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"internal curing is promoted as a way tpo mitigate autogenous shrinkage in high-performance concrete having a low water binder ratio (w/b). Different methods of internal curing have been proposed. In this study, the effect of substituting 20% of normalweight sand by an equal mass of lightweight sand on the development of shrinkage was investigated on a 0.35 w/b high performance concrete . Shrinkage was monitored using vibrating wire gauges cast at the center of 100x100x400 mm (4x4x16 in.) concrete samples. Two samples were sealed with self-adhesive aluminum foil to present a closed curing system without any exchanged of humidity between the concrete and its environment, After demolding at the age if 23 to 25 hours. two other samples were cured under water for 6 days . Thereafter these two samples were removed from water and maintained at 23 C (73 F ) and a 50% relative humidity (RH) Environment . Experimental results clearly demonstrate the effeciency of a 20% substitution of normalweight by a lightweight sand to reduce autogenous and drying shrinkage . The Incorporation of 20% lightweight sand did not significantly affect the 28-day compressive strength. The cementitious matrix presented low chloride ion permeability. Internal curing through the use of partial replacement of normalweight sang by lightweight sand definitely represent and efficient method to diminish autogenous and drying shrinkage in low w/b concretes where external water curing does not allow in-depth curing of concrete"

"Self-Consolidating Concrete (SCC) mixtures for use in Prestressed Concrete applications are evaluated in this paper . Twenty one SCC mixtures were made under laboratory conditions with varying water to cementitious materials ratios, sand to total aggregate rations, and cementitious materials combinations (type III cement , class C fly ash, ground-granular blast-furnance slag, and silica fume). The SCC mixtures archived prestress transfer compressive strengths between 5470 and 9530 psi (38 and 66 MPa). The moduli of elasticity of the SCC Mixtures were in reasonable agreement with the elastic stiffness assumed during the design of conventional slump concrete structures. The long term drying shrinkage strain for all the SCC mixtures were approximately the same or less than those measured for the control mixtures. A change in sand to total aggregate ratio had no significant effect on the long term drying shrinkage. At later ages of 56 and 112 days, the measured drying shrinkage corresponded reasonable well to those predicated by the ACI 209 procedure."

"Tujuan dari penelitian ini di fokuskan pada properti dari kuat rekat beton pada batang besi ulir yang tertanam dalam beton ringan dengan polimer sebagai agregat kasar pada campuran beton ringan. Campuran pertama menggunakan campuran 100 agregat kasar 25mm, pada desain campuran kedua meggunakan ukuran yaitu 70 25mm dan 30 20mm, kedua campuran tersebut menggunakan 0.4 superplasticizer. Total benda uji masing-masing campuran A dan B sebanyak 32 buah dengan diameter yang berbeda yaitu 10,12, dan 16mm. Hasil akhir dari penelitian ini menunjukan benda uji yang memiliki kuat tekan lebih tinggi akan menghasilkan hasil tes kuat tarik yang lebih tinggi.

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The purpose of this research is focused on studying the bond properties of deformed steel embedded in lightweight concrete with polypropylene as the coarse lightweight aggregate. By following ACI211.2.98 this research is using two types of mix design which one is using fully 100 of 25mm size of aggregate diameter and the second one is 70 25mm and 30 20mm diameter aggregate sizes, with both of the mix design is using superplasticizer additive 0.4 . The testing method of Pull out test followed RILEM 7 testing method, by using self made frame for 24 sample of the specimens, by each of the mixture is 12 specimens with different diameter of steel bar which is 10, 12, and 16 mm. Final result of this research shows that the sample with higher compressive strength is showing higher bond strength value. "

"ABSTRAKPada struktur-struktur beton dengan dimensi besar atau mass concrete, diwajibkan untuk memperhitungkan heat of hydration dari semen dan perubahan volume untuk mencegah terjadinya keretakan. Akan tetapi pada umur awal beton, masalah yang terjadi tidak sebatas permasalahan thermal tetapi adanya efek creep dan shrinkage. Dalam tulisan ini akan dibandingkan data pengukuran langsung hasil regangan dari VWSG yang ditanam berseberangan pada struktur pondasi tiang bor dengan hasil analisis yang memperhitungkan efek shrinkage sesuai ACI 209R-92 dengan metode heat of hydration analysis. Dari hasil perbandingan terlihat adanya simpangan sebesar 4,19% hingga 131,47% yang kemungkinan besar disebabkan oleh adanya ketidak-sempurnaan pada pengecoran

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ABSTRACTIn concrete structure with large dimension or mass concrete must consider heat from hydration of the cement and attendant volume change to minimize cracking. At early concrete, the problem is not limited to thermal problems but creep and shrinkage effects. In this paper, field measurement data which was obtained with strain gage installation at opposite position and will be compared with analysis results that consider the effect of creep and shrinkage according to ACI 209R-92 with heat of hydration analysis. Deviation from this result is vary between 4,19% and 131,47% due to imperfect casting at construction process"

"ABSTRAKTulisan ini menyampaikan tujuan dan kegunaan proses perawatan beton atau "concrete curing" terhadap beton yang masih berusia dini, terutama untuk pengecoran di daerah tropis seperti di Indonesia. Perawatan dalam hal ini berarti usaha untuk menjaga keseimbangan kadar air dan temperatur yang sesuai dan yang dibutuhkan dalam proses pengerasan beton, agar didapat beton dengan kinerja yang optimal. Dengan demikian perawatan beton berusia dini merupakan suatu proses penting dalam pertumbuhan kekuatan dan kinerja beton, untuk mencapai tingkat yang maksimal."