Portland-Limestone Cements

The performance of propylene glycol (PG) on the grindability, setting and hardening of Portland and Portland-Limestone cements (PLC) was studied. Propylene glycol was added to OPC clinker with percentage ratios; 0, 0.03, 0.04 and 0.05 wt.% of the OPC clinker. PLC was made by replacing 5 and 10 wt. % of OPC with limestone. PG offers better grinding aid performance with higher Blaine areas. Besides, presence of PG shows higher water of consistency and lower initial and final setting times. The mechanical properties of mortar specimens made from OPC and PLC admixed with PG were improved especially in the first 7 days. This explained due to increase in the cement fineness which leads to an increase in the degree of cement hydration, as well as

Alkanolamines such as diethanolaime (DEA) , triethanol amines (TEA) [3,4] and triisopropanol amine (TIPA). Glycols compounds[5] such as ethylene glycol (EG) and diethylene glycol (DEG). Phenol and phenolic compounds are also used as grinding aids [6]. Generally, the concentration range of grinding aids added is from 50 to 500 ppm [7]. Recently, the effect of grinding aids has been studied extensively. employing different parameters in the characterization of the performance of these products[8-10]. Effective GAs are those which have significant effects on physicochemical and mechanical properties of cement. Researchers and companies led to design an effective grinding aid based on an optimum combination of raw materials, some of which are obtained from byproducts of other industrial processes, providing an excellent cost benefit

The effect of addition of (PG) on the grindability. Setting times and the mechanical properties of OPC and OPC-limestone cement was also investigated.

2.Experimental

2.1.Materials

Industrial clinker used for the production of ordinary type I Portland cement (OPC-I, 42.5N). Limestone with CaCO3 content higher than 75% was used in our study. The chemical oxide composition of OPC clinker and lime stone theoretical phase ratios calculated by Bogue formulae are presented in Table 1. Propylene glycol provided from Aldrich-sigma was used as grinding aids. Commercial grinding aids (CG) was used as reference grinding aids used in market.

2.2.preparation of dry mixes

During the grinding of OPC clinker, the grinding aids are added with the ratios 0, 0.03, 0.04 and 0.05 wt.% of the clinker. OPC-limestone blended cement (PLC) are prepared by replacement 5 and 10 wt.% of OPC by limestone. Two percentage of the grinding aids are added to PLC, 0.03 and 0.04 wt.%, during the grinding process. A constant 5% of gypsum by weight of clinker has been added to each cement mixture. To compare the grindability of the different dry mixes, all the dry mixes were grinded for 45 minutes and the Blain surface area was