Experimental Comparative and Numerical Predictive Stu-dies on Strength Evaluation of Cement Types: Effect of Specimen Shape and Type of Sand

Abstract

Quality of cement is evaluated via group of tests. The most important, and close to understanding, is the compressive strength test. Recently, Egyptian standards adopted the European standards EN-196 and EN-197 for specifying and evaluating quality of cements. This was motivated by the large European investments in the local production of cement. The current study represents a comparative investigation, experimental and numerical, of the effect of different parameters on evaluation of compressive strength. Main parameters are shape of specimens and type of sand used for producing tested mortars. Three sets of specimens were made for ten types of cements. First set were 70.6 mm cubes molded according to old standards using single sized sand. Second group were prisms molded from standard sand (CEN sand) according to the recent standards. Third group were prisms molded from local sand sieved and regenerated to simulate same grading of CEN sand. All specimens were cured according to relevant standards and tested at different ages (2,3,7,10 and 28 days). Results show that CEM-I Type of cement does not fulfill, in all of its grades, the strength requirements of Ordinary Portland cement OPC specified in old standards. Also, the use of simulated CEN sand from local source gives strengths lower than those obtained using standard certified CEN sand. A limited number of tests were made on concrete specimens from two most common CEM-I types to investigate effect on concrete strength and results were also reported. Numerical investigation of the effect of specimen shape and type of sand on evaluation of compressive strength of mortar specimens, presented in the current study, applies one of the artificial intelligence techniques to simulate and predict the strength behavior at different ages. The Artificial Neural Network (ANN) technique is introduced in the current study to simulate the strength behavior using the available experimental data and predict the strength value at any age in the range of the experiments or in the future. The results of the numerical study showed that the ANN method with less effort was very efficiently capable of simulating the effect of specimen shape and type of sand on the strength behavior of tested mortar with different cement types.

An experimental study on strength and durability characteristics of self‐curing self‐compacting concrete

“…SCC is generally configured to use a lower water to cement ratio and less coarse aggregate, and to use new generation plasticizers that assist in the production of very deformable concrete. The excellent performance of SCC over ordinary concrete is mostly related to their ingredients; compared with ordinary mortar mixtures, the segregation resistance of self‐compacting mortar is more critical to small differences in properties such as gradation and moisture content of aggregates, type, and potion of super plasticize 73,74 …”

“…The excellent performance of SCC over ordinary concrete is mostly related to their ingredients; compared with ordinary mortar mixtures, the segregation resistance of selfcompacting mortar is more critical to small differences in properties such as gradation and moisture content of aggregates, type, and potion of super plasticize. 73,74…”

“…The reduction in free water can reduce the concentration of viscosity‐enhancing admixture (VEA) necessary to ensure proper stability during casting and thereafter until the onset of hardening. It has been demonstrated that a total fine aggregate content (“fines”, usually sand) of about 50% of total aggregate is appropriate in an SCC mix 71–74 . SCC must be designed for sufficient workability to show the property of self‐compaction.…”

“…It has been demonstrated that a total fine aggregate content ("fines", usually sand) of about 50% of total aggregate is appropriate in an SCC mix. [71][72][73][74] SCC must be designed for sufficient workability to show the property of self-compaction. This workability must not bring segregation and bleeding issues.…”

Evaluation of the Effects of Nigerian Portland-Limestone Cement Grades on the Strength of Concrete

“…Findings from the studies carried out by Hodhod and Abdeen [19], Mathur, Misra and Goel [20], have shown that in Ordinary Portland Cement, the stronger the cement grade, the stronger the concrete compressive strength, provided the mix ratio remains constant. However, due to the substitution of Portland-Limestone Cement for Ordinary Portland Cement in the Nigerian open market, Kazeem, Festus and Hamzat [21] studied PLC grades of 32.5N and 42.5 N commonly used for concrete production in Nigeria.…”