Suitability of Laterite Fines as a Partial Replacement for Sand in the Production of Sandcrete Bricks
The provision of affordable housing units from indigenous building materials has been the focus of most researchers in recent times. This paper focuses on the utilisation of laterite fines as replacement for sand in the production of sandcrete bricks as masonry units. With a mix ratio and a water/cement ratio of 1:6 and 0.50 respectively, batches with 0% (control specimens), 10%, 20%, 30%, 40% and 50% laterite fines replacing the sand were adopted in this study. In all, 96 bricks were cast, tested and compared with those of conventional sandcrete bricks (control specimens). Tests studied were density, compressive strengths (wet and dry) and water absorption. Data results revealed that the laterite fines used could satisfactorily replace the sand up to 30% for the production of structural masonry units even though bricks need to be protected when used in waterlogged areas or below ground level.
Experimental Investigation on Strength Parameters of Laterised Concrete after Adding Silica Fume
Cement, sand and aggregates are the basic needs for any construction industry. Sand is a prime material used for preparation of mortar and concrete and which plays a major role in mix design. Now a day’s erosion of rivers and considering environmental issues, there is a scarcity of river sand. The non-availability or shortage of river sand will affect the construction industry. Hence there is a need to find the new alternative material to replace the river sand. M-Sand is one of the major alterntive to river sand. But it’s over exploitation causes serious environmental issues. Many researchers are finding different materials to replace fine aggregate and one of the major materials is locally available soil. Laterite soil is one of the easily available local soils and using different proportion of this available soil along with M-sand the required concrete mix can be obtained. This paper presents a review on the study of effect of silica fume on laterised concrete (concrete in which the fine aggregate is replaced with laterite soil). Initially the optimum percentage of silica fume is determining, with this optimum percentage of silica fume, replacement of fine aggregate with locally available laterite soil with different percentages (10%, 20%, 30% & 40%) is done. Tests on workability, compressive strength, flexural resistance, split tensile strength and modulus of elasticity were conducted on specimens. The result is then compared with that of laterised concrete and control concrete. Silica fume improves the bonding as well as compressive strength of concrete. Properties of laterite soil is as good as the regular river sand and M-Sand.
Brushite-collagen composites for bone regeneration.
Brushite-based biomaterials are of special interest in bone regeneration due to their biocompatibility and biodegradability; on the other hand, collagen is a well-known osteoconductive biomaterial. In the present study a new brushite-collagen composite biomaterial is reported. This new biomaterial was prepared by combining citric acid/collagen type I solutions with a brushite cement powder. The obtained biomaterial was a cement paste, with improved handling properties. The effect of collagen on the setting reaction of brushite cement was studied, and was found to speed up the cement setting reaction. The cement paste set into a hard ceramic material within 18.5+/-2.1min and had compressive strength similar to that of spongeous bone (48.9+/-5.9MPa in dry conditions and 12.7+/-1.5MPa in humid conditions). The combination of collagen with citric acid revealed an interesting synergistic effect on the compressive strength of the composite material. Moreover, this new biomaterial had excellent cohesion properties (ninefold better than brushite cement), and high cellular adhesion capacity (threefold higher than brushite cement). The composite biomaterial described in this study combines good handling properties, compressive strength, cohesion and cell adhesion capacity, along with the osteoconductive and biodegradable properties inherent in brushite and in collagen-based biomaterials.