خواص الوحدات الخرسانیة الجاهزة الصب المنتجة باستخدام رکام ناعم ذو محتوى الاملاح اعلى من 0.5 %

Abstract

At the last period, the problems of the pre-cast concrete units have been increased rapidly due to its unconformity to the adopted specifications with regards to sulphate content. The high content of sulphate in Iraqi fine aggregate in many aggregate quarries, which are out of the Iraqi standard specification limits, causes many difficulties for most pre-cast concrete units Factories to provide an acceptable fine aggregate with regards to sulphate content. This study has been conducted to assess the possibility of using fine aggregate with sulphate content higher than the upper limit of the Iraqi standard (0.5%) to produce pre-cast concrete units: hollow concrete block and paving concrete brick, where the total amount of sulphate has been controlled by decreasing the fine aggregate content in the adopted mixes. The tests are conducted on reference mix with an acceptable fine aggregate according to the Iraqi standard (with regards to sulphate content) and three mixes with fine aggregates contain (1.19, 1.90 and 2.47%) of sulphate respectively. The hollow concrete block and paving concrete brick are produced from all these mixes. The results indicate the possibility of using unacceptable fine aggregate (those with sulphate content higher than 0.5%) to produce an acceptable hollow concrete block and paving concrete brick according to Iraqi specifications. This could be done by reducing the fine aggregate content in the mixtures within a specific limit.