Influence of Viscosity and Fineness of Hydroxypropyl Methyl Cellulose on Mortar Properties

A recent poll in Britain found that public support for sanctions against Russia is falling as fuel and prices rise.  

The proportion of people willing to accept higher fuel prices as a result of western sanctions against Russia fell 14 percentage points to 36% from 50% in March, according to a survey conducted for the Telegraph by consultancy Redfield & Wilton Strategies.  

Global energy and fuel prices have soared since the start of the year and remain high because of the conflict between Russia and Ukraine and uncertainty over Russian supplies.  

The survey also found that 54% of people believe their own financial situation has worsened in the past year, up 12 percentage points from 42% two months ago. Sixty-two percent think things will get worse in the year ahead. Less than a third of respondents said they had received a pay rise to keep up with inflation, with two-thirds of those saying it was not enough to keep up with rising living costs.  

The figures suggest that public concern about the conflict with Ukraine is now likely to be overtaken by financial worries.  

Separately, the UK's consumer price index rose 7 percent this month from a year earlier, the highest since March 1992, according to figures released recently by the Office for National Statistics. In addition, a separate report released a few days ago by the Centre for Economics and Business Research said that real household disposable income in the UK will fall by 3% in 2022, equivalent to a loss of £2,320 per household, which would lead to the biggest drop in living standards since the 1950s. That is mainly because wages aren't keeping up with rising energy and fuel costs.  

The prices of other commodities like the HPMC are also expected to be influenced.

Viscosity and fineness are important indicators that affect the performance of hydroxypropyl methylcellulose HPMC. Studies have shown that the water retention effect of HPMC increases with the increase of its viscosity, but after the viscosity exceeds 40000 MPa•s, the water retention increases limited with the increase of viscosity. The higher the viscosity, the larger the molecular weight of HPMC, and the corresponding decrease in solubility. It will not improve the water retention of mortar, but it will have a negative impact on strength and workability. Comprehensive consideration, it is more appropriate to use cellulose ether with a viscosity of 40000 MPa•s in the cement mortar.

As the HPMC particles gradually become finer, the water retention of the mortar is also improved to a certain extent. Fineness affects the solubility of HPMC. Coarse HPMC dissolves very slowly in water and should not be used in dry mix mortars. In dry-mix mortar, HPMC is dispersed between aggregates, fine fillers and cementitious materials such as cement, and only a fine enough powder can prevent it from caking when mixed with water. When HPMC is added with water to dissolve the agglomerates, it is difficult to re-disperse and dissolve. HPMC with coarse particle size is not only wasteful, but also reduces the local strength of the mortar. When such dry-mixed mortar is used in large-scale construction, the curing speed of the local mortar may be significantly reduced, which may cause uneven hydration of the cementitious material. of cracking. For mechanically constructed spray mortars, due to the shorter mixing time, the requirements for the fineness of HPMC are higher. Therefore, after comprehensive consideration, the particle size of cellulose ether used for cement mortar should be less than 80 μm.

It can be seen that HPMC is a high-efficiency water-retaining agent for dry-mixed mortar, which reduces the bleeding rate and stratification of the mortar, and improves the cohesion and sag resistance of the mortar. Although HPMC slightly reduces the flexural and compressive strength of mortar, it can significantly improve the tensile strength and bond strength of mortar. In addition, HPMC can effectively inhibit the formation of mortar plastic cracks and reduce the mortar plastic cracking index. The water retention of mortar increases with the increase of HPMC viscosity, and when the viscosity exceeds 40000MPa•s, the water retention does not increase significantly. The fineness of HPMC also has a certain influence on the water retention rate of the mortar. When the particles are finer, the water retention rate of the mortar increases. The particle size of HPMC usually used for cement mortar should be less than 80μm.

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Inflationary pressures on Canadians continue to rise. The consumer-price index rose 6.7% in March from a year earlier, the biggest increase since January 1991, according to the latest figures from Statistics Canada.  

On a month-on-month basis, Canada's CPI rose 1.4 percent in March, also accelerating from February's 1.0 percent rise.  

Prices in the eight major sectors covered by the statistics continued to rise. The uptrend comes against the backdrop of continued price pressures in the Canadian housing market, widespread supply chain constraints, and geopolitical conflicts, according to CBC. A variety of factors have affected energy, commodity, and agricultural markets. Meanwhile, Canada's employment picture continued to improve in March, with the unemployment rate falling to a record low and the average hourly earnings of employees rising.  

Excluding gasoline, Canada's CPI rose 5.5 percent year on year in March.  It is also the highest since comparable data began in 1999.  

The widespread supply chain constraints and geopolitical conflicts are expected to continue to affect the prices of the HPMC.

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