consumed as automobile engine antifreeze/coolant. Diethylene glycol (DEG) is used as a dehydrating agent for natural gas for its hygroscopicity. In addition, glycols are used for the production of alkyl-type resins.
The effect of glycol-based GAs from the dihydroxy compound class (including EG, PG and polypropylene glycol (PPG)) on the grind ability of clinker was studied by (Teoreanu and Guslicov, 1999) at dosage rates of 0.03, 0.05 and 0.1% of cement weight. For the same grinding duration, they concluded that the cement specific surface area increased by 29% when using PPG and by 20% with the use of EG and PG. For longer grinding durations when cement Blaine fineness exceeds 3500 cm2/g, the growth of the specific surface area becomes negligible with PPG whereas it varies from 14–24% with EG and PG.
Water solutions of surfactants significantly change the granulometric composition of cement with increased levels of small particle size and simultaneous agglomeration neutralize surface charges as a result dissociation of the surfactant and appearance of ions but have a negative effect on strength characteristics of cement stone. A surfactant solution in glycol merely modifies particle size of powder, but actively prevents agglomeration of fine particles. The modification due to presence surfactants of various reactive radicals, their position in molecule chain length and shape of molecular weight polymeric surfactant (Shakhova; L.D., 2014).
The aggregation process is essentially dependent on clinker nature, the dispersion state of the cement, working conditions of the grinding plant, the kinetic energy of the grinding media and their distribution, and the atmosphere within the mill. Elimination or diminution of ground solid mass aggregation and adhesion effects is carried out in three main ways (Meric, J.P., 1980)( Béke, B., 1973)( Dombrowe, H. et al, 1982) 1) decrease of grinding media size; 2) running of the grinding plant in a closed circuit; and 3) use of surfactants. The use of surface active additives in the grinding leads to a decrease in material hardness, by screening attractive surface forces and promoting fracture by the easier propagation of cracks.
The effect of the surfactants is emphasized at low concentration, ranging between 0.01% and 0.5%. Considerations based on surface science suggest the effect of surfactants is dependent on their nature and molecular structure (Teoreanu, I., Guslicov, G., 1995). The effect of this additive with higher molecular weight is demonstrated to be better than the effect of corresponding inferior dihydroxy compounds, but only for the early stage of the process, which corresponds to larger cement grains or larger pores, respectively. In the considered case, for high specific surfaces, the Traube-Duclaux rule, applicable to the homogenous adsorption, is inverted. Such a finding does not appear when comparing the effect of ethylene glycol and propylene glycol. For such a comparison, even if the difference between the observed effect when using ethylene glycol and propylene glycol is not high, the effect of the latter certainly is better. When using all three additives, it was found that, for the same grinding duration, it yielded an obviously higher specific surface of cement in comparison with the specific surface of the reference (non-additive) cement.
Hasegawa, M. and Kanda, Y., 1993 reported that alcohols were considerably effective as grinding aids for feldspar although the degree of effectiveness varied somewhat with the species and additional quantities of alcohol. Seven kinds of alcohols with different alkyl groups and three kinds of glycols, which have the same hydroxyl groups as alcohols, were used as liquid additives. Benzene and water were also used as additives to compare with the effect of alcohol additives. These additives, except for water, were special grade reagents and used without further Purification. Compared with alcohol and glycol additives, benzene and water were found non-effective as grinding aids for the ultrafine grinding of quartz. A relationship between the specific surface area of product and the grinding time with alcohol additives in the different amounts of addition was investigated. Although the specific surface area with additives increased with grinding time to a maximum value, further grinding caused a decrease in the specific surface area of products, especially with the use of small amounts of additives.
Biodiesel production results in glycerol production as the main by-product in the biodiesel industry. One of the utilization of glycerol obtained from biodiesel production is as a cement grinding aid (CGA). Results showed that crude glycerol content was 40.19% whereas pure glycerol content was 82.15%. BSS value of the cement with CGA supplementation was higher than that of non-supplemented cement (blank) indicating that CGA-supplemented cement had higher fineness than the non-supplemented one. It was also found that pure glycerol 95% and TEA 5% at 80ºC was the optimum CGA used to result in finest cement with BSS value of 4836 cm2/g (Farobie; O. et al, 2012).
