摘要
Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar may vary from several hours to 15 d at 5 ℃-35 ℃ due to quantities and average curing temperature. And its 28 d compressive strength is above 35 MPa. Thus the influence of quantities on setting time and 28 d compressive strength, and the relationship between setting time and average curing temperature were investigated. The optimum quantities were obtained by studying the interaction of admixtures, and the retarding mechanism was discussed. Based on 52 retard-bonded prestressed strands by manual work from 24 retard-bonded prestressed concrete T-beams, static friction drag, change factor κ and friction factor μ were obtained from the test when retard-bonded prestressed strands were tensioned. Application of the retarding mortar will be vast in practical concrete projects.
Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar may vary from several hours to 15 d at 5 ℃ - 35℃ due to quantities and average curing temperature. And its 28 d compressive strength is above 35 MPa. Thus the influence of quantities on setting time and 28 d compressive strength, and the relationship between setting time and average curing temperature were investigated. The optimum quantities were obtained by studying the interaction of admixtures, and the retarding mecha- nism was discussed. Based on 52 retard-bonded prestressed strands by manual work from 24 retard-bonded prestressed concrete T-beams, static friction drag, change factor κ and friction factorμ were obtained from the test when retard-bonded prestressed strands were tensioned. Application of the retarding mortar will be vast in practical concrete projects.
