How does hydroxypropyl methyl cellulose works in concrete materials?
Hydroxypropyl methyl cellulose (HPMC) has excellent thickening properties and can be used as an excellent concrete anti-dispersant. In recent years, with the continuous development of external wall insulation technology and the excellent characteristics of HPMC itself, HPMC has been widely used in the construction industry.
1.The strength of concrete
The hydroxypropyl methyl cellulose underwater non-dispersible concrete admixture in a highway bridge foundation project, the design strength grade is C25. by the foundation test, the cement dosage is 400 kg, compound with silica fume 25 kg / m3, the optimal amount of hydroxypropyl methylcellulose is 0.6% of the cement amount, the water-cement ratio is 0.42, and the sand ratio is 40% , the amount of high efficiency water reducing agent is 8% of the cement dosage, the average 28-day strength of concrete specimens in air was 42.6 MPa, and the average 28-day strength of concrete cast underwater with a drop height of 60 mm in water was 36.4 MPa. The strength ratio of concrete formed in water to that formed in air was 84.8%, which is a significant effect.
2.Dispersion resistance test
Hydroxypropyl methyl cellulose is a water-soluble polymer compound also known as water-soluble resin or water-soluble polymer, is by increasing the viscosity of the mixing water to increase the consistency of the mix, is a hydrophilic polymer materials, in water can be dissolved and form a solution or dispersion. Experiments show that when the admixture of naphthalene based superplasticizer increases, the admixture of water reducing agent will reduce the dispersion resistance of fresh cement mortar at the same time, it is found that as the admixture of HPMC increases, the dispersion resistance of fresh cement mortar becomes better and better.