The dredged sand in the lower reaches of the Yangtze River is mainly ultra-fine sand（with a fineness modulus of 0.1-0.5），with small particle size and uneven particle gradation，which can be hardly used in engineering. With dredged sand in the lower reaches of the Yangtze River as the main raw material，we replace ordinary cement with alkali-activated low-carbon geopolymers to prepare artificial blocks and test their mechanical properties and drying shrinkage characteristics. Moreover，we use chopped fibers to solve the problem of easy shrinkage and cracking caused by the alkali activation system. The test results show that：1）When the content of the activator Na2O is 5%，and the modulus is 1.0，the compressive strength and splitting tensile strength of the blocks after 28 days are 48.20 and 6.43 MPa，respectively，and the strength does not shrink in the later period. 2）Both basalt and polypropylene fibers can significantly inhibit the linear drying shrinkage of the blocks. Basalt fibers have stronger mechanical properties than polypropylene fibers，which can make the microstructure of blocks more compact and more integrated.