The Effect of Methyl Hydroxyethyl Cellulose on the Cement Matrix Properties

6 Pages Posted: 28 Dec 2020

Date Written: June 30, 2020

Abstract

The effect of a methyl hydroxyethyl cellulose additive on the technical and physical-mechanical properties of the cement matrix has been investigated. The study involved cellulose ether of low (11,000–16,000 MPa∙s), medium (17,000–23,000 MPa∙s), and high (20,000–30,000 MPa) viscosity. The additives were introduced into cement in the amount of 0.25, 0.5, and 0.75 % by weight. It has been established that the introduction of cellulose ether in cement leads to an increase in the normal density of the slurry and extends the duration of the mortar setting. The normal density of cement slurry increases with the introduction of cellulose ethers of low viscosity (LV) and medium viscosity (MV) by 5.4‒16.8 %; when introducing the ether of high viscosity (HV), by 21.3–41.4 %. This confirms the high water-retaining capacity of methyl hydroxyethyl cellulose, which increases with increasing viscosity of the additives. The setting duration of cement slurry increases, depending on the concentration and viscosity of the additives, by 2‒4 times, compared with an additive-free material. There is also a significant reduction in the strength of the cement matrix in the early periods of hardening (1–7 days) depending on the concentration of the additives, by 2.2–4.2 times. The strength of the samples is least affected by the cellulose ether of low viscosity, largest – by that of high viscosity. The reduction of strength is observed at the age of 28 days, although not very much pronounced. Compared to the additive-free cement, the strength amount to: for the ester of low viscosity at concentrations: 0.25 % by weight – 14.3 %, 0.50 % by weight – 23.9 %, 0.75 % by weight – 40.5 %; for the ether of medium viscosity, respectively, 23.8, 26.2, and 33.3 %; for the ether of high viscosity, 28.6; 45.2, and 61.0 %. The corrosion resistance of the cement matrix with methyl hydroxyethyl cellulose additives is increased at a concentration of up to 0.25 % by weight and then gradually decreases. The above results make it possible to recommend using, in the production of dry construction mixtures, the cellulose ethers of low and medium viscosity, which would ensure the required time to maintain the solution mobility and the sufficient strength of the resulting material.