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In this study, the compressive strength, water absorption, and thermal conductivity of palm oil fuel ash (POFA) lightweight geopolymer concrete (LWGC) incorporating high-calcium fly ash (FA) and Portland cement (PC) are reported. The POFA was replaced by FA or PC at the dosages of 60% by weight of binder. The wet density of POFA-based LWGC incorporating FA and PC was designed at 1000 kg/m3, based on ASTM C796. Test results found that the incorporation of FA and PC in POFA-based LWGC could significantly improve the strength development of LWGC. The reactive Ca ions could react with SiO2 from POFA, leading to the additional formation of reaction products within the LWGC. The thermal conductivity of LWGC showed an excellent option for reducing the temperature change in the wall section during a day. It was positive effects on the building's electricity cost. A combination of POFA-based LWGC with PC met the 28-day strength and water absorption requirements as per TIS.2601-2556. Therefore, POFA-based LWGC incorporated with PC can be used as the non-load-bearing brick masonry units.

Rubber trees (Hevea brasiliensis) are the main source of natural rubber, extracted from latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the latex after its collection. Knowing the contribution of C sources involved in latex biosynthesis will help in understanding how rubber trees face this additional C demand. Whole crown 13CO2 pulse labelling was performed on 4-year-old rubber trees in June, when latex production was low, and in October, when it was high. 13C content was quantified in the foliage, phloem sap, wood, and latex. In both labelling periods, 13C was recovered in latex just after labelling, indicating that part of the carbohydrate was directly allocated to latex. However, significant amounts of 13C were still recovered in latex after 100 d and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of latex C. The contribution of new photosynthates to latex regeneration was faster and higher when latex metabolism was well established, in October, than in June. An improved understanding of C dynamics and the source-sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable latex production., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)