Gusev N. I., Kochetkova M. V.

Departament of Quality Management and Technology of Building Production

«Penza State University of Architecture and Construction»,

Russia

The strength characteristics of polymer cement coating compositions of the outer walls of lightweight concrete

Crucial in determining the suitability of the solution for protective and decorative coatings wall from foam concrete have strength and deformation characteristics.

From these characteristics depend toughness and durability. To increase the strength and deformability of a cement-sand mortar is added the polymer. Is considered an optimum amount of from 7 to 20% by weight of binder, based relatively dry substance. On the strength characteristics of polymer-solution is significantly affected by water-cement ratio, temperature and humidity conditions of hardening.

The most favorable conditions for hardening should be considered as an air-dried at a temperature of +18 - +25 ° C and humidity of 50-60%. Samples for determination of compressive strength, tensile and shear maintained under these conditions.

The test results on the compressive strength of the samples after 28 days of storage are given in Table 1.

Table 1

Polymer	P:C	W:S	W:C	Slump cone cm	Bulk density kg / m^3	Compressive strength MPa
_	0	0,134	0,54	9,1	1510	4,2
PVA dispersion	0,07	0,115	0,47	8,1	1502	5,7
	0,10	0,114	0,47	7,2	1595	7,6
	0,20	0,112	0,47	7,2	1580	11,8
SCS-65PP	0,07	0,160	0,65	7,2	1478	5,8
	0,10	0,151	0,62	7,9	1518	9,4
	0,20	0,120	0,51	7,1	1455	10,9

Also, the compressive strength was determined after 7 days, 60 days and 180 days of storage the samples in an air-dry conditions. Thus, increasing the concentration of polymer in the solution indicated a more rapid increase in strength during the initial period of hardening (Fig. 1).

Figure 1.Compressive strength polymer solution, depending on the duration

of curing.

Same graph shows that the P:C more than 0.15, latex formulations reduces the compressive strength. Polymeric additives have plasticizing properties. Thus, increasing the proportion of the polymer-cement ratio to 0.15 in all stages of hardening increases.

Moreover, during storage of the samples in an air-dry conditions, the polymeric additive increases water holding capacity of the solution, which promotes more complete hydration of the cement with increasing P: C.

Some reduction in the compressive strength when the latex solution at P:C = 0.20, explained by the predominance of elastic and elastic rubber particles in the cement stone. In the polymer solution, this anomaly is observed when the P:C = 0.15.

The test results are shown in Table 2 and in Table 3.

Table 2

Polymer	P:C	Bulk density kg / m^3	Tensile strength (MPa)
			7 days	28 days	60days	180 days
–	0	1510	0,38	0,49	0,51	0,76
PVA dispersion	0,07	1502	0,72	0,96	0,99	1,16
	0,10	1595	0,86	1,16	1,24	1,22
	0,20	1580	1,02	1,41	1,31	1,43
SCS-65PP	0,07	1538	0,67	0,85	0,87	0,86
	0,10	1560	0,88	1,22	1,23	1,26
	0,15	1595	0,99	1,48	1,31	1,48
	0,20	1540	1,10	1,50	1,48	1,48

Table 3

Polymer	P:C	Bulk density kg / m^3	Shear strength (MPa)
			7 days	28 days	60days	180 days
–	0	1515	0,36	0,74	0,78	0,81
PVA dispersion	0,07	1572	0,72	1,01	0,99	1,10
	0,10	1555	0,91	1,16	1,21	1,26
	0,20	1586	1,08	1,22	1,22	1,37
SCS-65PP	0,07	1500	0,61	0,98	1,00	1,00
	0,10	1443	0,73	1,01	1,18	1,12
	0,15	1433	0,78	1,05	1,12	1,11
	0,20	1420	0,39	0,75	0,82	0,71

The strength increases with increasing P: C. In the solutions of latex, when the P: C more than 0.15, the strength is reduced.

The polymer solution can qualify for shear strength for protective and decorative coatings foam concrete.