Potential South African standard sand for cement mortar testing and research

Abstract

Mortars are used extensively in accelerated methods of testing the physical properties of cementitious materials. Mortar strength is invariably used to determine cement strength grade of cements and for general evaluation of material behavior, as typically employed in research and testing. Presently, the South African (SA) cement industry imports standard from Europe for cement testing purposes. This study was conducted to formulate South African standard sand that could be used to conduct mortar strength tests for compliance to specifications and for general research purposes. Two formulations of local South African silica sands, referenced as SA513S and SA413S, were developed to suit standard gradings. The formulated South African standard sands (SASS) where tested in comparison with European standard sand (ENSS) of EN196-1 and American graded standard sand (GSS) of ASTM C- 778. Following the formulation and grading of SASS, mortar mixtures of 1:3:0.5 cement to sand to water were cast in 50 mm cubes and tested for compressive strength for ages up to 90 days. Two types of cements were employed in the tests, the ordinary Portland cement CEM 1 42.5N and pozzolanic cement CEM V 32.5N. Comparison of the 28-day compressive strength results between the four SS types showed an excellent agreement, giving standard deviations of 1.96 and 2.51 for CEM I and CEM V. The flow results for the standard sand types varied, with EN196-1 giving the highest mortar flow followed by GSS sand and SA413S. The GSS and SA513S gave precisely the same flow results