Research On Anti-Cracking Performances Of The Cement Stable Macadam Adding Layered Materials

Cement stabilized macadam base has a good strength, integrity and the economic benefit is remarkable, and many other advantages, widely used in highway construction in our country. But as traffic load increasing, cement stabilized macadam base is prone to produce shrinkage crack. And the cracks can reflect to pavement surface, shorting pavement life. Considering the situation, the pavement performance and anti-cracking performance of the cement stabilized macadam adding layered materials have been researched on the basis of available research results at home and abroad. The main content includes:(1) According to research the pavement performance of cement stabilized macadam adding layered materials, in comparison with the blank test, the unconfined compressive strength increases with the addition of calcined palygorskite (weighed at 10% of the amount of cement) by 12.4%, at the curing age of 7 days; splitting tensile strength increases with the addition of calcined palygorskite by 32.4%. Compressive resilient modulus and splitting resilient modulus have been influenced variety with the addition of palygorskite with alkali activation. Water stability and freeze stability have shown some improvement.(2) According to research the anti-cracking performance of cement stabilized macadam adding layered materials, dry shrinkage strain and dry-shrinkage coefficient of cement stabilized macadam are the smallest adding layered materials’content of 10%; dry-shrinkage coefficient reduces by 28.1% with palygorskite with alkali activation,22.6% with untreated palygorskite and 18.9% with kaolin at the curing age of 7 days, respecetively; in addition, dry shrinkage strain and dry-shrinkage coefficient were decreased with the increase of curing ages and the decrease of the content of fine-grained soils. The anti-cracking performance enhances significantly with the addition of palygorskite with alkali activation and calcined palygorskite, and it is higher than that of montmorillonite and kaolinite.(3) The results show that more fibrous hydration products and a net-like micro structure exists in the cement pastes mixed with palygorskite clay, inducing the great decrease in shrinkage cracks of the cement-stabilized macadam by experiment including SEM、XRD、 TG-DSC.(4) Using palygorskite with alkali activation (weighed at 10% of the amount of cement) to rely on the laid in the project of cement stabilized macadam, and the research is applied in engineering practice.