper construction, overload and other reasons, thecement concrete pavement was destroyed seriously, which interferes with the normaltraffic. On the one hand the traditional cement-based repair material has long curingperiod, which seriously influences the open transportation time; on the other hand,low bond strength and poor durability lead to the damage of repaired cement concretepavement occur in a short time.Therefore, according to the alkali excitation slagcement and P.O compounding with R-SAC two technical routes, this paper studied theperformance of super early strength substrate, used the polymer emulsion to furthermodify and developed the rapid repair material of cement concrete pavement withoutstanding early strength performance, excellent bond performance and moderatesetting time. This paper also explored the hydration mechanism of the early strengthsubstrate and polymer modification and had a series of test on the engineeringapplication performance of rapid repair material. The results show that:1. Alkali excitation slag cement mortar has high early strength, which can meetthe requirements of6hours’ traffic open. However, because the alkalinity of alkaliexcitation gel system is strong, the polymer has serious demulsification. So it is notsuitable for application in polymer modification. The early strength of P.Ocompounding with R-SAC cement mortar is higher than alkali excitation slag cementmortar, which can meet the requirements of6hours’ traffic open. Besides, theperformance of polymer emulsion in composite gelling system is stable. So it issuitable for application in polymer modification.2. Different kinds of water reducing agent have a significant impact onthe fluidity, fluidity loss through time and early strength of the P.O compoundingwith R-SAC gel system. The FDN water reducing agent is the most ideal among them.3. The different mixed proportion of P.O and R-SAC has a significant effect onthe composite cement mortar early strength and setting time. When the mixedproportion of P.O and R-SAC is60%:40%, the6hours mechanical strength ofcomposite cement mortar is the highest, the late mechanical strength is steadilydeveloping, the setting time is moderate and the compatibility performance is good. The addition of polymer latex extends the operational time of composite cementmortar, improves the early and late flexural strength and bond strength, and greatlyimproves the ratio of bending compressive strength of composite cement mortar.4. The XRD and SEM micro test results show that the composite gel systemgenerates a large amount of acicular ettringite and C-S-H/AH3gel in6hours. Alongwith the prolongation of the age, the ettringite is stable and the gel is increasing. Sonot only the early strength is significant, but also the late strength is steadilydeveloping. The addition of polymer latex is helpful to eliminate the micro cracks ofcement paste and have effects of filling pore defects, but it does not produce newhydration products.5. The measurement performance of the optimization rapid repair mortar showsthat the shrinkage of rapid repair cement mortar is small and wear-resistingperformance is good, which are better than the ordinary Portland cement mortar.Different curing conditions have a lager influence on its mechanical properties. Theearly strength of confected concrete is high, which can satisfy the requirements of6hours’ traffic open. Comprehensive research shows it can satisfy the requirements ofcement concrete pavement rapid repair. |
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