超速硬ポリマーセメントコンクリートの調合設計法の提案

Abstract

In recent years, ultrarapid-hardening polymer-modified cement concretes have been used for the repair works of concrete structures. The purpose of this study is to establish the mix design method for the ultrarapid-hardening polymer-modified cement concretes, and to examine its applicability in the field. The ultrarapid-hardening polymer-modified cement concretes for the laboratory test were prepared with various polymer-cement ratios, unit cement contents, water-cement ratios, sand-aggregate ratios and retardercement ratios, and tested for slump, air content, handling time (which was defined as the elapsed time when the slump decreased to about 2cm) and compressive strength.The conclusions obtained from the test results are summarized as follows:(1) The slump of the ultrarapid-hardening polymer-modified cement concretes with various mix proportions may generally be expressed by the following equation:Sl=Ae-B(Vag+Vc)/Vwwhere Sl is the slump of the ultrarapid-hardening polymer-modified cement concretes, Vag, Vc and Vw are the volumes of aggregate, cement and water per unit volume of the ultrarapid-hardening polymer-modified cement concretes respectively, and A and B are empirical constants.(2) The compressive strength and handling time of ultrarapid-hardening polymer-modified cement concretes with various mix proportions may generally be expressed as a function of “void-cement ratio (α)”, “retarder-cement ratio (β)” and “polymer-cement ratio (γ)” by the following equations:F=J/(Kα·Lβ·Mγ)Ht=S·Tα·Uβ·Vγwhere F and Ht are the handling time and compressive strength of the ultrarapid-hardening polymer-modified cement concretes respectively, α is the void-cement ratio [α=(Vw+Va)/Vc], β is the retarder-cement ratio (β=Vr/Vc), γ is the polymer-cement ratio (γ=Vp/Vc), Va, Vr and Vp are the volumes of air, retarder and polymer per unit volume of the ultrarapid-hardening polymer-modified cement concretes respectively, and J, K, L, M, S, T, U and V are empirical constants.(3) The mix design system for the ultrarapid-hardening polymer-modified cement concretes is proposed by use of the respective equations for slump, handling time and compressive strength predictions.(4) The applicability of the mix design system for the ultrarapid-hardening polymer-modified cement concretes is confirmed in the field.