The effect of grinding aids has been explained mainly by two mechanisms. One is the alteration of the surface and mechanical properties of individual particles, such as a reduction of surface energy, and the other is the change in the arrangement of particles and their flow in suspension (Zheng; J. et al, 1997)(Oettel; W. and Husemann; K. 2004).
Surana, M.S. and Joshi, S.N., 1987 explained that the specific surface of a sample containing cement clinker, china clay and gypsum ground with 0.05% urea in the aqueous solution is 755 cm2/g higher than that of a sample without the grinding aid. The effect of methyl alcohol, ethyl alcohol, acetone, benzene, diethyl ether on the grinding of cement clinker in a ball mill was investigated by (Kim, B.K., 1975) and it was found that methyl and ethyl alcohol provided practical power saving and all of the aids decreased the compressive strength. Shakhbazyan, T.O. and Mikhaelyan, V.G., 1977 analyzed the effect of the wastes composed of activated carbon and zinc acetate on the specific surface area of the ground clinkers. Furthermore, 0.08–0.5% hydrophobic agents based on the weight of clinkers, such as calcium oleate, naphthenate, laurate, stearate or palmitate, or the free acids themselves are used at the clinker–gypsum grinding stage. But they may cause some retardation of setting (Bensted, J., 1992). Moreover, (Hekal, E.E. et al, 1999) (Hekal, E.E. et al, 2000) examined the mechanical and physicochemical properties of hardened Portland cement pastes containing hydrophobic admixtures. In addition, the waterproofing characteristics of polymer modified Portland cement mortars have been studied by (Saija, L.M., 1995). Besides these references, as known, whether the additives used to reduce the compressive strength according to the normal cement or not is very important. The main aim in this research is to investigate the effects of sunflower oil (SO) acid, oleic acid (OA), stearic acid (SA), myristic acid (MA) and lauric acid (LA) on the specific surface and the compressive strength of the normal cement.
I.4. The Object of Investigation:
The aim of this study is to examine the hydration characteristics of the different cementitious materials using various types of grinding aids in the presence and absence of limestone.
Twelve cementitious systems are used in this study:
1. Ordinary Portland cement (OPC) as a control mix.
2. (OPC) + Propylene glycol (PG) with different wt. % ratios (0.03, 0.04 and 0.05).
3. (OPC) + Commercial GA (CG) with various wt. % ratios (0.03, 0.04 and 0.05).
4. (OPC) +Ethylene glycol (EG) with different weight percent ratios (0.03, 0.04 and 0.05).
5. (OPC) + Triethanol amine (TEA) with different weight percent ratios (0.03, 0.04 and 0.05).
6. (OPC) + Propylene glycol and ethylene glycol (PEG) (1:1) with wt. % ratios of (0.04 and 0.05).
7. Portland limestone cement (PLC) with 5 % limestone as a control mix with the notation (OPC-L5).
8. Portland limestone cement (PLC) with 10% limestone as a control mix with the notation (OPC-L10).
9. OPC-L5 +PG with various wt. % ratios (0.03 and 0.04).
10. OPC-L10+ PG with various wt. % ratios (0.03 and 0.04).
11. OPC-L5+ CG with different wt. % ratios (0.03 and 0.04).
12. OPC-L10+ CG with different wt. % ratios of 0.03 and 0.04.
The aim of this work can be achieved via the following tests:
a. Determination of water of consistency and setting times
b. Determination of the compressive strength at various hydration ages (2, 7, 28 and 90 days).
c. Determination of the chemically combined water content at various hydration ages.
d. Determination of free lime contents at selected ages of hydration of certain systems.
e. Investigation of the change in phase composition by using X-ray diffraction (XRD) analysis for some selected hardened cement mortars.
f. Investigation the thermal analysis using differential thermal analysis (DTA) for some selected hardened cement mortars.
g. Examination of the change in microstructure using a scanning electron microscope (SEM).