Journal of Cement Based Composites (CEBACOM)

Saad Issa Sarsam

Roller compacted concrete is considered as a sustainable solution. In the present investigation, three types of additives namely (fly ash, fumed silica, and hydrated lime) are implemented as partial replacement of Portland cement for preparation of roller compacted concrete slab samples using dense and gap aggregate gradation. The slab samples were prepared at optimum cement requirement of 12 % and at (2 and 4) % cement below and above the optimum. Beam specimens of (38 x 10 x 8) Cm were extracted from the slab samples using diamond saw. The specimens were subjected to flexural strength determination using two testing modes, the three and the four points loading. It was noticed that the flexural strength under four-points loading mode is lower by a range of (0.787 to 0.732) folds than that under three-points loading mode for dense and gap graded mixtures respectively. It was concluded that the flexural strength increases by (96.2, 84, and 17.2) % and (109, 86, and 9.3) % after replacement of (10, 12, and 15) % of cement by hydrated lime while it declines by (50, 64.6, and 77) % and (0.1, 30.8, and 63.5) % after replacement of (5, 7, and 10) % of cement by fumed silica for dense and gap graded aggregates respectively. The flexural strength of dense graded mixtures increases by 63 % at 20 % replacement by fly ash, however, it increases by (99.7, 53.8, and 1.0) % after replacement of (10, 12, and 15) % of cement by fly ash for gap graded aggregates respectively.

https://doi.org/10.36937/cebacom.2021.001.001

chadli mounira Bensmail messaouda mekki mellas

Reactive Powder Concrete (RPC) currently represents the family of cementitious matrix materials with properties the most exceptional mechanics and durability. This study aims to investigate the physico-mechanical properties, and the durability in a sulphated environment of a reactive powder concrete using materials available in our region, we have integrated materials rich in silica (slag, silica fume and crushed quartz) in Portland cement with 15, 23 and 25%, respectively. After The remove of the specimens from the mold and place the RPC in the curing box under steam curing conditions of 90 ° C for 72h, let them cool naturally for 24 h, the test pieces are immersed in water at 20 ° C, the specimens are broken in flexion and compression. From this study we can make the following conclusions: The incorporation of additions increases the compressive and flexural tensile strengths, which gives an improvement in the compactness of the mixtures by the pozzolanic effect of these last, by removing the particle size phase in the RPC and the affluence of dune sand (southern Algeria) and slag (industrial waste from the iron ore blast furnace), because Na2SO4 has a major effect on the compressive strength notably for non-fibrous formulations. NaOH improve the compressive strength for all formulation.

https://doi.org/10.36937/cebacom.2021.001.002

Tirimisiyu Buari OLUTOGE FESTUS Ayininuola Gbenga POPOOLA CHRISTIANA Chinonu Egwanwor

The ever increasing environmental challenge arising from improper waste management has been a great concern to researchers and the society. One of such industrial waste is micro silica; a bye-product of the Carbothermic reduction of high purity quartz at temperature of about 2000oC in the presence of coke. The finess of this material and its pozollanic nature makes it suitable for use in the production of self-compacting concrete. In this research micro silica was introduced in percentages of, 5, 10 and 15% as partial replacement of cement in the production of self-compacting concrete. The fresh properties were examined using slump flow, T50cm, slump flow, V-funnel and blockage ratio using L-Box. As the Micro silica were introduced, T50cm time increased, Slump flow reduced, V-funnel flow time increased and L-Box value reduced, due to increase in viscosity. Comparing the experimental results with European Federation of National Associations of Representing for Concrete EFNARC 2002, blockage ratio for 15% was below 0.8. The compressive stresses at 28days were higher than the control at 28days compressive stress with 8.6%, 19.04% and 11.9% for 5%, 10% and 15% respectively. Thus, cement can be partially substituted with micro silica up to 15% with improvement in compressive strength in self-compacting concrete.

https://doi.org/10.36937/cebacom.2021.001.003

Zainab Kammouna

This article reviews the studies on the effect of temperature on the creep of concrete. Indeed, the temperature is one of the most important factors, as its rise leads to an acceleration of creep of concrete and thus an increase in its value compared to concrete under normal temperature. However, creep increases significantly if concrete under load is exposed to a high temperature. Thus, the creep value becomes higher than that of concrete exposed to a constant temperature (of the same level). Unfortunately, some of the codes for predicting creep of concrete (for instant the Eurocode)do not take into account the effect of high temperature on the creep of concrete under load. To clarify the impact of heating concrete under load (on creep) and distinguish it from its effect where it is constant, this study was carried out.

https://doi.org/10.36937/cebacom.2021.001.004

EL Moustapha Bouha Stéphanie BONNET Abdelhafid KHELIDJ Daniel FROELICH Nicolas MARANZANA Isselmou AHMEDOU BABAH CAROLE CHARBUILLET Abderahmane KHALIFA

Incorporating microcapsule phase change materials (MPCM) into geopolymer is one of the most successful solutions for enhancing building thermal comfort and replacing Portland cement-based materials. Although MPCM improves the thermal capacity of the cementitious matrix, whether it's made of cement or geopolymer, it presents a number of disadvantages in terms of mechanical and physical performance. Several researchers have pointed out that this scientific subject remains unresolved. The purpose of this study is to investigate the influence of 10% and 20% metakaolin (MK) inclusions on the mechanical properties and durability of geopolymer-MPCM mortars based on granulated blast furnace slag (GBFS) and to compare them with Portland cement-MPCM based mortars. The results show that the addition of two proportions of metakaolin is able to compensate well for the loss of mechanical strength associated with the addition of MPCM. Thus, up to 20% MPCM, the addition of metakaolin increases compressive strength by approximately 10 MPA. Compared to Portland-MPCM cement mortars, all geopolymer-MPCM mortars show higher compressive strength, better workability and lower porosity. Finally, in terms of durability evaluation, the resistivity measurements reveal that the risk of corrosion of the cement-based mortar on the steel bars is negligible, while the risk of corrosion of the geopolymer-based mortar on the steel bars is low.

https://doi.org/10.36937/cebacom.2021.001.005