Research On The Performance Of Ordinary Ready-mixed Mortar

Accompanying with the development of construction technology, people forward higherdemand for construction efficiency, environmental protection and construction quality. Someadditives such as cellulose, redispersible polymer powder, fibers and water reducer, play anessential part to improve the workability of mortar. Sand composition is a key facter effectingthe quality of mortar, how to make use additives to improve the performance of mortarprepared with unreasonable grading sand is a challenge.In this experiment, the influence of cellulose, redispersible polymer powder, fibers andwater reducer on the performance were studied, the results show that:(1) The addition of cellulose can improve retention, decrease loss of consistency andprolong the setting time. The retention can reach to94%and loss of consistency is inferior to10%by mass at0.3%; the ratio of flexural strength and compressive strength exceed0.35,when the0.2%HPMC was added; the longer the viscosity of HPMC, the greater thesetting time, the setting time of mortar mixed with0.5%H4can extend to900min; theshrinking percentage of mortar mixed with H4was about0%, but the shrinking percentage ofmortar mixed with H1, H2, H3were increased thanks to increase viscosity of HPMC. Thestrength and flow of mortar mixed with HPMC were decreased.(2) The strength of mortars mixed redispersible polymer powder was decreased to someextent. However, the ratio of flexural strength and compressive strength was improved, it canreach up0.26,0.28,0.29,0.29，0.30at1.0%P1,1.5%P2,2.0%P3,1.0%P4and2.0%P5,respectively. The binding strength of mortar mixed redispersible polymer powder wasincreased as the increase of dosage, it can reach up0.036MPa and0.035MPa at2.0%P1andP5.(3) As increase of dosage, the strength and cracking area of mortar were decreased andwater requirement was increased. However, the ratio of flexural strength and compressivestrength at28d was improved, it can reach to0.33and0.30by0.3%9mm polypropylene fiberand vegetable fiber. The shrinking percentage of mortar mixed0.3%polypropylene fiber and0.05%vegetable fiber were least, respectively.(4) Polycarboxylate superplasticizer has no water reducing effect, the segregation andbleeding was more serious. Superplasticizer and HPMC have no improvement in mortarprepared with0.3mm sand. The strength of mortar prepared with0.6mm-1.18mm and1.18mm-2.36mm sand mixed with superplasticizer and HPMC was higher than one mixed with ones, the compressive strength at28d reach to8.1Mpa and7.7MPa, the flexural strengthat28d reach to2.8Mpa and2.5MPa. the strength of mortar prepared with middle sand washighest with or without superplasticizer and HPMC.(5) The cost-effective mortar additive was manufactured, the improvement of waterretention and flexibility was superior to the additive used in engineering.