Effects of Cement Additions on Self-compacting Concrete Durability Indicators

This study highlights the effect of initial curing time on sustainability indicators such as sorptivity (S), water absorption (WA) and total porosity (P) of self- compacting concretes (SCC) containing the blended cement such as limestone cement (CEMIIA-L42.5) and pozzolanic cement (CEMII-A-P42.5). The durability test (acid and sulfate attack) of SCCs is also studied in this researcher. For this purpose, three water/binder (W/B) ratios were used, Six SCC mixtures were prepared and tested in the fresh state (slump follow, flow time, J-Ring, L-Box, V-Funnel and sieve segregation), the main properties in the hardened state compressive strength (Sc), S, WA and P of the SCC mixtures were studied and evaluated each in its different curing. Furthermore, the results of the Sc and transfer properties are globally significantly affected by the hot climate during the design and maturation phase. On the other hand, the values of S to SCC for pozzolanic cement are lower compared to limestone cement and this regardless of W/B ratio and the cure mode. The difference between the mixtures SCC-L32, SCC-L38 and SCC-L44 at the 28 day is between 2.45%, 87.57% depending on the cure mode and the W/B ratio. In addition, WA was observed to range from 5.8 to 7.1%. On the other hand, a good correlation was found between sustainability indicators and Sc. Durability has also been improved for pozzolanic cement compared to that of limestone cement as compressive strength against sulfate and acid attack have been improved

Effect of elevated temperature on the hydration heat and mechanical properties of blended cements mortars

This paper presents an experimental investigation for testing the effect of elevated temperature on the hydration heat and mechanical properties of blended cement mortars. Two tests on mortars were made. The first set of mortars is tested of mechanical properties at various temperatures of 20, 35 and 50°C and the second test consists to determine the hydration heat by a semi-adiabatic calorimeter at isothermal temperature of 20, 35 and 50°C during seven days. The new empirical equation has been proposed to estimate the compressive strength depending on the hydration heat for blended cement preserved in constant temperature at early. The results founded from this relationship illustrate a good accuracy with the experimental ones and reflect the best choice to be used to predict the compressive strength depending on the heat of hydration at early age (7 days)

Effect of elevated temperature on the hydration heat and mechanical properties of blended cements mortars

This paper presents an experimental investigation for testing the effect of elevated temperature on the hydration heat and mechanical properties of blended cement mortars. Two tests on mortars were made. The first set of mortars is tested of mechanical properties at various temperatures of 20, 35 and 50°C and the second test consists to determine the hydration heat by a semi-adiabatic calorimeter at isothermal temperature of 20, 35 and 50°C during seven days. The new empirical equation has been proposed to estimate the compressive strength depending on the hydration heat for blended cement preserved in constant temperature at early. The results founded from this relationship illustrate a good accuracy with the experimental ones and reflect the best choice to be used to predict the compressive strength depending on the heat of hydration at early age (7 days)

Beneficial Effect of Incorporation of Slag on the Hydration Heat, Mechanical Properties and Durability of Cement Containing Limestone Powder

This paper presents the experimental results of a wide research program, tending to determine the hydration mechanism, mechanical properties and the durability performance of ternary cement containing limestone powder and slag. The limestone powder increase the hydration at early ages inducing a high strength at, but it can reduce the later strength due to the dilution effect. On the other hands, Slag (S) contributes to increase the compressive strength at later ages. Hence, at medium blended cement (OPC-LP-S) with better performance could be produced. Results show at later age the Slag is very effective in producing ternary blended cements with similar on higher compressive strength than the ordinary Portland cement at 28 and 90 days. For durability, the incorporation of the slag into the cement containing limestone powder improves remarkably resistance to attack by acids and sulfates and it has been found that the durability of the cements never depends on the mechanical strength

Beneficial Effect of Incorporation of Slag on the Hydration Heat, Mechanical Properties and Durability of Cement Containing Limestone Powder

This paper presents the experimental results of a wide research program, tending to determine the hydration mechanism, mechanical properties and the durability performance of ternary cement containing limestone powder and slag. The limestone powder increase the hydration at early ages inducing a high strength at, but it can reduce the later strength due to the dilution effect. On the other hands, Slag (S) contributes to increase the compressive strength at later ages. Hence, at medium blended cement (OPC-LP-S) with better performance could be produced. Results show at later age the Slag is very effective in producing ternary blended cements with similar on higher compressive strength than the ordinary Portland cement at 28 and 90 days. For durability, the incorporation of the slag into the cement containing limestone powder improves remarkably resistance to attack by acids and sulfates and it has been found that the durability of the cements never depends on the mechanical strength

Effect of acids and sulphates on the durability of self-compacting concretes

International audienceThe deterioration of self-compacting concretes (SCC) in acid and sulphate media is a major problem in the evaluation of structural durability. The aim of our work is to study this effect and to do this, a test protocol was used to evaluate the effect of sulphate and acidic media on the mechanical properties and microstructure of SCCs. Two types of cement were used CEMIII-A-42.5 cement (60% slag) and cement CEMI-52.5 and three water / binder ratios (E / L = 0.32-0.38-0.44). The SCC specimens were stored in all three media, water (control), 5% H2SO4 and 5% Na2SO4. The measured properties were: The compressive strength of cubic test pieces at 30, 90 and 180 days and X-ray diffraction (XRD) analysis. These results show that high furnace slag improves the durability of SCCs